Diet or exercise, or both, for preventing excessive weight gain in pregnancy

  • Review
  • Intervention

Authors


Abstract

Background

This is an update of a Cochrane review first published in 2012, Issue 4. Excessive weight gain during pregnancy is associated with poor maternal and neonatal outcomes including gestational diabetes, hypertension, caesarean section, macrosomia, and stillbirth. Diet or exercise interventions, or both, may reduce excessive gestational weight gain (GWG) and associated poor outcomes; however, evidence from the original review was inconclusive.

Objectives

To evaluate the effectiveness of diet or exercise, or both, interventions for preventing excessive weight gain during pregnancy and associated pregnancy complications.

Search methods

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (5 November 2014), contacted investigators of the previously identified ongoing studies and scanned reference lists of retrieved studies.

Selection criteria

Randomised controlled trials (RCTs) of diet or exercise, or both, interventions for preventing excessive weight gain in pregnancy.

Data collection and analysis

Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy. We organised RCTs according to the type of interventions and pooled data using the random-effects model in the Review Manager software. We also performed subgroup analyses according to the initial risk of adverse effects related to poor weight control. We performed sensitivity analysis to assess the robustness of the findings.

Main results

We included 65 RCTs, out of which 49 RCTs involving 11,444 women contributed data to quantitative meta-analysis. Twenty studies were at moderate-to-high risk of bias. Study interventions involved mainly diet only, exercise only, and combined diet and exercise interventions, usually compared with standard care. Study methods varied widely; therefore, we estimated the average effect across studies and performed sensitivity analysis, where appropriate, by excluding outliers and studies at high risk of bias.

Diet or exercise, or both, interventions reduced the risk of excessive GWG on average by 20% overall (average risk ratio (RR) 0.80, 95% confidence interval (CI) 0.73 to 0.87; participants = 7096; studies = 24; I² = 52%). This estimate was robust to sensitivity analysis, which reduced heterogeneity, therefore we graded this evidence as high-quality. Interventions involving low glycaemic load diets, supervised or unsupervised exercise only, or diet and exercise combined all led to similar reductions in the number of women gaining excessive weight in pregnancy.

Women receiving diet or exercise, or both interventions were more likely to experience low GWG than those in control groups (average RR 1.14, 95% CI 1.02 to 1.27; participants = 4422; studies = 11; I² = 3%; moderate-quality evidence). We found no difference between intervention and control groups with regard to pre-eclampsia (RR 0.95, 95% CI 0.77 to 1.16; participants = 5330; studies = 15; I² = 0%; high-quality evidence); however, maternal hypertension (not a pre-specified outcome) was reduced in the intervention group compared with the control group overall (average RR 0.70, 95% CI 0.51 to 0.96; participants = 5162; studies = 11; I² = 43%; low-quality evidence).

There was no clear difference between groups with regard to caesarean delivery overall (RR 0.95, 95% CI 0.88 to 1.03; participants = 7534; studies = 28; I² = 9%; high-quality evidence); although the effect estimate suggested a small difference (5%) in favour of the interventions. In addition, for combined diet and exercise counselling interventions there was a 13% (-1% to 25%) reduction in this outcome (borderline statistical significance).

We found no difference between groups with regard to preterm birth overall (average RR 0.91, 95% CI 0.68 to 1.22; participants = 5923; studies = 16; I² = 16%; moderate-quality evidence); however limited evidence suggested that these effect estimates may differ according to the types of interventions, with a trend towards an increased risk for exercise-only interventions.

We found no clear difference between intervention and control groups with regard to infant macrosomia (average RR 0.93, 95% CI 0.86 to 1.02; participants = 8598; studies = 27; I² = 0%; high-quality evidence), although the effect estimate suggested a small difference (7% reduction) in favour of the intervention group. The largest effect size occurred in the supervised exercise-only intervention group (RR 0.81, 95% CI 0.64 to 1.02; participants = 2445; studies = 7; I² = 0%), which approached statistical significance (P = 0.07). Furthermore, in subgroup analysis by risk, high-risk women (overweight or obese women, or women with or at risk of gestational diabetes) receiving combined diet and exercise counselling interventions experienced a 15% reduced risk of infant macrosomia (average RR 0.85, 95% CI 0.73 to 1.00; participants = 3252; studies = nine; I² = 0; P = 0.05; moderate-quality evidence)

There were no differences in the risk of poor neonatal outcomes including shoulder dystocia, neonatal hypoglycaemia, hyperbilirubinaemia, or birth trauma (all moderate-quality evidence) between intervention and control groups; however, infants of high-risk women had a reduced risk of respiratory distress syndrome if their mothers were in the intervention group (RR 0.47, 95% CI 0.26 to 0.85; participants = 2256; studies = two; I² = 0%; moderate-quality evidence).

Authors' conclusions

High-quality evidence indicates that diet or exercise, or both, during pregnancy can reduce the risk of excessive GWG. Other benefits may include a lower risk of caesarean delivery, macrosomia, and neonatal respiratory morbidity, particularly for high-risk women receiving combined diet and exercise interventions. Maternal hypertension may also be reduced. Exercise appears to be an important part of controlling weight gain in pregnancy and more research is needed to establish safe guidelines. Most included studies were carried out in developed countries and it is not clear whether these results are widely applicable to lower income settings.

Résumé scientifique

Le régime alimentaire, l'exercice physique, ou les deux, dans la prévention d'une prise de poids excessive pendant la grossesse

Contexte

Ceci est une mise à jour d'une revue Cochrane publiée pour la première fois en 2012 (Numéro 4). Une prise de poids excessive pendant la grossesse est associée à de mauvais résultats maternels et néonatals, y compris le diabète gestationnel, l'hypertension, l'accouchement par césarienne, la macrosomie et la mortinatalité. Les interventions portant sur le régime alimentaire ou l'exercice physique, ou les deux, pourraient réduire la prise de poids gestationnelle excessive ainsi que les mauvais résultats qui y sont associés ; cependant, les preuves issues de la revue originale n'étaient pas concluantes.

Objectifs

Évaluer l'efficacité des interventions portant sur le régime alimentaire ou l'exercice physique, ou les deux, dans la prévention d'une prise de poids gestationnelle excessive et des complications de la grossesse associées.

Stratégie de recherche documentaire

Nous avons effectué des recherches dans le registre d'essais cliniques du groupe Cochrane sur la grossesse et l'accouchement (5 novembre 2014), contacté les investigateurs des études en cours précédemment identifiées et passé au crible les références bibliographiques des études trouvées.

Critères de sélection

Essais contrôlés randomisés (ECR) d'interventions portant sur le régime alimentaire ou l'exercice physique, ou les deux, visant à prévenir une prise de poids excessive pendant la grossesse.

Recueil et analyse des données

Deux auteurs de la revue ont indépendamment évalué les essais à inclure et le risque de biais, extrait les données et vérifié leur exactitude. Nous avons organisé les ECR selon le type d'intervention et avons regroupé les données en utilisant le modèle à effets aléatoires dans le logiciel Review Manager. Nous avons également effectué des analyses de sous-groupes en fonction du risque initial d'effets indésirables liés à un mauvais contrôle du poids. Nous avons effectué une analyse de sensibilité pour évaluer la fiabilité des résultats.

Résultats principaux

Nous avons inclus 65 ECR, dont 49 ECR portant sur 11 444 femmes ont fourni des données pour réaliser une méta-analyse quantitative. Vingt études étaient à risque de biais modéré à élevé. Les interventions étudiées portaient principalement sur des interventions de régime seul, d'exercice seul, ou combinant un régime alimentaire à l'exercice physique, qui étaient généralement comparées aux soins standard. Les méthodes d'étude variaient grandement ; par conséquent, nous avons estimé l'effet moyen dans les études et avons procédé à une analyse de sensibilité, le cas échéant, en excluant les valeurs aberrantes et les études présentant un risque élevé de biais.

Les interventions portant sur le régime ou l'exercice, ou les deux, ont réduit globalement le risque d'une prise de poids gestationnelle excessive en moyenne de 20 % (risque relatif (RR) moyen de 0,80 ; intervalle de confiance (IC) à 95 % de 0,73 à 0,87 ; 7 096 participantes ; 24 études ; I² = 52 %). Cette estimation a été robuste dans l'analyse de sensibilité, qui a réduit l'hétérogénéité, et nous avons donc jugé les données comme étant de qualité élevé. Les interventions impliquant un régime à faible charge glycémique, l'exercice supervisé ou non seul, ou une combinaison du régime et de l'exercice, ont toutes entraîné des réductions similaires dans le nombre de femmes en prise de poids excessive pendant la grossesse.

Les femmes bénéficiant d'interventions sur le régime ou l'exercice, ou les deux, étaient plus susceptibles de présenter une faible prise de poids gestationnelle que celles dans les groupes témoins (RR moyen 1,14 ; IC à 95 % de 1,02 à 1,27 ; 4 422 participantes ; 11 études ; I² = 3 % ; preuves de qualité modérée). Nous n'avons constaté aucune différence entre les groupes d'intervention et témoin en ce qui concerne la pré-éclampsie (RR 0,95 ; IC à 95 % de 0,77 à 1,16 ; 5 330 participantes ; 15 études ; I² = 0 % ; preuves de qualité élevée) ; cependant, l'hypertension maternelle (qui ne faisait pas partie des critères de jugement prédéfinis) a été globalement réduite dans le groupe d'intervention par rapport au groupe témoin (RR moyen 0,70 ; IC à 95 % de 0,51 à 0,96 ; 5 162 participantes ; 11 études ; I² = 43 % ; preuves de faible qualité).

Aucune différence claire n'a été observée entre les groupes en ce qui concerne globalement les accouchements par césarienne (RR 0,95 ; IC à 95 % de 0,88 à 1,03 ; 7 534 participantes ; 28 études ; I² = 9 % ; preuves de qualité élevée) ; bien que l'estimation de l'effet ait suggéré une petite différence (5 %) en faveur des interventions. En outre, les interventions de conseil combinant un régime alimentaire à l'exercice physique ont montré une réduction de 13 % (de -1 % à 25 %) sur ce critère de jugement (signification statistique limite).

Nous n'avons trouvé aucune différence entre les groupes en ce qui concerne globalement les naissances prématurées (RR moyen 0,91 ; IC à 95 % de 0,68 à 1,22 ; 5 923 participantes ; 16 études ; I² = 16 % ; preuves de qualité modérée) ; cependant des preuves limitées suggéraient que ces estimations d'effet pourraient varier en fonction du type d'interventions, avec une tendance à un risque accru pour les interventions d'exercice seul.

Nous n'avons constaté aucune différence claire entre les groupes d'intervention et témoin en termes de macrosomie du nourrisson (RR moyen 0,93 ; IC à 95 % de 0,86 à 1,02 ; 8 598 participantes ; 27 études ; I² = 0 % ; preuves de qualité élevée), bien que l'estimation de l'effet ait suggéré une petite différence (7 % de réduction) en faveur du groupe d'intervention. La plus grande taille d'effet a été retrouvée dans le groupe d'intervention d'exercice supervisé seul (RR 0,81 ; IC à 95 % de 0,64 à 1,02 ; 2 445 participantes ; 7 études ; I² = 0 %), qui était proche de la signification statistique (P = 0,07). En outre, dans l'analyse en sous-groupes en fonction du risque, les femmes à haut risque (en surpoids ou obèses, ou à risque/atteintes de diabète gestationnel) ayant reçu une intervention de conseil combinant un régime à l'exercice présentaient un risque réduit par 15 % de macrosomie du nourrisson (RR moyen 0,85 ; IC à 95 % de 0,73 à 1,00 ; 3 252 participantes ; neuf études ; I² = 0 ; P = 0,05 ; preuves de qualité modérée)

Il n'y avait aucune différence dans le risque de mauvais résultats néonatals, y compris la dystocie de l'épaule, l'hypoglycémie néonatale, l'hyperbilirubinémie ou le traumatisme à la naissance (toutes les preuves de qualité modérée) entre les groupes d'intervention et témoin ; cependant, les nourrissons nés de femmes à haut risque présentaient un risque réduit de syndrome de détresse respiratoire si les mères étaient dans le groupe d'intervention (RR 0,47 ; IC à 95 % de 0,26 à 0,85 ; 2 256 participantes ; deux études ; I² = 0 % ; preuves de qualité modérée).

Conclusions des auteurs

Des preuves de qualité élevée indiquent que le régime ou l'exercice, ou les deux, peuvent réduire le risque d'une prise de poids excessive pendant la grossesse. D'autres bénéfices pourraient inclure un plus faible risque d'accouchement par césarienne, de macrosomie et de morbidité respiratoire néonatale, en particulier chez les femmes à haut risque recevant une intervention combinant un régime alimentaire à l'exercice physique. L'hypertension maternelle pourrait également être réduite. L'exercice semble être un élément important dans la gestion de la prise de poids pendant la grossesse et des recherches supplémentaires sont nécessaires pour établir des recommandations sûres. La plupart des études incluses ont été menées dans des pays développés et il n'est pas clair si ces résultats sont applicables largement dans des contextes à faible revenu.

Notes de traduction

Traduction réalisée par le Centre Cochrane Français

Resumo

Dieta ou exercício, ou ambos, para prevenir o ganho excessivo de peso na gestação

Introdução

Esta é uma atualização de uma revisão Cochrane publicada inicialmente em 2012, na Edição 4. O ganho excessivo de peso durante a gestação está associado a desfechos maternos e neonatais adversos, incluindo diabete gestacional, hipertensão, parto cesariano, macrossomia fetal e natimortalidade. As intervenções dietéticas ou exercícios físicos, ou ambos, poderiam reduzir o ganho excessivo de peso durante a gestação e seus desfechos adversos; entretanto, as evidências eram inconclusivas na revisão sistemática original.

Objetivos

Avaliar a efetividade da dieta ou exercício, ou ambos, na prevenção do ganho excessivo de peso durante a gestação e as complicações associadas.

Métodos de busca

Fizemos a busca na base Cochrane Pregnancy and Childbirth Group's Trials Register (em 5 de novembro de 2014), contatamos os pesquisadores dos estudos que haviam sido identificados previamente como em andamento e também buscamos nas listas de referências dos estudos que encontramos.

Critério de seleção

Selecionamos ensaios clínicos randomizados com intervenções dietéticas ou exercícios ou ambas as intervenções para prevenir o ganho excessivo de peso na gestação.

Coleta dos dados e análises

Dois revisores selecionaram, de forma independente, os estudos para inclusão, fizeram a avaliação de riscos de viés dos estudos e extraíram os dados. Organizamos os ensaios clínicos randomizados de acordo com os tipos de intervenção e combinamos os dados usando o modelo de efeito randômico usando o software Review Manager. Realizamos, ainda, análise de subgrupos de acordo com o risco inicial dos efeitos adversos relacionados como controle inadequado de peso. Realizamos análise de sensibilidade para avaliar o quão robustos eram os achados.

Principais resultados

Incluímos 65 ensaios clínicos randomizados, dos quais 49 estudos, envolvendo 11.444 mulheres, forneceram dados para uma metanálise quantitativa. Vinte estudos tinham risco de viés moderado a alto. As intervenções do estudo envolveram principalmente ou só dieta, ou somente exercício, ou dieta combinada ao exercício físico comparados com o cuidado padrão. Os métodos dos estudos variaram amplamente, portanto, nós estimamos o efeito médio entre os estudos e realizamos uma análise de sensibilidade, na qualoptamos pela exclusão de valores extremos e de estudos com alto risco de viés.

No geral, a dieta e/ou exercício reduziram em média em 20% o risco de ganho excessivo de peso durante a gestação (razão de risco médio,RR, de 0,80, intervalo de confiança de 95%, 95% CI, de 0,73 – 0,87; 7.096participantes; 24 estudos; I² = 52%). Após análise de sensibilidade, que reduziu a heterogeneidade das intervenções, esta estimativa de risco foi considerada robusta e, portanto, classificamos a evidência como de alta qualidade. As intervenções envolvendo apenas dietas com baixa carga glicêmica, apenas exercícios supervisionados ou não, ou dieta combinada ao exercício reduziram de forma semelhante o número de mulheres que têm ganho excessivo de peso durante a gestação.

Mulheres que receberam dieta ou exercício ou ambas intervenções tiveram maior propensão para menor ganho ponderal gestacional do que aquelas do grupo controle (RR 1,14, 95% CI de 1,02 a 1,27; 4.422 participantes; 11 estudos; I² = 3%; evidência de qualidade moderada). Nós não encontramos diferenças entre os grupos intervenção e controle em relação a pré-eclâmpsia (RR 0,95, 95% CI 0,77 a 1,16; 5.330 participantes; 15 estudos; I² = 0%; evidência de alta qualidade ); entretanto, o risco de hipertensão materna (um desfecho não especificado previamente) foi menor no grupo intervenção do que no grupo controle (RR 0,70, 95% CI 0,51 a 0,96; 5.162 participantes; 11 estudos; I² = 43%; evidência de baixa qualidade).

No geral, não houve diferença evidente entre os grupos em relação ao parto cesáreo (RR 0,95, 95% CI de 0,88 a 1,03; 7.534 participantes; 28 estudos; I² = 9%; evidência de alta qualidade);embora a estimativa do efeito tenha sugerido uma pequena diferença (5%) em favor do grupo intervenção. No grupo intervenção que combinava dieta e aconselhamento para prática de exercícios também houve uma redução média de 13% desses desfecho (de -1% a 25%) que quase alcançou significância estatística.

No geral, não encontramos diferenças entre os grupos em relação ao parto prematuro (RR 0,91, 95% CI de 0,68 a 1,22; 5.923 participantes; 16 estudos; I² = 16%; evidência de qualidade moderada).No entanto, evidências limitadas sugerem que as estimativas de efeito podem diferir de acordo com os tipos de intervenções, com uma tendência de aumento dos riscos de parto prematuro no grupo submetido apenas ao exercício.

Não encontramos nenhuma diferença evidente entre os grupos intervenção e controle no que diz respeito à macrossomia (RR médio 0,93, 95% CI de 0,86 a 1,02; 8.598 participantes; 27 estudos; I² = 0%; evidência de alta qualidade),embora a estimativa do efeito tenha sugerido uma pequena diferença (7% de redução) em favor do grupo intervenção. O maior tamanho de efeito ocorreu no grupo de exercício supervisionado (RR 0,81, 95% CI de 0,64 a 1,02; 2.445 participantes; 7 estudos; I² = 0%), que quase alcançou significância estatística (p =0,07). Além disso, na análise de subgrupos de risco, mulheres de alto risco (com sobrepeso ou obesas, mulheres com diabetes gestacional ou em risco de desenvolvê-lo) que receberam aconselhamento dietético e exercícios tiveram redução de 15% no risco de terem bebês macrossômicos (RR médio 0,85, 95% CI de 0,73 a 1,00; 3.252 participantes; 9 estudos; I² = 0; P = 0,05; evidências de moderada qualidade).

Não houve diferença entre os grupos intervenção e controle em relação aos desfechos neonatais adversos, comodistócia de ombros, hipoglicemia neonatal, hiperbilirrubinemia, ou tocotraumas (todas evidências de moderada qualidade).Os recém-nascidos de mulheres de alto risco que estavam no grupo intervenção tiveram menor riscode síndrome da angústia respiratória (RR 0,47, 95% CI de 0,26 a 0,85; 2.256 participantes; 2 estudos; I² = 0%; evidências de média qualidade).

Conclusão dos autores

Evidências de alta qualidade indicam que a dieta ou o exercício, ou ambos durante a gestação podem reduzir o risco de ganho ponderal excessivo na gestação. Outros benefícios podem incluir o menor risco de parto cesariano, macrossomia e morbidade respiratória neonatal, particularmente em mulheres de alto risco recebendo dieta combinada com exercícios. O risco de hipertensão materna também pode ser menor. O exercício parece ser importante no controle de ganho ponderal na gestação e mais pesquisas são necessárias para estabelecer diretrizes seguras. A maioria dos estudos incluídos foi realizada em países desenvolvidos e não está claro se esses resultados são amplamente aplicáveis a países de baixa renda.

Notas de tradução

Tradução do Centro Cochrane do Brasil (Fernando Marques)

Plain language summary

Diet and exercise interventions for preventing excessive weight gain during pregnancy

The issue

A large proportion of women gain more weight than is recommended during pregnancy. Excessive weight gain in pregnancy is associated with complications such as diabetes, high blood pressure, caesarean section, and large babies. This review aimed to determine whether diet or exercise measures,or both, could prevent excessive gestational weight gain (GWG), and if they were safe.

How we conducted the review

This is an update of a review first published in 2012 and is current to November 2014 and included randomised controlled trials (RCTs) only in the updated review. We grouped studies according to the types of interventions, and according to the types of participants, i.e. normal weight women (the low-risk group), all pregnant women (the mixed-risk group), and overweight or obese women, or women with or at risk of gestational diabetes (the high-risk group).

Findings

We included 65 randomised controlled trials, of which 49 trials involving 11,444 women contributed data. Twenty studies were at a moderate-to high-risk of bias. The diets tested were low sugar (low glycaemic load), diabetic, low-calorie or low-fat diets, with or without food diaries and regular weighing. The exercise interventions were most often of moderate intensity and involving regular walking, dance or aerobic classes. The comparison or control group generally received standard care. Overall, weight management interventions led to a reduction in the number of women gaining excess weight by a fifth (20%; range 13% to 27%) over the pregnancy. We considered this evidence to be high-quality.

Overall, we found no clear benefits of all diet or exercise interventions, or both, on other outcomes including pre-eclampsia, caesarean section, preterm birth, and having a baby weighing more than 4 kg (macrosomia), although we could not rule out a small effect on caesarean section (5% reduction) and macrosomia (7% reduction), particularly for women receiving combined diet and exercise counselling interventions. There was a tendency for supervised exercise-only interventions to reduce macrosomia too. Maternal hypertension (high blood pressure) was also reduced with the interventions. We found no clear differences between study groups with regard to most infant complications, except that for high-risk women the babies born to the women in the intervention group were less likely to experience breathing difficulties (respiratory distress syndrome) than babies in the control group. This evidence was mostly of a moderate quality.

The studies had differences in the types of interventions, types of participants (for example in terms of body mass index (BMI), number of previous pregnancies and age), delivery of the intervention (whether the intervention was incorporated into antenatal visits or delivered separately by a dietician), timing of the measurements, timing of commencement of the intervention (first, second or third trimester), the intensity of the intervention, and how it was monitored or supervised. Most included studies were carried out in developed countries and it is not clear whether these results are widely applicable to lower income settings.

Conclusions

We found high-quality evidence that diet or exercise interventions, or both, help to reduce excessive weight gain in pregnancy. They may also reduce caesarean deliveries, especially with combined diet and exercise interventions, and maternal hypertension. In addition, the chances of having a baby over 4 kg and the chances of the newborn having breathing difficulties after birth may be reduced, especially in overweight and obese women. Moderate-intensity exercise appears to be an important part of weight-control strategies in pregnancy; however, more research is needed on side-effects to inform safe guidelines.

Résumé simplifié

Interventions portant sur le régime alimentaire et l'exercice physique pour prévenir une prise de poids excessive pendant la grossesse

Problématique

Une grande partie des femmes prennent plus de poids que ce qui est recommandé pendant la grossesse. Une prise de poids excessive pendant la grossesse est associée à des complications telles que le diabète, une pression artérielle élevée, un accouchement par césarienne et un bébé de grand poids. Cette revue visait à déterminer si les mesures portant sur le régime alimentaire ou l'exercice physique, ou les deux, pouvaient prévenir une prise de poids gestationnelle excessive, et si elles étaient sûres d'utilisation.

Comment cette revue a-t-elle été réalisée

Ceci est une mise à jour d'une revue publiée pour la première fois en 2012. Elle est à jour jusqu'à novembre 2014, et la revue actualisée inclut uniquement des essais contrôlés randomisés (ECR). Nous avons regroupé les études selon les types d'interventions et de participantes (groupe à faible risque : femmes de poids normal ; groupe à risque mixte : toutes les femmes enceintes ; groupe à haut risque : femmes en surpoids ou obèses, ou à risque/atteintes de diabète gestationnel).

Résultats

Nous avons inclus dans la revue 65 essais contrôlés randomisés, dont 49 essais portant sur 11 444 femmes ont fourni des données. Vingt études présentaient un risque de biais modéré à élevé. Les régimes alimentaires évalués étaient à teneur faible en sucres (faible charge glycémique), ou des régimes diabétiques, hypocaloriques ou hypolipidiques, avec ou sans la tenue d'un journal alimentaire et des pesées régulières. Les interventions d'exercice physique étaient le plus souvent d'intensité modérée et comportaient une pratique régulière de la marche, des cours de danse ou d'aérobic. Le groupe de comparaison ou témoin recevait généralement des soins standard. Dans l'ensemble, les interventions de contrôle du poids ont entraîné une réduction du nombre de femmes en prise de poids excessive par un cinquième (20 % ; allant de 13 % à 27 %) pendant la grossesse. Nous avons jugé ces données comme étant de qualité élevée.

Dans l'ensemble, nous n'avons constaté aucun bénéfice clair à l'ensemble des interventions portant sur le régime ou l'exercice, ou les deux, sur d'autres critères de jugement, y compris la pré-éclampsie, l'accouchement par césarienne, l'accouchement prématuré et les bébés pesant plus de 4 kg (macrosomie), bien que nous n'ayons pas pu exclure un petit effet sur les césariennes (5 % de réduction) et la macrosomie (7 % de réduction), en particulier chez les femmes recevant des interventions de conseil combinant le régime et l'exercice. Les interventions d'exercice supervisé seul avaient également tendance à réduire la macrosomie. L'hypertension maternelle (pression artérielle élevée) a également été réduite avec les interventions. Nous n'avons identifié aucune différence notable entre les groupes d'étude en ce qui concerne la plupart des complications infantiles, sauf chez les femmes à haut risque, dont les bébés nés dans le groupe d'intervention étaient moins susceptibles de présenter des difficultés respiratoires (syndrome de détresse respiratoire) que les bébés nés dans le groupe témoin. Ces données étaient majoritairement de qualité modérée.

Les études présentaient des différences dans les types d'interventions et de participantes (par exemple en termes de l'indice de masse corporelle (IMC), du nombre de grossesses précédentes et de l'âge), la mise en œuvre de l'intervention (intégrée dans des visites prénatales ou réalisée séparément par un diététicien), le moment des mesures et du début de l'intervention (premier, deuxième ou troisième trimestre), l'intensité de l'intervention et la façon dont elle était surveillée ou supervisée. La plupart des études incluses ont été menées dans des pays développés et il n'est pas clair si ces résultats sont applicables largement dans les contextes à faible revenu.

Conclusions

Nous avons relevé des preuves de qualité élevée indiquant que les interventions portant sur le régime alimentaire ou l'exercice physique, ou les deux, aidaient à réduire la prise de poids excessive pendant la grossesse. Elles pourraient également réduire les accouchements par césarienne, en particulier lorsque l'intervention associe le régime à l'exercice, ainsi que l'hypertension maternelle. En outre, le risque d'avoir un bébé pesant plus de 4 kg et le risque de difficultés respiratoires du nouveau-né après la naissance pourraient être réduits, en particulier chez les femmes en surpoids et obèses. L'exercice d'intensité modérée semble être un élément important des stratégies de gestion du poids pendant la grossesse ; toutefois, des recherches supplémentaires sont nécessaires sur les effets secondaires pour guider l'élaboration de recommandations sûres.

Notes de traduction

Traduction réalisée par le Centre Cochrane Français

Resumo para leigos

Intervenções dietéticas e exercícios para prevenir o ganho excessivo de peso durante a gestação

O problema

Uma grande proporção de mulheres ganha mais peso do que é recomendado durante a gestação. O excessivo ganho de peso na gestação está associado com complicações como a diabetes, aumento da pressão, partos cesáreos e bebês grandes. Esta revisão queria avaliar se medidas dietéticas ou exercícios ou ambos poderiam prevenir o excessivo ganho de peso durante a gestação e se essas medidas eram seguras.

Como esta revisão foi feita

Esta é uma atualização de uma revisão publicada pela primeira vez em 2012 e está atualizada até novembro de 2014. Ensaios clínicos randomizados foram incluídos somente na atualização. Nós agrupamos os estudos de acordo com os tipos de intervenções e de acordo com os tipos de participantes, isto é, mulheres com peso normal (grupo de baixo risco), todas as gestantes (grupo de risco misto) e mulheres com sobrepeso e obesidade, ou mulheres com ou em risco de desenvolver diabetes gestacional (grupo de alto risco).

Resultados

Nós incluímos 65 ensaios clínicos randomizados, sendo que 49 desses contribuíram com dados de 11.444 mulheres. Vinte estudos tinham risco de viés moderado a alto. Foram testadas diversas dietas como: dieta com pouco açúcar (com baixo índice glicêmico), dieta para diabéticos, dieta com poucas calorias ou com baixo teor de gorduras, com ou sem o uso de diários alimentares e pesagem regular. A maioria dos exercícios era de intensidade moderada e envolviam caminhadas regulares, dança ou aulas de aeróbica. Em geral, o grupo de comparação ou controle recebeu cuidados habituais. Em geral, as intervenções de controle de peso reduziram em um quinto o número de mulheres que tiveram ganho excessivo de peso durante a gravidez (20%; variação de 13 a 27%). Consideramos esta evidência como de alta qualidade.

Em geral, nós não encontramos benefícios evidentes em todas as dietas ou exercícios ou ambos sobre os demais desfechos, incluindo pré-eclâmpsia, parto por cesárea, parto prematuro e bebê com mais de 4 kg (macrossomia). Contudo, não podemos descartar um pequeno efeito no parto cesáreo (redução de 5%) e na macrossomia (redução de 7%), particularmente em mulheres que receberam intervenções dietéticas combinadas com aconselhamento de exercícios. Houve uma tendência de redução de macrossomia fetal em mulheres submetidas apenas a exercícios supervisionados. A hipertensão materna (pressão alta) também se reduziu com as intervenções. Nós não encontramos diferenças evidentes entre os grupos do estudo em relação à maioria das complicações dos bebês, exceto no grupo de mulheres de alto risco. Nesse último grupo, aquelas que receberam a intervenção tiveram menor risco de ter bebês com problemas respiratórios (síndrome da angústia respiratória) do que no grupo controle. Esta evidência era de qualidade moderada.

Os estudos tinham diferentes tipos de intervenções, tipos de participantes (por exemplo, em termos de índice de massa corpórea, IMC, número de gestações anteriores e idade), distribuição das intervenções (se a intervenção fazia parte das consultas de pré-natal ou era oferecida em separado por uma nutricionista), o tempo das medidas de peso, o início das intervenções (no primeiro, segundo ou terceiro trimestre da gestação), a intensidade da intervenção e como ela era monitorada e supervisionada. A maioria dos estudos incluídos foi realizada em países desenvolvidos e não está claro se esses resultados são amplamente aplicáveis a países de baixa renda.

Conclusões

Encontramos evidências de alta qualidade que mostram que a dieta ou o exercício, ou ambos, ajudam a reduzir o ganho excessivo de peso na gestação. Eles também podem reduzir o número de partos cesáreose a hipertensão materna, especialmente com dieta e exercícios combinados. Além disso, essas intervenções podem diminuir, especialmente nas mulheres obesas ou com sobrepeso, as chances de terem um bebê com mais de 4 kg e de terem recém-nascidos com dificuldades respiratórias logo após o nascimento. Exercícios de moderada intensidade parecem ser uma parte importante da estratégia de controle de peso na gestação. No entanto, são necessárias mais pesquisas sobre os efeitos colaterais dos exercícios na gestação para que se possa desenvolver orientações seguras.

Notas de tradução

Tradução do Centro Cochrane do Brasil (Fernando Marques)

Laienverständliche Zusammenfassung

Interventionen zur Vorbeugung übermäßiger Gewichtszunahme während der Schwangerschaft

Das Thema

Ein Großteil der Frauen nimmt während der Schwangerschaft mehr Gewicht zu als empfohlen wird. Übermäßige Gewichtszunahme in der Schwangerschaft ist mit Komplikationen wie Zuckerkrankheit (Diabetes mellitus), Bluthochdruck, Kaiserschnitt, und großen Babys verbunden. Dieser Review zielte darauf ab festzustellen, ob Diät oder körperliches Training oder beides einer übermäßigen Gewichtszunahme während der Schwangerschaft vorbeugen konnte und ob diese Interventionen sicher waren.

Wie wir den Review durchführten

Dies ist ein Update eines Reviews, der 2012 das erste Mal veröffentlicht wurde und ist nun auf dem Stand von November 2014. In der aktualisierten Version sind nur randomisierte kontrollierte Studien (RCTs) eingeschlossen. Wir gruppierten Studien nach der Art der Intervention und nach der Art der Teilnehmer, d.h. normalgewichtige Frauen (die Niedrigrisikogruppe), alle schwangeren Frauen (die Gruppe mit gemischtem Risiko), und übergewichtige oder adipöse Frauen oder Frauen mit bestehender Schwangerschaftsdiabetes oder einem Risiko für dieselbe (die Hochrisiko-Gruppe).

Ergebnisse

Eingeschlossen wurden 65 randomisierte kontrollierte Studien, von denen 49 Studien an 11.444 Frauen Daten beitrugen. Zwanzig Studien hatten ein moderates bis hohes Risiko für Bias. Die getesteten Diäten hatten wenig Zucker (niedrigen glykämischen Last), waren diabetische, kalorienarme oder fettarme Ernährung, mit oder ohne Ernährungstagebücher und regelmäßigem Wiegen. Die Trainings-Interventionen waren meist von mittlerer Intensität und schlossen regelmäßige Spaziergänge, Tanz oder Aerobic-Kurse ein. Die Vergleichs- oder Kontrollgruppe erhielt in der Regel Standardtherapie. Während der Schwangerschaft führten die Interventionen zum Gewichtsmanagement insgesamt zu einer Verringerung der Zahl der Frauen, die übermäßig an Gewicht zunahmen um ein Fünftel (20%; Bereich 13% bis 27%). Diese Evidenz war von hoher Qualität.

Insgesamt fanden wir keine klaren Vorteile von Diäten oder Training oder beiden, auf andere Endpunkte einschließlich Präeklampsie, Kaiserschnitt, Frühgeburt, und die Geburt eines Kindes mit einem Gewicht von mehr als 4 kg (Makrosomie), obwohl wir eine kleine Wirkung auf Kaiserschnitt (5% Reduktion) und Makrosomie (7% Ermäßigung) nicht ausschließen konnte, insbesondere für Frauen, die Beratungs-Interventionen für Diät und Training erhielten. Es gab eine Tendenz dahin, dass überwachte Trainings-Interventionen Makrosomie reduzierten. Mütterlicher Bluthochdruck wurde ebenfalls durch die Interventionen reduziert. Wir fanden keine klaren Unterschiede zwischen Studiengruppen in Bezug auf die meisten Komplikationen unter den Kindern, außer, dass Babys von Frauen mit hohem Risiko in der Interventionsgruppe weniger wahrscheinlich Atembeschwerden (Atemnotsyndrom) als Babys in der Kontrollgruppe erlebten. Die Evidenz war meist von moderater Qualität.

Die Studien hatten Unterschiede in der Art der Interventionen, die Art der Teilnehmer (zum Beispiel in Bezug auf den BMI, Anzahl der vorherigen Schwangerschaften und Alter), Art und Weise der Intervention (ob die Intervention in die Geburtsvorbereitung integriert oder separat von einem Diätassistenten durchgeführt wurde), Zeitpunkt der Messungen, den Zeitpunkt des Beginns der Intervention (erstes, zweites oder drittes Trimester), der Intensität der Intervention, und wie die Intervention überwacht bzw. betreut wurde. Die meisten eingeschlossenen Studien wurden in Industrieländern durchgeführt und es ist nicht klar, ob diese Ergebnisse auf Settings mit geringerem Einkommen übertragbar sind.

Schlussfolgerungen

Wir fanden hochwertige Evidenz dafür, dass Diät oder Training oder beide dazu beitragen, übermäßige Gewichtszunahme in der Schwangerschaft zu reduzieren. Sie könnten auch zu einer Verminderung der Kaiserschnitte und mütterlichem Bluthochdruck beitragen, vor allem wenn Diät und Training kombiniert werden. Darüber hinaus kann die Wahrscheinlichkeit, ein Kind von mehr als 4 kg zu gebären und die Wahrscheinlichkeit für Atembeschwerden des Neugeborenen nach der Geburt reduziert werden, vor allem bei übergewichtigen und adipösen Frauen. Training mittlerer Intensität scheint ein wichtiger Teil der Gewichtskontrollstrategien während der Schwangerschaft zu sein; jedoch ist mehr Forschung über Nebenwirkungen erforderlich, um als Grundlage für sichere Leitlinien zu dienen.

Anmerkungen zur Übersetzung

I. Töws, Koordination durch Cochrane Schweiz.

Резюме на простом языке

Вмешательства, включающие диету и упражнения, для предотвращения избыточного увеличения веса во время беременности

Вопрос

Большая часть женщин набирают во время беременности больший вес, чем это рекомендовано. Избыточное увеличение веса во время беременности связано с такими осложнениями/последствиями, как диабет, высокое артериальное давление, родоразрешение путем кесарева сечения, и рождение крупных детей. Целью этого обзора было определить, могут ли такие меры, как диета или упражнения, или и то и другое, предотвратить избыточное увеличение веса во время беременности, и безопасны ли они.

Как мы провели этот обзор

Это обновление обзора, впервые опубликованного в 2012 году, и актуальное по ноябрь 2014 года, с включением рандомизированных контролируемых испытаний (РКИ) только в обновленный обзор. Мы сгруппировали исследования по типам вмешательств и по типам участников, т.е. женщины с нормальным весом (группа низкого риска), все беременные женщины (группа смешанного риска) и женщины с избыточным весом или ожирением, или женщины с гестационным диабетом или риском его развития (группа высокого риска).

Результаты

Мы включили 65 рандомизированных контролируемых испытаний, из которых 49 испытаний с участием 11 444 женщин внесли данные в этот обзор. В двадцати исследованиях риск смещения был от среднего до высокого. Среди тестируемых диет были: диета с низким содержанием сахара (низкая гликемическая нагрузка), низко-калорийная диета или диета с низким содержанием жира, с ведением пищевых дневников и регулярным взвешиванием или без них. Вмешательства, включающие упражнения, чаще всего были умеренной интенсивности и включали регулярные прогулки, танцы или аэробные упражнения. Группа сравнения или контрольная группа, как правило, получала стандартную помощь. В целом, вмешательства по управлению весом привели к сокращению числа женщин, которые набирают избыточный вес во время беременности, на одну пятую (20%, диапазон от 13% до 27%). Мы оценили качество этих доказательств как высокое.

В целом, мы обнаружили отсутствие явной пользы всех вмешательств, включающих диету и/или упражнения, в отношении других исходов, включая пре-эклампсию, родоразрешение путем кесарева сечения, преждевременные роды, и рождение ребенка с весом более 4 кг (макросомия), хотя мы не могли исключить небольшое влияние на частоту кесарева сечения (снижение на 5%) и макросомии (снижение на 7%), особенно у женщин, получавших комбинированные вмешательства, включающие консультирование по диете и упражнениям. Также была обнаружена тенденция снижения частоты макросомии при вмешательствах, включающих только упражнения с руководителем (тренером). Частота материнской гипертензии (высокое артериальное давление) также была снижена с помощью этих вмешательств. Мы обнаружили отсутствие явных различий между группами исследований в отношении большинства осложнений/последствий со стороны ребенка, за исключением того, что в группе вмешательства у женщин с высоким риском дети вероятно испытывали меньше проблем с дыханием (респираторный дистресс-синдром), чем дети, рожденные от матерей в контрольной группе. Эти доказательства были, в основном, среднего качества.

В исследованиях были различия в типах вмешательств, типах участников (например, в отношении индекса массы тела (ИМТ), числа предыдущих беременностей и возраста), предоставлении вмешательства (было ли вмешательство включено в антенатальные посещения или предоставлялось отдельно диетологом), сроках измерений, времени начала вмешательства (первый, второй или третий триместр), интенсивности вмешательства, и как его мониторировали и контролировали. Большинство включенных исследований были проведены в развитых странах, и не ясно, могут ли эти результаты быть широко применимы в условиях с более низким уровнем доходов.

Выводы

Мы обнаружили доказательства высокого качества, что вмешательства, включающие диету и/или упражнения, помогают снизить избыточное увеличение веса во время беременности. Они могут также уменьшить частоту родоразрешения путем кесарева сечения, особенно при комбинации вмешательств с включением диеты и упражнений, и уменьшить частоту материнской гипертензии. Кроме того, могут быть снижены шансы рождения ребенка с весом более 4 кг и шансы развития проблем с дыханием у новорожденных после рождения, особенно у женщин с избыточной массой тела и ожирением. Представляется, что упражнения умеренной интенсивности являются важной частью стратегий по контролю веса во время беременности. Однако, необходимо больше исследований по побочным эффектам, чтобы информировать клинические руководства в отношении безопасности.

Заметки по переводу

Перевод: Юдина Екатерина Викторовна. Редактирование: Зиганшина Лилия Евгеньевна. Координация проекта по переводу на русский язык: Казанский федеральный университет - аффилированный центр в Татарстане Северного Кокрейновского Центра. По вопросам, связанным с этим переводом, пожалуйста, обращайтесь к нам по адресу: lezign@gmail.com

Laički sažetak

Učinci prehrane, tjelovježbe ili kombinacije prehrane i tjelovježbe za sprječavanje prekomjernog debljanja u trudnoći

Problem

Veliki udio žena tijekom trudnoće na težini dobije više nego što je preporučeno. Prekomjerno debljanje u trudnoći povezano je s komplikacijama kao što su dijabetes, visoki krvni tlak, carski rez i velika novorođenčad. Cilj ovog Cochrane sustavnog pregleda bio je odrediti mogu li određena prehrana, vježbanje, ili oboje, spriječiti prekomjerno debljanje u trudnoći te jesu li te intervencije sigurne.

Kako su autori proveli sustavni pregled

Ovo je ažurirani sustavni pregled originalno objavljen 2012. te uključuje dokaze dostupne do studenog 2014. godine. Randomizirani kontrolirani pokusi su uključeni samo u ažurirani sustavni pregled. Istraživanja su razvrstana prema vrstama intervencija i prema vrstama sudionika odnosno na žene normalne težine (skupina niskog rizika), sve trudne žene (skupina miješanog rizika) te preteške ili pretile žene i žene s dijabetesom ili s rizikom od gestacijskog dijabetesa (skupina visokog rizika).

Rezultati

Autori su uključili 65 randomiziranih kontroliranih pokusa, od kojih je 49 s 11.444 uključene žene doprinijelo podatcima. Dvadeset istraživanja imalo je od umjeren do visok rizik sustavne pogreške. Testirani tipovi prehrane su bili prehrana s niskim unosom šećera (nisko glikemijsko opterećenje), prehrana za dijabetičare, niskokalorične ili nemasne dijete, sa ili bez dnevnika prehrane i redovitog vaganja. Intervencije vježbanja bile su najčešće tjelovježbe umjerenog intenziteta koje uključuju su redovito šetanje, ples ili sate aerobika. Intervencija u kontrolnoj skupini je uglavnom bila standardna njega. Ukupno gledajući, intervencije za kontroliranje težine su smanjile broj žena koje su prekomjerno dobivale na težini za jednu petinu (20%; rasponu od 13% do 27%) kroz trudnoću. Radi se o dokazima visoke kvalitete.

