Continuous cardiotocography (CTG) as a form of electronic fetal monitoring (EFM) for fetal assessment during labour

  • Review
  • Intervention

Authors

  • Zarko Alfirevic,

    Corresponding author
    1. The University of Liverpool, Department of Women's and Children's Health, Liverpool, UK
    • Zarko Alfirevic, Department of Women's and Children's Health, The University of Liverpool, First Floor, Liverpool Women's NHS Foundation Trust, Crown Street, Liverpool, L8 7SS, UK. zarko@liverpool.ac.uk.

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  • Declan Devane,

    1. National University of Ireland Galway, School of Nursing and Midwifery, Galway, Ireland
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  • Gillian ML Gyte

    1. The University of Liverpool, Cochrane Pregnancy and Childbirth Group, Department of Women's and Children's Health, Liverpool, UK
    Search for more papers by this author

Abstract

Background

Cardiotocography (known also as electronic fetal monitoring), records changes in the fetal heart rate and their temporal relationship to uterine contractions. The aim is to identify babies who may be short of oxygen (hypoxic), so additional assessments of fetal well-being may be used, or the baby delivered by caesarean section or instrumental vaginal birth.

Objectives

To evaluate the effectiveness of continuous cardiotocography during labour.

Search methods

We searched the Cochrane Pregnancy and Childbirth Group Trials Register (31 December 2012) and reference lists of retrieved studies.

Selection criteria

Randomised and quasi-randomised controlled trials involving a comparison of continuous cardiotocography (with and without fetal blood sampling) with (a) no fetal monitoring, (b) intermittent auscultation (c) intermittent cardiotocography.

Data collection and analysis

Two review authors independently assessed study eligibility, quality and extracted data from included studies.

Main results

Thirteen trials were included with over 37,000 women; only two were judged to be of high quality.

Compared with intermittent auscultation, continuous cardiotocography showed no significant improvement in overall perinatal death rate (risk ratio (RR) 0.86, 95% confidence interval (CI) 0.59 to 1.23, n = 33,513, 11 trials), but was associated with a halving of neonatal seizures (RR 0.50, 95% CI 0.31 to 0.80, n = 32,386, nine trials). There was no significant difference in cerebral palsy rates (RR 1.75, 95% CI 0.84 to 3.63, n = 13,252, two trials). There was a significant increase in caesarean sections associated with continuous cardiotocography (RR 1.63, 95% CI 1.29 to 2.07, n = 18,861, 11 trials). Women were also more likely to have an instrumental vaginal birth (RR 1.15, 95% CI 1.01 to 1.33, n = 18,615, 10 trials).

Data for subgroups of low-risk, high-risk, preterm pregnancies and high-quality trials were consistent with overall results. Access to fetal blood sampling did not appear to influence the difference in neonatal seizures nor any other prespecified outcome.

Authors' conclusions

Continuous cardiotocography during labour is associated with a reduction in neonatal seizures, but no significant differences in cerebral palsy, infant mortality or other standard measures of neonatal well-being. However, continuous cardiotocography was associated with an increase in caesarean sections and instrumental vaginal births. The challenge is how best to convey these results to women to enable them to make an informed choice without compromising the normality of labour.

Résumé scientifique

Le monitorage fœtal électronique (MFE) par cardiotocographie en continu (CTG) pour l'évaluation fœtale au cours du travail

Contexte

La cardiotocographie (connue aussi comme monitorage fœtal électronique), enregistre les changements de rythme cardiaque fœtal et leur relation temporelle avec les contractions utérines. L'objectif est d'identifier les bébés susceptibles de manque d'oxygène (hypoxie), de sorte que des évaluations supplémentaires du bien-être fœtal puissent être utilisées, ou que le bébé soit mis au monde par césarienne ou par accouchement vaginal instrumental.

Objectifs

Évaluer l'efficacité de la cardiotocographie en continu pendant le travail.

Stratégie de recherche documentaire

Nous avons effectué des recherches dans le registre des essais cliniques du groupe Cochrane sur la grossesse et l'accouchement (le 31 décembre 2012), ainsi que dans les références bibliographiques des études trouvées.

Critères de sélection

Des essais contrôlés randomisés et quasi-randomisés portant sur une comparaison de la cardiotocographie en continu (avec ou sans prélèvement de sang fœtal) avec (a) l'absence de monitorage fœtal, (b) l'auscultation intermittente ou (c) la cardiotocographie intermittente.