Sveukupno, nisu utvrđene jasne koristi različitih tipova prehrane i tjelovježbe na druge ishode koji uključuju preeklampsiju, carski rez, prijevremeni porod i novorođenčad težu od 4 kg (makrosomija), iako se ne može isključiti mali učinak na carski rez (5% smanjenja) i makrosomiju (7% smanjenja), osobito za žene koje su primale savjete o kombinaciji prehrane i tjelovježbe. Nadgledane intervencije tjelovježbe su imale tendenciju ka smanjenju makrosomije. Trudnička hipertenzija (visok krvni tlak) bila je također smanjena uz pomoć intervencija. Nisu pronađene jasne razlike među istraživačkim skupinama vezane za dojenačke komplikacije osim da su djeca majki iz intervencijske skupine visoko rizičnih žena bila manje podložna poteškoćama s disanjem (sindrom respiratornog distresa) nego djeca majki iz kontrolne skupine. Ovi dokazi su uglavnom umjerene kvalitete.

Istraživanja su se razlikovala prema vrstama intervencija, vrstama sudionika (na primjer obzirom na indeks tjelesne mase (BMI), broj prethodnih trudnoća i godina), primjeni intervencije (je li intervencija bila uključena u prijeporodnu skrb ili je zasebno prepisao nutricionist), vremenu mjerenja, vremenu početka intervencije (prvi, drugi ili treći trimestar), intenzitetu intervencije te načinu praćenja i nadgledanja. Većina uključenih istraživanja bila je provedena u razvijenim zemljama i nije jasno jesu li ti rezultati široko primjenjivi na žene koje žive u sredinama s nižim prihodima.

Zaključci

Autori su našli visokokvalitetne dokaze da dijeta, tjelovježba, ili oboje, pomažu u smanjenju prekomjernog debljanja u trudnoći. One također mogu smanjiti stopu poroda carskim rezom, osobito kombinacijom prehrane i tjelovježbe, te majčinsku hipertenziju. Uz to mogu biti smanjeni nepovoljni ishodi za novorođenčad težu 4 kg i za novorođenčad s dišnim poteškoćama, osobito u preteških i pretilih žena. Vježbe umjerenog intenziteta čine se kao važan dio strategije kontrole težine u trudnoći, no potrebno je više istraživanja o nuspojavama kako bi se ponudile sigurne smjernice.

Bilješke prijevoda

Hrvatski Cochrane
Prevela: Josipa Kozina
Ovaj sažetak preveden je u okviru volonterskog projekta prevođenja Cochrane sažetaka. Uključite se u projekt i pomozite nam u prevođenju brojnih preostalih Cochrane sažetaka koji su još uvijek dostupni samo na engleskom jeziku. Kontakt: cochrane_croatia@mefst.hr

Streszczenie prostym językiem

Interwencje dietetyczne i ćwiczenia w zapobieganiu nadmiernemu przyrostowi masy ciała w czasie ciąży

Zagadnienie

Znaczna część kobiet w czasie ciąży przybiera na wadze więcej niż to jest zalecane. Nadmierny przyrost masy ciała w okresie ciąży jest związany z powikłaniami, takimi jak: cukrzyca, wysokie ciśnienie krwi, konieczność wykonania cięcia cesarskiego, czy poród dzieci o dużej masie ciała. Celem niniejszego przeglądu jest ustalenie, czy dieta lub ćwiczenia, bądź oba te działania naraz, mogą zapobiec nadmiernemu przyrostowi masy ciała ciężarnych (GWG - ang. gestational weight gain) oraz czy takie działania są bezpieczne dla matki i dziecka.

W jaki sposób przeprowadzono przegląd

Jest to aktualizacja przeglądu opublikowanego po raz pierwszy w 2012 roku i jest ona aktualna do listopada 2014 roku. Uaktualniony przegląd obejmował tylko badania z randomizacją (RCT). Włączone badania pogrupowano według rodzajów stosowanej interwencji oraz względem charakterystyki uczestników badania, czyli: kobiet o masie ciała w normie (grupa małego ryzyka), wszystkich kobiet w ciąży (grupa mieszanego ryzyka), kobiet z nadwagą lub otyłością, kobiet z cukrzycą ciążową lub nią zagrożonych (grupa dużego ryzyka).

Wyniki

Włączono 65 badań z randomizacją, z czego dane do przeglądu wniosło 49 badań, w których uczestniczyło 11,444 kobiet. Dwadzieścia badań charakteryzowało się umiarkowanym do dużego ryzykiem błędu systematycznego. Analizowano: rodzaj diety - nisko węglowodanowa (niski ładunek glikemiczny), cukrzycowa, niskokaloryczna lub niskotłuszczowa, z lub bez bieżącego notowania (sposób rejestrowania ilości i jakości spożywanej żywności - przyp. tłum.) oraz regularne ważenie. Interwencje w zakresie ćwiczeń fizycznych najczęściej obejmowały ćwiczenia o umiarkowanej intensywności, wymagające regularnego chodzenia, zajęć z tańca lub aerobiku. Grupa porównania lub kontrolna na ogół otrzymywała standardową opiekę. Generalnie, interwencje prowadziły do zmniejszenia o jedną piątą liczby kobiet o nadmiernym przyroście masy ciała w czasie ciąży (20%, zakres od 13% do 27%). Jakość tych danych została oceniona wysoko.

Podsumowując, nie stwierdzono wyraźnych korzyści wszystkich interwencji dietetycznych i/lub ćwiczeniowych, na pozostałe punkty końcowe (efekty postępowania- przyp. tłum), włączając w to: stan przedrzucawkowy, cesarskie cięcie, przedwczesny poród i masę urodzeniową dziecka ponad 4 kg (makrosomia), choć nie można wykluczyć niewielkiego wpływu wspominanych interwencji na częstość wykonywania cesarskiego cięcia (zmniejszenie o 5%) i makrosomii (zmniejszenie o 7%), szczególnie w przypadku kobiet otrzymujących interwencje obejmujące łącznie poradnictwo dietetyczne i ćwiczenia fizyczne. Ponadto, istniała także tendencja, wśród kobiet otrzymujących jedynie interwencję w postaci nadzorowanych ćwiczeń, do zmniejszenia częstości występowania makrosomii płodu. Jako efekt interwencji, także zaobserwowano zmniejszenie częstości nadciśnienia (wysokiego ciśnienia krwi) wśród matek. Nie stwierdzono jednoznacznych różnic między badanymi grupami w odniesieniu do większości powikłań u noworodków. Wyjątkiem były noworodki, urodzone przez kobiety z grupy dużego ryzyka otrzymujące interwencje, u których rzadziej występowały trudności w oddychaniu (zespół ostrej niewydolności oddechowej) w porównaniu do dzieci z grupy kontrolnej. Jakość tych danych oceniono jako umiarkowaną.

Włączone badania różniły się pod względem typów interwencji, charakterystyki uczestników (wskaźnik masy ciała (BMI), liczby poprzednich ciąż, wieku, sposobu poddania interwencji (czy interwencja włączona do wizyt przedporodowych lub udzielana oddzielnie przez dietetyka), czasu wykonywania pomiarów, czasu rozpoczęcia interwencji (pierwszy, drugi lub trzeci trymestr ciąży), intensywności interwencji, oraz sposobu monitorowania i nadzorowania. Większość włączonych badań przeprowadzono w krajach rozwiniętych, przez co nie jest jasne, czy otrzymane wyniki nadają się do szerokiego zastosowania w krajach o niższych dochodach.

Wnioski

Znaleźliśmy wysokiej jakości dowody potwierdzające, że interwencje dietetyczne i/lub ćwiczenia, pomagają zredukować nadmierny przyrost masy ciała w ciąży. Mogą one również zredukować liczbę porodów przez cesarskie cięcie i nadciśnienie tętnicze u matek, zwłaszcza w przypadku połączenia interwencji dietetycznej z ćwiczeniami. Ponadto, mogą także zredukować szanse na urodzenie dziecka o masie ciała przekraczającej 4 kg, czy prawdopodobieństwo wystąpienia trudności z oddychaniem u noworodka, po urodzeniu, zwłaszcza, przez kobiety z nadwagą i otyłością. Umiarkowanej intensywności ćwiczenia wydają się być ważnym elementem strategii mającej na celu kontrolę masy ciała w ciąży; jednak potrzebne są dalsze badania nad skutkami ubocznymi aby przedstawić jednoznaczne wytyczne.

Uwagi do tłumaczenia

Tłumaczenie Joanna Zając Redakcja Paulina Rolska, Małgorzata Bała

Summary of findings(Explanation)

Summary of findings for the main comparison. All diet and/or exercise interventions compared to standard/other care for preventing excessive weight gain in pregnancy
  1. 1Although heterogeneity was moderate-to-high (I² = 52%), the RR was robust to sensitivity analysis, which was associated with less heterogeneity (I² - 40%), therefore we did not downgrade this evidence

    2Downgraded due to imprecision of results according to types of intervention (-1)

    3Downgraded due to risk of bias concerns and concerns that data could not be included in the analysis due to studies excluding women with or at risk of preterm birth post-randomisation from analysis (Cordero 2014; Di Carlo 2014; Murtezani 2014; Rauh 2013). This omission might have led to publication bias in the review's 'preterm birth' outcome (-1)

All diet and/or exercise interventions compared to standard/other care for preventing excessive weight gain in pregnancy
Patient or population: pregnant women
Settings: antenatal care settings
Intervention: all diet and/or exercise interventions
Comparison: routine care or minimal interventions (e.g. brochures)
OutcomesIllustrative comparative risks* (95% CI)Relative effect
(95% CI)
No of Participants
(studies)
Quality of the evidence
(GRADE)
Comments
Assumed riskCorresponding risk
Standard/other care All diet and/or exercise interventions
Excessive weight gainStudy populationRR 0.80
(0.73 to 0.87)
7096
(24 RCTs)
⊕⊕⊕⊕
HIGH 1
 
453 per 1000362 per 1000
(330 to 394)
Mean GWG (kg)  Mean difference not estimated  Due to substantial heterogeneity among studies, we did not consider the pooled estimate to be meaningful. Limited subgroup analyses suggested that effect estimates might differ according to risk group.
Low weight gainStudy populationRR 1.14
(1.02 to 1.27)
4422
(11 RCTs)

⊕⊕⊕⊝

MODERATE2

 
227 per 1000259 per 1000
(232 to 288)
Preterm birthStudy populationRR 0.91
(0.68 to 1.22)
5923
(16 RCTs)
⊕⊕⊕⊝
MODERATE3
 
57 per 100052 per 1000
(39 to 70)
Pre-eclampsiaStudy populationRR 0.95
(0.77 to 1.16)
5330
(15 RCTs)
⊕⊕⊕⊕
HIGH
 
66 per 100062 per 1000
(50 to 76)
Caesarean deliveryStudy populationRR 0.95
(0.88 to 1.03)
7534
(28 RCTs)
⊕⊕⊕⊕
HIGH
 
288 per 1000274 per 1000
(254 to 297)
Macrosomia Infant birthweight > 4000 gStudy populationRR 0.93
(0.86 to 1.02)
8598
(27 RCTs)
⊕⊕⊕⊕
HIGH
 
178 per 1000166 per 1000
(153 to 182)
*The basis for the assumed risk was the median control group risk across studies. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
CI: Confidence interval.
GRADE Working Group grades of evidence
High quality: Further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: We are very uncertain about the estimate.

Summary of findings 2 Comparative table of findings by intervention type

Summary of findings 2. Comparative table of findings by intervention type
  1. Finding are presented with reference to the intervention group

    * Sensitivity analysis suggested that there may be a statistically significant difference in favour of the intervention for the mixed-risk subgroup.

    Abbreviations: NA = not available; NS = not statistically significant (P ≥ 0.05); BS = borderline significance

Intervention typeRisk groupEGWGMean GWGLow GWGPreterm birthCaesareanPre-eclampsiaMacrosomia

All interventions

(max 36

studies)

Overall20% reduction (13 to 27%)Not estimated

14% increase

(2% to 27%)

NSNSNSBS (7% reduction, -2% to 14%)

Low GL diet

(max 5 studies)

Overall23% reduction (9% to 33%)Not estimatedNSBS in favour of the interventionNSNANS
Low40% reduction (6% to 52%)NSNSNSNSNANA
Mixed21% reduction (1 study)NSNANSNSNANS
HighNSNSNSNSNSNANS

Diet and exercise counselling

(max 13 studies)

Overall14% reduction (2% to 25%)Not estimatedNSNSBS (13% reduction; -1% to 25%)NSNS
Low28% reduction (5% to 45%)NSNSNSNSNSNS
MixedNS1.80 kg reduction (0.24 to 3.36 kg)NANSBS (34% reduction; -5% to 59%)NANS
HighNS

0.71 kg reduction

(0.08 to 1.34)

NSNSBS (11% reduction; -4 to 24%)NS

15% reduction

(0% to 27%)

Exercise (supervised or unsupervised) only

(max 10 studies)

Overall21% reduction (11% to 30%)Not estimatedBS (19% increase; 0% to 41%)NSNSNSNS
LowBS (31%; -2 to 53%)1.50 kg reduction (0,92 to 2.08 kg; one study only)29% increase; 6% to 42%)BS (one study)NSNA 
Mixed23% reduction (12% to 34%)1.35 kg reduction (0.89 to 1.80)NSNSNSNSBS* (19% reduction; -2% to 36%)
High16% reduction (5% to 27%)NSNSNSNSNSNS

Unsupervised exercise only

(max 3 studies)

Overall17% reduction (3% to 29%)Not estimatedNSNSNSNSNS
Supervised exercise only (max 7 studies)Overall25% reduction (11% to 37%)Not estimatedBS (21% increase; -1% to 52%)NS (trend in favour of control)NSNSBS (19% reduction;-2% to 36%)
Diet and supervised exercise (max 5 studies)Overall29% reduction (15% to 41%)NSNSNANSNSNS
LowNS3.33 kg reduction (1,21 to 5.45; one study only)NANANot estimableNANA
Mixed36% reduction (16% to 52%)1.69 kg reduction (0.11 to 3.48)NSNANSNANS
HighNSNSNANANSNANS

Diet counselling/other

(max 7 studies)

OverallNSNot estimatedNSNSNSNSNS
MixedNSNANANSNSNSNA
HighNSNANANSNSNSNS

Background

Description of the condition

Pregnancy weight gain guidelines

In 2009, the Institute of Medicines (IOM) in the United States updated earlier guidelines on weight gain during pregnancy (Medicine 1990; Medicine 2009). The report set out specific ranges of weight gain for women with different prepregnancy weights: suggesting that underweight women (body mass index (BMI) less than 18.5 kg/m²) gain 28 lbs to 40 lbs (12.5 kg to 18 kg); normal weight women (BMI 18.5 kg/m² to 24.9 kg/m²) gain 25 lbs to 35 lbs (11.5 kg to 16 kg); whereas overweight women (BMI 25 kg/m² to 29.9 kg/m²) were advised to gain between 15 lbs and 25 lbs (7 kg to 11.5 kg) and obese women (BMI at least 30 kg/m²) to gain between 11 lbs and 20 lbs (5 kg to 9 kg) (Medicine 2009).

Previous guidelines from the IOM (Medicine 1990) had been widely adopted but not universally accepted. However, a review of relevant information confirmed that pregnancy weight gain within the IOM's recommended ranges was associated with the best outcomes for both mothers and infants, and that weight gain within the IOM's recommended ranges is not harmful for the mothers or for their infants (Abrams 2000).

No official recommendations or clinical guidelines for weight gain during pregnancy exist in the United Kingdom (UK) (Ford 2001). However, a report from the UK Centre for Maternal and Child Enquiries (CMACE 2010) suggested a more comprehensive guidance for the care of overweight and obese women, and recommended weighing women in the third trimester and again when women are admitted in labour. Guidelines in other countries have also recommended monitoring weight gain in pregnancy. In Sweden, it has been recommended that the optimal gestational weight gain for Swedish women is 4 kg to 10 kg for BMI less than 20, 2 kg to 10 kg for BMI 20 to 24.9; less than 9 kg for women with a BMI of 25 to 29.9, and less than 6 kg for women with a BMI of 30 or more (Cedergren 2007). Maternal weight gain recommendations based on data from high-income countries may not be applicable to Asian women, who appear to have lower weight gains compared with women in Europe and North America (Abrams 1995; Siega-Riz 1993). Weight gain limits for Chinese women, taking ethnic-specific differences into account, have been recommended as 13 kg to 16.7 kg, 11 kg to 16.4 kg, and 7.1 kg to 14.4 kg respectively for women of low (BMI less than 19), moderate (BMI 19 to 23.5), and high (BMI greater than 23.5) BMI (Wong 2000).

Trends in pregnancy weight gain

Although the 1990 IOM guidelines have now been promoted for two decades it has been estimated that over this time only 30% to 40% of pregnant women in the United States gain gestational weight within the IOM recommended ranges (Abrams 2000; Cogswell 1999; Medicine 1990; Olson 2003). Furthermore, gestational weight gain above the guidelines is more common than gestational weight gain below (Stotland 2006). Several studies on gestational weight gain in the USA and Europe indicate that about 20% to 40% of women are gaining weight above the recommendations (Cedergren 2006; Medicine 2009; Olson 2003) and the prevalence of excessive gestational weight gain is increasing (Abrams 2000; Rhodes 2003; Schieve 1998). A retrospective cohort study undertaken to examine the trend in weight gain during pregnancy of 1,463,936 women over 16 years in North Carolina found that the proportion of women gaining excessive gestational weight (more than 18 kg) increased from 15.5% in 1988 to 19.5% in 2003; an additional 40 women per 1000 gained excessive weight by 2003 (Helms 2006). The recent IOM report summarised the situation in a number of countries; compared with two decades earlier "Women today are also heavier; a greater percentage of them are entering pregnancy overweight or obese, and many are gaining too much weight during pregnancy" (Medicine 2009).

Weight gain during pregnancy is generally inversely proportional to prepregnancy weight category. Although underweight women are least likely to exceed weight gain recommendations, obese women tend to gain less weight than normal and overweight women (Abrams 1989; Bianco 1998; Edwards 1996; Walling 2006). Two large population-based studies, in Sweden and the United States, found that approximately 30% of average and overweight women had high-gestational weight gain, compared with 20% of obese women (Cedergren 2006; Cogswell 1995).

Pregnancy weight gain and outcomes for mothers and infants

It is well known from large studies in a number of countries that excessive weight gain during pregnancy is associated with multiple maternal and neonatal complications. Retrospective cohort studies have examined the relationship between gestational weight gain and adverse neonatal outcomes among infants born at term. Gestational weight gain above the upper limit of the IOM guideline has been associated with a low five-minute Apgar score, seizure, hypoglycaemia, polycythaemia, meconium aspiration syndrome and large-for-gestational age compared with women within weight gain guidelines (Hedderson 2006; Stotland 2006). For obese women, low-gestational weight gain has been shown to decrease the risk of several undesirable outcomes including pre-eclampsia, caesarean section, instrumental delivery, and large-for-gestational-age births; whereas, excessive weight gain increased the risk for caesarean delivery in all maternal BMI classes (Cedergren 2006).

Findings from a national study in the UK revealed that compared with pregnant women in general, obese pregnant women were at increased risk of having a co-morbidity diagnosed before or during pregnancy (in particular pregnancy-induced hypertension and gestational diabetes), were at increased risk of having induction of labour and a caesarean birth, were more likely to have postpartum haemorrhage, and their babies were at increased risk of stillbirth, neonatal death, of being large-for-gestational age and more likely to be admitted for special care (CMACE 2010).

A number of studies have concluded that excessive gestational weight gain increases postpartum weight retention (Gunderson 2000; Keppel 1993; Polley 2002; Rooney 2002; Rossner 1997; Scholl 1995) and is related to a two- to three-fold increase in the risk of becoming overweight after delivery (Gunderson 2000). Moreover, mothers who gained more weight during pregnancy have been shown to have children at higher risk of being overweight in early childhood (Oken 2007).

Description of the intervention

Pregnancy may be an optimal time to inform and challenge women to change their eating habits and physical activities, and thereby prevent excessive weight gain. Dietary control, exercise and eating behaviour modification are the main elements for controlling weight. Dietary interventions include low glycaemic, energy-restricted, diabetic, healthy eating, low carbohydrate and other diets. Regular exercise is an important part of a healthy lifestyle and most guidelines support moderate-intensity physical activity during pregnancy (Evenson 2014).

How the intervention might work

Diet and exercise interventions are recommended components of weight control programs in the general population. Diet interventions work mainly by limiting energy intake, whereas exercise interventions work by using energy. If one utilises more energy than one takes in, one creates an energy deficit, which facilitates the use of stored energy.

Why it is important to do this review

Pregnancy results in dramatic physiological changes, with weight gain occurring as part of the normal pregnancy process. This normal occurrence and expectation of weight gain in pregnancy can make it difficult for a woman of any prepregnancy weight to maintain her weight within recommended limits. Thus, pregnancy is a time when women especially need clear guidance on how best to maintain a healthy weight, in a way that will be safe for both mother and baby. Given the increasing prevalence and negative consequences of excessive gestational weight gain, preventing excessive weight gain during pregnancy is becoming increasingly important. The previous version of this review found weak evidence to support diet and exercise interventions to reduce gestational weight gain; however, findings were inconsistent and interventions heterogeneous. Despite this and another systematic review that included randomised and non-randomised studies (Thangaratinam 2012), it remains unclear which types of interventions will yield the best outcomes for mothers and their infants, and whether interventions work equally for all risk groups. Pregnancy offers an ideal opportunity to support women towards a healthier lifestyle; however, strategies for reducing weight gain in the non-pregnant population may not be suitable for use in pregnancy. The aim of this review was to determine whether diet or exercise interventions, or both, for preventing excessive weight gain are effective and safe in pregnancy and to stimulate further research in this field.

Objectives

To evaluate the effectiveness and safety of diet or exercise, or both, interventions for preventing excessive weight gain during pregnancy.

Methods

Criteria for considering studies for this review

Types of studies

Randomised controlled trials (RCTs) and cluster-RCTs. Quasi-RCTs were not eligible.

Types of participants

Pregnant women of any BMI. We considered studies recruiting women with normal BMIs to have a 'low risk' of weight-related complications at baseline, those recruiting women from the general population including women of any BMI to have a 'mixed-risk' status, and studies of overweight and/or obese women, or high-risk women, as defined by the investigators, to have a 'high-risk' status.

Types of interventions

Any diet or exercise, or both, intervention (e.g. healthy eating plan, low glycaemic diet, exercise intervention, health education, lifestyle counselling) compared with standard or routine care for preventing excessive weight gain in pregnancy. We organised our main comparison into different intervention types, as follows:

  • diet counselling only versus routine care;

  • diet and exercise counselling versus routine care;

  • diet interventions (e.g. low glycaemic diet) versus routine care;

  • exercise (supervised or unsupervised) interventions only versus routine care;

  • diet and supervised exercise interventions versus routine care.

We defined diet as a special selection of food, or energy intake, to which a participant was restricted. Exercise interventions included any activity requiring physical effort, carried out to sustain or improve health and fitness.

Types of outcome measures

Primary outcomes

Excessive weight gain as defined by investigators.

Secondary outcomes
For the mothers
  1. Weight gain.

  2. Low weight gain as defined by investigators.

  3. Preterm birth.

  4. Preterm prelabour rupture of membranes.

  5. Pre-eclampsia/eclampsia.

  6. Hypertension (not prespecified).

  7. Induction of labour.

  8. Caesarean delivery.

  9. Postpartum complication including postpartum haemorrhage, wound infection, endometritis, need for antibiotics, perineal trauma, thromboembolic disease, maternal death.

  10. Behaviour modification outcomes: diet, physical activity.

For the newborns
  1. Birthweight (not prespecified).

  2. Birthweight greater than 4000 g or greater than the 90th centile for gestational age and infant sex (macrosomia).

  3. Birthweight less than 2500 g or less than the 10th centile for gestational age and infant sex.

  4. Complication related to macrosomia including hypoglycaemia, hyperbilirubinaemia, infant birth trauma (palsy, fracture, shoulder dystocia), respiratory distress syndrome.

Long-term health outcomes
  1. Maternal weight retention postpartum.

  2. Childhood weight.

Gestational diabetes, an important outcome of many interventions aimed at preventing excessive weight gain in pregnancy, is the primary outcome of separate Cochrane reviews (Crane 2013; Han 2012; Tieu 2008) and is therefore not included in this review.

Search methods for identification of studies

The following methods section of this review is based on a standard template used by the Cochrane Pregnancy and Childbirth Group.

Electronic searches

We searched the Cochrane Pregnancy and Childbirth Group’s Trials Register by contacting the Trials Search Co-ordinator (5 November 2014).

The Cochrane Pregnancy and Childbirth Group’s Trials Register is maintained by the Trials Search Co-ordinator and contains trials identified from:

  1. monthly searches of the Cochrane Central Register of Controlled Trials (CENTRAL);

  2. weekly searches of MEDLINE (Ovid);

  3. weekly searches of Embase (Ovid);

  4. handsearches of 30 journals and the proceedings of major conferences;

  5. weekly current awareness alerts for a further 44 journals plus monthly BioMed Central email alerts.

Details of the search strategies for CENTRAL, MEDLINE and Embase, the list of handsearched journals and conference proceedings, and the list of journals reviewed via the current awareness service can be found in the ‘Specialized Register’ section within the editorial information about the Cochrane Pregnancy and Childbirth Group.

Trials identified through the searching activities described above are each assigned to a review topic (or topics). The Trials Search Co-ordinator searches the register for each review using the topic list rather than keywords.

Searching other resources

For this update, we also contacted investigators of the previously identified ongoing studies by email to enquire about any new or imminent publications.

We searched the reference lists of retrieved studies.

We did not apply any language or date restrictions.

Data collection and analysis

For methods used in the previous version of this review, see Muktabhant 2012.

For this update, we used the following methods based on a standard template used by the Cochrane Pregnancy and Childbirth Group for assessing the reports that were identified as a result of the updated search.

Selection of studies

Two review authors (Benja Muktabhant (BM); Theresa Lawrie (TL)) independently assessed for inclusion all the potential studies identified as a result of the search strategy. We resolved any disagreement through discussion or, if required, we consulted the third review author (Pisake Lumbiganon (PL)).

Data extraction and management

Using Microsoft Excel®, we designed a spreadsheet to collect study data and piloted it with two studies. Thereafter, two review authors (BM, TL) extracted data from included studies using the piloted form. We resolved discrepancies through discussion or, if required, we consulted a third review author (PL). Data were entered into Review Manager software (RevMan 2014) by one review author (TL) and checked for accuracy by another (BM).

For studies that reported results for obese and overweight women separately, we combined these data for the 'high-risk women' subgroup.

Assessment of risk of bias in included studies

Two review authors (BM, TL) independently assessed risk of bias for each study using the criteria outlined in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). Any disagreement was resolved by discussion or by involving a third assessor (PL or Malinee Laopaiboon (ML)).

(1) Random sequence generation (checking for possible selection bias)

We described for each included study the method used to generate the allocation sequence in sufficient detail to allow an assessment of whether it should produce comparable groups.

We assessed the method as:

  • low risk of bias (any truly random process, e.g. random number table; computer random number generator);

  • high risk of bias (any non-random process, e.g. odd or even date of birth; hospital or clinic record number);

  • unclear risk of bias.

(2) Allocation concealment (checking for possible selection bias)

We described for each included study the method used to conceal allocation to interventions prior to assignment and assessed whether intervention allocation could have been foreseen in advance of, or during recruitment, or changed after assignment.

We assessed the methods as:

  • low risk of bias (e.g. telephone or central randomisation; consecutively numbered sealed opaque envelopes);

  • high risk of bias (open random allocation; unsealed or non-opaque envelopes, alternation; date of birth);

  • unclear risk of bias.

(3.1) Blinding of participants and personnel (checking for possible performance bias)

We described for each included study the methods used, if any, to blind study participants and personnel from knowledge of which intervention a participant received. We considered that studies were at low risk of bias if they were blinded, or if we judged that the lack of blinding unlikely to affect results. We assessed blinding separately for different outcomes or classes of outcomes.

We assessed the methods as:

  • low, high or unclear risk of bias for participants;

  • low, high or unclear risk of bias for personnel.

(3.2) Blinding of outcome assessment (checking for possible detection bias)

We described for each included study the methods used, if any, to blind outcome assessors from knowledge of which intervention a participant received. We assessed blinding separately for different outcomes or classes of outcomes.

We assessed methods used to blind outcome assessment as:

  • low, high or unclear risk of bias.

(4) Incomplete outcome data (checking for possible attrition bias due to the amount, nature and handling of incomplete outcome data)

We described for each included study, and for each outcome or class of outcomes, the completeness of data including attrition and exclusions from the analysis. We stated whether attrition and exclusions were reported and the numbers included in the analysis at each stage (compared with the total randomised participants), reasons for attrition or exclusion where reported, and whether missing data were balanced across groups or were related to outcomes. Where sufficient information was reported, or could be supplied by the trial authors, we planned to re-include missing data in the analyses which we undertook.

We assessed methods as:

  • low risk of bias (e.g. no missing outcome data; missing outcome data balanced across groups);

  • high risk of bias (e.g. numbers or reasons for missing data imbalanced across groups; ‘as treated’ analysis done with substantial departure of intervention received from that assigned at randomisation);

  • unclear risk of bias.

(5) Selective reporting (checking for reporting bias)

We described for each included study how we investigated the possibility of selective outcome reporting bias and what we found.

We assessed the methods as:

  • low risk of bias (where it is clear that all of the study’s pre-specified outcomes and all expected outcomes of interest to the review have been reported);

  • high risk of bias (where not all the study’s pre-specified outcomes have been reported; one or more reported primary outcomes were not pre-specified; outcomes of interest are reported incompletely and so cannot be used; study fails to include results of a key outcome that would have been expected to have been reported);

  • unclear risk of bias.

(6) Other bias (checking for bias due to problems not covered by (1) to (5) above)

We described for each included study any important concerns we had about other possible sources of bias.

(7) Overall risk of bias

We made explicit judgements about whether studies were at high risk of bias, according to the criteria given in the Handbook (Higgins 2011). With reference to (1) to (6) above, we attempted to assess the likely magnitude and direction of the bias and whether we considered it is likely to impact on the findings. We explored the impact of the level of bias through undertaking sensitivity analyses - see Sensitivity analysis.

Measures of treatment effect

Dichotomous data

For dichotomous data, we presented results as summary risk ratios with 95% confidence intervals.

Continuous data

We used the mean difference if outcomes were measured in the same way between trials. We used the standardised mean difference to combine trials that measured the same outcome, but used different methods.

Unit of analysis issues

Cluster-randomised trials

We included cluster-randomised trials in the analyses along with individually-randomised trials provided that cluster-RCT data were adjusted for clustering and any baseline imbalances. We considered it reasonable to combine the results from both if there was little heterogeneity between the study designs and the interaction between the effect of intervention and the choice of randomisation unit was considered to be unlikely. We assessed risk of bias of these trials with particular attention to imbalances in baseline characteristics between the comparison arms, loss of clusters and appropriate analyses, and we acknowledged heterogeneity in the randomisation unit, performing sensitivity analyses to investigate the effects of including these studies on review findings.

Other issues

For studies that included three arms, we divided the control group into two equal groups and considered each comparison separately. If the number of events in the control group was an odd number, to reduce the risk of overestimating effects in favour of the intervention group, we halved it and rounded it down; for odd denominators (total number of participants in the control group), we rounded these numbers upwards for the same reason.

Dealing with missing data

For included studies, we noted levels of attrition. We imputed data for studies where results were incompletely reported, e.g. if percentages and denominators were known, but the number of events was missing. For all outcomes, we carried out, as far as possible, analyses on an intention-to-treat basis, that is, we attempted to include all participants randomised to each group in the analyses. The denominator for each outcome in each trial was the number randomised minus any participants whose outcomes were known to be missing.

Assessment of heterogeneity

We assessed statistical heterogeneity in each meta-analysis using the Tau², I² and Chi² statistics. We regarded heterogeneity as substantial if an I² was greater than 30% and either a Tau² was greater than zero, or there was a low P value (less than 0.10) in the Chi² test for heterogeneity. If we identified heterogeneity above 30%, we explored it by sensitivity and subgroup analyses.

Assessment of reporting biases

Where there were 10 or more studies in the meta-analysis, we investigated reporting biases (such as publication bias) using funnel plots, which we assessed visually for asymmetry. If asymmetry was suggested by a visual assessment, we performed exploratory analyses to investigate it.

Data synthesis

We carried out statistical analysis using the Review Manager software (RevMan 2014). We used random-effects meta-analysis to produce an overall summary, if an average treatment effect across trials.was considered clinically meaningful The random-effects summary was treated as the average of the range of possible treatment effects and we considered the clinical implications of treatment effects differing between trials. If the average treatment effect was not clinically meaningful, we did not combine trials. The results of these random-effects analyses are presented as the average treatment effect with 95% confidence intervals and estimates of I².

Subgroup analysis and investigation of heterogeneity

Subgroup analyses according to risk were not specified in the original review protocol. We conducted subgroup analyses according to the risk of adverse effects related to poor weight control with the high-risk group comprising only overweight and obese women, or women with or at risk of diabetes mellitus; a mixed-risk group comprising women in the general population, including women of any body mass indices (BMIs), and a low-risk group comprising normal weight women or women with BMIs of less than 25 kg/m2. Where possible, we performed subgroup analysis for the following outcomes.

  1. Excessive gestational weight gain (GWG)

  2. Mean GWG

  3. Low GWG

  4. Preterm birth

  5. Caesarean section

  6. Pre-eclampsia

  7. Macrosomia

For these analyses, we assessed subgroup differences by interaction tests available within RevMan (RevMan 2014) and reported the results of subgroup analyses quoting the Chi² statistic and P value, and the interaction test I² value.

We explored heterogeneity by organising studies within comparisons according to the types of interventions.

Sensitivity analysis

We carried out sensitivity analyses to explore the effect of trial quality by excluding studies with risk of bias concerns from the analyses in order to assess whether this made any difference to the overall result.

Quality of evidence

Following meta-analysis, the quality of the evidence was assessed using the GRADE approach (Schunemann 2009) for the following key outcomes.

  1. Excessive GWG

  2. Mean GWG

  3. Low GWG

  4. Preterm birth

  5. Caesarean section

  6. Pre-eclampsia

  7. Macrosomia

'Summary of findings' tables were created using this feature in RevMan 2014 with a summary of the intervention effect and a measure of quality produced for each of the above outcomes using the GRADE approach (GRADE 2014). The GRADE approach uses five considerations to assess the quality of the body of evidence for each outcome. We downgraded the evidence from 'high quality' by one level for serious (or by two levels for very serious) limitations, depending on assessments for risk of bias, indirectness of evidence, serious inconsistency, imprecision of effect estimates or potential publication bias.

Results

Description of studies

See Characteristics of included studies; Characteristics of excluded studies; Characteristics of studies awaiting classification; Characteristics of ongoing studies.

Results of the search

The original search identified 63 potential studies, of which we included 28 and excluded 12 studies in the original review (Muktabhant 2012). Two studies remained unclassified and 21 studies were ongoing.

Searches updated to November 2014 identified 169 eligible records. Of these 169 records, we included 102 records (pertaining to 41 new RCTs), and excluded 19 records (pertaining to 10 new studies, and one previously excluded study). Twelve of the 169 records were new reports of five previously included RCTs (Barakat 2011; Callaway 2010; Laitinen 2009; Luoto 2011; Phelan 2011), 36 records were of ongoing RCTs, and one record remained unclassified for this update (requiring translation from Farsi).

For this update, we excluded two previously included quasi-RCTs (Bechtel-Blackwell 2002; Moses 2006) and two RCTs that involved anti-suppressant drugs (Boileau 1968; Silverman 1971), which had previously been included under a broader title (see Differences between protocol and review).

Therefore, in summary, we included a total of 65 RCTs in this update (41 new and 24 previously included). Forty-nine studies (29 newly included) contributed data to quantitative synthesis. Twelve RCTs that had been identified as ongoing in the previous review have now been published, leaving 40 ongoing RCTs altogether (including new and previously included ongoing trials not yet reported) for this update (Characteristics of ongoing studies).

Included studies

Out of 65 included studies, two studies were cluster-RCTs (Luoto 2011; Rauh 2013); all other studies were RCTs. We were able to adjust data for one cluster-RCT (Luoto 2011; Appendix 1) and used adjusted data in meta-analyses, however we were unable to adjust data from Rauh 2013, which therefore did not contribute to meta-analyses. Seven RCT reports were conference abstracts (Angel 2011; Bisson 2014; Bogaerts 2012; Leiferman 2011; Marcinkevage 2012; Mujsindi 2014; Szmeja 2011). One of these studies (Leiferman 2011), also generated a substudy in the form of a PhD thesis (Nodine 2011), which we have linked to this study in the references section. When reported in full, these seven RCTs may yet contribute data to future versions of this review; however, in general, we gleaned very little methodological information and no usable data from the abstracts. We have included information about these trials in the Characteristics of included studies tables, but they are not otherwise discussed in the sections below.

Participants

Two studies (Bogaerts 2012; Leiferman 2011) did not report the number of participants. The remaining 63 included studies involved at least 13,523 pregnant participants, and the number of participants in each study ranged from 12 (Magee 1990) to more than 2000 (Dodd 2014). Fifty-five out of 65 studies reported age and body mass index (BMI) at baseline and these were similar between study and control groups, with a few exceptions (see Risk of bias in included studies). Four studies recruited only nulliparous women (Althuizen 2013; Haakstad 2011; Murtezani 2014; Pinzon 2012). Most studies recruited women less than 20 weeks' gestation (48/65; 74%), with 27/65 (42%) studies recruiting women less than or equal to 14 weeks' gestation. Thirteen studies recruited participants after 20 weeks' gestation, namely Rhodes 2010 (13 to 28 weeks); Ferrara 2011 (approximately 31 weeks on average); Louie 2011 (20 to 32 weeks); Angel 2011 (more than 20 weeks); Hui 2012, Hui 2006 and Jackson 2011 (up to 26 weeks); Magee 1990 (13 to 38 weeks); Moses 2009 (approximately 30 weeks on average); Pollak 2014 (up to 21 weeks); Stafne 2012 (18 to 22 weeks); Thornton 2009 (12 to 28 weeks); Vitolo 2011 (10 to 29 weeks). Gestation at recruitment was not clear for the remainder (Bogaerts 2012; Leiferman 2011; Mujsindi 2014; Quinlivan 2011).

Studies included participants of various weight categories with 'normal weight' generally defined as a BMI greater than 18 and less than 25 kg/m², 'overweight' was considered to be greater than or equal to 25 kg/m² and less than 30 kg/m², and 'obese' was considered to be a BMI of greater than or equal to 30 kg/m². Thirty-four studies recruited women from the 'general population' (i.e. of various BMIs) and the proportion of women with normal BMIs varied widely across study samples reporting this baseline characteristic, from 15% to 79% of participants. Most of these studies did not report results for high- (overweight/obese women) and low-risk (normal BMI) women separately; however, for eight of these studies (Althuizen 2013; Hui 2014; Jeffries 2009; Phelan 2011; Polley 2002; Ronnberg 2014; Ruiz 2013; Vitolo 2011), main outcomes were reported separately for women with low/normal versus overweight/obese prepregnancy weights; therefore, where possible, we used relevant data from these studies for meta-analyses pertaining to low, mixed-risk and high-risk groups. One study (ROLO 2012) recruited only secundigravid women who had previously given birth to a baby with macrosomia and reported certain outcomes separately for women in all weight categories.

Among 31 studies recruiting women in high-risk groups, 24 studies recruited overweight and obese women, or obese women only (Angel 2011; Bisson 2014; Bogaerts 2012; Callaway 2010; Dodd 2014; Guelinckx 2010; Kong 2014; Magee 1990; Marcinkevage 2012; Mujsindi 2014; Nascimento 2012; Oostdam 2012; Petrella 2013; Poston 2013; Pollak 2014; Quinlivan 2011; Renault 2014; Rhodes 2010; Santos 2005; Szmeja 2011; Thornton 2009; Vesco 2013; Vinter 2012; Wolff 2008); and seven recruited women with, or defined as at high risk of, gestational diabetes (Ferrara 2011; Harrison 2013; Korpi-Hyovalti 2011; Louie 2011; Luoto 2011; Moses 2009; Rae 2000).

Settings

Most studies were conducted in high-income countries, including Australia (Callaway 2010; Dodd 2014; Harrison 2013; Jeffries 2009; Louie 2011; Moses 2009; Moses 2014; Quinlivan 2011; Szmeja 2011; Wilkinson 2012), Belgium (Bogaerts 2012; Guelinckx 2010), Canada (Hui 2006; Hui 2012; Hui 2014; Hui 2014; Ruchat 2012), Denmark (Renault 2014; Vinter 2012; Wolff 2008), Finland (Korpi-Hyovalti 2011; Laitinen 2009; Luoto 2011), Germany (Rauh 2013), Ireland (ROLO 2012), Italy (Di Carlo 2014; Petrella 2013), Kosovo (Murtezani 2014), Norway (Haakstad 2011), Sweden (Petrov Fieril 2014; Ronnberg 2014), The Netherlands (Althuizen 2013; Oostdam 2012), Spain (Barakat 2011; Cordero 2014; Ruiz 2013), the United Kingdom (Poston 2013) and the United States of America (USA) (Angel 2011; Asbee 2009; Bisson 2014; Clapp 2002a; Clapp 2002b; Ferrara 2011; Hawkins 2014; Kieffer 2014; Kong 2014; Leiferman 2011; Magee 1990; Marcinkevage 2012; Mujsindi 2014; Phelan 2011; Pollak 2014; Polley 2002; Price 2012; Rhodes 2010; Thornton 2009; Vesco 2013). Two of these studies (Hui 2006; Polley 2002) recruited women with low-, or low-middle incomes in Canada and the USA, respectively. Of the six studies conducted in low-income countries, four were conducted in Brazil (De Oliveria Melo 2012; Nascimento 2012; Santos 2005; Vitolo 2011), one was conducted in Columbia (Pinzon 2012) and one was conducted in Taiwan (Huang 2011).

Interventions

All the interventions considered in this review included modifying or restricting diet or increasing exercise, or both; however there was considerable variation in the interventions used, which included:

Interventions varied in intensity. Control groups mostly comprised routine or standard care (which also varied considerably in different settings and was not always well-described). Hui 2006 compared a supervised group exercise and diet intervention with an exercise and diet information pack. Clapp 2002b compared different exercise intensities at different stages of pregnancy. Some studies included more than two arms (De Oliveria Melo 2012; Laitinen 2009; Guelinckx 2010; Renault 2014).

Outcomes

Gestational weight gain (GWG) or excessive GWG, or both, were reported as primary or secondary outcomes in 75% of included studies. Excessive GWG was usually defined according to prevailing IOM guidelines. Generally, baseline weight was measured at recruitment; however, several studies used self-reported prepregnancy weight as the baseline measurement (e.g. Di Carlo 2014; Haakstad 2011; Hui 2012; Louie 2011; Moses 2014; Oostdam 2012). The final weight measurement was either collected by researchers at the last clinic or hospital visit (usually greater than or equal to 36 weeks) or from medical records. Several studies collected these follow-up weight data earlier than 36 weeks, including Vesco 2013 (34 weeks), Oostdam 2012 (32 weeks), Harrison 2013 (28 weeks), and Petrov Fieril 2014 (25 weeks). The latter study included mean weight as an outcome, but not mean weight gain.

Other reported outcomes included postpartum weight retention, macrosomia, infant birthweight, gestational diabetes, pre-eclampsia/hypertension, diet and physical activity (PA) behaviour, breastfeeding, biochemical parameters, e.g. serum insulin levels, and various other maternal and neonatal outcomes.

Excluded studies

Initially, we excluded 26 studies (12 previously excluded, 10 new excluded and four previously included). One previously excluded study (Moses 2007), was a follow-up of a previously included study (Moses 2006) and these two reports are now listed together, reducing the number of excluded studies to 25 studies. The main reasons for exclusion were as follows.

  1. Non-randomised study or quasi-RCT: Bechtel-Blackwell 2002; Breslow 1963; Daley 2014; Davenport 2011; Graham 2014; Gray-Donald 2000; Kinnunen 2007; Maitland 2014; Mohebi 2009; Moses 2006; Mottola 2010; Olson 2004; Stutzman 2010; Walker 1966.

  2. Participants included non-pregnant or postpartum women: Campbell 2004; Faucher 2008; Hausenblas 2008; Te Morenga 2011; Wisner 2006.

  3. Not a diet or exercise intervention: Asemi 2011; Boileau 1968; Hauner 2012; Ismail 1990; Lindsay 2014; Silverman 1971.

Risk of bias in included studies

Details of the methodological quality of each study are given in Characteristics of included studies, Figure 1, and Figure 2. Studies were considered to be potentially at a moderate-to-high risk of bias if they were assessed to be at 'high risk' for at least one of the risk of bias items below, excluding blinding, as most studies were open-label. We considered 35/65 studies (54%) to be at a low risk of bias overall, and 20/65 (29%) to be at a moderate-to-high risk of bias overall (Asbee 2009; Barakat 2011; Callaway 2010; Cordero 2014; Di Carlo 2014; Ferrara 2011; Luoto 2011; Murtezani 2014; Nascimento 2012; Oostdam 2012; Petrov Fieril 2014; Pinzon 2012; Price 2012; Rauh 2013; Ruchat 2012; Santos 2005; Stafne 2012; Vitolo 2011; Wilkinson 2012; Wolff 2008). Five of the latter studies (Callaway 2010; Pinzon 2012; Rauh 2013; Vitolo 2011; Wilkinson 2012) did not contribute to quantitative analysis in this update. The remaining 10 studies were at an unclear risk of bias (Angel 2011; Bisson 2014; Bogaerts 2012; Korpi-Hyovalti 2011; Leiferman 2011; Magee 1990; Marcinkevage 2012; Mujsindi 2014; Polley 2002; Szmeja 2011).

Figure 1.

Methodological quality summary: review authors' judgements about each methodological quality item for each included study.

Figure 2.

Methodological quality graph: review authors' judgements about each methodological quality item presented as percentages across all included studies.

Allocation

Out of 65 studies, 45 (69%) were assessed as being at low risk of bias for generation of the randomisation sequence and 34 (52%) used methods that we judged to be at a low risk of bias for allocation concealment. The remaining studies (25%) were at an unclear risk of selection bias.

Blinding

Twenty-four out of 65 studies (37%) had taken some steps to implement performance or detection blinding, or both. Achieving participant and personnel blinding of treatment allocation for diet and exercise interventions was indicated to be not feasible in several studies and was not described in many others. Where studies were described as open-label or unblinded, we classified these as at a high risk of bias for this item; however, it was difficult to ascertain whether the lack of blinding, or unsuccessful blinding, impacted on outcomes or resulted in any systematic bias. In addition, the studies that did not describe blinding were probably unblinded. For these reasons we did not use blinding as a criterion in the overall assessment of individual study bias but rather took into account other types of bias.

Incomplete outcome data

We assessed 29/65 studies (45%) to be at a low risk of attrition bias. Fourteen studies (22%) (Callaway 2010; Cordero 2014; Di Carlo 2014; Ferrara 2011; Luoto 2011; Oostdam 2012; Petrov Fieril 2014; Pinzon 2012; Price 2012; Ruchat 2012; Santos 2005; Stafne 2012; Wilkinson 2012; Wolff 2008) had high attrition (greater than 20%) overall, or for the intervention or control group only, or for certain outcomes, and we considered these to be at a high risk of bias accordingly. In the remaining studies, loss of outcome data was either not stated or was less than 20% but there were other concerns (e.g. imbalance in attrition between arms) and for these we considered the risk of bias to be unclear.

Selective reporting

It was difficult to assess bias associated with the outcome reporting bias as we did not have access to the study protocols of most studies and we did not know whether results for all outcomes where data had been collected had been reported; we therefore assessed many of these studies as being unclear for the outcome reporting bias. However, we considered Cordero 2014 and Di Carlo 2014 to be at a potentially high risk of reporting bias as only per protocol findings were reported. During the course of these studies, women with preterm labour were excluded, therefore, this potential side-effect could not be evaluated. In addition, Cordero 2014 additionally excluded data from women with poor adherence to the intervention; therefore, the reported results may be biased in the direction of the intervention.

Other potential sources of bias

Six studies had important baseline imbalances in the characteristics of the women in the intervention and control groups (Barakat 2011; Cordero 2014; Di Carlo 2014; Price 2012; Rauh 2013; Santos 2005) that might have impacted the results in favour of the intervention. Barakat 2011, Cordero 2014, Di Carlo 2014 and Price 2012 did not adjust results for these imbalances and we therefore considered them to be at a potentially high risk of bias. Cordero 2014 additionally had an unexplained difference in intervention and control group sizes. Rauh 2013 is discussed below under 'Assessment of cluster-RCTs'.

In Price 2012, control participants were told not to exercise because it would blur the distinction between the groups. This contributed to high drop-out rates in the control group and bias in favour of the intervention, whilst making results less applicable by enforcing no exercise. Oostdam 2012 had issues with adherence to the intervention, which may have biased results in favour of the control group.

Most studies involving an exercise component excluded women at risk of miscarriage or preterm birth at screening. However, four studies excluded women with or at risk of preterm birth post-randomisation from analysis (Cordero 2014; Di Carlo 2014; Murtezani 2014; Rauh 2013). This omission might have led to publication bias in the review's 'preterm birth' outcome. Any other potential sources of bias were noted in the Characteristics of included studies.

Assessment of cluster-RCTs

Two trials were cluster-RCTs (Luoto 2011; Rauh 2013).

Recruitment bias: In Rauh 2013, intervention and control groups differed substantially in size as "During recruitment it turned out that it was easier to recruit women for the intervention group than for the control group, yielding a 2:1 ratio", instead of 1:1. In Luoto 2011, more than 20% and 30% in the intervention and control arms, respectively, were excluded from analysis based on oral glucose tolerance tests conducted between eight and 12 weeks' gestation. Only 40% and 47% of women in intervention and control groups, respectively, who were assessed as preliminary eligible were analysed.

Baseline imbalances: Baseline imbalances were limited to differences in educational levels between arms in Luoto 2011. However, in Rauh 2013, baseline characteristics differed significantly with regard to pregravid BMI (P = 0.003) and BMI at booking (P = 0.008), with a higher proportion of women in the control group considered obese or overweight (16.2% versus 31.4%; P = 0.009). In addition, mean age was younger and gestational age at booking was significantly earlier in the intervention clusters.

Loss of clusters: There was no loss of clusters in either study.

Analysis methods: Both Luoto 2011 and Rauh 2013 reported adjusting the summary effect size for clusters and baseline imbalances. However, outcome data for both studies needed to be estimated for use in meta-analysis, and this was not possible for Rauh 2013, due to insufficient data and the lack of an intracluster correlation coefficient. The results reported in Rauh 2013 favoured the intervention arm for weight gain outcomes (Appendix 2), and although these were adjusted for BMI, age and clustering, there may also have been other (unknown) differences between the women in these groups. We therefore considered this study to be at potentially high risk of bias; however, Rauh 2013 data did not contribute to meta-analyses.

Comparability with individually-randomised trials: These trials were comparable to individually-randomised trials except that large differences in study group sizes occurred in Rauh 2013. Study investigators reported that the clusters (gynaecology practices) differed significantly in size; the result was that 227 versus 129 women were eligible for the intervention and control clusters, respectively.

Overall assessment: We assessed these cluster-RCTs as moderate-to-high risk of bias. Adjusted Luoto 2011 data were used in meta-analyses; however, Rauh 2013 data could not be adjusted and were therefore not used.

Effects of interventions

See: Summary of findings for the main comparison All diet and/or exercise interventions compared to standard/other care for preventing excessive weight gain in pregnancy; Summary of findings 2 Comparative table of findings by intervention type

We compared diet or exercise, or both, interventions together (comparisons 1) organised by types of interventions (see Table 1 for the rationale for study categories). We also analysed each intervention category separately stratified for risk (comparisons 2, 3, 4, and 5 ) for all women (i.e. a mixed-risk population), low risk, and high-risk women.

Table 1. Types of Interventions assessed in studies contributing data
  1. BMI: body mass index
    CHO: carbohydrate
    GL: glycaemic load
    IOM: Institute of Medicine
    RDA: recommended dietary allowance

NumberStudy IDExperimental intervention (unless otherwise stated, the control intervention was routine care)Participants analysedContributed data
Low riskMixed riskHigh risk
Diet counselling/other
1 Di Carlo 2014The intervention involved a supervised personalised diet plan meeting both personal preferences and specific gestational needs with the average caloric intake being 1916 kcal. The only fat allowed was olive oil. Participants in the intervention group underwent monthly follow-up appointments with a dietician who monitored their weight gain and discussed issues. Control group received standard brochure on healthy eating.120 / 
2. Jeffries 2009Women were given a personalised weight measurement card, advised of their optimal gestational weight gain based on their BMI at the time of recruitment and the United States IOM guidelines, and instructed to record their weight at 16, 20, 24, 28, 30, 32 and 34 weeks' gestation.236 //
3. Laitinen 2009Dietary counselling was given by a dietitian at each study visit and aimed to modify dietary intake to conform with that currently recommended, particular attention being paid to the quality of dietary fat. Study visits took place 3 times during pregnancy and at 1, 6 and 12 months postpartum.171 / 
4. Quinlivan 2011This was a multi-faceted intervention that included weighing on arrival and a brief dietary intervention by a food technologist at every antenatal visit. Other aspects of the intervention involved continuity of care provider and psychological assessment.124  /
5. Rae 2000The intervention comprised instruction in a moderately energy restricted diabetic diet providing between 1590-1776 kcal (70% RDA).117  /
6. Thornton 2009Participants were counselled in nutrition and monitored by a registered dietitian and given a detailed nutrition program similar to a diabetic diet.232  /
7. Wolff 2008Intervention comprise a healthy diet according to the official Danish dietary recommendations (% fat, protein, CHO, 30%, 15%-20%, 50%-55%). The energy intake was restricted based on individually estimated energy requirements and estimated energetic cost of fetal growth.50  /
Low GL diet   
8. Clapp 2002bParticipants were randomised to either a low-glycaemic diet (aboriginal diet) or high-glycaemic diet (cafeteria diet).20 / 
9. Louie 2011Intervention was a healthy low-GL diet of protein (15%-25%), fat (25%-30%) and carbohydrate (40%-45%) (versus healthy high-fibre diet with moderate GL, similar to population average). Participants attended at least 3 face-to-face visits with the study dietician for monitoring adherence and encouragement. Intervention began after 29th week.92  /
10. Moses 2009Low-GL diet versus high-GL diet. The dietary advice by dietitian was individualised with specific mention of the energy and nutrient balance to achieve normal weight gain during the 3rd trimester.63 / 
11. Moses 2014The intervention involved a low glycaemic diet from 12 to 16 weeks' gestation for the remainder of pregnancy (compared with conventional healthy eating). Women received a detailed dietary education tailored for the group assignment at baseline - there were no difference in the macronutrient distribution in the diets, only the substitution of carbohydrate-rich foods with low GL alternatives in the experimental group. Information booklets were provided. 4 contact points with a research dietician were planned (first visit, phone call, midway and final visits) to collect data and ensure adherence.576  /
12. Rhodes 2010Nutrition education, dietary counselling, and a low-GL diet (vs a low-fat diet).50  /
13. ROLO 2012Low-GL dietary intervention given by a dietitian involving 1 dietary education session lasting 2 hours in groups of 2 -6 women at baseline. Follow-up reinforcement sessions were held at 28 and 34 weeks' gestation. Women also received written resources about low-GL foods.759///
Diet and exercise counselling   
14. Althuizen 2013The intervention involved counselling by members of the research team consisting of 5 x 15 minute sessions on weight, physical activity and diet. Interventions were face-to-face at 18, 22, 30, and 36 weeks' gestation, with a telephone session at 8 weeks postpartum. Counsellors discussed how to control weight gain during and after pregnancy, and how to maintain a healthy lifestyle.219 //
15 Asbee 2009At the initial visit, participants met with a registered dietician to receive a standardised counselling session, including information on pregnancy-specific dietary and lifestyle choices. Participants were instructed to engage in moderate-intensity exercise at least 3 times per week and preferably 5 times per week. Weight gain was reviewed at each routine antenatal visit.100 / 
16. Asbee 2009Comprehensive dietary and lifestyle intervention (counselling) (n = 1108) Intervention involved meetings and home visits with advice on dietary, exercise, and behavioural strategies delivered by a dietician and trained research assistants. Exercise advice primarily encouraged women to increase their amount of walking and incidental activity.2212  /
17. Ferrara 2011Lifestyle intervention involved 3 in-person sessions and up to 15 telephone calls with counselling re diet, physical activity and breast-feeding up to 12 months postpartum. The intervention was delivered by 2 dietitians. Participants were encouraged to engage in moderate-intensity physical activity for 150 minutes per week and received written materials about food size, foods with low GL or low fat, and how to read food labels were discussed,197  /
18. Guelinckx 20102 intervention arms: 1 involved a brochure only, the other involved a brochure and counselling by a trained nutritionist in 3 group sessions. A maximum of 5 women were brought together in these 1-hour sessions, which were scheduled at 15, 20, and 32 weeks of pregnancy. The sessions provided participants with recommendations on a balanced, healthy diet, and physical activity specifically designed for the study to limit weight gain.124  /
19. Harrison 2013Intervention provided dietary advice, simple healthy eating, and "physical activity messages" and weight gain self-monitoring. Also included "regular self-weighing as a key behavioural strategy".203  /
20. Hawkins 2014A lifestyle intervention consisting of a culturally and linguistically modified, motivationally targeted, individually tailored 6-month prenatal programme. Educators encouraged women to achieve guidelines for physical activity, decrease saturated fat and increase dietary fibre. The intervention consisted of 6 monthly in-person behavioural counselling sessions and 5 telephone booster sessions with follow-up to 6 weeks postpartum. Women were encourage to achieve ≥ 30 minutes of moderate-intensity activity on most days of the week through walking and developing a more active lifestyle.68  /
21. Huang 2011The intervention was delivered at regularly scheduled clinic visits by nurses with training in nutrition and physical fitness. The nurse discussed with each participant how to design an individualised diet and physical activity plan. The intervention consisted of 6 1-to-1 counselling sessions: 1 primary session (about 30–40 minutes) at the 16-week gestation visit, and 5 1-to-1 booster sessions (at 28 gestational weeks, 36–38 gestational weeks, before hospital discharge after a 3 to 7-day stay, 6 weeks' postpartum and 3 months postpartum). After each clinic visit, women in the experimental groups were sent a personalised graph of their weight changes. At the 1st session, the experimental groups also received a researcher-prepared brochure that provided detailed information on weight management goals during pregnancy and postpartum.160 / 
22. Korpi-Hyovalti 2011Individual dietary advice tailored to each participant at 6 visits to include a low fat diet rich in vegetables, fruit and berries. Moderate-intensity physical exercise was encouraged at 6 exercise counselling sessions.60  /
23. Luoto 2011Individual counselling on physical activity and diet and weight gain. At the first visit the recommendations for gestational weight gain were discussed and an appropriate weight gain graph was selected to guide the participant in monitoring her weight gain. Physical activity counselling was implemented at 8–12 weeks' gestation and the dietary counselling session occurred at 16–18 weeks' gestation. Physical activity counselling was enhanced at 4, and diet counselling at 3 subsequent visits.399  /
24. Petrella 2013Lifestyle intervention involving a caloric restricted diet (1500 kcal/day) and mild exercise 30 minutes/day, 3 times per week monitored by a pedometer.63  /
25. Phelan 2011The Fit for Delivery intervention included a face-to-face visit with an interventionist at the onset of treatment who discussed appropriate weight gains during pregnancy, physical activity (30 minutes of walking most days of the week), and calorie goals (20 kcal/kg). Emphasis was placed on decreasing high fat foods, increasing physical activity, and daily self-monitoring. Women also received personalised weight graphs after each clinic visit, automated supportive postcards and 3 supportive phone calls.401/ /
26. Polley 2002Intervention conducted at routine clinic visits by staff with training in nutrition or psychology involved education about weight gain, healthy eating, and exercise, and individual graphs of their weight gain. After each clinic visit, women were sent a personalised graph of their weight gain.110/ /
27. Poston 2013A lifestyle intervention (diet plus exercise) involving 1 1-to-1 counselling session with a health trainer and then weekly group sessions for 8 consecutive weeks from 19 weeks' gestation. Sessions delivered by health trainers involved diet and exercise advice informed by psychological models of health behaviour. Dietary advice focused on increased consumption of foods with a low-dietary GL, and reduction of saturated fats. Physical activity advice encouraged women to increase daily walking activity at moderate-intensity level, setting goals monitored by a pedometer. Women also received a DVD of a pregnancy specific exercise regimen.154  /
28. Renault 2014A 3-arm study with 2 intervention groups. 1 intervention involved unsupervised exercise only (women were given a pedometer), the other involved diet and exercise counselling only. The diet and exercise intervention included follow-up on a hypocaloric Mediterranean-style diet. Instruction was given by a dietician every 2 weeks with alternating outpatient visits and phone calls, including weight measurement, encouragement and correcting advice on exercise and diet.389  /
29. Vesco 2013Intervention involved a 45-minute diet consultation with an individualised caloric goal, a second individualised session, weekly group meetings with weigh ins, food/activity logs. Women are encouraged to accumulate at least 30 minutes of moderate-intensity activity per day. Pedometers recorded steps with a target of 10,000 steps daily and were only provided to the intervention group.114  /
Unsupervised exercise intervention   
30. Kong 2014Unsupervised exercise intervention involved a walking program on treadmill or other setting for a minimum of 150 min/week. Women were loaned treadmills for the study and steps monitored.42  /
31. Renault 2014A 3-arm study with 2 intervention groups. 1 intervention involved unsupervised exercise only (women were given a pedometer), the other involved diet and exercise counselling. The physical activity intervention included encouragement or increase physical activity, aiming at a daily step count of 11,000, monitored by pedometer assessment on 7 consecutive days, every 4 weeks.389  /
32. Ronnberg 2014Intervention involved prescribed exercise to be at a "moderate level of exertion for approximately 30 min/day".374///
Supervised exercise intervention   
33. Barakat 2011Intervention involved 35- to 45-minute exercise sessions 3 times per week from the start of the pregnancy (weeks 6-9) to the end of the 3rd trimester (weeks 38-39) - an average of 85 training sessions. Exercise intensity was light-to-moderate and was supervised by a fitness specialist in groups of 10-12 women.80 / 
34. Cordero 2014A supervised exercise program consisting of aerobic and toning exercises for 3 sessions per week. 2 weekly sessions were performed on land (60 minutes) and 1 session was aquatic based (50 minutes). Program commenced from 10-14 weeks to the end of the third trimester. Sessions were supervised by a qualified fitness specialist and an obstetrician.257 / 
35. De Oliveria Melo 2012Supervised moderate-intensity exercise (initiated at 13 weeks or 20 weeks) vs control . Sessions consisted of warming up and stretching exercises, followed by supervised walking 3 times a week in the open air. Supervised by physical education professionals and medical, physiotherapy and nursing students.187 / 
36. Haakstad 2011Exercise (60 minutes supervised aerobic dance at least twice a week for a minimum of 12 weeks) (n = 52). Women in the exercise group were advised to have moderate, self-imposed physical activity on the remaining weekdays.105 / 
37. Murtezani 2014The exercise training program started in the second trimester and was continued until the end of pregnancy. Each session consisted of 40-45 minutes of aerobic and strength exercise. Individuals were supervised by certified aerobic-instructors, and each session included a maximum of 10 participants. Intensity was moderate-to-vigorous; supine postures and Valsalva manoeuvres were avoided.63 / 
38. Nascimento 2012Intervention consisted of a supervised exercise program guided by a trained physical therapist in weekly classes with light-to-moderate-intensity exercise for 40 minutes. It also included home exercise counselling which was to be performed 5 times per week (consisting of a sequence of 22 exercises or walking).82  /
39. Oostdam 2012A supervised exercise intervention comprising 2 sessions of aerobic and strengthening exercises per week; each exercise session lasted for 60 minutes from 20 weeks' gestation.101  /
40. Petrov Fieril 2014Intervention group received supervised resistance exercise twice a week, with light barbells and weight plates in a group setting, performed at an activity level equivalent to within moderate–to-vigorous between weeks 14 to 25 gestation, and was self-adjusted. In addition, walking, cycling, water-gymnastics, Pilates, yoga and home exercises that included pelvic floor training were recommended.72 / 
41. Price 2012Intervention involved a program of supervised aerobic training of 45-60 minutes, 4 days per week.62 / 
42. Ruiz 2013Intervention involved light-to moderate-intensity supervised aerobic and resistance exercises (including pelvic floor exercises) performed 3 days a week (50-55 minutes per session) from 9 weeks to weeks 38-39. Exercise sessions involved 8-10 participants.962///
43 Santos 2005The intervention consisted of a program of supervised physical exercise of 60 minutes duration, performed 3 times per week for 12 weeks.72  /
44. Stafne 2012intervention comprised a 12-week regular standardised exercise program including aerobic activity, strength training, and balance exercises. The exercise program followed standard recommendations and included moderate-intensity to high-intensity activity 3 or more days per week. Physiotherapist-supervised training sessions of 60 minutes in groups of 8-15 women were offered once per week.702 / 
Supervised exercise and diet intervention   
45. Hui 2006Exercise intervention involved a weekly supervised group session including floor aerobics, stretching and strength exercises, and similar home-based exercise 3-5 times/week for 30-45 minutes per session. A video was provided to participants to assist with home-based exercise. Diet intervention involved a computer-assisted food choice map interview and a personalised plan by a dietician.46 / 
46. Hui 2012Exercise intervention involved an exercise regimen comprising 3 to 5 times per week, including a weekly supervised community-based session and multiple home sessions, of mild-to-moderate exercise for 30 to 45 minutes. Program started between 20-26 weeks. Group exercise sessions including aerobics were held in community centres and instructors were licensed fitness trainers. 2 dietary interviews with counselling were provided.190 / 
47. Hui 2014Lifestyle intervention (diet counselling and a supervised exercise program) vs control. Intervention included "a community-based exercise program specifically designed for pregnant women was provided". An exercise regimen, 3 to 5 times per week including a weekly exercise session and home sessions with DVD instruction of mild-to-moderate aerobic exercise for 30 to 45 minutes was recommended. Program started between 20-26 weeks and continued to 36 weeks. Group exercise sessions including aerobics were held in community centres and instructors were licensed fitness trainers. 2 dietary interviews with dietician counselling using a Food Choice Map were provided (baseline and 2 months later). Control group received standard care.113 //
48. Ruchat 2012Moderate-intensity exercise 3-4 times per week, including 1 supervised session (versus low-intensity exercise in the form of a walking program 3-4 times per week). All participants received a diet plan based on a modified diabetic diet.49 / 
49. Vinter 2012A lifestyle intervention consisting of dietary counselling and exercise. The intervention involved dietary advise on 4 occasions (15, 20, 28 and 35 weeks) by a dietician. Energy requirements were personalised for each participant. Exercise intervention included a pedometer and free gym membership for 6 months. Participants were encouraged to do 30-60 minutes moderate-physical activity daily. In addition, at the gym they had 1 supervised aerobic class with a physiotherapist for 1 hour each week.304  /

1. Diet and/or exercise interventions vs routine care in all pregnant women

Forty-nine studies involving 11,444 participants contributed data to these analyses. A maximum of 36 studies contributed data to Comparison 1 analyses. Funnel plots were asymmetrical for most analyses.

1.1 Excessive gestational weight gain (GWG)

Diet or exercise, or both, interventions resulted in an average risk reduction of excessive GWG of 20% in favour of the intervention group (risk ratio (RR) 0.80, 95% confidence interval (CI) 0.73 to 0.87; participants = 7096; studies = 24; I² = 52%; Analysis 1.1). Reductions in favour of the intervention arms were consistent across the different types of intervention groups, except for the heterogenous group comprising 'diet counselling or other interventions', with the largest reduction occurring with 'supervised exercise and diet' interventions.

Sensitivity analysis

When we removed five studies with risk of bias concerns from the meta-analysis (Cordero 2014; Di Carlo 2014; Ferrara 2011; Hui 2006; Ruchat 2012), heterogeneity was reduced and the average overall effect in favour of the intervention group was robust to the original result (RR 0.82, 95% CI 0.76 to 0.89; participants = 6437; studies = 19; I² = 40%). In addition, when we pooled data from exercise only interventions (supervised and unsupervised), findings were similar (RR 0.79, 95% CI 0.70 to 0.89; participants = 1901; studies = six; I² = 0%).

Quality of the evidence

We graded this evidence as high quality.

1.2 Mean gestational weight gain (GWG)

Thirty-six studies reported this outcome; however, due to substantial heterogeneity we did not pool these data (Analysis 1.2). Thirteen studies reported significant differences in mean GWG between intervention and control groups in favour of the interventions, with five studies reporting mean differences in GWG in excess of 5 kg (Clapp 2002a; Di Carlo 2014; Thornton 2009; Quinlivan 2011; Wolff 2008). The remainder of studies found no significant difference in mean GWG between groups.

1.3 Low weight gain

Women in the intervention group were significantly more likely to experience low GWG compared with the control group (average RR 1.14, 95% CI 1.02 to 1.27; participants = 4422; studies = 11; I² = 3%; Analysis 1.3). Results according to types of interventions were not statistically significant, with wide confidence intervals and a consistent trend in favour of the control group. However, when data from the supervised and unsupervised exercise groups were combined the effect was of borderline statistical significance (RR 1.19, 95% CI 1.00 to 1.41; participants = 1565; studies = four; I² = 0%).

Sensitivity analysis

There were no serious risk of bias concerns for this analysis.

Quality of the evidence

We graded this evidence as moderate quality.

1.4 Preterm birth

There was no statistically significant difference between intervention and control groups for preterm birth outcomes (average RR 0.91, 95% CI 0.68 to 1.22; participants = 5923; studies = 16; I² = 16%; Analysis 1.4). Point estimates for exercise only interventions favoured the control groups; however, when data from the supervised and unsupervised groups were combined the trend was not statistically significant (RR 1.59, 95% CI 0.76 to 3.33; participants = 1358; studies = five; I² = 0%).

Sensitivity analysis

When two studies with risk of bias concerns were excluded from the analysis (Price 2012; Petrella 2013), results were similar to the original analysis (average RR 0.88, 95% CI 0.70 to 1.10; participants = 5800; studies = 14; I² = 0%).

Quality of the evidence

We downgraded this evidence to moderate quality due to risk of bias concerns arising from potential under-reporting (in at least four studies, women at risk of preterm birth were withdrawn; see Risk of bias in included studies).

1.5 Pre-eclampsia

There was no statistically significant difference between the intervention and control groups with regard to pre-eclampsia (average RR 0.95, 95% CI 0.77 to 1.16; participants = 5330; studies = 15; I² = 0%; Analysis 1.5).

Quality of the evidence

We graded the quality of this evidence as high.

1.6 Hypertension (not prespecified)

Maternal hypertension occurred significantly more frequently in the control group compared with the intervention group (average RR 0.70, 95% CI 0.51 to 0.96; participants = 5162; studies = 11; I² = 43%; Analysis 1.6).

Sensitivity analysis and investigation of heterogeneity

When we excluded three studies (Petrella 2013; Price 2012; Stafne 2012) with risk of bias concerns, the result remained in favour of the interventions; however it was no longer statistically significant (RR 0.74, 95% CI 0.53 to 1.02; participants = 4314; studies = eight; I² = 44%). Heterogeneity could not be attributed to differences between the different types of interventions. We investigated heterogeneity further below, by subgrouping studies by participant risk group.

Quality of the evidence

We downgraded the evidence to low quality due to inconsistency and risk of bias concerns.

1.7 Induction of labour

There was no statistically significant difference between intervention and control groups for this outcome (average RR 1.06, 95% CI 0.94 to 1.19; participants = 3832; studies = eight; I² = 9%; Analysis 1.7).

Quality of the evidence

We graded the quality of this evidence as high.

1.8 Caesarean delivery

There was no statistically significant difference in the risk of caesarean section between intervention and control groups (average RR 0.95, 95% CI 0.88 to 1.03; participants = 7534; studies = 28; I² = 9%; Analysis 1.8); although the point estimate favoured a small reduction in favour of the intervention group. Effect estimates for supervised and unsupervised exercise interventions only, alone or combined, were robust to the overall findings. However, for the diet and exercise counselling interventions, the effect estimate approached statistical significance with a 13% reduction in caesarean delivery in the intervention group (RR 0.87, 95% CI 0.75 to 1.01; participants = 3406; studies = 9; I² = 15%; P = 0.06).

Sensitivity analysis

When we excluded two studies with risk of bias concerns (Di Carlo 2014; Price 2012), the results moved further toward the null (average RR 0.97, 95% CI 0.91 to 1.04; participants = 7323; studies = 26; I² = 2%).

Quality of the evidence

We graded the quality of this evidence as high, although effects may differ according to types of interventions.

1.9 and 1.10 Maternal postpartum weight retention (mean [kg] and rate)

Diet or exercise, or both, interventions on average were not associated with less postpartum weight retention in kilograms compared with the controls (average mean difference (MD) -1.12, 95% CI -2.49 to 0.25; participants = 818; studies = 7; I² = 55%; Analysis 1.9); however, pooled data from five studies indicated significantly lower rates of postpartum weight retention in the intervention group (average RR 0.78, 95% CI 0.63 to 0.97; participants = 902; studies = five; I² = 63%, Analysis 1.10).

Sensitivity analysis and investigation of heterogeneity

Time frames for these assessments ranged from six weeks to six months postpartum which may have accounted for the heterogeneity. Several studies had risk of bias concerns (mainly attrition bias) for these outcomes; therefore, we did not perform sensitivity analysis.

Quality of the evidence

We graded this evidence as low quality due to inconsistency and risk of bias concerns.

1.11 to 1.13 Behaviour modification outcomes (diet and physical activity)
Energy and fibre intake

Data on mean energy intake were available for 12 studies and revealed a statistically significant difference in energy intake (in kilojoules) between intervention and control groups (average MD -570.77, 95% CI -894.28 to -247.26; participants = 4065; studies = 12; I² = 73%;Analysis 1.11). Similarly, fibre intake in grams was significantly higher in the intervention group (MD 1.53, 95% CI 0.94 to 2.12; participants = 3466; studies = 8; I² = 0%; Analysis 1.12).

Physical activity score at 26 to 29 weeks

Women in the intervention group revealed higher physical activity scores on average compared with controls (average standardised mean difference (SMD) 0.40, 95% CI 0.18 to 0.61; participants = 2851; studies = 9; I² = 75%; Analysis 1.13).

Quality of evidence

We graded evidence relating to behaviour modification outcomes as low quality due to heterogeneity and risk of bias concerns, particularly detection (mainly self-reported outcomes) and attrition bias.

1.14 Infant birthweight greater than 4000 g

There was no statistically significant difference in the risk of macrosomia (birthweight greater than 4000 g) between intervention and control groups overall (average RR 0.93, 95% CI 0.86 to 1.02; participants = 8598; studies = 27; I² = 0%, Analysis 1.14), although the trend favoured the intervention groups. For the 'supervised exercise' intervention group, the effect in favour of the intervention bordered on statistical significance (average RR 0.81, 95% CI 0.64 to 1.02; participants = 2445; studies = seven; I² = 0%; P = 0.07), but not when supervised and unsupervised exercise interventions were combined (RR 0.87, 95% CI 0.71 to 1.07; participants = 2674; studies = nine; I² = 0%).

Sensitivity analysis

Results were similar when we performed sensitivity analysis by excluding seven studies (Cordero 2014;Ferrara 2011; Luoto 2011; Murtezani 2014; Stafne 2012; Ruchat 2012) with risk of bias concerns from the analysis (average RR 0.92, 95% CI 0.82 to 1.04; participants = 7021; studies = 20; I² = 11%).

Quality of the evidence

We graded the evidence as high, although further research may reveal important differences between intervention types.

1.15 Infant birthweight greater than 90th centile

There was no statistically significant difference in the risk of large-for-gestational-age infants between intervention and control groups (average RR 0.92, 95% CI 0.80 to 1.05; participants = 4525; studies = 18; I² = 0%; Analysis 1.15); however, the effect in the diet and exercise counselling group non-significantly favoured the intervention (RR 0.87, 95% CI 0.74 to 1.02; participants = 2777; studies = 6; I2 = 0%).

Quality of the evidence

We graded the quality of this evidence as high.

1.16 Mean birthweight (g)

There was no statistically significant difference in mean birthweight between intervention and control groups (average MD 12.20, 95% CI -15.26 to 39.65; participants = 8350; studies = 29; I² = 44%; Analysis 1.16).

Sensitivity analysis and investigation of heterogeneity

There were many risk of bias concerns for this outcome (e.g. due to post-randomisation exclusions of women with preterm birth in several studies) but the overall result remained fairly robust to exclusion of high-risk studies.

Quality of the evidence

We graded the quality of the evidence as moderate due to inconsistency.

1.17 and 1.18 Infant birthweight less 2500 g or less than 10th centile

There was no statistically significant difference between groups with respect to birthweight less than 2500 g (average RR 0.88, 95% CI 0.67 to 1.14; participants = 4834; studies = 12; I² = 0%; Analysis 1.17) or small-for-gestational-age infants (average (RR 1.09, 95% CI 0.61 to 1.94; participants = 662; studies = seven; I² = 0%, Analysis 1.18).

Quality of the evidence

We downgraded the quality of this evidence to moderate due to potential risk of bias concerns relating mainly to the limited reporting of this outcome.

1.19 Shoulder dystocia

There was no statistically significant difference in the risk of shoulder dystocia between intervention and control groups (average RR 1.02, 95% CI 0.57 to 1.83; participants = 3253; studies = four; I² = 8%, Analysis 1.19).

Quality of the evidence

We graded this evidence as moderate quality due to imprecision.

1.20 Neonatal hypoglycaemia

There was no statistically significant difference in the risk of neonatal hypoglycaemia between intervention and control groups (average RR 0.95, 95% CI 0.76 to 1.18; participants = 2601; studies = four; I² = 0%); Analysis 1.20).

Quality of the evidence

We graded this evidence as moderate quality due to indirectness (may not apply to all types of interventions).

1.21 Neonatal birth trauma

There was no statistically significant difference between intervention and control groups (average RR 0.89, 95% CI 0.35 to 2.30; participants = 2256; studies = two; I² = 0%; Analysis 1.21). Both included studies (Dodd 2014; Vesco 2013) were diet and exercise counselling interventions and were conducted in high-risk populations.

Quality of the evidence

We graded this evidence as moderate quality due to imprecision.

1,22 Neonatal hyperbilirubinaemia

There was no statistically significant difference between intervention and control groups (average RR 0.83, 95% CI 0.62 to 1.10; participants = 2256; studies = two; I² = 0%, Analysis 1.22). Both included studies (Dodd 2014; Vesco 2013) were diet and exercise counselling interventions and were conducted in high-risk populations.

Quality of the evidence

We graded this evidence as moderate quality due to indirectness (may not apply to all types of interventions).

1.23 Neonatal respiratory distress syndrome

Infants in the intervention group had a significantly reduced risk of experiencing respiratory distress than infants in the control group (average RR 0.47, 95% CI 0.26 to 0.85; participants = 2256; studies = two; I² = 0%; Analysis 1.23). Both included studies (Dodd 2014; Vesco 2013) were diet and exercise counselling interventions and were conducted in high-risk populations.

Quality of the evidence

We graded this evidence as moderate quality due to indirectness (may not apply to all types of interventions).

1.24 Postpartum haemorrhage

There was no difference in this outcome between intervention and control groups (average RR 0.94, 95% CI 0.78 to 1.14; participants = 2901; studies = two; I² = 0%; Analysis 1.24).

Quality of the evidence

We graded this evidence as high quality.

2. Diet interventions (low glycaemic load (GL) diet) versus routine care

A maximum of five studies contributed data to this comparison (Clapp 2002a; Louie 2011; Moses 2014; Rhodes 2010; ROLO 2012).

  1. Excessive GWG: Low GL dietary interventions significantly reduced the risk of excessive GWG in the intervention group compared with the control group (RR 0.74, 95% CI 0.55 to 0.99; participants = 833; studies = two; I² = 46%; Analysis 2.1). The test for subgroup differences was not significant (Chi² = 1.30, df = 1 (P = 0.25), I² = 22.9%).

  2. Mean GWG: Due to substantial heterogeneity, we did not pool these data.

  3. Low GWG: Only one study contributed data (Louie 2011) and found no statistically significant difference between intervention and control arms (Analysis 2.3).

  4. Preterm birth: One study contributed data to two subgroups in this analysis. There was no statistically significant difference between intervention and control groups (average RR 0.33, 95% CI 0.11 to 1.02; participants = 804; studies = two; I² = 0%; Analysis 2.4; Test for subgroup differences: Chi² = 0.21, df = 1 (P = 0.65), I² = 0%).

  5. Caesarean delivery: Two studies contributed data to the high-risk subgroup. There was no statistically significant difference between the intervention and control groups (average RR 0.99, 95% CI 0.33 to 3.01; participants = 133; studies = two; I² = 65%; Analysis 2.5).

  6. Infant birthweight greater than 4000 g: There was no statistically significant difference between the intervention and control groups (average RR 0.96, 95% CI 0.77 to 1.20; participants = 1472; studies = four; I² = 14%; Analysis 2.6; however, the test for subgroup differences suggested that subgroup results may differ in respect to this outcome, with more macrosomia babies born to high-risk women in the intervention group (Chi² = 2.12, df = 1 (P = 0.15), I² = 52.9%).

  7. Pre-eclampsia: no data available.

We graded the evidence relating to excessive GWG as moderate quality, and for the other outcomes analysed as low quality due to heterogeneity or imprecision and sparse data, therefore it is likely that further research may change these effect estimates.

3. Diet and exercise counselling versus routine care

A maximum of 13 studies contributed data to these meta-analyses. To avoid duplication of data from Althuizen 2013 we did not combine subgroup data.

  1. Excessive GWG: Interventions reduced the incidence of excessive GWG in low-risk participants (average RR 0.72, 95% CI 0.55 to 0.95; participants = 247; studies = 2; I² = 0%) and there was a trend towards a reduction in excessive GWG in the high-risk subgroup (RR 0.85, 95% CI 0.71 to 1.02; participants = 2725; studies = nine; I² = 69%; Analysis 3.1; Test for subgroup differences: Chi² = 3.51, df = 2 (P = 0.17), I² = 43.0%). We downgraded this evidence to moderate due to heterogeneity.

  2. Mean GWG: Mean GWG in kg was reduced with the intervention for the mixed-risk subgroup (MD -1.80, 95% CI -3.36 to -0.24; participants = 444; studies = three; I² = 76%) and the high-risk subgroup (MD -0.71, 95% CI -1.34 to -0.08; participants = 2741; studies = 11; I² = 57%) but heterogeneity was high (Analysis 3.2). In the latter, this could be explained by the timing of the measurements, and when two studies that measured weight gain at less than 34 weeks were excluded, data were homogeneous and favoured no clear difference between the intervention and control groups (MD -0.15, 95% CI -0.44 to 0.15; participants = 2424; studies = nine; I² = 0%; Test for subgroup differences suggested a difference in effect between subgroups: Chi² = 5.44, df = 2 (P = 0.07), I² = 63.2%).

  3. Low GWG: There was no significant difference in low GWG on average overall (RR 1.23, 95% CI 0.89 to 1.72; participants = 2552; studies = five; I² = 49%; Analysis 3.3; Test for subgroup differences: Chi² = 0.07, df = 1 (P = 0.79), I² = 0%) or for subgroups; however the overall trend favoured the control group.

  4. Preterm birth: There was no significant difference in preterm birth on average overall (RR 0.94, 95% CI 0.57 to 1.55; participants = 3170; studies = seven; I² = 52%; Analysis 3.4) or for subgroups; Test for subgroup differences: Chi² = 0.32, df = 1 (P = 0.57), I² = 0%). We downgraded this evidence to low due to imprecision and heterogeneity.

  5. Pre-eclampsia: There was no significant difference in pre-eclampsia on average between intervention and control groups for the high-risk population (average RR 1.06, 95% CI 0.79 to 1.43; participants = 2896; studies = seven; I² = 0%; Analysis 3.5). Only one study contributed events to the low-risk subgroup.

  6. Caesarean delivery: Interventions reduced the incidence of caesarean section on average (RR 0.89, 95% CI 0.80 to 1.00; participants = 3406; studies = nine; I² = 3%; Analysis 3.6; P = 0.05; borderline statistical significance). This trend was consistent across risk subgroups; Test for subgroup differences: Chi² = 1.53, df = 2 (P = 0.46), I² = 0%.

  7. Infant birthweight greater than 4000 g: There was no statistically significant difference in macrosomia on average between intervention and control groups overall (RR 0.92, 95% CI 0.77 to 1.11; participants = 3705; studies = 10; I² = 7%; Analysis 3.7). or for the low-risk or mixed-risk subgroups. However, in the high-risk subgroup an effect in favour of a reduction in macrosomia was of borderline statistical significance (average RR 0.85, 95% CI 0.73 to 1.00; participants = 3252; studies = nine; I² = 0%; P = 0.05) and the test for subgroup differences was statistically significant (Chi² = 3.86, df = 1 (P = 0.05), I² = 74.1%).

We graded the evidence for diet and exercise counselling interventions as moderate quality, except for the outcome preterm birth which we graded as low quality.

4. Exercise interventions versus routine care

A maximum of 13 studies contributed data to these analyses. Three studies (Kong 2014; Renault 2014; Ronnberg 2014) involved unsupervised (as opposed to supervised) exercise interventions and we performed sensitivity analyses to determine whether including unsupervised exercise intervention studies had an impact on the results. To avoid duplication of data, where individual studies contributed data to both risk subgroups (Ronnberg 2014; Ruiz 2013), we did not combine subgroup data.

  1. Excessive GWG: Exercise interventions significantly reduced this outcome consistently across risk subgroups with point estimates for low, mixed and high risk subgroups of 0.69, 0.77, and 0,84 respectively(Analysis 4.1). Test for subgroup differences were not significant: Chi² = 1.36, df = 2 (P = 0.51), I² = 0%.

  2. Mean GWG: When one study at a high risk of bias (Price 2012) was excluded from the mixed-risk subgroup, the intervention was associated with a statistically significant reduction in mean weight gain in kg compared with the control in the mixed-risk subgroup (MD -1.35, 95% CI -1.80 to -0.89; participants = 1134; studies = three; I² = 0%), and low risk subgroup (one study only), but not the high-risk subgroup (MD -0.32, 95% CI -1.15 to 0.50; participants = 476; studies = four; I² = 0%); Analysis 4.2. Test for subgroup differences suggested a difference in effect between subgroups: Chi² = 5.78, df = 2 (P = 0.06), I² = 65.4%.

  3. Low GWG: There was an increase in low GWG of borderline statistical significance between intervention and control groups for the mixed risk subgroup (average RR 1.20, 95% CI 1.00 to 1.43; participants = 1336; studies = two; I² = 0%; P = 0.05) and low risk subgroup (one study only) but not the high-risk subgroup (average RR 1.03, 95% CI 0.66 to 1.60; participants = 504; studies = three; I² = 0%; Analysis 4.3). Test for subgroup differences were not significant: Chi² = 0.98, df = 2 (P = 0.61), I² = 0%.