Recueil et analyse des données

Deux auteurs de la revue ont indépendamment évalué l'éligibilité, la qualité et extrait les données des études incluses.

Résultats principaux

Treize essais ont été inclus totalisant plus de 37 000 femmes, mais deux seulement ont été jugés de bonne qualité.

En comparaison avec l'auscultation intermittente, la cardiotocographie en continu n'avait montré aucune amélioration significative du taux global de mortalité périnatale (risque relatif (RR) 0,86 ; intervalle de confiance (IC) à 95 % 0,59 à 1,23 ; n = 33 513, 11 essais), mais était associée à une réduction de moitié des convulsions néonatales (RR 0,50 ; IC 95% 0,31 à 0,80 ; n = 32 386, neuf essais). Il n'y avait pas de différence significative dans les taux d'infirmité cérébrale (RR 1,75 ; IC 95% 0,84 à 3,63 ; n = 13 252, deux essais). La cardiotocographie en continu était associée à une augmentation significative du nombre de césariennes (RR 1,63 ; IC 95% 1,29 à 2,07 ; n = 18 861, 11 essais). Les femmes étaient également plus susceptibles d'avoir un accouchement vaginal instrumental (RR 1,15 ; IC 95% 1,01 à 1,33 ; n = 18 615, 10 essais).

Les données pour les sous-groupes de grossesses à faible risque, à haut risque et prématurées, ainsi que pour les essais de bonne qualité, étaient en cohérence avec les résultats globaux. L'accès au prélèvement de sang fœtal ne semblait pas avoir d'influence sur la différence dans les convulsions néonatales, ni sur aucun autre critère de résultat prédéterminé.

Conclusions des auteurs

La cardiotocographie en continu pendant le travail est associée à une réduction des convulsions néonatales, mais à aucune différence significative dans la paralysie cérébrale, la mortalité infantile ou d'autres mesures standard du bien-être néonatal. La cardiotocographie en continu était cependant associée à une augmentation des césariennes et des accouchements vaginaux instrumentaux. L'enjeu consiste à déterminer la meilleure façon de faire connaitre ces résultats aux femmes pour leur permettre de faire un choix éclairé sans compromettre la normalité du travail.

摘要

以連續性心律紀錄法(cardiotocography,簡稱CTG)(一種電子胎兒監測 [electronic fetal monitoring,簡稱EFM] 方法)監控分娩期間的胎兒狀況

背景

連續性心律紀錄法(又稱電子胎兒監測儀)紀錄胎兒心跳與子宮收縮的時間關係。目的在識別可能缺少氧氣的嬰兒,所以也可能用在其他評估胎兒狀態或剖腹產或使用器具協助的產道生產。

目的

評估於分娩期間使用連續性心律紀錄法的功效。

搜尋策略

我們搜尋Cochrane懷孕與生產小組之試驗登記系統(the Cochrane Pregnancy and Childbirth Group's Trials Register)(2012年12月31日),並從取得之試驗中搜尋參考文獻清單。

選擇標準

針對連續性心律紀錄法(有或無採集胎兒血液檢體)與(a)無胎兒檢測(b)間歇聽診(c)間歇性心律紀錄法比較隨機或準隨機對照試驗。

資料收集與分析

兩位回顧文獻作者獨立評估試驗是否符合納入條件及試驗品質,並從納入的試驗中擷取資料。

主要結果

我們納入13項試驗,總共超過37,000位女性受試者,僅兩項試驗是高品質試驗。

相較於間歇聽診,連續性心律紀錄法未顯著改善出生前後的整體死亡率(風險比[RR]為0.86,95% CI:0.59至1.23,n = 33,513,11項試驗),但可將新生兒的癲癇事件減半(RR為0.50,95% CI:0.31至0.80,n = 32,386,9項試驗),腦性麻痺的發生率則無顯著差異(RR為1.75,95% CI:0.84至3.63,n = 13,252,2項試驗)。使用連續性心律紀錄法時,剖腹產比率顯著增加(RR為1.63,95% CI:1.29至2.07,n = 18,861,11項試驗),女性受試者亦較可能接受使用輔助器具的產道生產(RR 1.15,95% CI:1.01至1.33,n = 18,615,10項試驗)。

低風險、高風險、早產與高品質試驗等子群的資料,皆與整體的結果一致。進行胎兒血液檢體採集未影響新生兒癲癇發生率的差異或任何其他預先指明的評估指標結果。

作者結論

分娩期間的連續性心律紀錄法可減少新生兒的癲癇事件,但是在腦性麻痺、嬰兒死亡率或新生兒健康的其他標準評估指標方面,則無顯著差異。不過,在使用連續性心律紀錄法時,會增加剖腹產與使用器具協助的產道生產。我們面對的挑戰為如何將這些結果傳達給婦女,讓她們能在充分知情的情形下做出選擇,以免對正常分娩造成不利影響。

Plain language summary

Comparing continuous electronic fetal monitoring in labour (cardiotocography, CTG) with intermittent listening (intermittent auscultation, IA)

Monitoring the baby's heartbeat is one way of checking babies' well-being in labour. By listening to, or recording the baby's heartbeat, it is hoped to identify babies who are becoming short of oxygen (hypoxic) and who may benefit from caesarean section or instrumental vaginal birth. A baby's heartbeat can be monitored intermittently by using a fetal Pinard stethoscope (special trumpet shaped device), or by a hand-held Doppler device. The heartbeat can also be checked continuously by using a CTG machine. This continuous CTG method is also called electronic fetal monitoring (EFM). It produces a paper recording of the baby's heart rate and mother's labour contractions. Whilst a continuous CTG gives a written record, it prevents women from moving during labour. This means that women may be unable to change positions freely or use a bath to help with comfort and control during labour. It also means that some resources tend to be focused on the needs to constantly interpret the CTG and not on the needs of a woman in labour.

This review included 13 trials involving over 37,000 women that compared continuous CTG monitoring with intermittent auscultation (listening). Most studies were not of high quality and the review is dominated by one large, well-conducted trial of almost 13,000 women who received one-to-one care throughout labour. In this trial, the membranes were ruptured artificially (amniotomy) as early as possible and oxytocin stimulation of contractions was used in about a quarter of the women.

Overall, there was no difference in the number of babies who died during or shortly after labour (about one in 300). Fits (neonatal seizures) in babies were rare (about one in 500 births), but they occurred significantly less often when continuous CTG was used to monitor the fetal heart rate. There was no difference in the incidence of cerebral palsy, however, other possible long-term effects have not been fully assessed and need further study. Continuous monitoring was associated with a significant increase in caesarean section and instrumental vaginal births. Both procedures are known to carry the risks for mothers although the specific adverse outcomes were not assessed in the included studies.

Résumé simplifié

Comparaison du monitorage fœtal électronique continu durant le travail (cardiotocographie, CTG) avec l'écoute intermittente (auscultation intermittente, AI)

La surveillance du rythme cardiaque du bébé durant le travail est une façon de vérifier que le bébé va bien. En écoutant ou en enregistrant les battements de cœur du bébé, on espère identifier les bébés qui commencent à manquer d'oxygène (hypoxie) et pour qui une césarienne ou un accouchement vaginal instrumental pourraient être bénéfiques. Le rythme cardiaque du bébé peut être contrôlé par intermittence à l'aide d'un stéthoscope fœtal Pinard (dispositif spécial en forme de trompette) ou d'un dispositif Doppler portatif. Le rythme cardiaque peut également être contrôlé en continu au moyen d'une machine de CTG. Cette méthode de CTG en continu est aussi appelée monitorage fœtal électronique (MFE). Elle produit un enregistrement sur papier de la fréquence cardiaque du bébé et des contractions de travail de la mère. La CTG en continu donne un compte rendu écrit, mais il empêche la femme de se déplacer pendant le travail. Cela signifie que les femmes risquent de ne pas être en mesure de changer librement de position ou d'utiliser un bain pour améliorer le confort et le contrôle pendant le travail. Cela signifie également que certaines ressources ont tendance à se concentrer sur la nécessité d'interpréter constamment la CTG et non sur les besoins de la femme en travail.

Cette revue a inclus 13 études (soit plus de 37 000 femmes) ayant comparé le monitorage par CTG en continu à l'auscultation intermittente (écoute). La plupart des études n'étaient pas de bonne qualité et la revue est dominée par un vaste essai bien mené sur près de 13 000 femmes qui avaient reçu des soins individuels pendant le travail. Dans cet essai, les membranes avaient été rompues artificiellement (amniotomie) le plus tôt possible et l'ocytocine avait été utilisée pour stimuler les contractions chez environ un quart des femmes.