  4. Preterm birth: There was no statistically significant difference in preterm birth on average between intervention and control groups for the low risk (one study only), mixed risk (average RR 1.92, 95% CI 0.75 to 4.93; participants = 1129; studies = three; I² = 0%) or the high-risk subgroup (average RR 1.34, 95% CI 0.51 to 3.55; participants = 504; studies = three; I² = 0%; Analysis 4.4); however the trend consistently favoured the control group. The test for subgroup differences was not significant: Chi² = 0.27, df = 1 (P = 0.60), I² = 0%.

  5. Pre-eclampsia: There was no statistically significant difference in pre-eclampsia overall between intervention and control groups (average RR 0.99, 95% CI 0.58 to 1.66; participants = 1253; studies = four; I² = 0%; Analysis 4.5) and subgroup findings were similar: Test for subgroup differences: Chi² = 0.51, df = 1 (P = 0.48), I² = 0%.

  6. Caesarean delivery: There was no statistically significant difference in caesarean delivery between intervention and control groups for low risk (one study only), mixed risk (average RR 0.96, 95% CI 0.76 to 1.22; participants = 2263; studies = six; I² = 24%) or the high-risk subgroup (average RR 0.98, 95% CI 0.81 to 1.20; participants = 645; studies = five; I² = 0%; Analysis 4.6); . Test for subgroup differences: Chi² = 0.37, df = 2 (P = 0.83), I² = 0%.

  7. Infant birthweight greater than 4000 g: There was no statistically significant difference in macrosomia between intervention and control groups for the low-risk (one study only), mixed-risk (average RR 0.81, 95% CI 0.64 to 1.02; participants = 2445; studies = seven; I² = 0%) or the high-risk subgroups (RR 0.65, 95% CI 0.22 to 1.91; participants = 504; studies = three; I² = 74%; Analysis 4.7 Test for subgroup differences: Chi² = 0.14, df = 1 (P = 0.71), I² = 0%. However, the trend across subgroups consistently favoured the intervention, and the effect for the mixed-risk subgroup was of borderline statistical significance.(P = 0.07) Furthermore, when three studies with risk of bias concerns were excluded (Cordero 2014; Murtezani 2014; Stafne 2012), the RR for the mixed-risk population clearly favoured the intervention group (average RR 0.56, 95% CI 0.36 to 0.88; participants = 1274; studies = eight; I² = 0%).

As the number of studies included in most analyses were few, we did not assess funnel plots. Including studies of unsupervised exercise did not have a significant impact on the results. We graded this evidence as moderate quality overall, except for the evidence on preterm birth (low quality) which was very imprecise and potentially subject to a serious risk of attrition and/or reporting bias.

5. Diet and supervised exercise interventions versus routine care

A maximum of five studies contributed data to these analyses; two studies contributed data to each of the mixed- and high-risk subgroups, one study (Hui 2014) reported results separately for both subgroups, therefore we were able to pool these data.

  1. Excessive GWG: Combined exercise and diet interventions significantly reduced excessive weight gain (average RR 0.75, 95% CI 0.61 to 0.92; participants = 689; studies = five; I² = 18%, Analysis 5.1; When one study at high risk of bias was excluded (Ruchat 2012), the test for subgroup differences suggested that there might be a difference in effect according to risk, with a smaller effect in the high-risk subgroup: Test for subgroup differences: Chi² = 4.54, df = 2 (P = 0.10), I² = 55.9%.

  2. Mean GWG: The interventions reduced mean GWG compared with controls (average MD -1.31, 95% CI -3.00 to 0.37; participants = 348; studies = three; I² = 43%; borderline significance, Analysis 5.2). However, the test for subgroup differences suggested that there might be a difference in effect according to risk,with a smaller effect in the high-risk subgroup :Test for subgroup differences: Chi² = 4.90, df = 2 (P = 0.09), I² = 59.2%.

  3. Low GWG: Only one study showing no difference contributed data to this outcome (Analysis 5.3).

  4. Preterm birth: No data available

  5. Pre-eclampsia: Only one study showing no difference contributed data to this outcome (Analysis 5.4).

  6. Caesarean delivery: There was no statistically significant difference in the risk of caesarean delivery between intervention and control groups (average RR 1.00, 95% CI 0.69 to 1.45; participants = 607; studies = three; I² = 0%; Analysis 5.5; Test for subgroup differences: Chi² = 0.29, df = 1 (P = 0.59), I² = 0%.

  7. Infant birthweight greater than 4000 g: There was no statistically significant difference between groups for this outcome (RR 1.02, 95% CI 0.71 to 1.46; participants = 398; studies = three; I² = 0%; Analysis 5.6; Test for subgroup differences: Chi² = 0.33, df = 1 (P = 0.56), I² = 0%.

We graded this evidence from analyses as low-to-moderate quality due to imprecision (sparse data) and some inconsistencies.

6. Diet counselling only versus routine care

A maximum of seven heterogeneous studies contributed data to these analyses (Di Carlo 2014; Jeffries 2009; Laitinen 2009; Quinlivan 2011; Rae 2000; Thornton 2009; Wolff 2008).

  1. Excessive GWG: We did not combine subgroup data for this analysis as one study contributed data to both subgroups. There was no statistically significant difference between intervention and control arms (Analysis 6.1). The test for subgroup differences showed that subgroup results were similar: Chi² = 0.49, df = 1 (P = 0.48), I² = 0%.

  2. Mean GWG: Data for this outcome were very heterogeneous (I² greater than 90%) with four out of seven studies finding a difference in mean GWG of greater than 4 kg, with the other three studies finding little difference; therefore, we did not combine these data (Analysis 6.2).

  3. Low GWG: Only one study contributed data (Laitinen 2009), which found that significantly more women in the intervention arm had low GWG compared with the control arm (Analysis 6.3).

  4. Preterm birth: There was no statistically significant difference in the risk of preterm birth between intervention and control groups (average RR 0.67, 95% CI 0.26 to 1.73; participants = 591; studies = three; I² = 0%,Analysis 6.4); Test for subgroup differences: Chi² = 0.00, df = 1 (P = 0.99), I² = 0%.

  5. Pre-eclampsia: There was no statistically significant difference in the risk of pre-eclampsia between intervention and control groups (RR 0.90, 95% CI 0.54 to 1.48; participants = 634; studies = four; I² = 0%; Analysis 6.5; Test for subgroup differences: Chi² = 2.05, df = 1 (P = 0.15), I² = 51.2%.

  6. Caesarean section: There was no statistically significant difference in the risk of caesarean delivery between intervention and control groups (average RR 1.06, 95% CI 0.93 to 1.21; participants = 754; studies = five I² = 2%; Analysis 6.6; Test for subgroup differences: Chi² = 0.30, df = 1 (P = 0.59), I² = 0%).

  7. Infant birthweight greater than 4000 g: There was no statistically significant difference in the risk of macrosomia between intervention and control groups when data from two studies conducted in high-risk women were pooled (RR 1.81, 95% CI 0.88 to 3.72; participants = 349; studies = two; I² = 0%, Analysis 6.7).

We graded the evidence relating to these interventions as low quality overall due to heterogeneity and risk of bias concerns. As the number of studies included in most analyses were few, we did not assess funnel plots.

Discussion

Summary of main results

This updated review included 65 randomised controlled trials (RCTs) in total with 49 RCTs involving at least 11,444 participants contributing data to quantitative synthesis. Twenty RCTs were considered to be at moderate-to-high risk of bias. Where these studies contributed data (14 studies), we performed sensitivity analysis to determine how including these data impacted on the results. Diet interventions most commonly involved a low GL, diabetic, calorie-controlled or low fat diet; exercise interventions were most commonly of moderate intensity involving walking, dance, or aerobic classes. Most included studies were conducted in developed countries. Overall findings are summarised in Summary of findings for the main comparison. Diet or exercise,or both, interventions reduced the risk of excessive gestational weight gain (GWG) by an average of 20% (95% CI, 13 to 27%) overall. Data were moderately heterogeneous; however this overall effect was robust to sensitivity analysis and consistent across the different types of interventions, therefore we graded this evidence as high quality. The greatest effect on excessive GWG was noted for combined diet plus supervised exercise interventions.

Data for mean GWG were too heterogenous to pool and were inconsistent between, and frequently within, the different types of intervention groups, therefore, we did not pool these data. However, for subgroup analyses according to the risk of weight-related complications, we pooled data if heterogeneity was mild or moderate, and downgraded the evidence accordingly. Limited evidence from diet and exercise counselling interventions, exercise only interventions, and diet and supervised exercise interventions suggested that there might be a difference in effect on mean weight gain according to risk, with a smaller effect in the high-risk subgroups (low quality evidence).

Women receiving diet or exercise, or both interventions were more likely to experience low GWG than controls (average risk ratio (RR) 1.14, 95% confidence interval (CI) 1.02 to 1.27; participants = 4422; studies = 11; I² = 3; moderate-quality evidence). We found no difference between intervention and control groups with regard to pre-eclampsia ((RR 0.95, 95% CI 0.77 to 1.16; participants = 5330; studies = 15; I² = 0%; high-quality evidence); however, maternal hypertension (not a pre-specified outcome) was reduced in the intervention group compared with the control group overall (average RR 0.70, 95% CI 0.51 to 0.96; participants = 5162; studies = 11; I² = 43%; low-quality evidence).

There was no clear difference between groups with regard to caesarean delivery overall (RR 0.95, 95% CI 0.88 to 1.03; participants = 7534; studies = 28; I² = 9%; high-quality evidence); although the effect estimate suggested a small difference (5%) in favour of the interventions. In addition, for combined diet and exercise counselling interventions there was a 13% (-1% to 25%) reduction in this outcome (borderline statistical significance).

We found no difference between groups with regard to preterm birth overall (average RR 0.91, 95% CI 0.68 to 1.22; participants = 5923; studies = 16; I² = 16%; moderate-quality evidence); however limited evidence suggested that these effect estimates may differ according to the types of interventions, with a trend towards an increased risk for exercise-only interventions.

We found no clear difference between intervention and control groups with regard to infant macrosomia overall (average RR 0.93, 95% CI 0.86 to 1.02; participants = 8598; studies = 27; I² = 0%; high-quality evidence), although the effect estimate suggested a small difference (7% reduction) in favour of the intervention group. The largest effect size occurred in the supervised exercise-only intervention group (RR 0.81, 95% CI 0.64 to 1.02; participants = 2445; studies = seven; I² = 0%), which approached statistical significance (P = 0.07). Furthermore, in subgroup analysis by risk, high-risk women receiving combined diet and exercise counselling interventions experienced a 15% reduced risk of infant macrosomia (average RR 0.85, 95% CI 0.73 to 1.00; participants = 3252; studies = nine; I² = 0; P = 0.05; moderate-quality evidence).

There were no differences in the risk of poor neonatal outcomes including shoulder dystocia, neonatal hypoglycaemia, hyperbilirubinaemia, or birth trauma (all moderate-quality evidence) between intervention and control groups; however, infants of high-risk women had a reduced risk of respiratory distress syndrome if their mothers were in the intervention group (RR 0.47, 95% CI 0.26 to 0.85; participants = 2256; studies = two; I² = 0%; moderate-quality evidence).

The effect on behaviour modification outcomes, i.e. dietary and physical activity outcomes, in general, favoured the intervention groups; however, these outcomes were at high risk of bias and mainly reflected whether the implementation of the interventions was successful. Low-quality evidence suggested that the beneficial effects of interventions on weight control during pregnancy may be sustained postpartum. For certain outcomes, e.g. childhood weight, we found no data for meta-analysis.

For a brief summary of the effects of the different types of interventions on the main outcomes, see Summary of findings 2.

Overall completeness and applicability of evidence

There is a growing body of evidence to support the use of diet or exercise, or both, interventions to reduce excessive GWG in pregnancy. We found high-quality evidence of other related health benefits for women and newborns, applicable to most pregnant women who are otherwise healthy, irrespective of their prepregnancy weight. Exercise appears to be an important component of weight reduction interventions; however the evidence with regard to the effect of exercise on the risk of preterm birth is of a moderate quality and this outcome should be rigorously evaluated in future studies to enable the establishment of appropriate guidelines.The evidence is not applicable to women with specific contraindications to exercise in pregnancy or pre-existing medical conditions. Although we included four studies conducted in women with gestational diabetes, data were sparse and it is not clear whether the review findings apply to women with this condition. More research (qualitative and quantitative) to improve outcomes in this high risk group is needed.

Most included studies were carried out in developed countries and it is not clear whether these results are widely applicable to lower income settings with fewer human and financial resources. More research is needed in these less developed settings, where obesity is increasingly a major health issue. Innovative interventions utilising mobile-phone technology (e.g. Pollak 2014) are of interest and further developments in this area are anticipated.

Quality of the evidence

Using the GRADE approach, we considered the quality of the evidence relating to excessive GWG as high quality. Although moderate heterogeneity was present, we upgraded our assessment of evidence quality from moderate-to-high quality as findings were precise and robust to sensitivity analysis. We graded the evidence with regard to the risk of low GWG as high quality as these estimates were consistent and precise across included studies. We downgraded the evidence with regard to preterm birth (no statistically significant difference) to moderate due to risk of bias concerns from attrition and under-reporting. We graded the quality of the evidence for pre-eclampsia, caesarean delivery and macrosomia as high quality and most other outcomes, as moderate quality.

We downgraded some evidence due to heterogeneity. Many factors might have contributed to this heterogeneity including obvious and subtle differences in the types of interventions, types of participants (e.g. BMIs, parity, age), delivery of the intervention (e.g. whether the intervention was incorporated into antenatal visits or delivered separately by a dietician), timing of the measurements (e.g. weight gain assessed at 34 versus 38 weeks), timing of commencement of the intervention (e.g. first, second or third trimester), sample sizes, etc. An in-depth evaluation of individual interventions was beyond the scope of this review; however, our impression was that the more intensely monitored/supervised the intervention, the better the study results.

Potential biases in the review process

We took a number of steps to minimise bias in the review process by including all relevant RCTs, with two review authors independently classifying them, extracting data, and resolving disagreements by discussion with the other authors. Where expected outcome data were missing we made an effort to contact the study investigators, and we included adjusted data from cluster-RCTs where possible. In the previous version of this review we included two quasi-RCTs (Bechtel-Blackwell 2002; Moses 2006), which we excluded for this update after deciding to limit the review to RCTs. Due to issues of scope and relevance, we also excluded two early studies of appetite suppressant drugs that had been included in the original review (Boileau 1968; Silverman 1971).

We considered it clinically meaningful to produce overall estimates of average effects across all studies where possible, organised by the type of intervention, using random effects methods. Interventions were often multifaceted and were quite heterogeneous in approach, for example, in the timing, duration, intensity, content and delivery. Some studies evaluated more than one type of intervention. Dodd 2014, for example, was mainly a diet and exercise counselling intervention study and we included it as such; however, 26% of participants in the intervention arm underwent a supervised walking exercise as part of a nested RCT. Where possible, when heterogeneity existed between studies evaluating apparently similar interventions, which could not be explained by our 'Risk of bias' assessment, we attempted to identify the possible reasons for it. In addition, although we made distinctions between types of diet and exercise interventions according to whether the exercise component was supervised or not, the results were robust on exploratory analyses when all combined diet and exercise intervention data for the main outcomes were pooled.

Two studies compared higher impact interventions with lower impact interventions (Ruchat 2012; Thornton 2009), and several studies of low GL diets compared the intervention with an alternative (low-fat, moderate/high GL or conventional healthy eating) diet (Rhodes 2010; Louie 2011; Moses 2009; Moses 2014). For these studies, we pooled the data of the alternative intervention with the control group which, in most other studies, comprised routine care. This may have contributed to heterogeneity in the meta-analyses and might have led to an underestimation of the summary effect of the intervention. Clapp 2002b compared different exercise intensities at different stages of pregnancy (before versus after 20 weeks' gestation) and found that low-intensity exercise in early pregnancy moving on to higher-intensity exercise after 20 weeks was associated with a lower pregnancy weight gain than either high- followed by low-intensity exercise or moderate-intensity exercise throughout. We did not explore the impact of higher- versus lower-intensity interventions, which may have provided important information for exercise interventions and certain outcomes, such as preterm birth. This was largely due to a sparseness of data and time constraints.

Several studies reported maternal 'hypertension', and not pre-eclampsia, and we extracted and analysed these data. This was not prespecified in the protocol (see Differences between protocol and review); however, we made every effort to minimise bias in this process, and consider the pooled findings to be of value, albeit low-quality evidence. The effect estimates for hypertension differed from those for pre-eclampsia with a consistent trend towards a reduction in hypertension, but not pre-eclampsia, in intervention arms.

We did not perform meta-analyses according to BMI classification of degree of obesity, although several studies stratified results by BMI (overweight or obese or morbidly obese). In one study that reported these BMI categories separately (Kong 2014), we combined these data for use in our meta-analysis. For studies of high-risk women that reported combined and separate results for overweight and obese categories (Harrison 2013; Petrella 2013; Nascimento 2012), we extracted all data but used the combined data only in our meta-analyses. It is possible that certain types of interventions may be more effective for different high-risk BMI categories and we may try to address this in future versions of this review.

Behaviour modification outcomes may have been subject to potential reviewer bias. Multiple and varied behaviour modification outcomes were reported by the various investigators and we pre-specified only three outcomes (energy intake, fibre intake and a physical activity measure) for inclusion in the review. In addition, numerous different scales and time points were reported by study investigators, a narrative discussion of which is beyond the scope of this review. However, in many respects, behaviour outcome measures are measures of the intervention rather than the effect of the intervention and we consider this outcome to be a poor (indirect) measure of effectiveness of an intervention. In addition, these outcomes were subject to other serious risk of bias concerns, including detection (often self-reported) and attrition bias.

Agreements and disagreements with other studies or reviews

A 2012 UK Health Technology Assessment review (Thangaratinam 2012) included 30 RCTs in a meta-analysis of GWG and reported an overall reduction (± 1 kg) in mean GWG in the intervention group compared with controls.Two other systematic reviews (Ronnberg 2010; Skouteris 2010) that included RCTs and non-randomised studies also reported GWG outcomes in favour of the interventions. Thangaratinam 2012 reported that the largest weight reduction occurred with dietary interventions (a mean reduction of 3.36 kg), which were also effective at reducing gestational hypertension, pre-eclampsia, preterm birth and shoulder dystocia. Due to substantial heterogeneity, we did not pool mean weight gain data and our review does not agree with these findings. Thangaratinam 2012 utilised data from non-randomised studies to provide evidence on adverse effects; however, most of these data were derived from studies on extreme diet and famine and therefore have limited applicability. Randomised controlled trial data on adverse effects remain sparse and we were unable to provide additional evidence in this regard.

We were unable to show a reduced risk of macrosomia overall, as was shown in Thangaratinam 2012, although our findings did not exclude a small reduction in risk. In addition, our findings suggested greater reductions may be achieved for high-risk women who received combined diet and exercise interventions, and women receiving supervised exercise-only interventions. Dodd 2014, the largest study included in this review additionally reported the rate of very high birthweight babies (greater than 4500 g), finding a significant reduction in this outcome in the intervention arm; however, we did not include this outcome.

We found limited evidence that certain interventions were somewhat less effective in reducing GWG in high-risk women compared with the lower-risk group. To our knowledge this has not been previously shown and requires further investigation. Several of our included studies reported gestational diabetes as an outcome and exploratory analysis suggested that the effect of diet and exercise interventions on this outcome might be significant. We did not modify our protocol to include this important outcome as a separate Cochrane review on the topic is in progress (Crane 2013).

Authors' conclusions

Implications for practice

High-quality evidence indicates that diet or exercise, or both, during pregnancy can reduce the risk of excessive gestational weight gain (GWG). Other benefits may include a lower risk of caesarean delivery, macrosomia, and neonatal respiratory morbidity, particularly for high-risk women receiving combined diet and exercise interventions. Moderate-intensity exercise appears to be an important part of controlling weight gain in pregnancy, however the evidence on the risk of preterm birth is limited and more research is needed to establish safe guidelines. Most included studies were carried out in developed countries and it is not clear whether these results are widely applicable to lower income settings.

Implications for research

The effectiveness of these interventions in low-income countries and in women with non-Western lifestyles needs further evaluation. In addition, further research is needed, particularly in high-risk women to determine whether other types of diet or adjuvant interventions (e.g. probiotics, metformin), are of value in reducing excessive GWG and improving maternal and infant outcomes. The evidence with regard to the effect of antenatal exercise on the risk of preterm birth is incomplete and this outcome should be carefully monitored and reported by researchers to enable the establishment of appropriate guidelines. Studies of interventions utilising mobile-phone technology are of interest and further developments in this area are anticipated. Research to investigate strategies to implement diet and exercise programs into routine antenatal care in different settings is needed.

Acknowledgements

We would like to acknowledge the staff of Cochrane Pregnancy and Childbirth Group for assistance with searching references and providing technical guidance. We also acknowledge Therese Dowswell for the significant contribution she made to the original review.

Theresa A Lawrie's work was financially supported by the UNDP/UNFPA/UNICEF/WHO/World Bank Special Programme of Research, Development and Research Training in Human Reproduction (HRP), Department of Reproductive Health and Research (RHR), World Health Organization. The authors alone are responsible for the views expressed in this review and they do not necessarily represent the views, decisions or policies of the institutions with which they are affiliated.

This project was supported by the National Institute for Health Research, via Cochrane Infrastructure funding to Cochrane Pregnancy and Childbirth. The views and opinions expressed therein are those of the authors and do not necessarily reflect those of the Systematic Reviews Programme, NIHR, NHS or the Department of Health.

As part of the pre-publication editorial process, this review has been commented on by three peers (an editor and two referees who are external to the editorial team) and the Group's Statistical Adviser.

Data and analyses

Download statistical data

Comparison 1. All diet and/or exercise interventions vs standard/other care
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Excessive weight gain247096Risk Ratio (M-H, Random, 95% CI)0.80 [0.73, 0.87]
1.1 Diet intervention (low GI diet)2835Risk Ratio (M-H, Random, 95% CI)0.77 [0.66, 0.91]
1.2 Diet and exercise counselling93144Risk Ratio (M-H, Random, 95% CI)0.86 [0.75, 0.98]
1.3 Unsupervised exercise3603Risk Ratio (M-H, Random, 95% CI)0.83 [0.71, 0.97]
1.4 Supervised exercise31298Risk Ratio (M-H, Random, 95% CI)0.75 [0.63, 0.89]
1.5 Supervised exercise and diet5689Risk Ratio (M-H, Random, 95% CI)0.71 [0.59, 0.85]
1.6 Diet counselling/other3527Risk Ratio (M-H, Random, 95% CI)0.46 [0.17, 1.23]
2 Weight gain (kg)36 Mean Difference (IV, Random, 95% CI)Totals not selected
2.1 Diet intervention (low GI diet)5 Mean Difference (IV, Random, 95% CI)0.0 [0.0, 0.0]
2.2 Diet and exercise counselling13 Mean Difference (IV, Random, 95% CI)0.0 [0.0, 0.0]
2.3 Unsupervised exercise1 Mean Difference (IV, Random, 95% CI)0.0 [0.0, 0.0]
2.4 Supervised exercise intervention7 Mean Difference (IV, Random, 95% CI)0.0 [0.0, 0.0]
2.5 Supervised exercise plus diet intervention3 Mean Difference (IV, Random, 95% CI)0.0 [0.0, 0.0]
2.6 Diet counselling/other7 Mean Difference (IV, Random, 95% CI)0.0 [0.0, 0.0]
3 Low weight gain114422Risk Ratio (M-H, Random, 95% CI)1.14 [1.02, 1.27]
3.1 Diet intervention (low GI diet)187Risk Ratio (M-H, Random, 95% CI)1.24 [0.64, 2.43]
3.2 Diet and exercise counselling52552Risk Ratio (M-H, Random, 95% CI)1.25 [0.90, 1.75]
3.3 Unsupervised exercise3603Risk Ratio (M-H, Random, 95% CI)1.13 [0.80, 1.60]
3.4 Supervised exercise1962Risk Ratio (M-H, Random, 95% CI)1.21 [0.99, 1.48]
3.5 Supervised exercise plus diet149Risk Ratio (M-H, Random, 95% CI)1.47 [0.40, 5.50]
3.6 Diet counselling/other1169Risk Ratio (M-H, Random, 95% CI)1.21 [0.80, 1.82]
4 Preterm birth165923Risk Ratio (M-H, Random, 95% CI)0.91 [0.68, 1.22]
4.1 Diet intervention (low GI diet)2804Risk Ratio (M-H, Random, 95% CI)0.33 [0.11, 1.02]
4.2 Diet and exercise counselling73170Risk Ratio (M-H, Random, 95% CI)0.95 [0.60, 1.51]
4.3 Unsupervised exercise2229Risk Ratio (M-H, Random, 95% CI)1.17 [0.35, 3.85]
4.4 Supervised exercise31129Risk Ratio (M-H, Random, 95% CI)1.92 [0.75, 4.93]
4.5 Diet counselling/other3591Risk Ratio (M-H, Random, 95% CI)0.67 [0.26, 1.73]
5 Pre-eclampsia155330Risk Ratio (M-H, Random, 95% CI)0.95 [0.77, 1.16]
5.1 Diet and exercise counselling73139Risk Ratio (M-H, Random, 95% CI)0.99 [0.74, 1.31]
5.2 Supervised exercise21024Risk Ratio (M-H, Random, 95% CI)0.91 [0.52, 1.60]
5.3 Unsupervised exercise2229Risk Ratio (M-H, Random, 95% CI)1.60 [0.38, 6.73]
5.4 Supervised exercise plus diet1304Risk Ratio (M-H, Random, 95% CI)0.84 [0.51, 1.40]
5.5 Diet counselling/other4634Risk Ratio (M-H, Random, 95% CI)0.90 [0.54, 1.48]
6 Hypertension (not prespecified)115162Risk Ratio (M-H, Random, 95% CI)0.70 [0.51, 0.96]
6.1 Diet and exercise counselling52648Risk Ratio (M-H, Random, 95% CI)0.84 [0.54, 1.29]
6.2 Unsupervised exercise2229Risk Ratio (M-H, Random, 95% CI)0.43 [0.12, 1.54]
6.3 Supervised exercise31749Risk Ratio (M-H, Random, 95% CI)0.55 [0.29, 1.03]
6.4 Supervised exercise plus diet1304Risk Ratio (M-H, Random, 95% CI)0.84 [0.51, 1.40]
6.5 Diet counselling/other1232Risk Ratio (M-H, Random, 95% CI)0.30 [0.08, 1.06]
7 Induction of labour83832Risk Ratio (M-H, Random, 95% CI)1.06 [0.94, 1.19]
7.1 Diet intervention (low GI diet)1734Risk Ratio (M-H, Random, 95% CI)1.64 [1.14, 2.36]
7.2 Diet and exercise counselling42522Risk Ratio (M-H, Random, 95% CI)1.03 [0.93, 1.14]
7.3 Unsupervised exercise1192Risk Ratio (M-H, Random, 95% CI)0.98 [0.65, 1.48]
7.4 Supervised exercise135Risk Ratio (M-H, Random, 95% CI)0.32 [0.01, 7.26]
7.5 Diet counselling/other2349Risk Ratio (M-H, Random, 95% CI)0.89 [0.59, 1.35]
8 Caesarean delivery287534Risk Ratio (M-H, Random, 95% CI)0.95 [0.88, 1.03]
8.1 Diet intervention (low GI diet)2133Risk Ratio (M-H, Random, 95% CI)0.99 [0.33, 3.01]
8.2 Diet and exercise counselling93406Risk Ratio (M-H, Random, 95% CI)0.87 [0.75, 1.01]
8.3 Unsupervised exercise intervention2229Risk Ratio (M-H, Random, 95% CI)0.91 [0.53, 1.59]
8.4 Supervised exercise82405Risk Ratio (M-H, Random, 95% CI)0.96 [0.82, 1.11]
8.5 Supervised exercise plus diet3607Risk Ratio (M-H, Random, 95% CI)1.00 [0.69, 1.45]
8.6 Diet counselling/other5754Risk Ratio (M-H, Random, 95% CI)1.06 [0.93, 1.21]
9 Postpartum weight retention (kg)7818Mean Difference (IV, Random, 95% CI)-1.12 [-2.49, 0.25]
9.1 Diet intervention (low GI diet)1414Mean Difference (IV, Random, 95% CI)-1.40 [-2.63, -0.17]
9.2 Diet and exercise counselling2188Mean Difference (IV, Random, 95% CI)-1.13 [-4.88, 2.61]
9.3 Supervised exercise2132Mean Difference (IV, Random, 95% CI)0.17 [-1.61, 1.96]
9.4 Supervised exercise plus diet149Mean Difference (IV, Random, 95% CI)-0.80 [-2.84, 1.24]
9.5 Diet counselling/other135Mean Difference (IV, Random, 95% CI)-6.9 [-15.28, 1.48]
10 Postpartum weight retention (n/N; investigator defined time frame)5902Risk Ratio (M-H, Random, 95% CI)0.78 [0.63, 0.97]
10.1 Diet and exercise counselling3615Risk Ratio (M-H, Random, 95% CI)0.72 [0.51, 1.01]
10.2 Supervised exercise plus diet intervention2287Risk Ratio (M-H, Random, 95% CI)0.85 [0.66, 1.10]
11 Energy intake (kj)124065Mean Difference (IV, Random, 95% CI)-570.77 [-894.28, -247.26]
11.1 Diet intervention (low GI diet)41462Mean Difference (IV, Random, 95% CI)-297.26 [-562.80, -31.72]
11.2 Diet and exercise counselling42190Mean Difference (IV, Random, 95% CI)-897.66 [-1763.09, -32.23]
11.3 Supervised exercise plus diet intervention3274Mean Difference (IV, Random, 95% CI)-1090.80 [-2263.86, 82.26]
11.4 Diet counselling/other1139Mean Difference (IV, Random, 95% CI)-172.0 [-686.85, 342.85]
12 Fibre intake (g)83466Mean Difference (IV, Random, 95% CI)1.53 [0.94, 2.12]
12.1 Diet intervention (low GI diet)41223Mean Difference (IV, Random, 95% CI)1.35 [0.55, 2.15]
12.2 Diet and exercise counselling21996Mean Difference (IV, Random, 95% CI)1.97 [0.95, 2.99]
12.3 Supervised exercise plus diet intervention1112Mean Difference (IV, Random, 95% CI)1.0 [-3.06, 5.06]
12.4 Diet counselling//other1135Mean Difference (IV, Random, 95% CI)1.10 [-0.91, 3.11]
13 Physical activity score (26-29 weeks)92851Std. Mean Difference (IV, Random, 95% CI)0.40 [0.18, 0.61]
13.1 Diet and exercise counselling52395Std. Mean Difference (IV, Random, 95% CI)0.27 [0.03, 0.51]
13.2 Supervised exercise intervention2232Std. Mean Difference (IV, Random, 95% CI)0.43 [0.06, 0.79]
13.3 Supervised exercise plus diet intervention2224Std. Mean Difference (IV, Random, 95% CI)0.73 [0.46, 1.00]
14 Macrosomia Infant birthweight > 4000 g278598Risk Ratio (M-H, Random, 95% CI)0.93 [0.86, 1.02]
14.1 Diet intervention (low GI diet)41472Risk Ratio (M-H, Random, 95% CI)0.96 [0.84, 1.10]
14.2 Diet and exercise counselling103705Risk Ratio (M-H, Random, 95% CI)0.93 [0.77, 1.12]
14.3 Unsupervised exercise2229Risk Ratio (M-H, Random, 95% CI)1.16 [0.74, 1.81]
14.4 Supervised exercise intervention72445Risk Ratio (M-H, Random, 95% CI)0.81 [0.64, 1.02]
14.5 Supervised exercise plus diet intervention3398Risk Ratio (M-H, Random, 95% CI)1.02 [0.71, 1.46]
14.6 Diet counselling/other2349Risk Ratio (M-H, Random, 95% CI)1.81 [0.88, 3.72]
15 Infant birthweight > 90th centile184525Risk Ratio (M-H, Random, 95% CI)0.92 [0.80, 1.05]
15.1 Diet and exercise counselling62777Risk Ratio (M-H, Random, 95% CI)0.87 [0.74, 1.02]
15.2 Unsupervised exercise1192Risk Ratio (M-H, Random, 95% CI)1.07 [0.34, 3.43]
15.3 Supervised exercise intervention4397Risk Ratio (M-H, Random, 95% CI)1.09 [0.59, 2.00]
15.4 Supervised exercise plus diet intervention3607Risk Ratio (M-H, Random, 95% CI)1.06 [0.67, 1.66]
15.5 Diet intervention (low GI diet)3200Risk Ratio (M-H, Random, 95% CI)1.25 [0.50, 3.11]
15.6 Diet counselling/other2352Risk Ratio (M-H, Random, 95% CI)0.95 [0.54, 1.69]
16 Birthweight (g) (not prespecified)298350Mean Difference (IV, Random, 95% CI)12.20 [-15.26, 39.65]
16.1 Diet intervention (low GI diet)41447Mean Difference (IV, Random, 95% CI)-0.84 [-1.16, -0.52]
16.2 Diet and exercise counselling93516Mean Difference (IV, Random, 95% CI)52.33 [-33.23, 137.89]
16.3 Unsupervised exercise137Mean Difference (IV, Random, 95% CI)-124.21 [-435.86, 187.44]
16.4 Supervised exercise112714Mean Difference (IV, Random, 95% CI)16.27 [-38.56, 71.11]
16.5 Supervised exercise and diet149Mean Difference (IV, Random, 95% CI)-107.0 [-343.33, 129.33]
16.6 Diet counselling/other3587Mean Difference (IV, Random, 95% CI)1.40 [-78.04, 80.84]
17 Infant birthweight < 2500 g124834Risk Ratio (M-H, Random, 95% CI)0.88 [0.67, 1.14]
17.1 Exercise and diet counselling52934Risk Ratio (M-H, Random, 95% CI)0.84 [0.60, 1.17]
17.2 Unsupervised exercise2229Risk Ratio (M-H, Random, 95% CI)2.14 [0.24, 18.80]
17.3 Supervised exercise41387Risk Ratio (M-H, Random, 95% CI)0.99 [0.61, 1.63]
17.4 Supervised exercise plus diet149Risk Ratio (M-H, Random, 95% CI)2.67 [0.11, 62.42]
17.5 Diet counselling/other1235Risk Ratio (M-H, Random, 95% CI)0.67 [0.29, 1.53]
18 Infant birthweight < 10th centile7662Risk Ratio (M-H, Random, 95% CI)1.09 [0.61, 1.94]
18.1 Diet intervention (low GI diet)2155Risk Ratio (M-H, Random, 95% CI)1.49 [0.47, 4.71]
18.2 Diet and exercise counselling2207Risk Ratio (M-H, Random, 95% CI)0.95 [0.28, 3.29]
18.3 Supervised exercise3300Risk Ratio (M-H, Random, 95% CI)0.99 [0.45, 2.19]
19 Shoulder dystocia43253Risk Ratio (M-H, Random, 95% CI)1.02 [0.57, 1.83]
19.1 Diet intervention (low GI diet)1759Risk Ratio (M-H, Random, 95% CI)0.52 [0.10, 2.82]
19.2 Diet and exercise counselling12142Risk Ratio (M-H, Random, 95% CI)1.25 [0.81, 1.93]
19.3 Diet counselling/other2352Risk Ratio (M-H, Random, 95% CI)0.35 [0.05, 2.64]
20 Neonatal hypoglycaemia42601Risk Ratio (M-H, Random, 95% CI)0.95 [0.76, 1.18]
20.1 Diet and exercise counselling22256Risk Ratio (M-H, Random, 95% CI)1.02 [0.79, 1.32]
20.2 Diet counselling/other2345Risk Ratio (M-H, Random, 95% CI)0.88 [0.36, 2.15]
21 Birth trauma22256Risk Ratio (M-H, Random, 95% CI)0.89 [0.35, 2.30]
21.1 Diet and exercise counselling22256Risk Ratio (M-H, Random, 95% CI)0.89 [0.35, 2.30]
22 Neonatal hyperbilirubinaemia22256Risk Ratio (M-H, Fixed, 95% CI)0.83 [0.62, 1.10]
22.1 Diet and exercise counselling22256Risk Ratio (M-H, Fixed, 95% CI)0.83 [0.62, 1.10]
23 Neonatal respiratory distress syndrome22256Risk Ratio (M-H, Random, 95% CI)0.47 [0.26, 0.85]
23.1 Diet and exercise counselling22256Risk Ratio (M-H, Random, 95% CI)0.47 [0.26, 0.85]
24 Postpartum hemorrhage22901Risk Ratio (M-H, Random, 95% CI)0.94 [0.78, 1.14]
24.1 Diet intervention (low GL diet)1759Risk Ratio (M-H, Random, 95% CI)0.83 [0.23, 3.08]
24.2 Diet and exercise counselling12142Risk Ratio (M-H, Random, 95% CI)0.94 [0.78, 1.14]
Analysis 1.1.

Comparison 1 All diet and/or exercise interventions vs standard/other care, Outcome 1 Excessive weight gain.

Analysis 1.2.

Comparison 1 All diet and/or exercise interventions vs standard/other care, Outcome 2 Weight gain (kg).

Analysis 1.3.

Comparison 1 All diet and/or exercise interventions vs standard/other care, Outcome 3 Low weight gain.

Analysis 1.4.

Comparison 1 All diet and/or exercise interventions vs standard/other care, Outcome 4 Preterm birth.

Analysis 1.5.

Comparison 1 All diet and/or exercise interventions vs standard/other care, Outcome 5 Pre-eclampsia.

Analysis 1.6.

Comparison 1 All diet and/or exercise interventions vs standard/other care, Outcome 6 Hypertension (not prespecified).

Analysis 1.7.

Comparison 1 All diet and/or exercise interventions vs standard/other care, Outcome 7 Induction of labour.

Analysis 1.8.

Comparison 1 All diet and/or exercise interventions vs standard/other care, Outcome 8 Caesarean delivery.

Analysis 1.9.

Comparison 1 All diet and/or exercise interventions vs standard/other care, Outcome 9 Postpartum weight retention (kg).

Analysis 1.10.

Comparison 1 All diet and/or exercise interventions vs standard/other care, Outcome 10 Postpartum weight retention (n/N; investigator defined time frame).

Analysis 1.11.

Comparison 1 All diet and/or exercise interventions vs standard/other care, Outcome 11 Energy intake (kj).

Analysis 1.12.

Comparison 1 All diet and/or exercise interventions vs standard/other care, Outcome 12 Fibre intake (g).

Analysis 1.13.

Comparison 1 All diet and/or exercise interventions vs standard/other care, Outcome 13 Physical activity score (26-29 weeks).

Analysis 1.14.

Comparison 1 All diet and/or exercise interventions vs standard/other care, Outcome 14 Macrosomia Infant birthweight > 4000 g.

Analysis 1.15.

Comparison 1 All diet and/or exercise interventions vs standard/other care, Outcome 15 Infant birthweight > 90th centile.

Analysis 1.16.

Comparison 1 All diet and/or exercise interventions vs standard/other care, Outcome 16 Birthweight (g) (not prespecified).

Analysis 1.17.

Comparison 1 All diet and/or exercise interventions vs standard/other care, Outcome 17 Infant birthweight < 2500 g.

Analysis 1.18.

Comparison 1 All diet and/or exercise interventions vs standard/other care, Outcome 18 Infant birthweight < 10th centile.

Analysis 1.19.

Comparison 1 All diet and/or exercise interventions vs standard/other care, Outcome 19 Shoulder dystocia.

Analysis 1.20.

Comparison 1 All diet and/or exercise interventions vs standard/other care, Outcome 20 Neonatal hypoglycaemia.

Analysis 1.21.

Comparison 1 All diet and/or exercise interventions vs standard/other care, Outcome 21 Birth trauma.

Analysis 1.22.

Comparison 1 All diet and/or exercise interventions vs standard/other care, Outcome 22 Neonatal hyperbilirubinaemia.

Analysis 1.23.

Comparison 1 All diet and/or exercise interventions vs standard/other care, Outcome 23 Neonatal respiratory distress syndrome.

Analysis 1.24.

Comparison 1 All diet and/or exercise interventions vs standard/other care, Outcome 24 Postpartum hemorrhage.

Comparison 2. Diet intervention (low GI diet) vs standard/other care
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Excessive weight gain2833Risk Ratio (M-H, Random, 95% CI)0.74 [0.55, 0.99]
1.1 Low risk population1317Risk Ratio (M-H, Random, 95% CI)0.60 [0.38, 0.94]
1.2 High risk population2516Risk Ratio (M-H, Random, 95% CI)0.81 [0.61, 1.08]
2 Weight gain (kg)5 Mean Difference (IV, Random, 95% CI)Totals not selected
2.1 Mixed risk population3 Mean Difference (IV, Random, 95% CI)0.0 [0.0, 0.0]
2.2 High risk population2 Mean Difference (IV, Random, 95% CI)0.0 [0.0, 0.0]
3 Low weight gain1 Risk Ratio (M-H, Random, 95% CI)Totals not selected
3.1 High risk population1 Risk Ratio (M-H, Random, 95% CI)0.0 [0.0, 0.0]
4 Preterm birth2804Risk Ratio (M-H, Random, 95% CI)0.33 [0.11, 1.02]
4.1 Mixed risk population1759Risk Ratio (M-H, Random, 95% CI)0.39 [0.10, 1.46]
4.2 High risk population145Risk Ratio (M-H, Random, 95% CI)0.22 [0.03, 1.81]
5 Caesarean delivery2133Risk Ratio (M-H, Random, 95% CI)0.99 [0.33, 3.01]
5.1 High risk population2133Risk Ratio (M-H, Random, 95% CI)0.99 [0.33, 3.01]
6 Macrosomia (Infant birthweight > 4000 g)41472Risk Ratio (M-H, Random, 95% CI)0.96 [0.77, 1.20]
6.1 Mixed risk population21335Risk Ratio (M-H, Random, 95% CI)0.93 [0.75, 1.17]
6.2 High risk population2137Risk Ratio (M-H, Random, 95% CI)2.47 [0.68, 8.95]
Analysis 2.1.

Comparison 2 Diet intervention (low GI diet) vs standard/other care, Outcome 1 Excessive weight gain.

Analysis 2.2.

Comparison 2 Diet intervention (low GI diet) vs standard/other care, Outcome 2 Weight gain (kg).

Analysis 2.3.

Comparison 2 Diet intervention (low GI diet) vs standard/other care, Outcome 3 Low weight gain.

Analysis 2.4.

Comparison 2 Diet intervention (low GI diet) vs standard/other care, Outcome 4 Preterm birth.

Analysis 2.5.

Comparison 2 Diet intervention (low GI diet) vs standard/other care, Outcome 5 Caesarean delivery.

Analysis 2.6.

Comparison 2 Diet intervention (low GI diet) vs standard/other care, Outcome 6 Macrosomia (Infant birthweight > 4000 g).