Globalement, il n'y avait pas de différence dans le nombre de bébés morts pendant ou peu après l'accouchement (environ un sur 300). Les convulsions néonatales chez les bébés étaient rares (environ une pour 500 naissances), mais elles étaient significativement moins fréquentes lorsque la CTG en continu était utilisée pour surveiller le rythme cardiaque fœtal. Il n'y avait pas de différence dans l'incidence de la paralysie cérébrale, cependant, d'autres effets possibles à long terme n'ont pas été pleinement évalués et doivent encore être étudiés. La surveillance continue était associée à une augmentation significative des césariennes et des accouchements vaginaux instrumentaux. Les deux procédures sont connues pour comporter des risques pour les mères, mais les effets indésirables spécifiques n'avaient pas été évalués dans les études incluses.

Notes de traduction

Traduit par: French Cochrane Centre 8th November, 2013
Traduction financée par: Pour la France : Minist�re de la Sant�. Pour le Canada : Instituts de recherche en sant� du Canada, minist�re de la Sant� du Qu�bec, Fonds de recherche de Qu�bec-Sant� et Institut national d'excellence en sant� et en services sociaux.

淺顯易懂的口語結論

比較分娩期間使用連續性心律紀錄(CTG,有時也稱電子胎兒監測EFM)持續電子監測嬰兒心跳與間歇性聽診

監測嬰兒心跳是分娩期間檢查嬰兒是否健康的方式之一,希望能藉由聽取或紀錄嬰兒的心跳,確認即將缺氧的嬰兒以及可能需要剖腹產或使用器具協助產道生產的嬰兒。嬰兒的心跳可使用胎兒Pinard聽診器(特殊的喇叭形裝置)或手持式Doppler裝置進行間歇監測,亦可使用連續性心律紀錄(CTG)儀器連續檢查心跳。此連續性心律紀錄方法亦稱為電子胎兒監測(electronic fetal monitoring,簡稱EFM),可使用紙本紀錄嬰兒的心跳速率與母親的陣痛收縮,雖然連續性心律紀錄法(CTG)可提供書面紀錄,但是,會妨礙產婦分娩期間的移動,也就是說,產婦可能無法在分娩期間自由變換姿勢,或利用泡澡讓自己感覺舒服與擁有掌控感,此亦表示有些醫療資源通常僅著重於持續解讀CTG的需要,而非分娩中的產婦需求。

本文獻回顧納入了13項比較連續性CTG監測與間歇聽診的試驗(總計有超過37,000位女性受試者),大部分試驗皆非高品質試驗,本文獻回顧主要是根據一項大型且執行狀況佳的試驗,該試驗納入了將近13,000位在整體分娩期間接受一對一專人照護的女性受試者。在此項試驗中,皆會儘早以人工方式將羊膜刺破(羊膜穿破術),並有大約四分之一的產婦使用催產素(oxytocin)刺激收縮。

整體而言,在分娩期間或分娩後不久死亡的嬰兒人數無差異(每300人約1人),而新生兒癲癇極罕見(每500次生產約一人),但是使用連續性CTG監測胎兒心跳速率,還可再顯著減少癲癇,腦性麻痺的發生率無差異,不過尚未完全評估其他可能的長期作用,因此仍需要再進行進一步的研究。在進行持續性監測時,剖腹產與使用器具協助的產道生產會顯著增加,且已知這兩種程序會對母親造成風險,但是在納入的試驗中未針對特定的不良事件評估指標進行評估。

譯註

翻譯: East Asian Cochrane Alliance
翻譯補助: 台灣衛生福利部/台北醫學大學實證醫學研究中心

Резюме на простом языке

Сравнение непрерывного электронного мониторинга плода в родах (кардиотокография, КТГ) с периодическим прослушиванием сердцебиений плода (периодическая аускультация, ПА)

Мониторинг сердцебиений плода является одним из способов оценки его состояния в родах. Прослушивание сердцебиений или проведение электрокардиографии плода в родах позволяет выделить группу детей, которым недостаточно кислорода (состояние гипоксии), и случаи, когда целесообразно проведение Кесарева сечения или инструментального пособия при вагинальных родах. Сердцебиение плода можно контролировать с помощью стетоскопа по Пинарду (устройство в форме специальной трубы) или с помощью портативного (переносного) доплеровского устройства. Сердцебиения плода также можно контролировать непрерывно с помощью специального прибора – кардиотокографа (КТГ). Этот непрерывный метод также называют электронным мониторингом плода (ЭМП). Это устройство проводит запись на бумагу электокардиограммы плода и родовых схваток матери. Несмотря на то, что КТГ предоставляет письменные данные, он не позволяет женщинам двигаться во время родов. Это означает, что женщины не могут свободно изменить положение или использовать ванну, чтобы увеличить комфорт и контроль во время родов. Это также означает, что некоторые ресурсы, как правило, нацелены на необходимость постоянно интерпретировать КТГ, а не на потребности женщины в родах.