Comparison 3. Diet and exercise counselling vs standard/other care
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Excessive weight gain9 Risk Ratio (M-H, Random, 95% CI)Subtotals only
1.1 Low risk population2247Risk Ratio (M-H, Random, 95% CI)0.72 [0.55, 0.95]
1.2 Mixed risk population1219Risk Ratio (M-H, Random, 95% CI)0.98 [0.83, 1.15]
1.3 High risk women92725Risk Ratio (M-H, Random, 95% CI)0.85 [0.71, 1.02]
2 Weight gain (kg)13 Mean Difference (IV, Random, 95% CI)Subtotals only
2.1 Low risk population2241Mean Difference (IV, Random, 95% CI)-0.92 [-2.12, 0.29]
2.2 Mixed risk population3444Mean Difference (IV, Random, 95% CI)-1.80 [-3.36, -0.24]
2.3 High risk women112741Mean Difference (IV, Random, 95% CI)-0.71 [-1.34, -0.08]
3 Low weight gain52552Risk Ratio (M-H, Random, 95% CI)1.23 [0.89, 1.72]
3.1 Low risk population2247Risk Ratio (M-H, Random, 95% CI)1.34 [0.74, 2.39]
3.2 High risk women52305Risk Ratio (M-H, Random, 95% CI)1.21 [0.79, 1.85]
4 Preterm birth73170Risk Ratio (M-H, Random, 95% CI)0.94 [0.57, 1.55]
4.1 Low risk population2243Risk Ratio (M-H, Random, 95% CI)0.98 [0.19, 5.09]
4.2 Mixed risk population1197Risk Ratio (M-H, Random, 95% CI)1.63 [0.84, 3.18]
4.3 High risk population62730Risk Ratio (M-H, Random, 95% CI)0.83 [0.43, 1.60]
5 Pre-eclampsia73139Risk Ratio (M-H, Random, 95% CI)1.00 [0.75, 1.34]
5.1 Low risk population2243Risk Ratio (M-H, Random, 95% CI)0.34 [0.10, 1.22]
5.2 High risk women72896Risk Ratio (M-H, Random, 95% CI)1.06 [0.79, 1.43]
6 Caesarean delivery93406Risk Ratio (M-H, Random, 95% CI)0.89 [0.80, 1.00]
6.1 Low risk population2243Risk Ratio (M-H, Random, 95% CI)0.93 [0.59, 1.48]
6.2 Mixed risk population2310Risk Ratio (M-H, Random, 95% CI)0.66 [0.41, 1.05]
6.3 High risk women72853Risk Ratio (M-H, Random, 95% CI)0.89 [0.76, 1.04]
7 Macrosomia (Infant birthweight > 4000 g)103705Risk Ratio (M-H, Random, 95% CI)0.92 [0.77, 1.11]
7.1 Low risk population2243Risk Ratio (M-H, Random, 95% CI)2.18 [0.63, 7.58]
7.2 Mixed risk population1210Risk Ratio (M-H, Random, 95% CI)1.39 [0.75, 2.56]
7.3 High risk women93252Risk Ratio (M-H, Random, 95% CI)0.85 [0.73, 1.00]
Analysis 3.1.

Comparison 3 Diet and exercise counselling vs standard/other care, Outcome 1 Excessive weight gain.

Analysis 3.2.

Comparison 3 Diet and exercise counselling vs standard/other care, Outcome 2 Weight gain (kg).

Analysis 3.3.

Comparison 3 Diet and exercise counselling vs standard/other care, Outcome 3 Low weight gain.

Analysis 3.4.

Comparison 3 Diet and exercise counselling vs standard/other care, Outcome 4 Preterm birth.

Analysis 3.5.

Comparison 3 Diet and exercise counselling vs standard/other care, Outcome 5 Pre-eclampsia.

Analysis 3.6.

Comparison 3 Diet and exercise counselling vs standard/other care, Outcome 6 Caesarean delivery.

Analysis 3.7.

Comparison 3 Diet and exercise counselling vs standard/other care, Outcome 7 Macrosomia (Infant birthweight > 4000 g).

Comparison 4. Exercise vs standard/other care
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Excessive weight gain6 Risk Ratio (M-H, Random, 95% CI)Subtotals only
1.1 Low risk population2953Risk Ratio (M-H, Random, 95% CI)0.69 [0.47, 1.02]
1.2 Mixed risk population31592Risk Ratio (M-H, Random, 95% CI)0.77 [0.66, 0.88]
1.3 High risk population5690Risk Ratio (M-H, Random, 95% CI)0.84 [0.73, 0.95]
2 Weight gain (kg)8 Mean Difference (IV, Random, 95% CI)Subtotals only
2.1 Low risk population1687Mean Difference (IV, Random, 95% CI)-1.5 [-2.08, -0.92]
2.2 Mixed risk population41196Mean Difference (IV, Random, 95% CI)-1.00 [-2.01, 0.01]
2.3 High risk women5548Mean Difference (IV, Random, 95% CI)-0.34 [-1.15, 0.47]
3 Low weight gain4 Risk Ratio (M-H, Random, 95% CI)Subtotals only
3.1 Low risk population1687Risk Ratio (M-H, Random, 95% CI)1.29 [1.06, 1.58]
3.2 Mixed risk population21336Risk Ratio (M-H, Random, 95% CI)1.20 [1.00, 1.43]
3.3 High risk population3504Risk Ratio (M-H, Random, 95% CI)1.03 [0.66, 1.60]
4 Preterm birth5 Risk Ratio (M-H, Random, 95% CI)Subtotals only
4.1 Low risk population1687Risk Ratio (M-H, Random, 95% CI)4.20 [0.90, 19.65]
4.2 Mixed risk population31129Risk Ratio (M-H, Random, 95% CI)1.92 [0.75, 4.93]
4.3 High risk population3504Risk Ratio (M-H, Random, 95% CI)1.34 [0.51, 3.55]
5 Pre-eclampsia41253Risk Ratio (M-H, Random, 95% CI)0.99 [0.58, 1.66]
5.1 Mixed risk population21024Risk Ratio (M-H, Random, 95% CI)0.91 [0.52, 1.60]
5.2 High risk population2229Risk Ratio (M-H, Random, 95% CI)1.60 [0.38, 6.73]
6 Caesarean delivery10 Risk Ratio (M-H, Random, 95% CI)Subtotals only
6.1 Low risk population1687Risk Ratio (M-H, Random, 95% CI)0.88 [0.63, 1.21]
6.2 Mixed risk population62263Risk Ratio (M-H, Random, 95% CI)0.96 [0.76, 1.22]
6.3 High risk population5645Risk Ratio (M-H, Random, 95% CI)0.98 [0.81, 1.20]
7 Macrosomia (Infant birthweight > 4000 g)9 Risk Ratio (M-H, Random, 95% CI)Subtotals only
7.1 Low risk population1687Risk Ratio (M-H, Random, 95% CI)0.60 [0.26, 1.41]
7.2 Mixed risk population72445Risk Ratio (M-H, Random, 95% CI)0.81 [0.64, 1.02]
7.3 High risk population3504Risk Ratio (M-H, Random, 95% CI)0.65 [0.22, 1.91]
Analysis 4.1.

Comparison 4 Exercise vs standard/other care, Outcome 1 Excessive weight gain.

Analysis 4.2.

Comparison 4 Exercise vs standard/other care, Outcome 2 Weight gain (kg).

Analysis 4.3.

Comparison 4 Exercise vs standard/other care, Outcome 3 Low weight gain.

Analysis 4.4.

Comparison 4 Exercise vs standard/other care, Outcome 4 Preterm birth.

Analysis 4.5.

Comparison 4 Exercise vs standard/other care, Outcome 5 Pre-eclampsia.

Analysis 4.6.

Comparison 4 Exercise vs standard/other care, Outcome 6 Caesarean delivery.

Analysis 4.7.

Comparison 4 Exercise vs standard/other care, Outcome 7 Macrosomia (Infant birthweight > 4000 g).

Comparison 5. Diet and supervised exercise vs standard/other care
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Excessive weight gain5689Risk Ratio (M-H, Random, 95% CI)0.75 [0.61, 0.92]
1.1 Low risk population2106Risk Ratio (M-H, Random, 95% CI)0.53 [0.16, 1.71]
1.2 Mixed risk population2235Risk Ratio (M-H, Random, 95% CI)0.64 [0.47, 0.88]
1.3 High risk women2348Risk Ratio (M-H, Random, 95% CI)0.83 [0.66, 1.06]
2 Weight gain (kg)3348Mean Difference (IV, Random, 95% CI)-1.31 [-1.00, 0.37]
2.1 Low risk population157Mean Difference (IV, Random, 95% CI)-3.33 [-5.45, -1.21]
2.2 Mixed risk population2235Mean Difference (IV, Random, 95% CI)-0.88 [-2.40, 0.64]
2.3 High risk women156Mean Difference (IV, Random, 95% CI)0.82 [-1.00, 4.64]
3 Low weight gain1 Risk Ratio (M-H, Random, 95% CI)Subtotals only
3.1 Mixed risk population149Risk Ratio (M-H, Random, 95% CI)1.47 [0.40, 5.50]
4 Pre-eclampsia1 Risk Ratio (M-H, Random, 95% CI)Subtotals only
4.1 High risk women1304Risk Ratio (M-H, Random, 95% CI)0.84 [0.51, 1.40]
5 Caesarean delivery3607Risk Ratio (M-H, Random, 95% CI)1.00 [0.69, 1.45]
5.1 Low risk157Risk Ratio (M-H, Random, 95% CI)0.0 [0.0, 0.0]
5.2 Mixed risk population1190Risk Ratio (M-H, Random, 95% CI)0.58 [0.10, 3.36]
5.3 High risk women2360Risk Ratio (M-H, Random, 95% CI)0.97 [0.48, 1.96]
6 Macrosomia (Infant birthweight > 4000 g)3398Risk Ratio (M-H, Random, 95% CI)1.02 [0.71, 1.46]
6.1 Mixed risk population294Risk Ratio (M-H, Random, 95% CI)0.74 [0.23, 2.35]
6.2 High risk women1304Risk Ratio (M-H, Random, 95% CI)1.05 [0.72, 1.54]
Analysis 5.1.

Comparison 5 Diet and supervised exercise vs standard/other care, Outcome 1 Excessive weight gain.

Analysis 5.2.

Comparison 5 Diet and supervised exercise vs standard/other care, Outcome 2 Weight gain (kg).

Analysis 5.3.

Comparison 5 Diet and supervised exercise vs standard/other care, Outcome 3 Low weight gain.

Analysis 5.4.

Comparison 5 Diet and supervised exercise vs standard/other care, Outcome 4 Pre-eclampsia.

Analysis 5.5.

Comparison 5 Diet and supervised exercise vs standard/other care, Outcome 5 Caesarean delivery.

Analysis 5.6.

Comparison 5 Diet and supervised exercise vs standard/other care, Outcome 6 Macrosomia (Infant birthweight > 4000 g).

Comparison 6. Diet counselling/other vs standard/other care
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Excessive weight gain3 Risk Ratio (M-H, Random, 95% CI)Subtotals only
1.1 Mixed risk population3443Risk Ratio (M-H, Random, 95% CI)0.47 [0.08, 2.85]
1.2 High risk population184Risk Ratio (M-H, Random, 95% CI)0.92 [0.53, 1.62]
2 Weight gain (kg)7 Mean Difference (IV, Random, 95% CI)Totals not selected
2.1 Mixed risk population3 Mean Difference (IV, Random, 95% CI)0.0 [0.0, 0.0]
2.2 High risk population5 Mean Difference (IV, Random, 95% CI)0.0 [0.0, 0.0]
3 Low weight gain1 Risk Ratio (M-H, Fixed, 95% CI)Totals not selected
3.1 Mixed risk population1 Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
4 Preterm birth3591Risk Ratio (M-H, Random, 95% CI)0.67 [0.26, 1.73]
4.1 Mixed risk population1235Risk Ratio (M-H, Random, 95% CI)0.67 [0.15, 2.93]
4.2 High risk population2356Risk Ratio (M-H, Random, 95% CI)0.66 [0.19, 2.32]
5 Pre-eclampsia4634Risk Ratio (M-H, Random, 95% CI)0.90 [0.54, 1.48]
5.1 Mixed risk population1235Risk Ratio (M-H, Random, 95% CI)2.69 [0.55, 13.03]
5.2 High risk population3399Risk Ratio (M-H, Random, 95% CI)0.80 [0.47, 1.35]
6 Caesarean delivery5754Risk Ratio (M-H, Random, 95% CI)1.06 [0.93, 1.21]
6.1 Mixed risk population2355Risk Ratio (M-H, Random, 95% CI)0.96 [0.60, 1.54]
6.2 High risk population3399Risk Ratio (M-H, Random, 95% CI)1.10 [0.96, 1.27]
7 Macrosomia (Infant birthweight > 4000 g)2349Risk Ratio (M-H, Random, 95% CI)1.81 [0.88, 3.72]
7.1 High risk population2349Risk Ratio (M-H, Random, 95% CI)1.81 [0.88, 3.72]
Analysis 6.1.

Comparison 6 Diet counselling/other vs standard/other care, Outcome 1 Excessive weight gain.

Analysis 6.2.

Comparison 6 Diet counselling/other vs standard/other care, Outcome 2 Weight gain (kg).

Analysis 6.3.

Comparison 6 Diet counselling/other vs standard/other care, Outcome 3 Low weight gain.

Analysis 6.4.

Comparison 6 Diet counselling/other vs standard/other care, Outcome 4 Preterm birth.

Analysis 6.5.

Comparison 6 Diet counselling/other vs standard/other care, Outcome 5 Pre-eclampsia.

Analysis 6.6.

Comparison 6 Diet counselling/other vs standard/other care, Outcome 6 Caesarean delivery.

Analysis 6.7.

Comparison 6 Diet counselling/other vs standard/other care, Outcome 7 Macrosomia (Infant birthweight > 4000 g).

Appendices

Appendix 1. Adjusted data for Luoto 2011

Continuous

outcome

Intervention (Original data)

(Total number = 216)

Control (Original data)

(Total number = 179)

M1ICC2

Design

effect3

Adjusted sample4

sizes

Cluster

number

x̄ ± SD

Cluster

number

x̄ ± SDInterventionControl

Maternal

weight gain

713.8±5.8714.2±5.128.210.124.2750.6441.96

1 M = average cluster size = ((total number of intervention + total number of control)/(cluster number of intervention + cluster number of control)

2 ICC = intraclass correlation; obtained from the reliable external source (Luoto 2010).

3 Design effect = 1 + (M-1)ICC

4 Adjusted sample sizes = n / design effect

Dichotomous outcomes

Intervention

(Original data)

(Total number = 216,

cluster number = 7)

Control

(Original data)

(Total number = 179,

cluster number = 7)

M1ICC2

Design

effect3

Intervention

(Adjusted data)4

Control

(Adjusted data)4

nnTotal NnTotal Nn
Pre-eclampsia141028.210.124.2750.643.2841.962.34
Birthweight > 4000 g373628.210.124.2750.648.6741.968.44

Infant birthweight

> 90th centile

263428.210.124.2750.646.1041.967.97

Infant birthweight

< the 10th centile

10528.210.124.2750.642.3441.961.17

Appendix 2. Data for Rauh 2013

Continuous outcomesInterventionControlAdjusted P value
x̄ ± SDTotal numberx̄ ± SDTotal number
Weight gain14.1 ± 4.115215.6 ± 5.8740.035

Weight retention

(at 4 months postpartum)

2.1 ± 4.31523.3 ± 5.1720.070
Infant birthweight3406 ± 4021563414 ± 44579-
Dichotomous outcomesInterventionControlAdjusted P value
NumberTotal numberNumberTotal number
Excessive weight gain5815244740.032
Low weight gain3215214740.972
Weight retention ( > 5 kg)2615222720.034
Preterm41565790.088
Caesarean delivery4715633790.145
Gestational diabetes81569790.183
Infant birthweight > 90th centile101567790.702
Infant birthweight < 10th centile61563790.990
Induction of labour4015629790.191

What's new

DateEventDescription
12 June 2015AmendedMinor correction to acknowledgements.

History

Protocol first published: Issue 2, 2008
Review first published: Issue 4, 2012

DateEventDescription
23 April 2015New citation required and conclusions have changedHigh-quality evidence suggests that diet or exercise, or both, interventions are effective in reducing excessive gestational weight gain. Hypertension, caesarean delivery, macrosomia and neonatal respiratory distress may also be reduced, particularly with combined diet and exercise interventions. Exercise appears to be an important part of controlling weight gain in pregnancy and more research is needed to establish safe guidelines.
5 November 2014New search has been performed

Search updated and 169 new records identified. There are now 65 (previously 28) included studies, 49 (previously 27) of which contribute data.

The title has been changed from 'Interventions for preventing excessive weight gain during pregnancy' to 'Diet or exercise, or both, for preventing excessive weight gain during pregnancy'. This was done to limit the otherwise enormous scope of the review. As a result of the title modification, two previously included 1970s studies of (obsolete) appetite suppressant drug interventions were excluded in this update. Drug interventions (e.g. metformin, probiotics), will now need to be addressed under a separate title.

Methods updated and GRADE 'Summary of findings' tables have been incorporated.

10 November 2008AmendedThe Types of interventions section was amended by the inclusion of the phrase 'or other interventions for preventing excessive weight gain in pregnancy'. This amendment was made to ensure that the selection criteria are consistent with the objectives of the review which are to evaluate the effectiveness of all interventions (or combinations of interventions) to prevent excessive weight gain.

Contributions of authors

B Muktabhant (BM) conceived and designed the draft protocol. P Lumbiganon (PL) and C Ngamjarus (CN) reviewed and commented on the revisions of the protocol. For the original review, BM, CN and T Dowswell (TD) selected studies, extracted data and conducted data analysis. BM and TD drafted the original review with feedback from PL and CN. For the update, BM and T Lawrie (TL) selected studies, extracted data, conducted data analysis and prepared the review. ML and PL contributed to data analysis, discussion and revision of the manuscript. All authors approved the final version of the review.

Declarations of interest

None known.

Sources of support

Internal sources

  • Khon Kaen University, Thailand.

  • University of Liverpool, UK.

External sources

  • Thai Cochrane Network, Thailand.

  • Thailand Research Fund/Distinquished Professor Award, Thailand.

  • UNDP/UNFPA/UNICEF/WHO/World Bank Special Programme of Research, Development and Research Training in Human Reproduction (HRP), Department of Reproductive Health and Research (RHR), World Health Organization, Switzerland.

Differences between protocol and review

This update differs from the protocol and previous versions of the review in the following ways.

  1. The title has been changed from 'Interventions for preventing excessive weight gain during pregnancy' to 'DIet or exercise, or both, for preventing excessive weight gain during pregnancy'. This was done to limit the otherwise enormous scope of the review. As a result of the title modification, two previously included 1970s studies of (obsolete) appetite suppressant drug interventions were excluded in this update. Drug interventions (e.g. metformin, probiotics), will now need to be addressed under a separate title.

  2. The protocol and previous versions of this review included quasi-RCTs. For this update, we have excluded quasi-RCTs. We believe that the large and growing number of RCTs in this field justifies our approach of only using the best quality trials (RCTs).

  3. We amended the Subgroup analysis and investigation of heterogeneity section of the methods by including subgroup analysis according to the risk of excess weight-related adverse outcomes (low-risk, mixed-risk and high-risk populations).

  4. For this update, we decided to include the additional outcomes 'birthweight' and 'hypertension'; these are frequently reported outcomes in the context of the review interventions. Although they were not prespecified, the decision to include these outcomes was taken before commencing data extraction. We re-visited previously included studies to retrieve these data, where reported. By capturing these additional data we hope that this and future versions of the review will be more complete.

  5. We amended the outcome 'complications relating to macrosomia' to include 'neonatal respiratory distress syndrome'.

Characteristics of studies

Characteristics of included studies [ordered by study ID]

Althuizen 2013

MethodsRCT, 8 midwifery practices in The Netherlands from February 2005 to May 2006.
Participants

246 randomised, 219 analysed.

Inclusion criteria: women expecting their first child, able to read and speak Dutch, and in the first 14 weeks of gestation.

Exclusion criteria: miscarriage, gestation ≥ 15 weeks.

Interventions

Intervention group: counselling (5 x approximately 15 minute sessions on weight, physical acitvity and diet) (n = 106). Interventions were face-to-face at 18, 22, 30, and 36 weeks' gestation, with a telephone session at 8 weeks postpartum.

Control group: routine care (no counselling) (n = 113).

OutcomesPrimary outcomes were excessive weight gain, BMI, postpartum weight retention, birthweight, macrosomia, preterm birth, gestational diabetes.
Notes

Age (intervention, control): 29.2 ± 3.3/30.4 ± 4.

Enrolment gestational age < 14 weeks.

Prepregnancy BMI: 24 ± 4.2/23.5 ± 3.8.

Authors concluded that "The lifestyle counselling intervention evaluated in this study did not have an effect on excessive weight gain or postpartum weight retention. Our findings for overweight and obese women need to be confirmed in a larger, randomised trial".

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk"A computerised random number generator drew up an allocation schedule pre-stratified for midwifery practices."
Allocation concealment (selection bias)Unclear riskNot described.
Blinding of participants and personnel (performance bias)
All outcomes
High riskBlinding not possible for the intervention.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskResearch assistants blinded to treatment allocation.
Incomplete outcome data (attrition bias)
All outcomes
Unclear risk11% of participants (17 in intervention and 10 in control group) dropped out during the course of the study.
Selective reporting (reporting bias)Unclear riskAll expected outcomes reported.
Other biasLow riskNone noted. Baseline characteristics comparable.

Angel 2011

MethodsRCT conducted at San Francisco General Hospital, USA between 2006 and 2009 (abstract only).
Participants

64 randomised.

Inclusion criteria: obese/overweight, ages 18-42 years, from 20 weeks.

Exclusion criteria: NR.

Interventions

Intervention group: low glycaemic load diet.

Control group: low fat diet.

OutcomesExcessive weight gain, excessive fat gain.
Notes

Age (intervention, control): NR.

Enrolment gestational age approx. 20 weeks.

Prepregnancy BMI: NR.

Abstract only with no usable data. "This evidence suggests that dietary patterns are important for achieving weight gain recommendations among overweight and obese pregnant women."

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk"randomly assigned."
Allocation concealment (selection bias)Unclear riskNot described.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot described.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot described.
Incomplete outcome data (attrition bias)
All outcomes
Unclear risk14% drop out. Not yet reported in full.
Selective reporting (reporting bias)Unclear riskAbstract only with little data.
Other biasUnclear riskAbstract only with little data.

Asbee 2009

MethodsRCT, set in resident obstetric clinic in Charlotte, North Carolina, USA.
Participants

Inclusion criteria: prenatal care established at 6-16 weeks of gestation, age 18-49 years, all prenatal care received at the Resident Obstetrics Clinic, English-speaking, Spanish-speaking, or both, and singleton pregnancy.

Exclusion criteria: BMI higher than 40, pre-existing diabetes, untreated thyroid disease, or hypertension requiring medication or other medical conditions that might affect body weight, delivery at institution other than Carolinas Medical Center Main, pregnancy ending in premature delivery (less than 37 weeks), and limited prenatal care (fewer than 4 visits).

Interventions

Intervention group (n = 57) received consistent program of dietary and lifestyle counselling. At the initial visit, participants met with a registered dietician to receive a standardised counselling session, including information on pregnancy-specific dietary and lifestyle choices. The counselling consisted of recommendations for a patient-focused caloric value divided in a 40% CHO, 30% protein, and 30% fat fashion. Participants were instructed to engage in moderate-intensity exercise at least 3 times per week and preferably 5 times per week. They also received information on the appropriate weight gain during pregnancy using the IOM guidelines. Each participant met with the dietician only at the time of enrolment. At each routine obstetrical appointment, the healthcare provider informed the participant whether her weight gain was at the appropriate level. If her weight gain was not within the IOM guidelines, the participant’s diet and exercise regimen were reviewed and she was advised on increasing or decreasing her intake and increasing or decreasing exercise.

Control group (n = 43) received routine prenatal care, including an initial physical examination and history, routine laboratory tests, and routine visits per ACOG standards. The only counselling on diet and exercise during pregnancy was that included in a standard prenatal booklet. The healthcare provider did not counsel the participant regarding any changes in diet or lifestyle.

Outcomes

Weight gain, caesarean delivery, pre-eclampsia, shoulder dystocia.

Total weight gain was defined as weight just before delivery minus prepregnancy weight.

Notes

Age (intervention, control): 26.7 ± 6.0, 26.4 ± 5.0.

Enrolment gestational age (intervention, control): 13.7 ± 3.6, 13.6 ±.2 weeks.

Prepregnancy BMI: 25.5 ± 6.0, 25.6 ± 5.1 kg/m².

BMI category, n (intervention, control):

  • underweight and normal weight (BMI < 26): 35, 25;

  • overweight (BMI 26-29.0): 10, 8;

  • obese (BMI > 29.0): 12, 10.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskRandomisation was performed using computer-generated random allocation.
Allocation concealment (selection bias)Low riskStudy allocation was concealed in numbered and sealed opaque envelopes.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot described.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot described.
Incomplete outcome data (attrition bias)
All outcomes
Low risk

No loss to follow-up reported.

Trial authors stated that they had carried out an ITT analysis: data were analysed for participants according to their randomly-allocated group; all participants were included in the analysis.

Selective reporting (reporting bias)Low riskThe outcomes reported as in the published protocol.
Other biasHigh risk

Demographic data were similar. Age, prepregnancy weight, height and BMI were not different at baseline.

Women with delivery before 37 weeks were excluded.

Barakat 2011

MethodsRCT, set in Hospital de Fuen-labrada, Madrid, Spain.
Participants

80 women randomised.

Inclusion criteria: healthy pregnant women (age, 23-38 years), had uncomplicated, singleton pregnancies.

Exclusion criteria: any type of absolute obstetric contraindication to aerobic exercise during pregnancy, which included other contraindications that the authors considered to have a relevant influence on maternal perception of health: significant heart disease, restrictive lung disease, incompetent cervix/cerclage, multiple gestation, risk of premature labour, pre-eclampsia/pregnancy-induced hypertension, thrombophlebitis, recent pulmonary embolism (last 5 years), acquired infectious disease, retarded intrauterine development, serious blood disease, and/or absence of prenatal care.

Interventions

Intervention group: (40 randomised) moderate physical activity, included a total of 35- to 45-min weekly sessions 3 days each week from the start of the pregnancy (weeks 6-9) to the end of the 3rd trimester (weeks 38-39), an average of 85 training sessions, exercise intensity was light-to-moderate. Exercise was supervised by a fitness specialist and was in groups of 10-12 women.

Control group: (40 randomised) routine care.

OutcomesWeight gain, caesarean, birthweight < 4000 g, birthweight > 4000 g.
NotesAuthors concluded that a moderate physical activity program that is performed over the first, second, and third trimester of pregnancy improves the maternal perception of health status.
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskRandomly assigned by use of a random number table.
Allocation concealment (selection bias)Unclear riskNot described.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot described.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot described. It is not clear how lack of blinding would impact on the outcomes measured.
Incomplete outcome data (attrition bias)
All outcomes
Unclear risk80 women were randomised and 67 were analysed; 34 in the exercise group, 33 in the control group. Reason of discontinued were similar in both groups.
Selective reporting (reporting bias)Unclear riskAssessment from published study report.
Other biasHigh riskNo between-group differences regarding most potential confounding variables (such as occupational activities, standing, smoking habits, alcohol intake) but parity was not balanced between groups; the exercise group had a higher percentage of nulliparous women (76.5%) than the control group (36.4%).

Bisson 2014

MethodsRCT conducted at Centre Mere Enfant CHU de Quebec, Laval University, Quebec City, Canada.
Participants

37 randomised, 4 withdrawals. Numbers in each group not stated.

Inclusion criteria: obese pregnant women < 15 weeks.

Exclusion criteria: NR.

Interventions

Intervention group:12 week supervised moderate exercise program consisting of 3 weekly 1-hr sessions in a hospital-based setting from 15th to 28th week.

Control group: routine care.

Outcomes"perinatal and maternal outcomes."
Notes

Abstract only with no usable data. Exercising women maintained their fitness compared with control women (P = 0.047) and "had reduced weekly weight gain (0.3±0.1 kg/wk vs 0.5±0.2 kg/wk for exercise and control, respectively, p=0.047." "3 exercising versus 6 control women developed either gestational diabetes or hypertension." "Based on preliminary data, birth weight and gestational age at delivery were comparable between groups (3587±459 g and 39 3 /7 ± 1 1 /7 weeks, vs 3387±409 g and 39 3 /7 ± 1 1 /7 weeks in the exercising and control groups respectively, NS."

Authors concluded that "An individualized exercise training effective in maintaining maternal fitness and limiting gestational weight gain in obese, pregnant women does not increase prematurity. However larger gestational weight gain in obese, pregnant women does not increase prematurity. However larger interventional study in this population will determine the potential benefits of maternal exercise during pregnancy on child growth, metabolism and development."

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk"randomly assigned."
Allocation concealment (selection bias)Unclear riskNot described.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot described.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskUnclear due to limited reporting (abstract only) but 4 dropped out. Numbers in each arm was not stated.
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskAbstract only with sparse data.
Selective reporting (reporting bias)Unclear riskAbstract only with sparse data.
Other biasUnclear riskAbstract only with sparse data.

Bogaerts 2012

Methods3-arm RCT conducted in University hospital, Leuven and East Limburg Hospital Belgium.
Participants

Inclusion criteria: obese pregnant women.

Exclusion criteria: NR.

Interventions

Counselling involving psycho-education (4 sessions) vs a brochure vs control.

Control group: routine care.

OutcomesGWG and psychological vulnerability (depression and anxiety).
Notes

Data collected during the first, second and third trimester. They found a significant reduction in GWG in the brochure and prenatal groups compared with controls. No differences in delivery method, birthweight, anxiety or depressed mood noted.

Authors concluded that: findings justify "the clinical implementation of a psycho-educational program in order to reduce GWG and psychological vulnerability in obese pregnant women".

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk"women were randomised."
Allocation concealment (selection bias)Unclear riskNot described.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot described.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot described.
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskDetails not provided.
Selective reporting (reporting bias)Unclear riskAbstract only with little data.
Other biasUnclear riskAbstract only with little data.

Callaway 2010

MethodsRCT, set in a hospital in Brisbane, Australia.
Participants

50 women randomised.

Inclusion criteria: obese pregnant women were recruited at 12 weeks’ gestation, aged 18-45, BMI ≥ 30  kg/m2,  pregnancy care at study hospital, willing and able to be randomised to an exercise intervention.

Exclusion criteria: non-English  speaking, contraindication or inability to exercise, medical or obstetric contraindication to exercise including haemodynamically significant heart disease, restrictive lung disease, incompetent cervix (cerclage), multiple  gestation, severe anaemia, chronic bronchitis, type 1 diabetes, orthopaedic limitations, poorly controlled seizure disorder, poorly controlled hyperthyroidism, or a heavy smoker.

Interventions

Intervention group: the intervention group received an individualised exercise program with an energy expenditure (EE) goal of 900 kcal/ week. Advice from physiotherapist and diaries for self-monitoring.

Control group: routine obstetric care.

OutcomesSelf-report of exercise (behaviour change).
Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskRandomisation was by a random number allocation technique conducted by a 3rd party.
Allocation concealment (selection bias)Unclear riskNot clear but external randomisation.
Blinding of participants and personnel (performance bias)
All outcomes
High riskNo blinding.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNo blinding. The impact of the lack of blinding was not clear. The use of self-monitoring diaries by the intervention group may have introduced recall bias.
Incomplete outcome data (attrition bias)
All outcomes
High riskRandomised 50 women, at 36 weeks 36 were followed up (30% attrition).
Selective reporting (reporting bias)Unclear riskAssessment from published study report and online supplement.
Other biasUnclear risk"There were no statistically significant differences between the intervention and control groups in any baseline variable." Different monitoring techniques in the 2 groups (diaries in the intervention group) may have led to recall bias.

Clapp 2002a

MethodsA prospective randomised design.
Participants20 healthy women with uncomplicated pregnancy.
InterventionsThe participants were enrolled prior to pregnancy and placed on a regular regimen of supervised exercise and began a weight maintaining diet (low glycaemic sources of CHO). At 8 weeks' gestation, they were randomised to either diet containing low glycaemic CHO sources (n = 10) (aboriginal CHO diet) or high glycaemic CHO sources (n = 10) (cafeteria CHO diet). All continued the same exercise regimen throughout pregnancy.
Outcomes

Weight gain.

Total weight gain was defined as weight at delivery minus prepregnancy weight.

NotesDuring pregnancy, all women were allowed to increase caloric intake according to appetite with advancing gestation.
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskNot described.
Allocation concealment (selection bias)Unclear riskNo information provided.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot described.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot described.
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskUnspecified loss to follow-up.
Selective reporting (reporting bias)High riskOutcomes not prespecified and appear to be selected.
Other biasUnclear riskPoorly reported.

Clapp 2002b

MethodsRCT, set in Case Western Reserve University at metro health medical centre, USA.
Participants

Inclusion criteria: 80 healthy, regularly exercising (≥ 3 times/week), non-substance-abusing women were enrolled before pregnancy.

After conception (which occurred within 4 months in all cases) and ultrasonic confirmation of a viable singleton pregnancy, these women were assigned in week 8 of gestation to the exercise regimens.

Exclusion criteria: not stated.

Number of participants: 75 women enrolled and complete the protocol; 26 in Lo-Hi group, 24 in Mo-Mo group, 25 in Hi-Lo group.

Interventions

There were 3 study groups:

group 1: low-high exercise (n = 26): exercise 20 mins 5 days a week through to week 20, gradually increasing to 60 mins 5 days a week by week 24 and maintaining that regimen until delivery (Lo-Hi);

group 2: moderate-moderate exercise (n = 24): exercise 40 mins 5 days a week from week 8 until delivery (Mod-Mod);

group 3: high-low exercise (n = 25): exercise 60 mins 5 days a week through to week 20, gradually decreasing to 20 mins 5 days a week by week 24 and maintaining that regimen until delivery (Hi-Lo).

OutcomesWeight gain.
NotesAge 31 ± 1, 30 ± 1, 32 ± 1 in Lo-Hi, Mo-Mo, Hi-Lo.
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskWomen were randomly assigned.
Allocation concealment (selection bias)Unclear riskWomen were randomly assigned by envelope but it was not stated whether envelopes were sequentially numbered, opaque and sealed.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot described.
Blinding of outcome assessment (detection bias)
All outcomes
High riskA member of the study team carried out morphometric assessment of placenta and infant at the time of birth.
Incomplete outcome data (attrition bias)
All outcomes
Low riskLoss to follow-up 6.25%.                     
Selective reporting (reporting bias)Unclear riskCould not determine.
Other biasLow riskBaseline data were similar.

Cordero 2014

MethodsOpen-label RCT conducted at Hospital Puerta de Hierro, Madrid, Spain.
Participants

342 randomised, 257 women analysed.

Included pregnant women in Spain at 10-12 weeks according to ultrasound, with no medical or obstetric contraindications to exercise.

Excluded women with medical or obstetric contraindications.

Interventions

Intervention group (101 women): a supervised exercise program consisting of aerobic and toning exercises for 3 sessions per week. 2 weekly sessions were performed on land (60 min) and 1 session was aquatic based (50 min). Program commenced from 10-14 weeks to the end of the third trimester. Sessions were supervised by a qualified fitness specialist and an obstetrician.

Control group (156 women): routine care.

OutcomesGDM (primary outcome, diagnosed by fasting GTT before 30 weeks' gestation, according to medical records). Excessive GWG, gestational age at delivery, mode of delivery, birthweight and length, SGA, macrosomia.
Notes

Enrolment age (intervention, control): 33.6 ± 4.1, 32.9 ± 4.5.

Enrolment gestational age (intervention, control): NR.

Prepregnancy BMI (intervention, control):22.5 ± 3.2, 23.6 ± 4.

NCT01790412.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskSequence generation and ratio was not described.
Allocation concealment (selection bias)Unclear riskNot described.
Blinding of participants and personnel (performance bias)
All outcomes
High riskOpen-label.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskInsufficient detail in report.
Incomplete outcome data (attrition bias)
All outcomes
High riskAttrition of 21 women (16.4%) in the intervention group and 64 in the control group (29.1%).
Selective reporting (reporting bias)High riskPer protocol analysis performed based on adherence to exercise "A minimum of 80% adherence to exercise classes was required for women assigned to the intervention group". Excluded women with poor adherence, and those who developed hypertension or were at risk of preterm labour. Possible side effects of exercise, e.g. preterm labour, were NR.
Other biasHigh risk

Sample sizes differed substantially (101 and 156 women in intervention and control groups, respectively).

For intervention and control groups, respectively, 2.7% vs 4.8% had previous GDM. 17.8% vs 27.6% had sedentary lifestyles before pregnancy. These might have biased GDM and GWG results in favour of the intervention group.

De Oliveria Melo 2012

MethodsOpen-label 3-arm RCT conducted at Department of Obstetrics, University of Campinas in Brazil with recruitment from May 2008 to Sept 2010.
Participants

General population, 187 randomised.

Inclusion criteria: healthy pregnant women who were sedentary at admission to the study, gestational age 13 weeks or less confirmed by ultrasonography and with single live fetus.

Exclusion criteria: excluded if smoked, chronic diseases, a history of premature delivery, fetal abnormalities, placenta previa, a history of vaginal bleeding, placental detachment, and cervical length less than 2.5 cm.

Interventions

Intervention group: exercise (initiated at 13 weeks) (n = 62) vs exercise (initiated at 20 weeks) (n = 63) vs control (n = 62). Exercise consisted of walking 3 times a week.

Control group: routine care.

OutcomesUteroplacental blood flow, birthweight, pre-eclampsia, fetal growth restriction, macrosomia (assessed by ultrasound at 38 weeks), LGA and SGA at birth.
Notes

Fitness evaluated at 13, 20 and 28 weeks.

Age (intervention 1, intervention 2, control): 24 [5.8]/26 [5.3]/24 [5.4].

Enrolment gestational age: ≤ 13 weeks.

Prepregnancy BMI (intervention 1, intervention 2, control): 24.7 [4.3]/23.4 [3.8]/23.5 [3.5].

Authors concluded that "Moderate intensity walking improved the physical fitness level of healthy pregnant previously sedentary women without affecting feto-placental blood flow or fetal growth".

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk"Randomisation sequence generated in blocks of ten" using Random Allocation software program 1.0."
Allocation concealment (selection bias)Low riskSealed opaque envelopes. "Groups were assigned only after the woman agreed to participate."
Blinding of participants and personnel (performance bias)
All outcomes
High riskOpen-label.
Blinding of outcome assessment (detection bias)
All outcomes
Low risk"Investigators involved in monitoring and ...analysis were unaware of the group to which the patient had been assigned."
Incomplete outcome data (attrition bias)
All outcomes
Unclear risk16 women declined to participate after randomisation (8.5%). 31 women (19%) were missing follow-up data for the 38 week visit; these missing data were balanced across study arms. Delivery/birth data were available for 161/187 women (86%).
Selective reporting (reporting bias)Unclear riskProtocol not seen.
Other biasLow riskNone noted. Baseline characteristics similar.

Di Carlo 2014

MethodsRCT at antenatal clinic in Italy from January 2010 to January 2011.
Participants

General population, 154 randomised, 120 analysed.

Inclusion criteria: pregnant at 6-13 weeks' gestation (median 8 weeks). Women were excluded if they had any significant maternal condition.

Exclusion criteria: any significant maternal condition including essential hypertension, thyroid diseases, gestational diabetes, miscarriages, preterm births, multiple pregnancies with more than 2 fetuses, maternal BMI ≤ 20 and ≥ 40 kg/m².

Interventions

Intervention group: dietary intervention (personalised diet plan with monthly dietician supervision) (n = 77; 59 in final analysis).

Control group: brochure on healthy eating (n = 77; 61 in final analysis).

OutcomesWeight gain, birthweight.
Notes

Age (intervention, control): 31.3 [4.7]/28.2 [5.3] (P = 0.002).

Enrolment gestational age: 8-13 weeks (median 8 weeks).

Prepregnancy BMI: 26.5 [6.3]/25 [4.2] (P = 0.3).

Authors concluded that "This study suggests that a personalised nutritional intervention, in which the dietician plays an active role within the obstetric team, may represent a successful approach to limiting weight gain in pregnant women".

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk"Randomly allocated" in 1:1 ratio.
Allocation concealment (selection bias)Low risk" ...attached a sequentially numbered, opaque sealed and stapled envelope containing the allocation treatment to the patient clinical record."
Blinding of participants and personnel (performance bias)
All outcomes
High riskParticipants not blinded due to nature of intervention.
Blinding of outcome assessment (detection bias)
All outcomes
Low risk"The allocation sequence was concealed from the researchers."
Incomplete outcome data (attrition bias)
All outcomes
High risk22% of participants were excluded due to miscarriages (9 vs 8 in diet and control groups respectively), loss to follow-up (6 vs 7) and preterm births (3 vs 1). "Analysis was performed per protocol" but protocol deviations and individual denominators were NR.
Selective reporting (reporting bias)High riskPer protocol data reported with individual denominators missing from most results. Results not adjusted for baseline difference in maternal age (older in the intervention group).
Other biasHigh riskBaseline difference in age of women (average of 3 years older in intervention group).

Dodd 2014

MethodsRCT at 3 public maternity hospitals, Adelaide in Australia from June 2008 to December 2011.
Participants

High risk (overweight and obese), 2212.

Inclusion criteria: women with a singleton pregnancy, between 10 + 0 and 20 + 0 weeks' gestation, and BMI ≥ 25.

Exclusion criteria: women with type 1 and 2 diabetes were ineligible.

Interventions

Intervention group: comprehensive dietary and lifestyle intervention (counselling) (n = 1108) Intervention involved meetings and home visits with advice on dietary, exercise, and behavioural strategies delivered by a dietician and trained research assistants. Exercise advice primarily encouraged women to increase their amount of walking and incidental activity.

Control group: routine care (n = 1104).

A nested RCT was also conducted in which women randomised to the intervention group were further randomised to receive written/verbal education about physical activity (n = 295) or to participate in a supervised walking group of moderate intensity 3 times per week for 40 mins (n = 287).

OutcomesPrimary outcome measures are: incidence of infants born LGA (birthweight ≥ 90th centile for gestation and sex). Secondary outcomes included birthweight > 4000 g, hypertension, pre-eclampsia, and gestational diabetes.
Notes

Age (intervention, control): 29.3 [5.4]/29.6 [5.3].

Enrolment gestational age (intervention, control): 14 (11.9-17)/14.1 (11.9-17).

Recruitment BMI: 31 (28.1-35.9)/31.1 (27.7-35.6).

Authors concluded that "For women who were overweight or obese, the antenatal lifestyle advice used in the study did not reduce the risk of delivering a baby weighing above the 90th centile for gestational age and sex or improve maternal pregnancy and birth outcomes".

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk"The computer generated randomisation schedule used balanced variable blocks in the ratio 1:1". The investigator who prepared the randomisation schedule also was not involved with the recruitment or clinical care.
Allocation concealment (selection bias)Low risk"Telephoning the central randomisation service."
Blinding of participants and personnel (performance bias)
All outcomes
High riskNot feasible to blind participants.
Blinding of outcome assessment (detection bias)
All outcomes
Low riskFollow-up done by interviewers not involved with the trial.
Incomplete outcome data (attrition bias)
All outcomes
Low risk< 20% missing data for all outcomes.
Selective reporting (reporting bias)Low riskAll outcomes reported according to protocol.
Other biasLow riskNone noted. Baseline characteristics comparable.

Ferrara 2011

MethodsRCT at Kaiser Permanente Medical Care Program of Northern California in USA from October 2005 and May 2008.
Participants

High risk (GDM), 197 randomised.

Inclusion criteria: women with GDM.

Exclusion criteria: age < 18 years; multiple gestation; diagnosis of diabetic retinopathy; high-risk pregnancy (i.e. drug or alcohol abuse, chronic health problems, or pregnancy complications); thyroid diseases diagnosed in the last 30 days; and non-English speaker.

Interventions

Intervention group: lifestyle intervention called DEBI (n = 96). Lifestyle intervention involved 3 in-person sessions and up to 15 telephone calls with counselling re diet, physical activity and breastfeeding up to 12 months postpartum. The intervention was delivered by 2 dietitians. Participants were encouraged to engage in moderate intensity physical activity for 150 mins per week and received written materials about food size, foods with low GI or low fat, and how to read food labels were discussed.

Control group: routine care (n = 101).

OutcomesMeeting a set postpartum weight goal, weight gain, birthweight and breastfeeding.
Notes

Data collected at baseline (GDM diagnosis) and at 6 weeks, 7 months and 12 months.

Enrolment gestational age (intervention, control): 31 [5.6]/31 [6.1].

Authors concluded that: "This study suggests that a lifestyle intervention that starts during pregnancy and continues postpartum is feasible and may prevent pregnancy weight retention and help overweight women lose weight. Strategies to help postpartum women overcome barriers to increasing physical activity are needed".

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk"A computer randomisation program was used to ensure that the conditions remained balanced with regards to the following characteristics: age(< 30 and ≥ 30 years), parity (≤ 1 and < 1), pregravid BMI (< 27.0 and ≥ 27 kg/m²)."
Allocation concealment (selection bias)Unclear riskNot described.
Blinding of participants and personnel (performance bias)
All outcomes
High riskParticipants not blinded due to nature of intervention.
Blinding of outcome assessment (detection bias)
All outcomes
Low risk"data were collected by research assistants who were unaware of the condition assignment."
Incomplete outcome data (attrition bias)
All outcomes
High risk20% attrition at 7 and 12 months follow-up with great loss to follow-up in the intervention groups. This could bias results in the direction of the intervention if the heavier women chose to drop out.
Selective reporting (reporting bias)Unclear riskProtocol not seen. GWG was NR.
Other biasLow riskBaseline characteristics comparable.

Guelinckx 2010

MethodsRCT, set in the prenatal clinic, University Hospital of Leuven, Belgium.
Participants

Inclusion criteria: obese (BMI > 29.0 according to IOM criteria), white women consecutively attending the prenatal clinic before 15 week of gestation.

Exclusion criteria: pre-existing diabetes or developing GDM, multiple pregnancy, recruitment after 15 weeks of gestational age, premature labour (delivery before 37 week of gestation), primary need for nutritional advice in case of a metabolic disorder, kidney problems, Crohn's disease, allergic conditions, and inadequate knowledge of the Dutch language.

Interventions

2 intervention groups: the passive group (n = 37): received a brochure during the 1st prenatal consultation. This brochure was specifically designed for the study and provided advice on nutrition and on physical activity and tips to limit pregnancy-related weight gain. The active group (n = 42): received the same brochure and women were actively counselled by a trained nutritionist in 3 group sessions. A maximum of 5 women were brought together in these 1-hour sessions, which were scheduled at 15, 20, and 32 weeks of pregnancy. The sessions provided participants with recommendations on a balanced, healthy diet, based on the Official National Dietary Recommendations (9%–11% of the energy should come from proteins, 30%–35% from fat, and 50%–55% from CHOs).

Control group (n = 43): received routine prenatal care.

(Energy intake was not restricted in any group.)

Outcomes

Excessive weight gain (weight gain more than the upper limit recommendation for overweight women; > 11.2 kg).

Gestational weight gain.

Obstetrical and neonatal outcome: pre-eclampsia, induction of labour, caesarean section, birthweight > 4000 g.

Average energy intake.

Weight gain was defined as weight at birth minus prepregnancy weight.

Total physical activity score at 3rd trimester.

For analysis 3.10 and 4.10 a physical activity score was calculated by using a questionnaire including a total 16 questions classified into 3 domains: work, sports, and non-sports leisure-time activities, scored on a 5-point scale, ranging from “never”, “seldom”, “sometimes”, “very often”, to “always”.  A total score for physical activity from a minimum of 3 to a maximum of 15 was obtained. A higher score indicated more activity.

Notes

Age 29.4 ± 4.4, 28.7 ± 4.0, 28.0 ± 3.6 years for control group, passive group, active group.

Enrolment gestational age: 10.2 ± 2.4, 10.2 ± 2.6, 9.3 ± 2.8 weeks for control group, passive group, active group.

Prepregnancy BMI: 33.5 ± 3.9, 33.4 ± 3.07, 34.1 ±4 .5 kg/m2 for control group, passive group, active group.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskNo information provided.
Allocation concealment (selection bias)Low riskPatients were randomly assigned by using block randomisation.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot described.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot described.
Incomplete outcome data (attrition bias)
All outcomes
Low risk

Loss to follow-up 9.7%.

Reasons for excluding the participants from each group were similar.

Selective reporting (reporting bias)Unclear riskCould not determine.
Other biasLow riskBaseline characteristics of participants were similar between intervention and control groups.

Haakstad 2011

MethodsParallel-arm RCT at Norwegian School of Sport Sciences in Norway from September 2007-March 2008.
Participants

General population, 105.

Inclusion criteria: ability to speak Norwegian; nulliparous, sedentary women whose exercise levels did not include participation in a structured exercise program including brisk walks for the past 6 months were eligible for the trial, and must be in their first 24 weeks of pregnancy.

Exclusion criteria: history of more than 2 miscarriages, severe heart disease (including symptoms of angina, myocardial infarction or arrhythmias), persistent bleeding after 12 weeks of gestation, multiple pregnancy, poorly controlled thyroid disease, pregnancy-induced hypertension or pre-eclampsia, diabetes or gestational diabetes, and other diseases that could easily interfere with participation.

Interventions

Intervention group: exercise (60 min supervised aerobic dance at least twice a week for a minimum of 12 weeks) (n = 52). Women in the exercise group were advised to have moderate, self-imposed physical activity on the remaining weekdays.

Control group: routine care (n = 53).

OutcomesInfant birthweight, excessive weight gain, postpartum weight retention. Maternal weight gain and the proportion of women with excessive weight gain according to IOM recommendations (used self-reported pre-pregnancy weight as baseline).
Notes

Participants were assessed 3 times: first visit (12-24 weeks), second visit (36-38 weeks) and last visit (6-12 weeks postpartum). Adherence was a problem - 31 (60%) women attended less than 80% of the exercise sessions and 4 women never showed up. Investigators performed subgroup analysis of participants who attended more than 24 sessions and the difference was significant in this subgroup of 21 women vs 53 controls (GWG 11.0 vs 13.8; P = 0.01). No women in this group had excessive weight gain (P = 0.006).

Age (intervention, control): 31.2 [3.7]/30.3 [4.4].

Enrolment gestational age (intervention, control): 17.3 [4.1]/18 [4.3].

Prepregnancy BMI: 23.8 [3.8]/23.9 [4.7].

Authors concluded that "Regular participation in aerobic dance exercise can contribute to significantly reduced weight gain in pregnancy." However, "not associated with a reduction in birth weight".

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskUsed "a simple (not block) computerised randomisation programme".
Allocation concealment (selection bias)Low risk"An independent person...assigned the participants to either an exercise group or a control group."
Blinding of participants and personnel (performance bias)
All outcomes
Low riskParticipant blinding not possible but principal investigator was blinded to group allocation.
Blinding of outcome assessment (detection bias)
All outcomes
Low risk"Assessor blinded". The principal investigator was "blinded to group allocation when assessing the outcome measures".
Incomplete outcome data (attrition bias)
All outcomes
Low riskDrop-out rates of 19% and 21% in exercise and control arms, respectively. Drop-outs were due to pain, hypertension, preterm birth and other reasons and were similar between the study arms.
Selective reporting (reporting bias)Unclear riskCould not determine.
Other biasUnclear riskDenominators in report tables were the total exercise and control group N, despite stating drop-outs in each group of 10 and 11 women, respectively.

Harrison 2013

MethodsRCT at 3 large tertiary hospitals in Victoria, Australia.
Participants

High risk, 228 randomised; 203 analysed.

Inclusion criteria: women 12-15 weeks of gestation, overweight (BMI ≥ 25 or ≥ 23 kg/m²) if high risk ethnicity (Polyasian, Asian, African populations) or obese (BMI ≥ 30 kg/m²), and at the increased risk for developing GDM identified by validated risk prediction tool.

Exclusion criteria: exclusion criteria included multiple pregnancies, diagnosed type 1 or 2 diabetes, a BMI ≥ 45 kg/m², a pre-existing chronic medical condition, and non-English speaking women.

Interventions

Intervention group: lifestyle counselling intervention program (individual 4 sessions based on Social Cognitive Theory provided by a health coach) (n = 121) Intervention provided dietary advice, simple healthy eating, and "physical activity messages" and weight gain self-monitoring. Also included "regular self-weighing as a key behavioural strategy".

Control group: routine care (n = 107).

OutcomesThe primary outcome was GWG with secondary outcomes including GDM screening.
Notes

Outcomes were assessed at 12-15 and 26-28 weeks' gestation. Postpartum outcomes NR in primary report.

Age (intervention, control): 32.4 [4.6]/31.7 [4.5].

Enrolment gestational age (overall): 14 [0.8].

Recruitment BMI: 30.4 [5.6]/30.3 [5.9].

Authors concluded that "Results indicate that a low-intensity lifestyle intervention, integrated with antenatal care, optimizes healthy GWG and attenuates physical activity decline in early pregnancy

Efficacy in limiting weight gain was greatest in overweight women and in high-risk ethnically diverse women".

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk"Randomly assigned …through computer-generated randomised sequencing."
Allocation concealment (selection bias)Unclear risk"Sealed opaque envelopes."
Blinding of participants and personnel (performance bias)
All outcomes
Low risk"Care providers….were blinded to group allocation."
Blinding of outcome assessment (detection bias)
All outcomes
Low risk"Participants wore a blinded pedometer" and "investigators and outcome data analysers were blinded to group allocation."
Incomplete outcome data (attrition bias)
All outcomes
Low riskLoss to follow-up was similar in the 2 groups and < 20% for primary outcomes. Pedometer (PA) outcomes showed high loss to follow-up; therefore we did not use these data.
Selective reporting (reporting bias)Unclear riskCould not determine.
Other biasUnclear riskFollow-up weight gain data were collected at 28 weeks (much earlier than other included studies).

Hawkins 2014

MethodsParallel arm pilot RCT. Conducted at medical centres in Western Massachusetts, USA. Recruitment from April 2010 to Aug 2011.
Participants

68 high-risk (overweight and obese) pregnant women randomised.

Overweight and obese pregnant Hispanic women (pre-pregnancy BMI > 25 kg/m2) aged 18–40 years, with a gestational age of < 18 weeks, and who self-reported participating in < 30 mins of moderate-intensity activity per week.

Excluded if history of Type 2 diabetes, hypertension, heart disease or chronic renal disease; current medications that adversely influence glucose tolerance; contraindications to participating in moderate-intensity physical activity or a low-fat/high-fibre diet; self-reported participation in > 30 min of moderate-intensity exercise on > 3 days/week or > 20 min of vigorous-intensity exercise on > 1 day/week; or 6) multiple gestation (e.g. twins).

Interventions

A lifestyle intervention (n = 33), consisting of a culturally and linguistically modified, motivationally targeted, individually tailored 6-month prenatal programme. Educators encouraged women to achieve guidelines for physical activity, decrease saturated fat and increase dietary fibre. The intervention consisted of 6 monthly in-person behavioural counselling sessions and 5 telephone booster sessions with follow-up to 6 weeks postpartum. Women were encourage to achieve ≥ 30 min of moderate-intensity activity on most days of the week through walking and developing a more active lifestyle.

Controls had routine care (n = 35).

OutcomesGWG, infant birthweight and biomarkers of insulin resistance.
Notes

Mean recruitment age and BMI not given; these baseline variables were stratified and reported as categorical variables. Mean recruitment age was 14.9 weeks overall. Group characteristics were similar.

Exercise outcomes were reported for 24-28 weeks' gestation and at 6 weeks' postpartum.

"Findings suggest that a motivationally matched lifestyle intervention is feasible and may help attenuate pregnancy-related decreases in vigorous physical activity in a population of overweight and obese Hispanic women." NCT01141582.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk"randomisation was stratified by age and prepregnancy BMI with a block size of four."
Allocation concealment (selection bias)Unclear riskNot described.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot clearly described.
Blinding of outcome assessment (detection bias)
All outcomes
Low riskAssessors blinded to the assigned intervention group.
Incomplete outcome data (attrition bias)
All outcomes
Low riskLow attrition.
Selective reporting (reporting bias)Unclear riskBirth outcomes other than birthweight, and maternal weight at 6 weeks postpartum, were NR.
Other biasLow riskBaseline characteristics similar. Analysis by ITT.

Huang 2011

MethodsRCT; 3 groups intervention design; 2 experimental groups (from pregnancy to 6 months postpartum (EP) and from birth to 6 months postpartum (EPP). The group receiving the intervention in the postnatal period only is not included in our analysis) and 1 comparison group.
Participants

From January to June 2006, pregnant women were recruited from the obstetric clinics of a hospital in Taiwan (160 women randomised).

Inclusion criteria: 16 gestational weeks, age 18 years or older, no cognitive impairment or psychiatric illness, ability to speak and read Chinese, not participating in another study, and intention to give birth at the study site.

Interventions

Intervention group: (80 participants). The educational intervention began at 16 gestational weeks (baseline) and to 6 months postpartum. The intervention was delivered at regularly scheduled clinic visits by nurses with training in nutrition and physical fitness. The nurse discussed with each participant how to design an individualised diet and physical activity plan. The intervention consisted of 6 1-to-1 counselling sessions: 1 primary session (about 30–40 mins) at the 16-week gestation visit, and 5, 1-to-1 booster sessions (at 28 gestational weeks, 36–38 gestational weeks, before hospital discharge after a 3–7-day stay, 6 weeks' postpartum and 3 months postpartum). After each clinic visit, women in the experimental groups were sent a personalised graph of their weight changes. At the 1st session, the experimental groups also received a researcher-prepared brochure that provided detailed information on weight management goals during pregnancy and postpartum.

Control group: (80 participants) routine care, provided once each trimester, which included health education on nutrition and exercise during pregnancy.

Outcomes

GWG, weight retention at 6 months postpartum, health-promoting behaviour; physical activity.

For analysis 1.9.1 physical activity measurement was a part of the health-promoting lifestyle profile composed of 50-item scale uses a 4-point response format (range = 50–200) to measure the frequency of engaging in activities related to self-actualisation, nutrition, physical activity,interpersonal support, health responsibility and stress management.

Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskUsing a table of random numbers.
Allocation concealment (selection bias)Unclear riskNot stated.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot described.
Blinding of outcome assessment (detection bias)
All outcomes
Low riskThe research assistant collecting outcome data was reported to be blind to the group assignments.
Incomplete outcome data (attrition bias)
All outcomes
Unclear risk80 women in each group were randomised, 61 and 64 of intervention and control group were analysed (78% followed up).
Selective reporting (reporting bias)Unclear riskAssessment from published study report.
Other biasLow riskNo notable baseline differences were found between groups.

Hui 2006

MethodsRCT, set in a community nurse-managed centre and the Manitoba Clinic, both in urban Winnipeg, Manitoba, Canada.
Participants

Inclusion criteria: women < 26 weeks pregnant with no pre-existing diabetes were recruited on a voluntary basis.

Exclusion criteria: pregnant women who had medical obstetric, skeletal or muscular disorders that could contraindicate physical exercise during pregnancy.

Interventions

Intervention (n = 24): additional intervention: lifestyle intervention including exercise intervention and dietary intervention.

Exercise intervention: participants were instructed in group-session exercises and in home-based exercise. Weekly group session included floor aerobics, stretching and strength exercises, 3-5 times/week for 30-45 mins per session, video provided to participants to assist with home-based exercise.

Nutrition intervention: computer-assisted food choice map interview, dieticians provided a personalised plan for participants.

Control (n = 21): standard care group received an information package on diet and physical activity for a healthy pregnancy.

Outcomes

Excessive weight gain, weight gain, caesarean section, infant birthweight > 4000 g, and physical activity at end of study.

Weight gain was defined as weight at birth (from medical chart) minus prepregnancy weight.

For analysis 1.9.1 physical activity was defined as recreational physical activity which was measured by using the PARmed-X for Pregnancy form based on Health Canada recommendations. Low levels (physical activity = 0) are defined as either no physical activity or activity < 1 to 2 times per week and for < 20 min per session; moderate levels (physical activity = 1) are defined as activity 1 to 2 times per week and for > 20 min per session or > 2 times per week and for < 20 min per session; high level (physical activity = 2) are defined as activity > 2 times per week and for > 20 min per session.

Notes

Age (intervention, control): 26.2 ± 5.7, 26.2 ± 5.4.

Prepregnancy BMI (intervention, control): 25 ± 6.3, 23.4 ± 3.9 kg/m².

Excessive weight gain was assessed based on prepregnant BMI:

  • BMI < 20 kg/m², weight gain during pregnancy 12.5 -18 kg;

  • BMI 20-27 kg/m², upper limit of weight gain 16 kg;

  • BMI > 27 kg/m², upper limit of weight gain 11.5 kg.

(Canadian guidelines for healthy weights)

Majority of participants (89%) were from low-income families or low-middle income families.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskParticipants were enrolled and randomised into additional intervention and standard care groups.
Allocation concealment (selection bias)Unclear riskNo information provided.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot described.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot described.
Incomplete outcome data (attrition bias)
All outcomes
Unclear risk

52 enrolled, 45 completed. Loss = 7/52*100 = 13.5%; 7 pregnant women dropped out due to school or work commitments.

The participants who dropped out were significantly younger and had lower incomes than those who completed the program (P < 0.01).

Selective reporting (reporting bias)Unclear riskCould not determine.
Other biasLow riskNo significant differences were found in age, prepregnancy BMI, and family income between additional intervention and standard care groups.

Hui 2012

MethodsRCT at Tertiary hospital, Winipeg, Canada, from July 2004 to February 2010.
Participants

General population, 224 randomised, 190 completed the study (88 controls and 102 interventions).

Inclusion criteria: non-diabetic pregnant women living in Winnipeg, < 26 weeks' gestation, signed informed consent.

Exclusion criteria: medical or obstetric contraindications to exercise during pregnancy.

Interventions

Intervention group: lifestyle intervention (diet counselling and an exercise program) (n = 112) Intervention included "a community-based exercise program specifically designed for pregnant women was provided". An exercise regimen, 3 to 5 times per week including a weekly exercise session and multiple home sessions of mild-to-moderate exercise for 30 to 45 mins was recommended. Program started between 20-26 weeks. Group exercise sessions including aerobics were held in community centres and instructors were licensed fitness trainers. 2 dietary interviews with counselling were provided.

Control group: routine care (n = 112).

OutcomesPrimary outcome - prevalence of excessive GWG and measures of physical activity and food intake between the 2 groups. Other measures included physical activity, gestational diabetes, weight-related obstetric procedures, gestational weight gain, the prevalence for LGA and birthweights.
Notes

Participants logbooks were collected weekly. Delivery data and maternal weight at delivery were collected from medical records.

Age (intervention, control): 30.1 [5.2]/28.7 [5.9].

Enrolment gestational age given as < 26 weeks' gestation.

Prepregnancy BMI: 24.9 [5.4]/25.7 [5.1].

Authors concluded that a "lifestyle intervention during pregnancy increased physical activity, improved dietary habits and reduced excessive GWG in urban-living pregnant women".

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk"Randomisation was performed using a computer-generated randomisation allocation table by a staff member without involvement in the study design."
Allocation concealment (selection bias)Low risk"After randomisation, participants received a sealed envelope labelled with the assigned randomisation number."
Blinding of participants and personnel (performance bias)
All outcomes
High risk"The study staff were not blinded to the types of intervention."
Blinding of outcome assessment (detection bias)
All outcomes
High risk"The study staff were not blinded to the types of intervention."
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskLow risk for primary outcomes - 30 participants (15%) withdrew from the study (7 in intervention group and 23 in the control group). However, only half the women completed dietary logbooks, so these data could not be used.
Selective reporting (reporting bias)Unclear riskCould not determine.
Other biasLow riskNone noted. Baseline characteristics comparable.

Hui 2014

MethodsParallel arm RCT conducted in Winipeg, Canada between May 2009 and December 2011.
Participants

116 normal and high BMI women were randomised (BMI < 25 and BMI > 25), 113 analysed.

Included if < 20 weeks' gestation, no existing GDM.

Excluded if they had medical or obstetric contraindications to exercise during pregnancy.

Interventions

Lifestyle intervention (diet counselling and a supervised exercise program) (n = 57) vs control (n = 56). Intervention included "a community-based exercise program specifically designed for pregnant women was provided". An exercise regimen, 3 to 5 times per week including a weekly exercise session and home sessions with DVD instruction of mild to moderate aerobic exercise for 30 to 45 mins was recommended. Program started between 20-26 weeks and continues to 36 weeks. Group exercise sessions including aerobics were held in community centres and instructors were licensed fitness trainers. 2 dietary interviews with dietician counselling using a Food Choice Map were provided (baseline and 2 months later).

Control group received standard care.

OutcomesGWG, birthweight, delivery route, physical activity and food intake, gestational diabetes, LGA.
Notes

Investigators stratified results by BMI (< 25 and > 25 kgm2). Recruitment age: overweight group 31 [4]/32 [5]; normal weight group 31 [3]/29 [6].

Gestational age: < 26 weeks.

Recruitment BMI: overweight group 29.5 [5.1]/ 29.7 [1.3]; normal weight group 21.6 [2.2]/22.6 [1.9].

Authors concluded that "the lifestyle intervention program decreased EGWG, GWG, and offspring birth weight in pregnant women with normal, but not above normal, pre-pregnancy BMI, which was associated with increased physical activity and decreased carbohydrate intake".

NCT00486629.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskComputer-generated randomisation table.
Allocation concealment (selection bias)Low riskAllocation by a staff member not involved in study design by sealed, numbered envelope.
Blinding of participants and personnel (performance bias)
All outcomes
High risk"the study staff were not blinded to the types of intervention."
Blinding of outcome assessment (detection bias)
All outcomes
Low riskPregnancy and maternal weight outcomes were collected by student assistants without knowledge of assignment. (High risk for participant logbooks for exercise and diet).
Incomplete outcome data (attrition bias)
All outcomes
Low riskNo withdrawals.
Selective reporting (reporting bias)Unclear riskNot able to determine.
Other biasLow riskNone noted. Baseline characteristics comparable.

Jackson 2011

MethodsRCT, set in 5 prenatal care practices in the San Francisco Bay Area, USA, including 3 public hospitals, 2 academic practices, and a community hospital. 2006-2007.
Participants

327 women randomised.

Inclusion criteria: English-speaking women 18 years or older and less than 26 weeks of gestation.

Exclusion criteria: women who report smoking, alcohol use, drug use, or partner violence.

Interventions

Intervention group: (163 randomised) The Video Doctor: an interactive computer program including in-depth behavioural risk assessments and tailored counselling messages, and producing printed output for both the patient and clinician. An actor-portrayed Video Doctor appears and offers education on exercise, nutrition and weight gain based on principles of Motivational Interviewing. Dietary counselling focused on increasing intake of fruits and vegetables and whole grains, increasing healthful vs unhealthful fats and decreasing sugary foods. The Video Doctor emphasised dietary and exercise behaviour changes over weight gain. The Video Doctor programme required 10–15 mins to complete. After 4 weeks, participants received a brief ‘‘booster’’ Video Doctor counselling.

Control group: (164 randomised) usual care. The usual care group did not interact with the Video Doctor and the program did not produce a Cueing Sheet or Educational Worksheet. Behavioural counselling for the usual care group was determined by the clinician.

OutcomesSelf-reported servings per day or week of healthful foods (e.g. fruits and vegetables) and unhealthful foods (e.g. sweets), and exercise duration and frequency, and weight gain above the IOM guidelines.
Notes

Mean baseline age (intervention, control): 26.1 ± 5.8, 26.9 ± 6.2.

Enrolment BMI (intervention, control): reported as % categories: overweight and obese women comprised 48% and 41% of intervention and control groups respectively.

Gestation (intervention, control): 19.7 ± 5.5, 19.2 ± 6.0.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskRandomisation by computer.
Allocation concealment (selection bias)Low riskRandomisation by computer (interactive computer programme intervention).
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskParticipants would not have been blinded to group allocation.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskIt was not stated that staff or outcome assessors were blinded.
Incomplete outcome data (attrition bias)
All outcomes
Low risk6 women were excluded after randomisation: 3 due to insufficient English, 1 because of inaccurate gestational age, and 2 withdrew during the baseline assessment leaving 158 in the Video Doctor group and 163 in the usual care group. ITT analysis was performed for primary outcome (weight gain) for other outcomes 327 were randomised and 287 (88%) completed follow-up.
Selective reporting (reporting bias)Unclear riskNot able to determine as assessed from published study report.
Other biasUnclear riskThere were no significant differences between the control and Video Doctor groups for any of the demographic variables listed except education. Results for weight gain were not fully reported by randomisation group. Results for  mean weight gain of each group were reported without SDs.

Jeffries 2009

MethodsRCT, set in a tertiary obstetric hospital in Melbourne, Australia.
Participants

Inclusion criteria: pregnant women at < 14 weeks' gestation.

Exclusion criteria: age < 18 or > 45 years, type 1 or type 2 diabetes mellitus, multiple pregnancy, or non-English speaking.

Interventions

Intervention (n = 125): women allocated to the intervention group were given a personalised weight measurement card, advised of their optimal GWG (based on their BMI at the time of recruitment and the United States IOM guidelines, and instructed to record their weight at 16, 20, 24, 28, 30, 32 and 34 weeks' gestation.

Control (n = 111): not given instructions about regular weight measurement.

Outcomes

Weight gain above IOM guideline, mean weight gain from recruitment to follow-up at 36 weeks' gestation.

SGA (< 10th centile), large-for-gestational age (> 90th centile), preterm (< 37 weeks), instrumental delivery, caesarean delivery, pre-eclampsias, neonatal hypoglycaemia, shoulder dystocia.

Weight gain was weight difference between weight at about 36 weeks' gestation and weight at 1st antenatal appointment.

Notes

Gestation age at recruitment (intervention, control): 11.6, 11.4 weeks.

BMI category, n (intervention, control):

  • underweight (BMI ≤ 19.8): 5, 5;

  • normal (BMI > 19.8, ≤ 26.0): 75, 67;

  • overweight (BMI > 26, ≤ 29.0): 20, 18;

  • obese (BMI > 29.0): 25, 21.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskUsing computer random number generation.
Allocation concealment (selection bias)Low riskUsing opaque, sequentially numbered envelopes.
Blinding of participants and personnel (performance bias)
All outcomes
Low riskAll participants were blinded to the purpose of the study.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot described.
Incomplete outcome data (attrition bias)
All outcomes
Low risk

Loss to follow-up, 23/148 in intervention group, 27/138 in control group.

Similar reason of loss to follow-up in intervention and control groups.

Selective reporting (reporting bias)Low riskThe outcomes reported as in the published protocol.
Other biasLow riskBaseline characteristics were similar.

Kieffer 2014

MethodsParallel-arm RCT at community health centre in Detroit, USA from 2004 to 2006.
Participants

General population, 278 randomised, all included in primary analysis.

Inclusion criteria: pregnant Latinas were eligible if they were age 18 or older, South Detroit residents, and at less than 20 gestation weeks at eligibility screening.

Exclusion criteria: see inclusion criteria.

Interventions

Intervention group: a counselling intervention (MOMS intervention included home visits, group classes, related activities and social support from community health workers to influence eating and exercise, weight beliefs and behaviours) (n = 139) Intervention was administered over 11 weeks.

Control group: routine care (n = 139).

OutcomesDietary behaviour outcomes including sugar, fats, and fibre.
Notes

Little usable data extracted from this report.

Age (intervention, control): 27.3 [5.3]/27.1 [5.1].

Enrolment gestational age < 20 weeks.

Recruitment BMI: 24.2 [5.1]/24.7 [5].

Authors concluded that "We confirmed the hypothesis that a community-planned CHW-led healthy lifestyle intervention could improve dietary behaviors of low-income Lantina women during pregnancy".

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskA "statistician generated random allocation sequence in blocks of 40".
Allocation concealment (selection bias)Low risk"After baseline data collection, each women received...a sealed envelope containing her group assignment."
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskBlinding of participants was not feasible.
Blinding of outcome assessment (detection bias)
All outcomes
Low riskData collected by trained interviewers who were blinded to group allocation.
Incomplete outcome data (attrition bias)
All outcomes
Low risk< 20% loss to follow-up. Data were available for 139/139 and 136/139 women in the intervention and control groups, respectively, for the primary analysis.
Selective reporting (reporting bias)Unclear riskCould not determine.
Other biasLow riskNone noted. Baseline characteristics comparable.

Kong 2014

MethodsRCT at Low State University in USA (accrual dates not stated).
Participants

Obese/overweight pregnant women, 42 randomised.

Inclusion criteria: maternal age between 18 and 45 years, singleton pregnancy, nonsmoker, self-reported overweight (BMI ≥ 25 kg/m2) or obese (BMI ≥ 30 kg/m2) before pregnancy, no prior history of chronic diseases (including type 1 diabetes, cardiovascular disease, thyroid, or lung disorder), and no prior history of gestational diabetes. Only enrolled women with < 3 30-min episodes of physical activity in previous 6 months.

Exclusion criteria: see inclusion criteria.

Interventions

Intervention group: exercise intervention (unsupervised walking program on treadmill or other setting for a minimum of 150 min/week) (n = 18).

Control group: routine care (n = 19).

OutcomesActivity, weight gain, pregnancy risks and labour procedures, infant birth outcomes.
Notes

Women were loaned treadmills for the study. Interventions continued at least to gestational week 35. Data reported separately for overweight (n = 18) and obese (n = 19) participants. Data were collected for 1 week periods at weeks 10-14 (baseline), weeks 17-19 (V2), weeks 27-29 (V3), and weeks 34-36 (V4).

Age (obese group: intervention, control): 28.6 [5.3]/25.7 [4].

Age (overweight group: intervention, control): 26.2 [2.6]/27.3 [3.6].

Enrolment gestational age < 15 weeks.

Recruitment BMI (obese group: intervention, control): 34.7 [4.6]/34.2 [3.6].

Recruitment BMI (overweight group: intervention, control): 26.5 [1.2]/27.4 [1.4].

Authors concluded that a "pilot, unsupervised walking intervention increased the moderate-intensity physical activity (MPA) of overweight and obese women during pregnancy" with "trend to more favourable maternal and birth outcomes" in the intervention group.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk"After the initial enrollment, participants were randomly assigned …using a computer-based random number generator (Microsoft Excel 2010)."
Allocation concealment (selection bias)Unclear risk"All participants and research staff were blinded to the group allocation."
Blinding of participants and personnel (performance bias)
All outcomes
High riskBlinding of participants to intervention was not possible due to the nature of the intervention. Study coordinator not blinded.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskBlinding of outcome assessor not described. Pregnancy outcome measures self-reported by participants via a postpartum questionnaire and may be subject to bias.
Incomplete outcome data (attrition bias)
All outcomes
Unclear risk9 withdrawals (19.6%, 5 in physical activity group and 4 in control group).
Selective reporting (reporting bias)Low riskAll expected outcomes reported.
Other biasUnclear riskNone noted. Baseline characteristics comparable.

Korpi-Hyovalti 2011

MethodsRCT, set in 2 hospitals in rural municipalities (Kauha-joki and Lapua) in Finland.
Participants

60 women randomised.

Inclusion criteria: women at high risk of gestational diabetes: women had 1 or more risk factors (BMI > 25 kg/m2, previous history of GDM or birth of child > 4.5 kg, age > 40 years, family history of diabetes or the venous plasma glucose concentration after 12 hours fasting in the morning was 4.8-5.5 mmol/L and 2-hour OGTT plasma glucose < 7.8 mmol/L.

Exclusion criteria: women who were diagnosed as having GDM in this study and women who had risk factors for GDM or whose fasting venous plasma glucose was 4.8-5.5 mmol/L but who for personal or professional reasons did not wish to participate in the trial.

Interventions

Intervention group: (n = 30) a lifestyle intervention; included diet counselling and exercise counselling. Dietary advice tailored to each woman individually on 6 occasions. Women were encouraged to eat a diet rich in vegetables, berries and fruits, and to use low-fat. Moderate-intensity physical exercise during pregnancy was encouraged, 6 sessions for exercise counselling

Control group: close follow-up group (n = 30). All women were given general information on diet and physical activity to decrease the risk of GDM during pregnancy as part of routine care.

OutcomesWeight gain, GDM, birthweight.
Notes

Age: 29.2 [5.4]/29.8 [5.4].

Gestation at recruitment given as 8-12 weeks.

Baseline BMI: 27.3 [6.0]/25.5 [3.4].

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskWomen were randomly assigned to the lifestyle intervention group or to the close follow-up group by the study physician in the Central Hospital with the use of a computed randomisation list.
Allocation concealment (selection bias)Unclear riskNot stated.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskWomen were aware of group assignment although it was stated that the nurses scheduling study visits did not have access to the randomisation list. It is not clear what impact the lack of blinding would have on the outcomes measured.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot described.
Incomplete outcome data (attrition bias)
All outcomes
Unclear risk60 women were randomised, 54 were followed up.
Selective reporting (reporting bias)Unclear riskAssessment from published study report.
Other biasUnclear riskThere were no statistically significant differences in baseline measures between the lifestyle intervention and the close follow-up groups although women in the intervention group had slightly higher prepregnancy weight (mean 76.6 kg compared with 69.6 kg in controls.

Laitinen 2009

MethodsRCT, set in maternal welfare clinics in the city of Turku and neighbouring areas in south-west Finland.
Participants

Women were eligible for participation if they were less than 17 weeks’ gestation and had no metabolic or chronic diseases such as diabetes.

Participants were Caucasian.

Interventions

At 1st trimester 256 pregnant women were allocated to 3 groups: modification of dietary intake according to current recommendations with probiotics or placebo and a control group receiving placebo only.

  1. Control group, (placebo) (n = 85).

  2. Intervention group 1 (n = 86) (diet counselling and placebo).

  3. Intervention group 2 (n = 85) (diet counselling and probiotics), probiotic capsules containing Lactobacillus rhamnosus GG and Bifidobacterium lactis Bb12.

Dietary counselling given by a dietitian at each study visit aimed to modify dietary intake to conform with that currently recommended, particular attention being paid to the quality of dietary fat

Study visits took place 3 times during pregnancy at 13·9 (SD 1·6), 23·8 (SD 1·4) and 33·9 (SD 1·4) weeks of gestation and at 1, 6 and 12 months postpartum.

Outcomes

Weight gain, energy intake, dietary fibre intake at 3rd trimester of pregnancy.

Weight gain was calculated by subtracting self-reported prepregnancy weight from that recorded at a prenatal visit or at hospital within 1 week before delivery.

Notes

Age (intervention 1, intervention 2, control): 30.1 ± 5.2, 29.7 ± 4.1, 30.2 ± 5.0.

Enrolment BMI NR.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskWomen were randomly assigned to 3 study groups according to computer-generated block randomisation.
Allocation concealment (selection bias)Low riskUsing sealed envelopes. At the 1st study visit the envelopes were opened. The random allocation sequence was thus concealed until interventions were assigned.
Blinding of participants and personnel (performance bias)
All outcomes
Low riskProbiotics/placebo were double-blind in the intervention groups but single blind in the control group.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot described.
Incomplete outcome data (attrition bias)
All outcomes
Low riskNo loss to follow-up (to delivery).
Selective reporting (reporting bias)Low riskThe outcomes reported as in the published protocol.
Other biasLow riskNo other bias apparent.

Leiferman 2011

MethodsRCT conducted by the Colorado School of Public Health, Denver, USA.
Participants

Pregnant women.

Inclusion/exclusion criteria not described.

InterventionsMy Baby My Move (MBMM) was an 8-week community-based program that involved both didactic and experiential components. Peer leaders delivered the program.
OutcomesSparse information and no data were available on this trial.
Notes

Conference abstract only with no usable data.

Authors concluded that "These findings suggest that implementing community-based interventions to increase antenatal PA are well received and show promise in ultimately changing PA behaviour".

Full report is pending (personal communication).

Nodine 2011 is a substudy of 29 women from this study that examined the effect of exercise on sleep parameters.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskInsufficient information on which to base judgement.
Allocation concealment (selection bias)Unclear riskInsufficient information on which to base judgement.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskInsufficient information on which to base judgement.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskInsufficient information on which to base judgement.
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskInsufficient information on which to base judgement.
Selective reporting (reporting bias)Unclear riskInsufficient information on which to base judgement.
Other biasUnclear riskInsufficient information on which to base judgement.

Louie 2011

MethodsParallel-arm RCT conducted in Australia.
Participants

99 randomised, 92 analysed.

Inclusion criteria: women with GDM diagnosed by GTT at 20-32 weeks' gestation and singleton pregnancy.

InterventionsDietary intervention: low GI diet (n = 47) vs conventional high-fibre, moderate GI diet (n = 45). Intervention included 3 face-to-face visits with the study dietician.
OutcomesBirthweight, LGA, SGA, caesarean section, macrosomia, GWG.
Notes

Age (intervention, control): 34 [4.1]/32.4 [4.5].

Enrolment gestational age: 26.1 [4]/26 [4.3].

Prepregnancy BMI: 23.9 [4.4]24.1 [5.7].

Authors concluded that "In intensively monitored women with GDM, an LGI diet and a conventional HF diet produce similar pregnancy outcomes". They suggested that because the intervention began after the 29th week gestation this may have attributed to the lack of difference.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskCentral randomisation by "computer-generated numbers, stratified by BMI (BMI < 30 vs ≥ 30) and weeks of gestation (< 28 vs ≥ 28)".
Allocation concealment (selection bias)Low risk"The allocation sequence was unpredictable and concealed from the recruiter."
Blinding of participants and personnel (performance bias)
All outcomes
Low riskNot described.
Blinding of outcome assessment (detection bias)
All outcomes
Low risk"A biostatician blinded to the diet allocation performed the statistical analyses."
Incomplete outcome data (attrition bias)
All outcomes
Low risk"Four women delivered prematurely and three women withdrew after first dietary instruction."
Selective reporting (reporting bias)Low riskAll pre-specified outcomes reported.
Other biasLow riskBaseline characteristics comparable.

Luoto 2011

MethodsCluster-RCT, set in primary healthcare centres in 14 municipalities in Pirkanmaa region in south-western Finland.
Participants

Recruitment 2007-8.

Inclusion criteria: pregnant women at 8–12 weeks' gestation at high risk of developing gestational diabetes;  BMI ≥ 25 kg/m² based on measured height and self-reported prepregnancy weight; GDM or any signs of glucose intolerance or newborn’s macrosomia (≥ 4500 g) in any earlier pregnancy; type 1 or 2 diabetes in 1st- or 2nd-degree relatives; or age ≥ 40 years.

Exclusion criteria: at least 1 of the 3 baseline (8–12 weeks' gestation) OGTT measurements was abnormal (fasting blood glucose ≥ 5.3 mmol/L, 10.0 mmol/L at 1 hr, and 8.6 mmol/L at 2 hr); prepregnancy type 1 or 2 diabetes; inability to speak Finnish; age <18 yr; multiple pregnancy; physical restriction preventing physical activity; substance abuse; treatment or clinical history of psychiatric illness.

Interventions

Intervention group: (7 municipalities) Individual counselling on physical activity and diet and weight gain. At the 1st visit the recommendations for GWG were discussed and an appropriate weight gain graph was selected to guide the participant in monitoring her weight gain. The primary physical activity counselling was implemented at 8–12 weeks' gestation and the primary dietary counselling session at 16–18 weeks' gestation. Physical activity counselling was enhanced at 4, and diet counselling at 3 subsequent visits.

Control group: (7 municipalities) usual care group received no counselling beyond usual care, which included some dietary counselling (partly on different topics) and follow-up of gestational weight, but little physical activity counselling.

OutcomesIncidence of GDM as assessed by OGTT (maternal outcome) and newborns’ birthweight adjusted for gestational age, maternal weight gain and the need for insulin treatment during pregnancy, changes in physical activity and diet (intake of total fat, saturated and polyunsaturated fatty acids, saccharose, and fibre.
Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskThe unit of randomisation was municipality. In the randomisation process, participating municipalities were 1st pair-wise matched. 14 municipalities were then randomised by computer.
Allocation concealment (selection bias)Low riskCluster-randomised trial with computer randomisation.
Blinding of participants and personnel (performance bias)
All outcomes
High riskUnblinded.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskWomen in the intervention group were provided with notebooks to record diet and activity, women in the control group were not; this may have affected recall and may have introduced bias. It was not clear whether staff collecting outcome data were blind to group assignment.
Incomplete outcome data (attrition bias)
All outcomes
High riskNo loss of clusters (14 clusters were randomised and all were included in the analysis). 343 women in the intervention and 297 in the usual care group agreed to participate in the trial. However, 81 (23.6%) of the participants in intervention group and 93 (31.3%) of the participants in the usual care group had an abnormal OGTT result at baseline and were thus excluded. The final number of participants in the analyses was 219 (89.0% of participants receiving allocated intervention) in the intervention group and 180 (91.8% of participants receiving allocated intervention) in the usual care group. However about 40% of eligible participants of each group were followed up.
Selective reporting (reporting bias)Unclear riskAssessment from published study reports. Analysis appropriate for clusters.There was adjustment of data for clustering and various cluster, clinic and individual level differences at baseline.
Other biasUnclear riskBaseline characteristics of each group were similar, except that women in the intervention group had higher education than in the usual care group.

Magee 1990

MethodsRCT, set in prenatal care at the University of Washington Obstetrics Clinics.
ParticipantsPregnant women with obesity (prepregnancy weight > 120% of ideal body weight) and diagnosed with gestational diabetes, recruited at 28 weeks' gestation.
Interventions

All women were hospitalised for 2-week duration in the metabolic ward.

Intervention: calorie-restricted (n = 7): during the 1st week, the women consumed normal diet with 2400 kcal/day; 50% CHO, 30% fat and 20% protein with 11 g of total dietary fibre per 500 kcal During the 2nd week, the women were placed on 1200 kcal/day diet. This reduction was accomplished by decreasing portion sizes without changing other features of diet.

Control (n = 5): during the 1st week, the women consumed identical diet as the intervention group; 2400 kcal/day, and continued on the same diet (2400 kcal/day) during the 2nd week.

Outcomes

Metabolic indices: fasting plasma glucose, OGTT, insulin, triglyceride, free fatty acids, glycerol, ß-hydroxybutyrate, and urine ketones.

We have not included outcome data from this hospital inpatient study in the analyses in the review.

NotesAge (calorie-restricted, control): 30 ± 4, 36 ± 5 years.
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskNo information provided.
Allocation concealment (selection bias)Unclear riskNo information provided.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNo information provided.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNo information provided.
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskNo information provided.
Selective reporting (reporting bias)Unclear riskCould not determine.
Other biasUnclear riskNo information provided.

Marcinkevage 2012

MethodsRCT in a large urban hospital in the USA.
Participants

High risk (obese and overweight), 55 randomised, 36 analysed so far (ongoing).

Inclusion criteria: overweight and obese 'minority' women receiving prenatal care. Gestation at recruitment: 14.4 +-2.8.

Exclusion criteria: see inclusion criteria.

Interventions

Intervention group: lifestyle intervention (monthly behavioural counselling meeting focused on reducing sedentary behaviour and increasing levels of physical activity) (n = 17).

Control group: routine care (n = 19).

OutcomesPhysical activity, GWG, glucose values.
Notes

Abstract only with no usable data. Preliminary analysis shows decrease in median(range) total activity in both groups from first visit to mid-pregnancy. Reduction in sedentary behaviour from first trimester to mid-pregnancy in intervention but not regular group. Median(range) GWG at mid-pregnancy is similar for both groups. At mid-pregnancy lower fasting and 30 min glucose values in intervention vs regular care. Preliminary data demonstrate the feasibility of modifying lifestyle during early pregnancy in underserved black women.

Authors concluded that "Preliminary data demonstrate the feasibility of modifying lifestyle during early pregnancy in underserved black women".

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskNot described. "randomly assigned".
Allocation concealment (selection bias)Unclear riskNot described.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot described.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot described.
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskInsufficient information.
Selective reporting (reporting bias)Unclear riskInsufficient information.
Other biasUnclear riskInsufficient information.

Moses 2009

MethodsRandomised controlled trial, set in the city of Wollongong, New South Wales, Australia.
Participants

Inclusion criteria: pregnant women, age 18–40 years (inclusive), singleton pregnancy, no previous GDM, nonsmoker, diagnosis of GDM and seen for the 1st dietary visit between 28 and 32 weeks of gestation, and ability to follow the protocol requirements.

Exclusion criteria: any condition or medication that could affect glucose levels and unwillingness to follow the prescribed diet.

Interventions

63 women were randomly assigned to receive 1 of 2 different diets, low–GI diet (n = 31) or higher–GI diet (n = 32). Both diets were compatible with the recommended nutritional intake in pregnancy. The CHO intake was designed to achieve a minimum of 175 g/day with only the recommended choice of CHO foods varying. The dietary advice by dietitian was individualised with specific mention of the energy and nutrient balance to achieve normal weight gain during the 3rd trimester.

The low–glycaemic diet: based on previously verified low–GI food, including pasta, grain breads, and unprocessed breakfast cereals with a high fibre content. Women were specifically asked to avoid consuming white bread, processed commercial breakfast cereals, potatoes, and some rice varieties.

The higher–glycaemic diet: a diet with a high-fibre and low-sugar content, with no specific mention of the GI. Potatoes, whole wheat bread, and specific high-fibre, moderate-to-high–GI breakfast cereals were recommended.

OutcomesInduction of labour, method of delivery, LGA baby (> 90th centile), SGA baby (< 10th centile).
Notes

Age (LGI, HGI): 30.8 + 0.7, 31.3 + 0.8.

Gestational age at entry to study (LGI, HGI): 30.3 + 0.2 weeks, LGI 29.9 + 0.2 weeks.

BMI at enrolment (LGI, HGI): 32.0, 32.8 kg/m².

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskWomen were randomly assigned using permuted blocks of unequal size with the list generated using STATA (version 7.0).
Allocation concealment (selection bias)Unclear riskNot stated.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear risk

The physician caring for the women was blinded. Study dietitians were not blinded to dietary assignment but were aware of the need for impartiality and equivalent treatment

Participants were impossible to blind to the GI concept, as it is widely known and discussed in the lay press.

Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot described.
Incomplete outcome data (attrition bias)
All outcomes
Low riskNo dropout apparent.
Selective reporting (reporting bias)Unclear riskCould not determine.
Other biasLow riskThere were no significant differences in the baseline characteristics of the 2 groups.

Moses 2014

MethodsParallel-arm RCT conducted in Australia from Feb 2010 to Sept 2012.
Participants

691 randomised, 576 analysed.

Inclusion: healthy pregnant women at 12 to 16 weeks' gestation who agree to be randomised.

Exclusion: women with pregestational diabetes; multiple birth; assisted reproduction; special diet or referred to a dietitian for other reasons.

InterventionsA low glycaemic diet (n = 354) or a conventional healthy diet (n = 337) from 12 to 16 weeks' gestation for the remainder of pregnancy.
Outcomes

Primary outcomes: prevalence of LGA at birth (more than 90th centile); prevalence of childhood obesity as determined by BMI.

Secondary outcomes: prevalence of gestational diabetes; ponderal index; prevalence of SGA; GWG.

Notes

Age (intervention, control): 29.9 [0.3]/29.9 [0.3].

Enrolment gestational age: 16.5 [0.1]/16.2 [0.1].

Prepregnancy BMI: 24.3 [0.3]/24.7 [0.3].

Outcomes were assessed at baseline, 28 weeks and 34 weeks.

Authors concluded that "A low-intensity dietary intervention with an LGI diet compared with an HE diet in pregnancy did not result in any significant differences in birth weight, fetal percentile, or PI. In conclusion, the outcome of this study was neutral. Infants of women instructed to consume LGI CHO foods during pregnancy were of normal size and had a similar PI to those of infants of women who received conventional HE advice".

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk"Randomly assigned."
Allocation concealment (selection bias)Unclear risk"Randomly assigned."
Blinding of participants and personnel (performance bias)
All outcomes
High risk"Study personnel were not blinded to the dietary assignment but were aware of the need for impartiality and equivalent treatment. Obstetric care providers were not specifically blinded to the study allocation but were also not informed."
Blinding of outcome assessment (detection bias)
All outcomes
Low riskNot described.
Incomplete outcome data (attrition bias)
All outcomes
Low riskDropout < 20%. In the low GI group, 58 women were later excluded (27 women had developed GD). In the HE group, 57 women were later excluded (28 women had developed GD).
Selective reporting (reporting bias)Low riskPrespecified outcomes reported.
Other biasLow riskNone noted. Baseline characteristics comparable.

Mujsindi 2014

MethodsRCT (setting not mentioned) in USA (accrual dates NR).
Participants

High risk (obese and overweight), 79 randomised.

Inclusion criteria: overweight and obese 'minority' women receiving prenatal care.

Exclusion criteria: see inclusion criteria.

Interventions

Intervention group: lifestyle intervention (behaviour counselling with 5 dietary/nutrition consultations during pregnancy and at 3 months postpartum, food records, pedometers and logs, pregnancy activity questionnaire and food frequency questionnaire) (n = ?).

Control group: routine care (n = ?).

OutcomesPrimary outcome was GWG and postpartum weight retention rates. Secondary outcomes included obstetric, delivery and neonatal outcomes.
Notes

Abstract only with no usable data. Obese women enrolled in a structured nutrition program during pregnancy and in the postpartum period had similar GWG and postpartum weight retention to women in standard care. There was no difference in demographic data, parity, smoking status and socioeconomic status. When comparing the PEN vs STD groups, there was no difference in mean GWG at 20 weeks, 24, 30 and 36 weeks. Return to study entry weight was compared between the groups at 3 and 6 months. There was no difference between the groups at either time (P = 0.21 and 0.18 respectively).

Authors concluded that "Obese women enrolled in a structured nutrition program during pregnancy and in the postpartum period had similar gestational weight gain and postpartum weight retention as women in standard care".

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskNot described. "Randomly assigned."
Allocation concealment (selection bias)Unclear riskNot described.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot described.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot described.
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskInsufficient information.
Selective reporting (reporting bias)Unclear riskInsufficient information.
Other biasUnclear riskInsufficient information.

Murtezani 2014

MethodsA parallel arm RCT conducted in the Republic of Kosovo. Accrual dates not given.
Participants72 pregnant women randomised, 63 analysed.
Interventions

Intervention (n = 30) involved an exercise training program that started in the second trimester and was continued until the end of pregnancy. Each session consisted of 40-45 min of aerobic and strength exercise. Individuals were supervised by certified aerobic-instructors, and each session included a maximum of 10 participants. Intensity was moderate to vigorous; supine postures and Valsalva manoeuvres were avoided.

Controls had routine care (n = 33).

OutcomesGWG, neonatal weight, Apgars, macrosomia.
Notes

The participants were examined twice during the study period. The first visit was between 14-20 weeks of gestation (baseline visit) and the second at week 36-38 (after the intervention).

Recruitment age: 26.9 [4.7]/25.7 [5.1].

Recruitment gestation: 18.9 [1.8]/ 18.3 [1.4].

Prepregnancy BMI: 23 [2.6]/ 22.4 [2.2].

"Supervised aerobic and strength conditioning exercise performed over the second and third trimester ….does not have a negative impact on the newborn's size and health."

Reported gestational weight, not weight gain.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskRandom assignment procedure was performed using random numbers generated by a computer program.
Allocation concealment (selection bias)Unclear riskNot described.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskReport states 'single blind' but details not provided.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskReport states 'single blind' but details not provided.
Incomplete outcome data (attrition bias)
All outcomes
Unclear risk9 participants (4 from the control group and 5 from the intervention group) withdrew after randomisation for medical and personal reasons: hypertension (n.= 2), vascular disease (n = 1), intrauterine growth restriction (n = 1), amniotic-fluid leakage (n = 2), premature birth (n = 1) , injured n = 1) and unknown (n = 1). It was not stated from which group these withdrawals occurred.
Selective reporting (reporting bias)High riskWomen with hypertension, preterm birth and amniotic fluid leakage were excluded after randomisation, yet these are potential side effects of vigorous exercise in pregnancy.
Other biasHigh riskBaseline characteristics were similar for study groups. Women with hypertension, preterm birth and amniotic fluid leakage were excluded after randomisation, yet these are potential side effects of vigorous exercise in pregnancy and needed to be reported.

Nascimento 2012

MethodsRCT conducted at an antenatal outpatient clinic in Brazil from August 2008 to March 2010.
Participants

High risk. Overweight or obese, 82 randomised.

Inclusion criteria: pregnant women ≥ 18 yrs, pre-gestational BMI ≥ 26 kg/m², gestational age 14-24 weeks.

Exclusion criteria: multiple pregnancy, exercising regularly, and conditions that contraindicate exercise, such as cervical incompetence, severe arterial hypertension, diabetes with vascular disease and risk of abortion.

Interventions

Intervention group: supervised exercise program (n = 40). Intervention consisted of an exercise program guided by a trained physical therapist in weekly classes with light to moderate intensity exercise for 40 mins. It also included home exercise counselling which was to be performed 5 times per week (consisting of a sequence of 22 exercises or walking).

Control group: routine prenatal care program (n = 42).

OutcomesPrimary outcomes were GWG and excessive weight gain. Secondary outcomes were increased arterial blood pressure, perinatal outcomes and QoL (WHOQOL).
Notes

Outcomes measured at baseline and 36 weeks. Delivery data were collected from medical records.

Age (intervention, control): 29.7 [6.8]/30.9 [5.9].

Enrolment gestational age (intervention, control): 14.3 [4.5]/13.6 [3.5].

Prepregnancy BMI: 34.8 [6.6]/36.4 [6.9].

Slight baseline imbalances noted as 8/40 vs 15/42 were diabetic and 15/40 vs 22/42 were hypertensive in exercise and control groups, respectively, at baseline.

Authors concluded that "The exercise programme was not associated with control of gestational weight gain in our sample as a whole, but was beneficial for lower gestational weight gain in overweight women. Exercise was not associated with adverse perinatal outcomes and did not affect variation in arterial blood pressure or the perception of QoL".

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk"Randomised to the groups using the SAS statistical program (SAS Institute, Cary, NC, USA), which generated a list of random numbers based on a uniform distribution."
Allocation concealment (selection bias)Low risk"The sequence was randomly distributed in opaque envelopes, which were sealed and sequentially numbered. Each participant received a sequence number corresponding to a sealed envelope."
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot described.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot described.
Incomplete outcome data (attrition bias)
All outcomes
Unclear risk1 woman in each group withdrew. For neonatal weight outcome, missing data were > 20% but similar numbers missing in each group. Authors indicate that this was because some women delivered at other hospitals.
Selective reporting (reporting bias)Low riskPrespecified outcomes reported.
Other biasUnclear riskBaseline imbalances noted as 8/40 vs 15/42 were diabetic and 15/40 vs 22/42 were hypertensive in exercise and control groups, respectively, at baseline. Also, the control group had a greater proportion of obese women. This could affect some outcomes (e.g. LGA, GWG) in favour of the intervention.

Oostdam 2012

MethodsRCT at hospitals and midwifery practices in The Netherlands from January 2007 to January 2011.
Participants

High risk. Overweight or obese, 121 randomised, 101 analysed.

Inclusion criteria: pregnant women who were overweight or obese and at risk for GDM. AND had at least 1 of the 3 following characteristics: (1) history of macrosomia. (2) history of GDM; or (3) first-grade relative with Type 2 diabetes.

Exclusion criteria: recruitment after 20 weeks of gestation; age under 18 years; non-Dutch speaker; having been diagnosed with GDM before randomisation; hypertension; alcohol abuse; drug abuse; use of any medication that affects insulin secretion or insulin sensitivity; serious pulmonary, cardiac, hepatic, or renal impairment; malignant disease; and serious mental or physical impairment.

Interventions

Intervention group: exercise intervention (2 sessions of aerobic and strengthening exercises per week; each exercise session lasted for 60 mins) (n = 62).

Control group: routine care (n = 59).

OutcomesMaternal outcome measures were fasting blood glucose (mmol/L, fasting insulin (pmol/L) and HbA1c (%), body weight (kg), BMI (kg/m2), and daily physical activity (min/week).
Offspring outcome measures were birthweight and fetal growth.
Notes

Outcomes assessed at baseline, 24 and 32 weeks.

Age (intervention, control): 30.8 [5.2]/30.1 [4.5].

Enrolment gestational age was 15 weeks.

Prepregnancy BMI: 33 [3.7]/33.9 [5.6].

Authors concluded that exercise intervention "had no effects on fasting blood glucose, insulin sensitivity, and birthweight, most probably because of low compliance".

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskBlock randomisation, stratified by hospital.
Allocation concealment (selection bias)Low risk"Women were recruited by midwives and gynaecologists who were unaware of the allocation of other women, with no risk of compromising allocation concealment."
Blinding of participants and personnel (performance bias)
All outcomes
High risk"By the nature of the intervention the researcher and research assistant could not be blinded for allocation after randomisation."
Blinding of outcome assessment (detection bias)
All outcomes
Low risk"All outcome measures were assessed by independent examiners, unaware of group allocation."
Incomplete outcome data (attrition bias)
All outcomes
High riskHigh dropout rates, especially at 32 weeks (19/62 [31%] did not respond in intervention group and 12/59 [20%] did not respond in control group). For GWG outcome dropout rate was 31% overall.
Selective reporting (reporting bias)Low riskPrespecified outcomes reported.
Other biasHigh risk

Poor adherence to the intervention - "only a small proportion (16.3%) of the women in our intervention group attended at least half of the training sessions".

Follow-up weight gain data were collected at 32 weeks (much earlier than most other included studies).

Petrella 2013

MethodsRCT in Italy (setting and accrual dates NR).
Participants

High risk. Overweight or obese. 61 randomised.

Inclusion criteria: women with BMI > 25 at 1st trimester, > 18 years with singleton pregnancy at 12 weeks' gestation.
Exclusion criteria: women with twin pregnancy, chronic disorders, GDM in previous pregnancy, smoking, previous surgery, women who engaged in regular physical activity, or used dietary supplements or herbal products known to affect body weight were excluded.

Interventions

Intervention group: lifestyle intervention involving a caloric restricted low GI diet (1500 kcal/day) and prescribed moderate-intensity exercise 30 min/day, 3 times per week. Pedometers were to be worn (n = 33).

Control group: routine care with a nutritional brochure about health eating (n = 28).

OutcomesGDM, GWG, hypertension, and preterm delivery.
Notes

Recruitment age: 31 [4.2]/32.4 [5.9].

Gestational age: first trimester.

Recruitment BMI: 32.1 [5]/ 32.9 [6.2].

Authors concluded that "A constant physical activity and a change toward healthy eating improves nutrients intake, prevents excessive weight gain and avoids the maternal unfavorable outcomes associated with overweight/obese women".

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskComputer-generated randomisation in blocks of 3.
Allocation concealment (selection bias)Low risk"Study randomization is numbered and sealed in white envelopes. Randomization occurs in consecutive order at time of the first visit."
Blinding of participants and personnel (performance bias)
All outcomes
High risk"Due to study design, both gynecologist and dietitian know the allocation of the patient."
Blinding of outcome assessment (detection bias)
All outcomes
High riskAssessor knew the allocation.
Incomplete outcome data (attrition bias)
All outcomes
Low riskOnly 2 women in the control group withdrew.
Selective reporting (reporting bias)Low riskPrespecified outcomes reported.
Other biasLow riskBaseline characteristics similar.

Petrov Fieril 2014

MethodsRCT conducted at 2 ANCs in Gothenburg, Sweden with recruitment from Feb 2006 to Nov 2006 and Sept 2008 to April 2009.
Participants

92 pregnant women randomised, 72 analysed.

Included if singleton pregnancy < 14 weeks' gestation, no medical or obstetric complications, ability to understand Swedish.

Excluded if contraindications to exercise in pregnancy.

InterventionsIntervention group received supervised resistance exercise twice a week, with light barbells and weight plates in a group setting, performed at an activity level equivalent to within moderate–to-vigorous between weeks 14 to 25 gestation, and was self-adjusted (n = 51). In addition, walking, cycling, water-gymnastics, Pilates, yoga and home exercises that included pelvic floor training were recommended. Controls received a generalised exercise recommendation, a home-based training program and a telephone (n = 41).
OutcomesHealth-related quality of life, physical strength, pain, weight, blood pressure, functional status, activity level and perinatal data.
Notes

Little usable review data (birthweight only).

Age (intervention, control): 30.8 [3.6]/30.6 [3.4].

Enrolment gestational age: 13 weeks.

Prepregnancy BMI: 22.6 [2.5]/23 [2.6].

Authors concluded that "supervised, moderate–to vigorous resistance exercise does not jeopardize the health status of healthy pregnant women or the fetus".

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk"participants were randomly assigned to either the intervention group or the control group (allocation ratio 1:1)", however the group sizes were significantly different (51 vs 41, respectively).
Allocation concealment (selection bias)Low risk"The research coordinator performed the randomization by using opaque sealed envelopes, which were randomly picked out before the meeting with each participant."
Blinding of participants and personnel (performance bias)
All outcomes
High riskNot blinded.
Blinding of outcome assessment (detection bias)
All outcomes
Low risk"All data were collected at a primary health care location by an investigator who was blinded to" group allocation.
Incomplete outcome data (attrition bias)
All outcomes
High risk25% and 18% of participants dropped out of the intervention and control groups, respectively.
Selective reporting (reporting bias)Unclear riskProtocol not seen. GWG and EGWG NR.
Other biasLow riskBaseline characteristics were similar in study groups.

Phelan 2011

MethodsRCT, 2 arms with individual randomisation stratified by prepregnancy weight, set in 6 obstetric offices in Providence, Rhode Island, USA  from 2006 to 2008.
Participants

401 women randomised.

Inclusion criteria: gestational age between 10 and 16 weeks, BMI between 19.8 and 40, nonsmoking , adults (aged > 18 yr), fluency in English, access to a telephone, and a singleton pregnancy.

Exclusion criteria: major health or psychiatric diseases, weight loss during pregnancy, or a history of ≥ 3 miscarriages.

Interventions

Intervention group: standard care plus a behavioural lifestyle intervention. The Fit for Delivery intervention included a face-to-face visit with an interventionist at the onset of treatment who discussed appropriate weight gains during pregnancy, physical activity (30 min of walking most days of the week), and calorie goals (20 kcal/kg); emphasis was placed on decreasing high fat foods, increasing physical activity, and daily self-monitoring of eating, exercise, and weight. Body-weight scales, food records, and pedometers were provided to promote adherence to daily self-monitoring. Automated postcards that prompted healthy eating and exercise habits were mailed weekly. In addition, after each clinic visit, women were sent personalised graphs of their weight gains with feedback. All women in the intervention received 3 brief (i.e. 10–15 min) supportive phone calls from the dietitian during the intervention. Women who were over- or under weight-gain guidelines during any 1 month interval received additional brief, supportive phone calls (2 calls/month) that provided structured meal plans, and specific goals until weight gains returned to appropriate amounts.

Control group: routine care. Women received standard nutrition counselling provided by physicians, nurses, nutritionists, and counsellors. As part of routine care women were weighed by nurses at each clinical visit; weight graphs were not provided.

OutcomesExcessive weight gain, low weight gain, preterm birth, pre-eclampsia or eclampsia, caesarean delivery rate, high birthweight, low birthweight, maternal weight retention.
Notes

Baseline age (intervention, control): 28.8 ± 5.2, 28.6 ± 5.2.

Baseline BMI (intervention, control): 26.48 ± 5.9, 26.32 ± 5.6.

Enrolment gestation (intervention, control): 13.5 ± 1.8, 13.6 ± 1.8.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskRandomisation was computer-generated in randomly varying block sizes and stratified by clinic and BMI category.
Allocation concealment (selection bias)Low riskAllocation was concealed in opaque envelopes prepared by the study statistician.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskUnblinded.
Blinding of outcome assessment (detection bias)
All outcomes
Low riskIn the abstract it was stated that outcome assessors were blinded.
Incomplete outcome data (attrition bias)
All outcomes
Low risk

Lost to follow-up 34 in the standard care group, 36 in the intervention group. Exclusions: 18  in the standard care group, 25 in the intervention group.

401 participants were randomly assigned into the intervention (n = 201) and control groups ( n = 200), included in 6 month postpartum analysis; 182 control, 176 intervention.

ITT analysis was performed assuming that those lost to follow-up were treatment failures. It was reported that this revealed almost identical results as for those completing the study (data not shown).

Selective reporting (reporting bias)Unclear riskAssessment from published study report.
Other biasUnclear riskThe 2 study groups did not significantly differ on key baseline measures (sample stratified).

Pinzon 2012

MethodsRCT conducted in Colombia with recruitment from March 2008 to November 2009.
Participants

General population. 64 women randomised.

Inclusion criteria: nulliparous women in gestational week 16-20 with live fetus and normal pregnancy.

Exclusion criteria: history of high BP, chronic illness, persistent bleeding after 12 weeks' gestation, poorly-controlled thyroid disease, placenta praevia, incompetent cervix, oligohydramnios, miscarriage in previous 12 months.

Interventions

Intervention group: exercise intervention (n = 33) involved a supervised exercise program 3 times a week for 12 weeks. Exercise sessions involved walking (10 min) aerobic exercise (30 min), stretching (10 min) and relaxation exercise (10 min).

Control group: usual activities (n = 31).

OutcomesFitness (VO2 max, BP, heart rate at rest, and other parameters) changes in blood lipids, insulin sensitivity (HOMA-IR) and body composition (fat-free mass, body fat, skinfold thickness and muscular area), maternal weight, birthweight, neonatal outcomes.
Notes

Age (intervention, control): 19.2 [2.6]/19.5 [3.4].

Enrolment gestational age: 17.5 [3.4]/17 [4.5].

Recruitment BMI: 21.4 [2.4]/22.4 [3.8].

"Regular aerobic exercise improves endothelium-dependent vasodilation in pregnancy." (Ramirez-velez 2011) "At the end of the 3-month program, there was no difference in the change in blood lipids. Triglycerides and VLDL were significantly lower in the experimental group. The experimental group showed lower values of body fat and skinfold thicknesses than did the control group, but these differentials were non-significant." (Pinzon 2012) There was no significant difference between groups regarding maternal weight gain during pregnancy.

Authors concluded that "The potential public health benefits of exercise are to great and this study supports existing guidelines indicating that latina women may begin or maintain an exercise program during pregnancy".

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk"computer-generated randomisation list."
Allocation concealment (selection bias)Low riskSequentially numbered sealed opaque envelopes. "The treatment allocation system was set up so that the researcher in charge of randomly assigning participants to each group did not know in advance which treatment the participant was going to receive."
Blinding of participants and personnel (performance bias)
All outcomes
Low risk"double-blind" "research assistants were blinded to the group assignment of the subjects and were in charge of the prenatal care of the women". "Due to the nature of the study, it was not possible to blind the women participating."
Blinding of outcome assessment (detection bias)
All outcomes
Low risk"all study measurements were done by a person blinded to the distribution of the patients."
Incomplete outcome data (attrition bias)
All outcomes
High risk14 women withdrew early (22%; 9 in study and 5 in control arm) therefore 50/64 women assessed for fitness outcomes. Weight and pregnancy outcome data were only available for 35/64 women (55%; 18 in study and 17 in control group).
Selective reporting (reporting bias)Unclear riskUnable to comment as study protocol not seen.
Other biasLow riskNone noted. Adherence was 75%. Baseline characteristics were similar.

Pollak 2014

MethodsPilot RCT with ratio 2:1, conducted in 2 antenatal clinics in USA in 2012.
Participants

35 overweight and obese women randomised.

Included if 18 years or older, English-speaking, registered for prenatal care at participating clinics, pre-pregnancy BMI of 25–40, 12–21 weeks' gestation, and having a cell phone with an unlimited texting plan for the next 5 months.

Excluded if pre-existing diabetes, limited mobility or inability to walk,impaired cognition or mental health with inability to provide consent.

Interventions

SMS texting intervention (n = 22) targeting weight-related behaviours including increasing daily steps to 10000, avoiding sweetened drinks, eating 5 fruit and veg per day, and eliminating fast food intake. Tests were sent 3 times per week and women were asked to text back their self-monitored weight measurement.

Control intervention (n = 11) was a general 'text4baby' intervention with general information about pregnancy with few tests related to healthy eating or physical activity.

Women were asked to wear a pedometer.

Outcomes

Weight at 40 weeks, eating habit scores, physical activity scores.

Follow-up surveys were conducted at approximately 22 and 32 weeks' gestation and women weighed. In addition, weights were obtained from clinical records from baseline and delivery.

Notes

No usable data for this review. The main results were that mean weight gain in the intervention group was estimated to be 6 pounds less than the control group at 40 weeks' gestation for women who completed the intervention (n = 23).

Mean age: 29 vs 32 years.

Gestation at recruitment: 16 vs 17 weeks.

Pre-pregnancy BMI: 29 vs 28 kg/m2.

Investigators concluded that "SMS texting is a promising vehicle for behavior change among pregnant women".

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk"randomized eligible women in a 2:1 fashion."
Allocation concealment (selection bias)Unclear riskNot described.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot described.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot described.
Incomplete outcome data (attrition bias)
All outcomes
Low risk10 women withdrew from the study; however, their weight data from clinical records were included (ITT analysis). 2 others miscarried and were excluded.
Selective reporting (reporting bias)Unclear riskProtocol not seen but no usable (extractable) outcome data were provided in the report.
Other biasLow riskBaseline characteristics were similar.

Polley 2002

MethodsRCT, set in an obstetric clinic for low-income women at a hospital in Pittsburgh, PA, USA.
Participants

Inclusion criteria: pregnant women before 20 weeks of gestation. (Women were recruited in to 4 cells; normal and overweight, black and white.) 

Exclusion criteria: underweight women, younger than 18 years, 1st prenatal visit > 12 weeks' gestation, high-risk pregnancy (i.e. drug abuse, chronic health problems, previous complications during pregnancy, current multiple gestation).

Interventions

Intervention (n = 57): the intervention was provided at regular scheduled clinic visits by staff with training in nutrition or clinical psychology. Education about weight gain, healthy eating, and exercise and individual graphs of their weight gain.

Shortly after recruitment, written and oral information were given in the following area: appropriate weight gain, exercise, healthy eating. Newsletters prompting healthy eating and exercise habits were mailed bi-weekly. After each clinic visit, women were sent a personalised graph of their weight gain.

Those exceeding weight gain goals were given additional individualised nutrition and behavioural counselling using the format listed; a stepped care approach.

Control (n = 53): usual care: standard nutrition counselling provided by the physicians, nurses, nutritionists and WIC counsellors. This counselling emphasised a well-balanced dietary intake and advice to take a multivitamin/iron supplement.

Outcomes

Excessive weight gain, total weight gain, low weight gain.

Low birthweight infants, macrosomia infants, preterm delivery, caesarean delivery, pre-eclampsia, weight retention at 4 weeks' postpartum.

Total weight gain was based on self-reported prepregnancy weight and weight at last clinic visit prior to delivery.

Notes

Excessive weight gain categorised as above the IOM recommendations.

Low weight gain categorised as below the IOM recommendations.

IOM recommends a weight gain of 6.8-11.3 kg for overweight women (BMI of 26-29) and a weight gain of 6.8 kg (with no specified upper limit) for obese women (BMI > 29).

Age of participants 25.5 ± 4.8.

Gestational age at recruitment (intervention, control): 14.7 ± 3.1 weeks.

BMI category, n (intervention, control):

  • normal weight (BMI19.8-26): 30, 31;

  • overweight (BMI > 26): 27, 22.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskWomen were randomly assigned to the standard care control group or to the intervention.
Allocation concealment (selection bias)Unclear riskNo information provided.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNo information provided.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNo information provided.
Incomplete outcome data (attrition bias)
All outcomes
Low risk

Using ITT approach.

Loss to follow-up < 10%.

Selective reporting (reporting bias)Unclear riskCould not determine.
Other biasUnclear riskRefusal rates were higher among black women (28/74 refused) than among white (16/90 refused), and higher in overweight black women than in any of the other 3 weight-by-race categories.

Poston 2013

MethodsA pilot RCT conducted at multiple tertiary and university hospitals in the UK with recruitment from March 2010 to May 2013. (UPBEAT study).
Participants

183 randomised, 154 analysed.

Inclusion criteria: BMI ≥30 kg/m² and singleton pregnancy; gestational age > 15 weeks and < 17 weeks' gestation.

Exclusion criteria: unable or unwilling to give written informed consent; gestation < 15 weeks and > 17 weeks, pre-existing diabetes, pre-existing hypertension (treated), pre-existing renal disease, multiple pregnancies; systemic lupus erythematous antiphospholipid syndrome, sickle cell disease, thalassaemia, coeliac disease, currently prescribed metformin, thyroid disease or current psychosis.

Interventions

Intervention group: a lifestyle intervention (diet plus exercise) (n = 94) involving 1 1-to-1 session with a health trainer and then weekly group sessions for 8 consecutive weeks from 19 weeks' gestation. Sessions delivered by health trainers involved diet and exercise advice informed by psychological models of health behaviour. Dietary advice focused on increased consumption of foods with a low dietary GI, and reduction of saturated fats. Physical activity advice encouraged women to increase daily walking activity at moderate intensity level, setting goals monitored by a pedometer.
Women also received a DVD of a pregnancy specific exercise regimen.

Control group: routine care (n = 89).

OutcomesPrimary outcome: GDM. Others were GWG, macrosomia, LGA, dietary and exercise parameters, anxiety and depression.
Notes

Age (intervention, control): 30.4 [5.7]/30.7 [4.9].

Enrolment gestational age was 16 weeks.

Recruitment BMI: 36.5 [4.7]/36.1 [4.8].

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk"Randomisation was performed online" "balanced by minimisation for maternal age, centre, ethnicity, parity and BMI."
Allocation concealment (selection bias)Low risk"randomised treatment was allocated automatically" by online randomisation program.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot described.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot described.
Incomplete outcome data (attrition bias)
All outcomes
Low risk14 women (15.7%) dropped out of the control arm, and 15 lost to follow-up in the intervention group (15.8%).
Selective reporting (reporting bias)Unclear riskPrespecified outcomes reported, except for GWG. ITT analysis.
Other biasLow riskBaseline characteristics were comparable.

Price 2012

MethodsRCT at local obstetric practices in Austin, Texas, in USA from July 2006 to March 2010.
Participants

General population, 91 randomised, 62 analysed.

Inclusion criteria: sedentary women 12-14 weeks' gestation; viable singleton pregnancy at 12–14 weeks by reasonable dates and/or ultrasound; body mass index (BMI) less than 39 kg/m2.

Exclusion criteria: no aerobic exercise more than once per week for at least the past 6 months; chronic heart or lung disease; poorly controlled diabetes, hypertension, epilepsy, or hyperthyroidism; severe anaemia no orthopedic limitations; and history of premature delivery, infant delivered for SGA, or unexplained fetal death.

Interventions

Intervention group: exercise intervention (n = 43). Exercise intervention involved a program of supervised aerobic training (45-60 mins, 4 days a week).

Control group: sedentary women (n = 48). "Control subjects were told not to exercise."

OutcomesCardiorespiratory fitness. Strength, flexibility, and discomfort. Pregnancy complications, delivery data, postpartum recovery.
Notes

Outcomes assessed at 5 points: 12-14 weeks, 18-20 weeks, 24-26 weeks, 30-32 weeks, and 6-8 weeks postpartum.

Age (intervention, control): 30.5 [5]/27.6 [7.3] (P = 0.08).

Enrolment gestational age was at 12-14 weeks.

Prepregnancy BMI: 26.6 [3.1]/28.7 [5.4] (P = 0.042).

"Previously sedentary women who began exercising at 12–14 weeks had improved fitness and delivery outcomes."

Authors concluded that "Compared with women who remained sedentary, active women improved aerobic fitness and muscular strength, delivered comparable size infants with significantly fewer cesarean deliveries, and recovered faster postpartum, at least related to the lower incidence of cesarean section. Active women developed no gestational hypertension and reported no injuries related to the exercise regimen".

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk"Randomly assigned."
Allocation concealment (selection bias)Low risk"Subjects were randomized using numbered, opaque envelopes containing an equal number of group assignments prepared by the study statistician."
Blinding of participants and personnel (performance bias)
All outcomes
High riskParticipants and personnel not blinded.
Blinding of outcome assessment (detection bias)
All outcomes
High riskNot blinded. "Author kept a log of attendance" and seemed to perform the fitness assessments.
Incomplete outcome data (attrition bias)
All outcomes
High risk12/43 (28%) and 17/48 (35%) dropped out in the intervention and control groups, respectively. Reasons for drop outs in intervention group were logistics (9) and other reasons (3). Reasons in control group were immediate withdrawal due to wanting to exercise (5), and later withdrawal due to wanting to exercise (3) and logistics (9).
Selective reporting (reporting bias)Unclear riskMean weight gain (12.4 kg vs 10.5 kg in intervention and control groups, respectively) was NR with standard deviations or denominators so these data were not usable in our meta-analysis.
Other biasHigh riskBaseline BMI was significantly lower in the intervention group and loss to follow-up was high. Also, "control subjects were told not to exercise because it would blur the distinction between the groups". This contributed to high drop out rates in the control group and may make results less generalisable by enforcing no exercise. This study design seems ethically flawed.

Quinlivan 2011

MethodsRCT set in the maternity service of a public general hospital serving a socio-economically disadvantaged area in Melbourne, Australia.
Participants

132 randomised.

Inclusion criteria: pregnant with a fetus with no known anomalies, spoke English, did not intend to relinquish their infant, did not have a multiple gestation, were able to attend hospital for antenatal care and were overweight (BMI 25–29. 9) or obese (BMI > 29 .9).

Exclusion criteria: not described.

Interventions

Intervention group: a 4-step multidisciplinary protocol of antenatal care which had the following 4 criteria: (i) continuity of care provider; (ii) weighing on arrival; (iii) brief dietary intervention by a food technologist at every antenatal visit; and (iv) psychological assessment. Women attended special study clinics.

Control group: routine care (with access to high-risk clinics if medically indicated).

OutcomesWeight gain, preterm delivery.
Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskRandomisation to the intervention or control groups occurred using computer-generated sequence.
Allocation concealment (selection bias)Low riskNumbered sealed opaque envelopes, stratified by category (overweight or obese;16), which were only opened by the midwife after each woman’s enrolment was completed.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot described.
Blinding of outcome assessment (detection bias)
All outcomes
Low riskOutcome data for mother and infant were audited by a nurse independent of clinical care pathways and blinded to randomisation status.
Incomplete outcome data (attrition bias)
All outcomes
Low risk132 randomised, 124 analysed (8 excluded from analysis (4 of each group).
Selective reporting (reporting bias)Unclear riskAssessment from published study report.
Other biasUnclear riskThere were no significant differences in terms of antenatal, demographic and health behaviour variables between intervention and control groups.
Women in the intervention group attended special study clinics; these clinics may have been different from standard clinics in more ways than the intended study interventions (although it was stated that care was standard apart from the 4 stage intervention).

Rae 2000

MethodsRCT, set in the Diabetes Service, King Edward Memorial Hospital for Women, Perth, Western Australia
Participants

Inclusion criteria: gestation < 35 weeks and 6 days, > 110% of ideal body weight for height (adjusted for expected pregnancy weight gain and using a BMI of 25 as equal to 100% ideal body weight), OGTT with fasting plasma glucose > 5.4 mmol/L and/or 2-hour plasma glucose > 7.9 mmol/L.

Exclusion criteria: not stated.

Interventions

Intervention (n = 63): the intervention comprised instruction in a moderately energy restricted diabetic diet providing between 1590-1776 kcal (70% RDA).

Control (n = 54): the control group were instructed in a diabetic diet which was not energy restricted, providing approximately 2010-2220 kcal a day.

Outcomes

Weight gain, pre-eclampsias, induction of labour, caesarean delivery, shoulder dystocia, birthweight > 4000 g, birthweight > 90th centile, assisted delivery.

Weight gain was calculated as the difference between prepregnancy weight and delivery weight.

Notes

Age (intervention, control) 30.2, 30.6 years.

Gestation at diagnosis(intervention, control) 28.1 ± 5.8, 28.3 ± 4.6 weeks.

BMI at diagnosis (intervention, control) 37.9 ± 0.7, 38.0 ± 0.7 kg/m².

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskNot stated.
Allocation concealment (selection bias)Low riskWomen were allocated at random using opaque numbered envelopes.
Blinding of participants and personnel (performance bias)
All outcomes
Low risk

Both participants and the Diabetes Service staff were blinded to the allocation to diet group.

Medical staff were blinded to the group allocation of each participant.

Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot described.
Incomplete outcome data (attrition bias)
All outcomes
Low riskLoss to follow-up 6.4% (8), 4 for each group.
Selective reporting (reporting bias)Unclear riskCould not be determined.
Other biasLow risk

The groups were similar in level of education, employment, racial distribution, and alcohol and cigarette consumption.

There were no significant differences at enrolment in weight, or energy expenditure.

Rauh 2013

MethodsCluster-RCT, open-label at 8 gynaecological practices in Germany from February 2010 to August 2012.
Participants

General population. 250.

Inclusion criteria: older than 18, 1 live fetus, < 18 weeks' gestation, BMI ≥18.5 kg/m², and able to speak sufficient German.

Exclusion criteria: if they had any condition preventing physical activity, such as cervical incompetence, placenta praevia, or persistent bleeding. Prepregnancy diabetes or uncontrolled diseases that may affect weight development like thyroid dysfunction, or psychiatric diseases.

Interventions

Intervention group: lifestyle counselling (n = 167) Intervention consisted of 2 individually delivered counselling sessions focusing on diet, physical activity and weight self-monitoring, delivered at the 20th (60 min) and 30th week (30 min) by trained researchers.

Control group: routine care (n = 83).

OutcomesThe primary outcome was the proportion of pregnant women exceeding weight gain recommendations of the IOM. The secondary outcome variables were maternal weight retention at 4 months postpartum and short-term obstetric and neonatal outcomes.
Notes

Age (intervention, control): 32.2 [4.4]/30.8 [4.9].

Enrolment gestational age: 9 (8-11)/7 (6-8).

Prepregnancy BMI: 21.7 (19.9-23.7)/22.8 (20.6-26.6).

We were unable to adjust reported data for clustering and baseline differences, therefore we did not pool these data.

The study report gave adjusted MD for GWG of -1.7 kg (-3.0 to -0.3) in favour of the intervention, and for excessive GWG an adjusted OR of 0.5 (0.3 to 0.9).

Authors concluded that "Lifestyle counselling given to pregnant women reduced the proportion of pregnancies with excessive GWG without increasing suboptimal weight gain, and may exert favourable effects on postpartum weight retention".

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk"Computer generated allocation table." "Gynaecological practices were randomised (rather than individuals)."
Allocation concealment (selection bias)Low risk"Randomisation was performed by a researcher not involved in the study design thereby preventing allocation bias."
Blinding of participants and personnel (performance bias)
All outcomes
High riskBlinding not possible due to "the nature of the study".
Blinding of outcome assessment (detection bias)
All outcomes
High riskBlinding not possible for study staff due to "the nature of the study".
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskNo loss of clusters. 15/167 women in the intervention group and 9/83 control group women were lost to follow-up. Women in the intervention group dropped out for personal reasons (5), miscarriage or late-term abortion (3), complications of pregnancy (3) and preterm delivery (4). Control women dropped out because of personal reasons (1), moved away (1), unable to contact (2) and preterm delivery (5).
Selective reporting (reporting bias)Unclear riskProtocol not seen. Appropriate analysis methods used for clusters. Results were adjusted for age and prepregnancy BMI, which was higher in the control group. ITT not stated.
Other biasHigh risk

"During recruitment it turned out that it was easier to recruit women for the intervention group than for the control group, yielding a 2:1 ratio", instead of 1:1. Practices differed in size with 227 vs 129 women were eligible for the intervention and control groups, respectively.

Baseline characteristics differed significantly with regard to pregravid BMI (P = 0.003) and BMI at booking (P = 0.008), with a higher proportion of women in the control group considered obese or overweight (16.2% vs 31.4%; P = 0.009). Mean age was younger and gestational age at booking was significantly earlier in the intervention clusters. Although results were adjusted for BMI, age and clustering, there may also have been other (unknown) differences between the women in these groups.

Preterm birth and pregnancy complications NR as outcomes and these women were excluded from the analysis.

Renault 2014

Methods3-arm RCT at 1 hospital in Hvidovre in Denmark from March 2009 to March 2012.
Participants

High risk. Obese. 425 randomised. 389 analysed.

Inclusion criteria: pregnant women with a prepregnancy BMI of 30 kg/m2 or greater. Age older than 18 years, a singleton pregnancy, and a normal scan in weeks 11-14, gestational age at inclusion of less than 16 weeks, and an ability to read and speak Danish.

Exclusion criteria: multiple pregnancy, pregestational diabetes, or other serious diseases limiting their level of physical activity, previous bariatric surgery, or alcohol or drug abuse.

Interventions

Comparison of 3 groups.

Intervention groups: intervention 1: physical activity and diet (n = 130); intervention 2: physical activity only (n = 125). The physical activity intervention included encouragement of increase physical activity, aiming at a daily step count of 11,000, monitored by pedometer assessment on 7 consecutive days, every 4 weeks. Dietary intervention included follow-up on a hypocaloric Mediterranean-style diet. Instruction was given by a dietician every 2 weeks with alternating outpatient visits and phone calls, including weight measurement, encouragement and correcting advice

Control group: routine care (n = 134).

Outcomes

Primary outcome: GWG.

Secondary outcomes: complications of pregnancy and delivery and neonatal outcome.

Notes

Age (intervention 1, intervention 2, control): 31.2 [4.4]/ 30.9 [4.4]/31.3 [4.2].

Enrolment gestational age was 11-14 weeks.

Prepregnancy BMI: 34.4 [4.2]/34.1 [4.4]/33.7 [3.5].

GWG was calculated from the 36-37 week weight minus prepregnancy self-reported weight and was reported as median (range) so could not be included in the review meta-analysis for this outcome. GWG in the physical activity plus diet group was 8.6 kg (-9.6 to 34.1) vs 9.4 kg in the physical activity group (-4.4 to 28.2) vs 10.9 kg in the control group (-4.4 to 28.7) (P = 0.024). 1 woman in the physical activity group had a placental abruption and stillbirth.

Authors concluded that "No significant difference was found between the 2 intervention groups. Physical activity intervention assessed by pedometer with or without dietary follow-up reduced GWG compared with controls in obese pregnant women. The pedometer intervention is an inexpensive methods of increasing daily physical activity and can easily be implemented into daily clinical practice".

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk"The randomization was stratified according to parity to ensure equal distribution of primiparous in the 3 groups."
Allocation concealment (selection bias)Low risk"Web allocation by an independent organization properly concealed the procedure."
Blinding of participants and personnel (performance bias)
All outcomes
High riskBlinding not possible due to the nature of the study.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskAssessor blinding not described.
Incomplete outcome data (attrition bias)
All outcomes
Low riskLow attrition rates for most outcomes. However, physical activity scores had > 20% missing data and we considered these data high risk.
Selective reporting (reporting bias)Unclear riskCould not determine.
Other biasLow riskBaseline characteristics were comparable. Good compliance.

Rhodes 2010

MethodsRCT (pilot study), set in Beth Israel Deaconess Medical Center, Boston, MA, and Children’s Hospital Boston, Boston, MA, USA.
Participants

Inclusion criteria: pregnant women with prepregnancy or 1st trimester BMI equal to or greater than 25 kg/m² and less than 45 kg/m², singleton pregnancy, willing to consume the diets for duration of pregnancy, participant to be at week 28 or less of pregnancy at baseline visit.

Exclusion criteria: smoking during pregnancy, major medical illness (e.g. diabetes mellitus, hypertension, thyroid disease), taking prescription medication known to affect body weight, alcohol consumption during pregnancy, intention to deliver infants in the environment outside of Beth Israel Deaconess MedicalCenter, Boston, high level of physical activity.

Interventions

Intervention group 1: nutrition education, dietary counselling, and a low-GI diet.

Intervention group 2: nutrition education, dietary counselling, and a low-fat diet.

Outcomes

Maternal outcome: weight change.

Infant outcome: macrosomia, large-for-gestational age, caesarean delivery.

Notes

Age (intervention, control): 33.7 [3.9]/33.2 [3.7].

Enrolment gestational age: 19.8 (5)/19.6 (4.3).

Prepregnancy BMI (intervention, control): 32.1(4.6)/ 31.2 (3.1).

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskRandomly “permuted blocks of 2 and 4 preventing anticipation of future assignments.
Allocation concealment (selection bias)Low riskSeparate random assignment envelopes for each stratum. Random assignment envelopes were prepared by the hospital clinical trials unit.
Blinding of participants and personnel (performance bias)
All outcomes
Low riskFormal blinding of participants was not possible, although participants were not informed of their group assignments. The following staff were blinded to group assignment: obstetricians who provided clinical care to women; nurses who measured maternal body weight and blood pressure, collected and processed maternal blood samples, and analysed urinalyses; labour and delivery room nurses who obtained birthweight; laboratory staff who analysed maternal blood; and staff who performed data entry.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskStaff who performed maternal body composition analysis, 24-h dietary recalls, and infant anthropometric measurements “were predominantly, but not always”, blinded due to logistical considerations.
Incomplete outcome data (attrition bias)
All outcomes
Unclear risk46 women were randomised and infant outcomes were available for 45. There was some loss to follow-up among women with outcome data at 36 weeks available for 38. Reasons for loss were explained and loss was reasonably balanced across groups. It was stated that analysis was by randomisation group irrespective of whether or not women received the intended intervention.
Selective reporting (reporting bias)Unclear riskAssessment from published study report.
Other biasLow riskBaseline characteristics of participants did not differ between intervention groups.

ROLO 2012

MethodsRCT conducted at a maternity hospital in Ireland with recruitment from January 2007 to January 2011.
Participants

800 randomised, 759 analysed.

Inclusion criteria: secundigravid women whose first baby was macrosomic (birthweight > 4.0 kg).

Exclusion criteria: underlying medical disorders, previous history of gestational diabetes, those on any drugs, and those unable to give full informed consent, age less than 18 years, gestation greater than 18 weeks, and multiple pregnancy.

Interventions

Low GI dietary intervention (n = 394 ) involving 1 dietary education session lasting 2 hours in groups of 2-6 women with a dietitian at baseline. Follow-up reinforcement sessions were held at 28 and 34 weeks' gestation. Women received written resources about low GI foods.

Control group: routine care (n = 406).

Outcomes

Primary outcome: birthweight.

Secondary outcomes: GWG, maternal GI and dietary intake.

Notes

GTT was done at 28 weeks' gestation. Women completed food diaries. Other outcomes were recorded on delivery.Age (intervention, control): 32 [4.2]/32 [4.2].

Enrolment gestational age: 13 [2.3]/12.9 [2.2].

Recruitment BMI: 26.8 [5.1]/26.8 [4.8].

Glucose challenge test at 28 weeks showed significantly less women in the intervention group vs control group with glucose intolerance defined as GCT > 7.8 mmol/L (54/350 [15%] vs 79/371 [21%]).

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk"The research midwife did the randomisation by using computer generated allocations in a ratio of one to one."
Allocation concealment (selection bias)Low risk"sealed opaque envelopes."
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot described.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot described.
Incomplete outcome data (attrition bias)
All outcomes
Low riskLow attrition rates for most outcomes.
Selective reporting (reporting bias)Unclear riskExcluded women who did not receive allocated intervention (i.e. per protocol analysis).
Other biasLow riskBaseline characteristics were comparable. Good compliance.

Ronnberg 2014

MethodsRegistered, open-label, parallel assignment RCT conducted in Sweden. ID NCT00451425.
Participants

General population: 445 women randomised, 374 analysed.

Included if > 18 years old, Swedish speaking, BMI ≥ 19, gestation < 16 weeks, and healthy.

Excluded if history of eating disorders or history of previous growth restricted child.

InterventionsIntervention group: a motivational exercise intervention that included a personalised weight graph, GWG monitoring at each antenatal visit, and prescribed exercise to be at a "moderate level of exertion for approximately 30 min/day". The intervention was administered at routine antenatal visits by midwives.
Control group: standard care. All women received basic dietary advice according to Swedish national guidelines.
OutcomesGWG (1990 IOM guidelines), weight retention up to 1ne year, fetal and maternal complications in pregnancy and during delivery, infant birthweight and infant weight up to 1 year of age.
Notes

Age: 29.9 [4.5]/ 29.9 [4.8].

Enrolment gestational age: 10.7 vs 9.7 weeks.

72% normal weight women, 28% overweight or obese.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk"computer-generated in blocks of variable sizes between 4 and 8."
Allocation concealment (selection bias)Low risk"Sealed, opaque, sequentially numbered envelopes were kept by administrative personnel not related to the study." A research assistant opened the next envelope and informed the midwife telephonically of each group allocation.
Blinding of participants and personnel (performance bias)
All outcomes
High riskNot blinded.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot described.
Incomplete outcome data (attrition bias)
All outcomes
Low riskLoss to follow-up was 8% in the intervention group and 11% in the control group. ITT analysis performed.
Selective reporting (reporting bias)Unclear riskOnly GWG outcomes reported. Other maternal and fetal outcomes were stated as having "no significant difference between groups". Unpublished data requested.
Other biasUnclear riskGestational age at recruitment was statistically significantly different (10.7 weeks vs 9.7 weeks, for intervention and control groups, respectively).

Ruchat 2012

MethodsRCT of 2 interventions compared with historical control in Canada.
Participants

General population, 73 recruited, 49 analysed.

Inclusion criteria: normal weight women with singleton pregnancies between 16 and 20 weeks' gestation.

Exclusion criteria: specific exclusion criteria included the following: maternal age < 18 years or > 40 years, smoking, multiple pregnancy, presence of chronic disease, or other contraindications to exercise.

Interventions

2 lifestyle interventions vs an historical control.

Intervention groups: interventions were moderate-intensity exercise plus diet (n = 26), vs low-intensity exercise plus diet (n = 23). The low-intensity exercise intervention consisted of a walking program that corresponded with 30% HRR (oxygen consumption reserve) whereas the moderate-intensity program corresponded with a 70% HRR. The exercise was performed 3 to 4 times per week, with 1 session per week supervised. Participants wore an HR monitor to ensure they were exercising within the predetermined target HR zone.

Control group: control group were 45 normal weight women with singleton pregnancies who did not participate in a structured exercise program.

All participants received a diet plan based on a modified diabetic diet.

OutcomesGWG, maternal weight retention 2 months postpartum, infant birthweight.
Notes

We only included data from the randomised participants, i.e. the low intensity intervention vs moderate intensity intervention. As control group was not randomised, we did not use these data.

Age (intervention 1, intervention 2): 30.4 [4.5]/ 31 [3.8].

Enrolment gestational age: 17 [1.5]/17.5 [1.5].

Prepregnancy BMI: 21.7 [1.9]/22.1 [1.7].

Diet outcomes were collected between 34 and 36 weeks' gestation. Women were weighed weekly in the laboratory. Delivery and newborn data were obtained from medical records and complication during delivery were obtained from maternal recall within 6-18 hours after delivery.

Authors concluded that "Results suggest that a prenatal nutrition exercise program regardless of exercise intensity, reduced excessive GWG and decreased weight retention at 2 months postpartum in women of normal weight before pregnancy".

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk"All the participants were randomised using a block procedure with four subjects per block."
Allocation concealment (selection bias)Unclear riskNot described.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot described.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskAssessor blinding not described. Exercise and diet logs were recorded by the participants at home.
Incomplete outcome data (attrition bias)
All outcomes
High riskOnly 49 participants (67%) out of 73 completed the study. Even if 1 excludes the 7 women who "decided to withdraw after the peak exercise test" (before randomisation), withdrawal is still > 20%. Similar numbers withdrawn from both groups.
Selective reporting (reporting bias)Unclear riskCould not determine.
Other biasHigh riskControl group was historical, not randomised; therefore, these data were not used in the review. See Potential biases in the review process.

Ruiz 2013

MethodsRCT at 3 primary care hospitals in Madrid, Spain, from September 2007-January 2011.
Participants

General population, 962 randomised and analysed.

Inclusion criteria: women who were sedentary (not exercising for > 20 mins on > 3 days a week), with singleton and uncomplicated gestations, not at high risk of preterm delivery (i.e.. previous preterm birth) and not participating in any other trial were able to participate in this study.

Exclusion criteria: women with any obstetric contraindication to exercise were not eligible to participate.

Interventions

Intervention group: exercise intervention (n = 481). The intervention included light- to moderate-intensity aerobic and resistance exercises performed 3 days a week (50-55 mins per session) from 9 weeks to weeks 38-39. Exercise sessions included 8-10 participants.

Control group: routine care (n = 481).

OutcomesPrimary outcome: GWG. Secondary outcomes: Maternal and fetal outcomes, including birthweight, gestational age, type of delivery (caesarean, etc), Apgar scores, childbirth, gestational diabetes and hypertension.
Notes

Age (intervention, control): 31.6 [4]/ 31.9 [4].

Enrolment gestational age was 5-6 weeks.

Prepregnancy BMI: 23.7 [3.9]/23.5 [4.2].

GWG was calculated from measured weight at last visit minus weight at first prenatal visit. Other outcomes were obtained from hospital records after delivery.

Authors concluded that "Supervised exercise of light to moderate intensity can be used to prevent excessive gestational weight gain, especially in normal weight women. The effects seemed to be more pronounced in normal weight women…".

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk"Computer generated."
Allocation concealment (selection bias)Unclear riskNot described.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot described.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot described.
Incomplete outcome data (attrition bias)
All outcomes
Unclear risk14% attrition overall. 68 women in the control arm were lost to follow-up because of threat of premature delivery (n = 11), persistent bleeding (n = 9), a move to another hospital (n = 20), or miscellaneous personal reasons (n = 28). 70 women in the intervention arm were lost to follow-up due to threat of premature delivery (n = 14), persistent bleeding (n = 7), a move to another hospital (n = 25), or miscellaneous personal reasons (n = 24). No protocol deviations.
Selective reporting (reporting bias)Low riskExpected outcomes reported.
Other biasLow riskNone noted. Baseline characteristics were comparable.

Santos 2005

MethodsRandomised clinical trial, set in a referral centre prenatal clinic in Porto Alegre, Brazil, during the period 2000–2002.
Participants

Inclusion criteria: healthy, nonsmoking pregnant women, aged 20 years or more, of gestational age less than 20 weeks, having a BMI between 26 and 31 kg/m² (corresponding to a prepregnancy BMI of 25-30 kg/m²) (overweight), and without diabetes or hypertension.

Exclusion criteria: not stated.

Interventions

Intervention (n = 37): the intervention consisted of a program of supervised physical exercise of 60 mins duration, performed 3 times per week for 12 weeks. Each session consisted of 5-10 mins of warm up, 30 mins of heart rate-monitored aerobic activity, 10-15 mins of exercise involving upper and lower limbs, and 10 mins of stretching and relaxation. Aerobic activities were always performed between 50% and 60% of the maximum predicted heart rate, never exceeding 140 beats per min. The exercises followed the recommendations concerning physical activity practice during pregnancy according to the American College of Sports Medicine, and the ACOG.

Control (n = 35): the control group participated in once-weekly sessions that included relaxation (respiratory exercises and light stretching but no aerobic or weight-resistance exercises) and focus group discussions concerning maternity. Control participants were neither encouraged to exercise nor discouraged from exercising.

Outcomes

Weight gain, low birthweight, prematurity.

Weight gain was calculated from different between weight at baseline and weight after 12 weeks of intervention.

Notes

At baseline; age (exercise, control) 26.0 ± 3.4, 28.6 ± 5.9 years.

BMI (exercise, control) 28.0 ± 2.1, 27.5 ± 2.1 kg/m².

Gestational age (exercise, control) 17.5 ± 3.3, 18.4 ± 3.9 weeks.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskWomen were randomised following a blocked sequence generated from a random number table by a statistician not participating in other aspects of the study.
Allocation concealment (selection bias)Low riskThe study co-ordinator implemented the randomisation by using numbered, opaque envelopes.
Blinding of participants and personnel (performance bias)
All outcomes
High riskUnblinded.
Blinding of outcome assessment (detection bias)
All outcomes
Low risk

The same cardiologist, blinded to treatment allocation, performed both tests.

The anaerobic threshold was determined by review of the gas exchange curves by 2 cardiologists working independently and blinded to treatment allocation.

Incomplete outcome data (attrition bias)
All outcomes
High riskLoss to follow-up 22%, 19.6%, and 23.9% in intervention and control groups         .                                      
Selective reporting (reporting bias)Unclear riskCould not determine.
Other biasHigh riskWomen in the intervention group were somewhat younger, had higher physical activity, and were earlier in their pregnancy.

Stafne 2012

MethodsRCT conducted at St Olavs Hospital, Trondheim University Hospital, and Stavanger University Hospital in Norway with recruitment from April 2007 to June 2009.
Participants

855 randomised, 702 analysed.

Inclusion criteria: white women aged 18 years or older with a singleton live fetus.

Exclusion criteria: high-risk pregnancies or diseases that could interfere with participation (or both). For practical reasons, women who lived too far from the hospitals to attend weekly training groups (more than 30-min drive) were excluded.

Interventions

Intervention group: 12 weeks regular standardised exercise program including aerobic activity, strength training, and balance exercises. The exercise program followed standard recommendations and included moderate-intensity to high-intensity activity 3 or more days per week. Physiotherapist-supervised training sessions of 60 mins in groups of 8-15 women were offered once per week.

Control group: routine care (women were not discouraged from exercising).

Outcomes

Primary outcome: GDM, insulin resistance.

Secondary outcomes: maternal weight, BMI, newborn weight, gestational age, Apgar score.

Notes

Baseline assessment at 18-22 weeks, outcomes assessed at 32 to 36 weeks' gestation.

Age (intervention, control): 30.5 [4.4]/ 30.4 [4.3].

Enrolment gestational age was 18-22 weeks.

Recruitment BMI: 24.7 [3]/25 [3.4].

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk"Concealed randomization in blocks of 30 was performed at the Unit for Applied Clinical Research, by a Web-based computerized procedure."
Allocation concealment (selection bias)Low risk"concealed randomisation."
Blinding of participants and personnel (performance bias)
All outcomes
High risk"Because of the nature of the study it was not blinded."
Blinding of outcome assessment (detection bias)
All outcomes
Low riskAssessment of primary outcome (insulin resistance) "was blinded for group allocation".
Incomplete outcome data (attrition bias)
All outcomes
High risk18% dropout overall with more dropouts in the control group (24% vs the intervention group 13%).
Selective reporting (reporting bias)Unclear riskCould not determine. ITT performed.
Other biasLow riskNone noted. Baseline characteristics similar.

Szmeja 2011

MethodsRCT conducted in Adelaide, Australia. Study period not stated.
Participants

HIgh risk. 193 women included.

Inclusion criteria: women with a BMI ≥ 25 kg/m2 and a live singleton pregnancy between 10 and 20 weeks' gestation.

Exclusion criteria not stated.

Interventions

Intervention group (98 women): received an "informational DVD".

Control group (95 women): "No DVD".

OutcomesSelf-reported knowledge of health dietary and lifestyle choices, satisfaction with pregnancy care.
NotesNo statistically significant differences reported. Authors concluded that the intervention was not effective.
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskNot described.
Allocation concealment (selection bias)Unclear riskNot described.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot described.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskAppear to be self-reported outcomes only.
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskInsufficient information to make a judgement.
Selective reporting (reporting bias)Unclear riskInsufficient information to make a judgement.
Other biasUnclear riskThis report has not been published in full, possibly because the intervention was not effective.

Thornton 2009

MethodsRCT, set in the ambulatory obstetric clinics of 3 tertiary care medical centres - Morristown Memorial Hospital, St Luke’s-Roosevelt Hospital Center, and Jamaica Hospital Medical Center. Each study site was an urban, public clinic of a teaching hospital, New York Medical College.
Participants

Inclusion criteria: pregnant with a single fetus between 12 and 28 weeks of gestation that had a BMI greater than or equal to 30 kg/m².

Exclusion criteria: women with pre-existing diabetes, hypertension, or chronic renal disease.

Interventions

Intervention (n = 116): monitored group; counselled in nutrition by a registered dietitian and given a more detailed dietary intake protocol. The nutrition program for the monitored women followed dietary guidelines similar to those used in women with the diagnosis of gestational diabetes. The women in this group were asked to record in a diary all of the foods and beverages eaten during each day.

Control (n = 116): unmonitored group; counselled in nutrition by a registered dietitian regarding conventional prenatal nutrition guidelines.

Outcomes

Weight gain, weight retention (calculated from the difference between weight at 6 weeks' postpartum and weight at baseline).

GDM, pre-eclampsia, gestational hypertension, haemorrhage/infection postpartum, preterm delivery (< 37 weeks), labour induction, caesarean delivery, macrosomal infant (> 4500 g).

Weight gain was weight difference between the baseline(12-28 weeks) pregnancy weight and weight before delivery.

Notes

Age (intervention, control) 26.8, 27.3.

BMI (intervention, control) 37.41 ± 7.01, 38.22 ± 7.48 kg/m².

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskA random-number table was used to assign each consecutively numbered envelope to either the study or control group in blocks of 10.
Allocation concealment (selection bias)Low riskEnvelopes were prepared and sequentially numbered. A card indicating the assigned group was placed in the envelope, and the envelope was sealed.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot described.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot described.
Incomplete outcome data (attrition bias)
All outcomes
Low riskThe ITT principle was performed. Loss to follow-up 9.7%.
Selective reporting (reporting bias)Unclear riskCould not determine.
Other biasLow riskDemographic data for the randomised groups were comparable.

Vesco 2013

MethodsParallel-arm RCT conducted by Harvard Medical School, USA.
Participants

160 planned, 114 randomised so far.

Inclusion criteria: women aged 18 or older, who were obese at the beginning of pregnancy (BMI ≥ 30 kg/m²); 10-20 weeks' gestation.

Exclusion criteria: gestational age > 20 weeks, multifetal pregnancy, anticipated disenrolment prior to delivery, non-English speaking, plans to move within the year, type 1 or 2 diabetes mellitus (or gestational diabetes), and other medical conditions that require specialised nutritional care (e.g. history of bariatric surgery) or conditions that may affect weight gain (e.g. severe hyperemesis gravidarum).

Interventions

Intevention group: lifestyle intervention (diet plus exercise) (n = 56). Following randomisation, all participants receive a 45-min dietary consultation. They were encouraged to follow the Dietary Approaches to Stop Hypertension diet (DASH) without sodium restriction and received an individualised calorie intake goal, a second individual counselling session and attend weekly group meetings (90 min) with weigh-ins, food and activity logs until they give birth. Women are encouraged to accumulate at least 30 min of moderate intensity activity per day. Pedometers recorded steps with at target of 10,000 steps daily and were only provided to the intervention group.

Control group: usual care (n = 58) with a 1-time advice session about healthy eating.

Outcomes

Primary outcomes: GWG, excessive weight gain, postpartum weight retention at 1 year (mean difference between postpartum and baseline weight), proportion of LGA neonates.

Secondary outcomes: feasibility and acceptability of the intervention, maternal dietary intake and physical activity, and infant birthweight, feeding patterns, and growth during the first year of life.

Notes

Median age (intervention, control): 29 (27-32), 29 (26-31).

Mean BMI 36.7 (5.2) / 36.8 (4.7).

21% of sample had BMI > 40 kg/m2.

Data collection at 34-weeks' gestation and at 2-weeks' and 1-year postpartum.

Enrolment at 10-20 weeks' gestation.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk"Randomisation ...using a computerised algorithm to generate the random assignments in blocks of four."
Allocation concealment (selection bias)Unclear riskNot described.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot described.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot described.
Incomplete outcome data (attrition bias)
All outcomes
Low riskGood follow-up achieved.
Selective reporting (reporting bias)Low riskPrespecified outcomes were reported. ITT analysis.
Other biasUnclear riskFollow-up weight gain data were collected at 34 weeks (i.e. earlier than most other included studies).

Vinter 2012

MethodsRCT conducted at 2 university hospitals in Odense, Denmark from October 2007 to October 2010.
Participants

360 randomised, 304 analysed.

Included obese women aged 18-40 years, 10-14 weeks' gestation, BMI of 30-45kg/m2.

Excluded if chronic medical conditions, prior serious obstetric complications, alcohol/drug abuse, non-Danish speaking, multiple pregnancy, positive GTT.

Interventions

Intervention group: a lifestyle intervention consisting of dietary counselling and exercise (n = 180). The intervention involved dietary advise on 4 occasions (15, 20, 28 and 35 weeks) by a dietician. Energy requirements were personalised for each participant. Exercise intervention included a pedometer, free gym membership for 6 months, encouraged to do 30-60 min moderate physical activity daily. At the gym they had closed training classes with a physiotherapist for 1 hour each week.

Control group: routine care (n = 180).

OutcomesGWG, pre-eclampsia, hypertension, GDM, caesarean section, macrosomia, LGA, admission to NICU, maternal weight retention at 6 months postpartum, infant and childhood weight.
Notes

GWG was defined as weight gain at 35 weeks. Obstetric and neonatal outcomes were obtained from medical records. Childhood weight not yet reported.

Age (intervention, control): 29 (27-32)/29 (26-31).

Enrolment gestational age was 10-14 weeks.

Recruitment BMI: 33.4 (31.7-36.5)/33.3 (31.7-36.9).

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk"computer-generated numbers" 1:1, stratified for smoking.
Allocation concealment (selection bias)Low risk"sealed envelopes."
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot described.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot described.
Incomplete outcome data (attrition bias)
All outcomes
Low risk56/360 (15%) dropped out for primary outcomes. Similar between groups.
Selective reporting (reporting bias)Low riskAll expected outcomes reported.
Other biasLow riskNone noted. Baseline characteristics comparable.

Vitolo 2011

MethodsRCT (pilot study), set in primary care settings in Porto Alegre, Brazil.
Participants

Inclusion criteria: gestational age between 10 and 29 weeks; women attending the prenatal care unit of the health unit.

Exclusion criteria: positive testing for HIV, previous diagnostic of diabetes, hypertension, anaemia or another condition that needed a special diet and age over 35 years.

Interventions

Intervention group: (159 women) weight and diet were assessed at recruitment. The aim of the intervention was to improve diet and encourage weight-appropriate weight gain in pregnancy. For low weight women, the priority was increasing the energetic density of the meals. For normal weight women, daily consumption of vegetables, greens, fruit and water were encouraged and women were advised to restrict consume of fat-rich foods and oil in cooking. For the overweight women, the intervals between meals were prioritised and women were encouraged to restrict their consumption of snacks. Women received a further interview 1 month later to reinforce messages.

Control group: (162 women) women did not receive any special intervention but were informed about their weight and nutritional status and advised to seek professional help if they were under or overweight. Their doctors were also provided with the results of the nutritional evaluation.

OutcomesWeight gain.
NotesReported average weekly weight gain which was significantly lower in the overweight women in the intervention group than the control group (342.2 g [143.6[ vs 420 g [185.4]; P = 0.01).
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskWomen were randomised by means of a dark pouch with 2 equal sized cubes containing the term intervention in 1 and control in the other.
Allocation concealment (selection bias)Unclear risk2 cubes were concealed in a dark pouch and 1 was removed at the point of randomisation which indicated allocation. (It is possible that this could be changed by the person carrying out randomisation.)
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot described.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot described.
Incomplete outcome data (attrition bias)
All outcomes
Low risk315 women accepted participation in the study.There were 307 women with anthropometric data collected in the last trimester.
Selective reporting (reporting bias)Unclear riskThe results relate to the number of women with excessive or low weight gain at different gestational ages.
Other biasUnclear risk'Risk of bias' assessment from translated notes.

Wilkinson 2012

MethodsRCT conducted at a maternity hospital in Australia with recruitment from August 2010 to March 2011.
Participants

Randomised 360, analysed 242.

Included if attending their booking visit at the MH research site and were 18 years or older (or under 18 years, with the consent of a parent or guardian).

Excluded if unable to read and speak English at a level that allowed completion of pen-and-paper surveys.

Interventions

Intervention group: a lifestyle intervention (diet plus exercise, smoking cessation, etc) (n = 178) consisting of a 1-hour 'Healthy start to pregnancy' workshop with a 12 page booklet with evidence based information, with goal setting and self-monitoring activities.

Control group: routine care (n = 182).

OutcomesGood nutrition, PA, GWG awareness, number of cigarettes smoked, BMI.
Notes

Outcomes assessed at recruitment and 12 weeks later at around 26 weeks.

Age (intervention, control): 29.5 [5.1]/29 [4.7].

Enrolment gestational age: 14.5 [3]/14.2 [3].

Prepregnancy BMI: 25.4 [5.2]/24.6 [5.5].

ITT analysis showed increased weekly activity scores in mins in the intervention group. Only per protocol analyses showed significant differences in diet quality and mean servings of vegetables and fruit in the intervention group at the follow-up interview (26 weeks).

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk"computerized randomisation process."
Allocation concealment (selection bias)Low risk"allocation was concealed using sealed opaque envelopes."
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot described.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskAssessor blinding was not described. Most outcomes, including activity scores and food consumption were self-reported.
Incomplete outcome data (attrition bias)
All outcomes
High riskOnly half the women attended the workshop, and overall response at the second assessment was 67%.
Selective reporting (reporting bias)Unclear riskCould not determine. Reported ITT and per protocol analyses. Few review outcomes reported. Little usable data.
Other biasLow riskBaseline characteristics overall were comparable.

Wolff 2008

  1. a

    ACOG: the American Congress of Obstetricians and Gynecologists
    ANC: antenatal clinic
    BMI: body mass index
    BP: blood pressure
    CHO: carbohydrate
    GDM: gestational diabetes mellitus
    GI: glycaemic index
    GWG: gestational weight gain
    HbA1C: haemoglobin A1C
    HGI: high glycaemic index
    Hi-Lo: high-low exercise
    IOM: Institute of Medicine
    ITT: intention-to-treat
    LGA: large-for-gestational age
    LGI: low glycaemic index
    Lo-Hi: low-high exercise
    min: minutes
    Mo-Mo: moderate-moderate exercise
    n: number
    NICU: neonatal intensive care unit
    NR: not reported
    OGTT: oral glucose tolerance test
    QoL: quality of life
    RCT: randomised controlled trial
    RDA: recommended dietary allowance
    SD: standard deviation
    SGA: small-for-gestational age
    VLDL: very low-density lipoprotein
    vs: versus

MethodsRCT, set in Copenhagen, Denmark.
Participants

Inclusion criteria: pregnant obese women (BMI > 30 kg/m²), nondiabetic non-smoking and Caucasian recruited at 15 ± 3 weeks of gestation. 

Exclusion criteria: smoking, age < 18 or > 45, multiple pregnancy, or medical complication.

Interventions

Intervention (n = 23): restriction of GWG to 6-7 kg by 10 consultation of 1 hour each with trained dietitian. The women were instructed to eat a healthy diet according to the official Danish dietary recommendations (% fat, protein, CHO, 30, 15-20, 50%-55%). The energy intake was restricted based on individually estimated energy requirements and estimated energetic cost of fetal growth.

Control (n = 27): the control group had no consultations with the dietitian and had no restrictions on energy intake or GWG.

All participants followed the routine clinical schedule.

Outcomes

Weight gain, weight retention at 4 weeks' postpartum, pre-eclampsias, caesarean delivery.

Weight gain was calculated as difference between self-reported prepregnancy weight and weight just before delivery.

Notes

Age (intervention, control) 28 ± 4, 30 ± 5 years.

Gestational age (intervention, control) 15 ± 2, 16 ± 3 weeks.

BMI at inclusion visit (intervention, control) 34.9 ± 4, 34.6 ± 3 kg/m².

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskThe computerised randomisation took place after the women had given written informed consent.
Allocation concealment (selection bias)Unclear riskNo information provided.
Blinding of participants and personnel (performance bias)
All outcomes
Low riskThe physicians and midwives were blinded in regard to the treatment assignment, and women were asked not to reveal their allocation.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot described.
Incomplete outcome data (attrition bias)
All outcomes
High riskLoss to follow-up 24%: 17.8% in intervention group, 28.9% in control group.
Selective reporting (reporting bias)Unclear riskCould not determine.
Other biasLow riskBaseline characteristics were similar.

Characteristics of excluded studies [ordered by study ID]

StudyReason for exclusion
  1. a

    RCT: randomised controlled trial

Asemi 2011RCT of effect of probiotic yogurt during pregnancy on inflammatory factors, lipid profiles, oxidative stress and insulin resistance, not on preventing excessive weight gain.
Bechtel-Blackwell 2002Quasi-RCT.
Boileau 1968Irrelevant intervention.
Breslow 1963Non-RCT.
Campbell 2004Participants included pregnant and nonpregnant women.
Daley 2014Abstract of the process evaluation of an RCT.
Davenport 2011Quasi-RCT of a target weight program intervention in pregnancy.
Faucher 2008It was not clear that women in this study were pregnant (community weight loss intervention).
Graham 2014Formative research for e-Mons study not RCT results.
Gray-Donald 2000Non-RCT.
Hauner 2012RCT omega-3 fatty acids on infant adipose tissue, not an intervention to reduce excessive weight gain in pregnancy.
Hausenblas 2008Participants included both pregnant and postpartum women.
Ismail 1990Not a relevant intervention.This study examined the use of cefoxitin (an antibiotic) for the prevention of post-cesarean-section infection.
Kinnunen 2007Non-RCT.
Lindsay 2014Abstract of RCT (probiotics) without gestational weight gain outcomes.
Maitland 2014Abstract of a pilot cross-over study of only 16 women to evaluate a dietary supplement.
Mohebi 2009Quasi-RCT protocol.
Moses 2006Quasi-RCT.
Mottola 2010Not a RCT.
Olson 2004Non-RCT.
Silverman 1971Irrelevant intervention.
Stutzman 2010Quasi-RCT on the effect of exercise on blood pressure and heart rate variability, not excessive weight gain.
Te Morenga 2011This study did not include pregnant women.
Walker 1966Non-RCT.
Wisner 2006Participants were postpartum women.

Characteristics of studies awaiting assessment [ordered by study ID]

Shakeri 2012

MethodsThis study requires translation from Farsi before it can be classified.
Participants 
Interventions 
Outcomes 
Notes 

Characteristics of ongoing studies [ordered by study ID]

Astrup 2013

Trial name or titleAn optimised programming of healthy children (APPROACH).
Methods

RCT, single blind, parallel assignment.

Location: Denmark.

Participants390 obese pregnant women.
InterventionsHigh-protein/low-GL diet vs low-protein/high-GL diet.
Outcomes

Primary: GWG. changes in bodyweight, body composition, body fat.

Secondary: growth and development of fetus.

Starting date01/11/2013.
Contact informationNina RW Geiker, nina.rica.wium.geiker@regionh.dk, Copenhagen University Hospital at Herlev.
NotesEstimated completion date: December 2015 (final data collection date for primary outcome measure).

Atkinson 2013

Trial name or titleBe healthy in pregnancy (B-HIP): an RCT to study nutrition and exercise approaches for healthy (BHIP).
Methods

RCT, 2-arm randomised 1-site trial, parallel assignment, single blind.

Location: Canada.

Participants

110 women with singleton pregnancies.

Excluded: currently breastfeeding previous child, pregnancy resulting from in vitro fertilisation, and others.

InterventionsNutrition (energy high protein, low fat diet) and exercise (aerobic) vs standard prenatal care.
OutcomesGWG within IOM guidelines, maternal and infant outcomes.
Starting date01/07/2012.
Contact informationStephanie A Atkinson, PhD, satkins@mcmaster.ca, McMaster University.
NotesEstimated completion date: November 2016 (final data collection date for primary outcome measure).

Barakat 2012

Trial name or titleEffect of a supervised exercise program in obese and overweight pregnant women on outcomes and level of depression.
Methods

RCT.

Location: Spain.

Participants

150 obese and overweight pregnant women.

Inclusion criteria

· Being healthy and able to exercise following American College of Obstetricians and Gynecologists (ACOG) guidelines.

· Being able to communicate in Spanish.

· Giving birth at Hospital Universitario de Fuenlabrada.

· Having a BMI greater than 24.9.

Exclusion criteria

· Multiparity.

· Obstetrician complications.

· Being interested in the study after 18 weeks.

· Not being regular in physical exercise program (minimum adherence 80%).

· Younger than 18 years old.

Interventions

Behavioural: exercise group.

Supervised physical conditioning program of 3, 55-60 minute sessions per week during whole pregnancy (from week 9 to 38). Each session consists of 25-30 minutes of cardiovascular exercise, 10 minutes of specific exercises (strength and balance exercises), and 10 minutes of pelvic floor muscles training.
Aerobic activity was prescribed at light-to-moderate intensity, aiming for 55-60 of maximal heart rate. All women wore a heart rate (HR) monitor (Polar FT7) during the training sessions to ensure that exercise intensity was light-to-moderate.

Outcomes

Primary outcomes: change from level of depression at the end of the pregnancy [Time frame: Up to 36 weeks] The Center for Epidemiological Studies-Depression scale (CES-D) was administered to all obese and overweight pregnant women at the beginning and at the end of their pregnancies.

Secondary outcomes

· Maternal GWG [Time frame: 40-42 weeks].

· Maternal outcomes [Time frame: after labour].

· Fetal weight [Time frame: after labour].

Starting dateOctober 2009.
Contact informationRuben Barakat,PhD, barakatruben@gmail.com, Universidad Politécnica de Madrid, Spain.
NotesFinal data collection date for primary outcome measure, January 2013.

Brownfoot 2011

Trial name or titleWeighing in pregnancy.
MethodsRCT.
ParticipantsPregnant women attending for antenatal care at < 20 weeks' gestation 18-45 years. Excluded multiple gestation or medical or psychiatric illness. (Target sample size 650.)
InterventionsWeighing as part of each antenatal visit compared with routine care.
OutcomesWeight gain within IOM and WHO recommendations; medical complications of pregnancy (pre-eclampsia, hypertension, gestational diabetes); need for induction of labour; mode of delivery; postpartum complication; infant birthweight; macrosomia and complications relating to macrosomia.
Starting date1st January 2010.
Contact informationfiona.brownfoot@thewomens.org.au
NotesEmailed 22/9/14.

Callaway 2012

Trial name or titleProbiotics for the prevention of gestational diabetes in overweight and obese women.
Methods

RCT, placebo, parallel, blinded.

Location: Australia.

Participants

640 obese and overweight women. 18 to 50 years.

Excluded: gestation > 16 weeks, pre-existing diabetes, pre-existing impaired fasting glucose or impaired glucose tolerance, GDM on early screening, and others.

InterventionsDiet (administration of probiotics) vs placebo.
OutcomesGestational diabetes. GWG. pre-eclampsia, induction of labour, caesarean section. neonatal outcomes, biochemical and other outcomes.
Starting date01/06/2012.
Contact informationProf Leonie Callaway, l.callaway@uq.edu.au, Royal Brisbane and Women's Hospital.
Notes 

Chasan-Taber 2009

Trial name or titleA RCT of prenatal physical activity to prevent gestational diabetes: design and methods.
Methods

RCT.

A blocked randomisation is used such that both treatment groups are assigned an equal number of times in each set of 4 sequentially enrolled women.

Participants

Location: Bay State Medical Center in western Massachusetts.

Target number of participants: 364.

Inclusion criteria: women are sedentary, with a diagnosis of GDM in a prior pregnancy defined according to American Diabetes Association (ADA) criteria.

Exclusion criteria: age < 18 or > 40 years, history of diagnosis of diabetes outside of pregnancy, hypertension, heart disease or chronic renal disease, current medications that adversely influence glucose tolerance, > 16 weeks' gestation, contraindications to participating in moderate-physical activity, inability to read English at a 6th grade level, self-reported participation in > 30 minutes of moderate-intensity or vigorous-intensity exercise on > 3 days/week, and non singleton pregnancy.

Interventions

Exercise intervention: person education on exercise followed by weekly, biweekly and monthly mail and telephone follow-up.

Health and wellness intervention: person education health and wellness followed by weekly and monthly mail and telephone follow-up.

OutcomesMaternal weight gain (change in weight from pregravid to delivery), birthweight, Apgar score, caesarean delivery, macrosomia (> 4000 g) and LGA, defined as newborn weight the 90th percentile for completed gestational weeks using cutoff points defined by Oken.
Starting dateApril 2010.
Contact information

Lisa Chasan-Taber; lct@schoolph.umass.edu

Megan Ward Harvey, meward@schoolph.umass.edu

Notes1 paper has been published (Hawkins 2014). It found that the exercise arm had significantly greater increases in sports or exercise activity. Findings on GWG and neonatal outcomes are pending.

Chasan-Taber 2013

Trial name or titleLifestyle intervention in overweight and obese pregnant Hispanic women.
Methods

RCT, parallel, double blind.

Location: USA.

Participants

Estimated enrolment 333.

Overweight or obese Hispanic women 16-45 years old.

Excluded if type 2 diabetes, heart disease, or chronic renal disease. multi-gestational, and other exclusions.

InterventionsPA and diet intervention materials and health education vs standard prenatal care.
OutcomesInsulin resistance, GWG, postpartum weight loss, postpartum cardiovascular risk and others.
Starting date01/01/2014.
Contact informationLisa Chasan-Taber, ScD, lct@schoolph.umass.edu, University of Massachusetts, Amherst
NotesEstimated completion date: 01/12/2018.

Choi 2011

Trial name or titleA pilot study of a mobile phone-based physical activity program in pregnant women.
Methods

RCT, parallel, single blind.

Location: USA.

Participants

30 physically inactive women at 10 - 20 weeks' gestation with pre-pregnancy BMI >= 18.5.

Excluded if known medical or obstetric complication that restricts physical activity. History of eating disorders.

InterventionsStudy mobile phone app and activity monitor vs activity monitor.
OutcomesPhysical activity, measured steps.
Starting date01/10/2012.
Contact informationJiWon Choi, PhD, no email given, University of California, San Francisco.
NotesEstimated completion date: May 2014.

Downs 2011

Trial name or titleDeterminants and outcomes of physical activity in pregnancy: findings from active MOMS, a randomised physical activity intervention for pregnant women.
MethodsRCT.
ParticipantsPregnant women (inclusion and exclusion criteria not described).
Interventions2 physical activity interventions and a control group. 1 group received a structured intervention with face-to-face physical activity education, motivational support and moderate-physical activity on 2 days per week for 70 mins with an instructor. The 2nd group (lifestyle support) received educational support via mailed materials and phone support. The control group received standard care.
OutcomesPerformance (physical activity).
Starting date 
Contact informationDanielle S Downs,The Pennsylvania State University, University Park, PA, USA.
NotesStudy reported in brief abstract with preliminary findings.

Farajzadegan 2013

Trial name or titleMaternal-centred life-style modification program for weight gain management during pregnancy.
Methods

RCT.

Location: Iran.

Participants160 pregnant women between 6 to 10 weeks' gestational age who have no condition that requires medical care nor drug taking.
InterventionsNutrition and exercise (educational package, prenatal care log book and 10, 20-minute counselling sessions) vs standard prenatal care.
OutcomesGWG, BMI.
Starting dateNot stated.
Contact informationDr Zahra Amini Pozveh, aminizahra2005@yahoo.com, Isfahan University of Medical Sciences.
Notes 

Fernandez 2011

Trial name or titleElectronically-mediated weight interventions for pregnant and postpartum women.
Methods

RCT, 3-armed, parallel, double blind.

Location: USA.

Participants

Estimated enrolment 1641 pregnant women at or before 20 weeks' gestation.

Excluded BMI < 18.5 and > 35, multiple gestation, any previous conditions that could interfere with weight loss.

InterventionsBehavioural intervention through a website during pregnancy and until 18 months postpartum or intervention through website during pregnancy only vs non weight-related content.
OutcomesGWG, postpartum weight retention, caloric intake, PA.
Starting date01/05/2011.
Contact informationDiana Fernandez, no email given, University of Rochester.
NotesEstimated completion date December 2014.

Ferrara 2014

Trial name or titleA pragmatic cluster randomised clinical trial of diabetes prevention strategies for women with gestational diabetes: design and rationale of the Gestational Diabetes’ Effects on Moms (GEM) study.
Methods

Cluster-RCT, multicentre, blinded.

Location: USA.

Participants

2,320 women with a GDM diagnosis between March 27, 2011 and March 30, 2012.

Excluded: neonatal loss, no telephone contact.

InterventionsNutrition and exercise (diabetes prevention program-derived print/telephone lifestyle intervention of 13 telephonic sessions) vs usual care.
OutcomesProportion of women who reach a postpartum weight goal and total weight change. Postpartum glycaemia, blood pressure, depression, percent of calories from fat total caloric intake and physical activity levels.
Starting dateMarch 27, 2011.
Contact informationAssiamira Ferrara, Assiamira.Ferrara@kp.org, Kaiser Permanente Northern California.
Notes 

Goldberg 2012

Trial name or titleRandomised control pilot of a behaviour-based exercise and diet intervention to reduce risk factors for gestational diabetes among otherwise healthy pregnant women.
Methods

RCT, parallel, open label.

Location: USA.

Participants

30 healthy first trimester pregnant women 18 to 40 years.

Excluded: hypertension, diabetes, known cardiopulmonary disease; orthopaedic problems or other conditions that would prevent regular physical activity.

InterventionsNutrition and exercise (20 interactive weekly sessions to promote daily exercise, vegetable and fruit intake, maintain a diet that is relatively lower in fat and rich in whole grains) vs standard medical care.
OutcomesAchieving 30 minutes of daily exercise, 4 or more times each week. Eating 5 or more servings of vegetables and/or fruits each day, pregnancy weight gain, fasting glucose, HbA1C, pregnancy weight gain, blood pressure, lipid and lipoprotein levels, pedometer records and more.
Starting date01/11/2012.
Contact informationLinn Goldberg MD, goldberl@ohsu.edu, Oregon Health and Science University.
Notes 

Graziano 2013

Trial name or titleWATE study - gestational weight gain and the electronic medical record.
Methods

RCT, parallel, open label.

Location: USA.

Participants

Estimated enrolment 300.

Pregnant women with a single intrauterine gestation.

Excluded multiple gestation pregnancy.

InterventionsWeight alerts (electronic medical record popup/highlight in their chart, displaying the weight gain, patient perception, recommended guidelines for weight gain in pregnancy) vs usual display, with no flag nor highlight.
OutcomesWeight gain, primary outcome will be measured as the percent of patients who achieve their recommended weight gain goal in pregnancy.
Starting date01/10/2013.
Contact informationScott Graziano, MD MS, sgrazia@lumc.edu, Loyola University.
NotesEstimated primary completion date: October 2014 (final data collection date for primary outcome measure).

Hivert 2012

Trial name or titleIntervention to promote changes of healthy lifestyle (physical activity and nutrition) during gestation.
Methods

RCT, parallel, open label.

Location: Canada.

Participants

Estimated enrolm