В обзор включены 13 исследований с участием более 37 000 женщин, у которых проводили сравнение метода непрерывного мониторинга КТГ с периодической аускультацией сердцебиений плода (слушанием ухом). Большинство исследований не были высокого качества, и обзор преимущественно основан на одном большом хорошо спланированном исследовании с участием почти 13000 женщин, которым предоставляли помощь один-на-один в течение всего периода родов. В этом исследовании, вскрытие плодного пузыря (амниотомия) было проведено как можно раньше, и около четверти женщин получили окситоцин для стимуляции сокращений матки.

В целом, не было различий по числу младенцев, которые умерли во время или вскоре после родов (около одного из 300). Развитие судорог у младенцев было редким явлением (примерно в одном случае на 500 родов), но они были значительно реже при использовании непрерывной КТГ для мониторинга частоты сердечных сокращений плода. Не было выявлено различия в частоте развития церебрального паралича, однако, другие возможные долгосрочные исходы не были полностью оценены и требуют дальнейшего изучения. Непрерывный мониторинг был ассоциирован со значительным увеличением частоты проведения Кесарева сечения и инструментального пособия при вагинальных родах. Обе процедуры, как известно, несут риски для матерей, но во включенных исследованиях конкретные неблагоприятные исходы оценены не были.

Заметки по переводу

Заметки по переводу: Перевод: Кораблева Анна Александровна. Редактирование: Зиганшина Лилия Евгеньевна. Координация проекта по переводу на русский язык: Казанский федеральный университет. По вопросам, связанным с этим переводом, пожалуйста, свяжитесь с нами по адресу: lezign@gmail.com

Summary of findings(Explanation)

Summary of findings for the main comparison. Continuous CTG versus intermittent auscultation for fetal assessment during labour
  1. 1 Limitations in design: Most of the pooled effect provided by studies “B” or “C” without a substantial proportion (i.e. < 40% (actual 33% weight) from studies “C”.
    2 95% confidence interval around the pooled or best estimate of effect includes both 1) no effect and 2) appreciable benefit favouring CTG.
    3 Limitations in design: Most of the pooled effect provided by studies “B” or “C” without a substantial proportion (i.e. < 40% (actual 5.2% weight) from studies “C”
    4 Limitations in design: Most of the pooled effect provided by studies “B” or “C” without a substantial proportion (i.e. < 40% (actual 0% weight) from studies “C”
    5 95% confidence interval around the pooled or best estimate of effect includes both 1) no effect and 2) appreciable benefit favouring IA.
    6 Limitations in design: Most of the pooled effect provided by studies “B” or “C” without a substantial proportion (i.e. < 40% (actual 20.9% weight) from studies “C”
    7 Severe heterogeneity (I² = 60% & Chi² P = 0.005)
    8 Limitations in design: Most of the pooled effect provided by studies “B” or “C” without a substantial proportion (i.e. < 40% (actual 17.3% weight) from studies “C”
    9 Severe heterogeneity (I² = 60% & Chi² P = 0.008)
    10 Limitations in design: Most of the pooled effect provided by studies “C” (i.e. > 40%, actual 56.4%)
    11 Severe heterogeneity (I² = 77% & Chi² P = 0.04)
    12 95% confidence interval around the pooled or best estimate of effect includes both 1) no effect and 2) appreciable benefit and appreciable harm.
    13 Limitations in design: Most of the pooled effect provided by studies “B” or “C” without a substantial proportion (i.e. < 40% (actual 0% weight) from studies “C”
    14 Severe heterogeneity (I² = 72% & Chi² P = 0.03)

Continuous CTG versus intermittent auscultation for fetal assessment during labour
Patient or population: Women undergoing fetal assessment during labour
Settings:
Intervention: Continuous CTG versus intermittent auscultation
OutcomesIllustrative comparative risks* (95% CI)Relative effect
(95% CI)
No of Participants
(studies)
Quality of the evidence
(GRADE)
Comments
Assumed riskCorresponding risk
Control Continuous CTG versus intermittent auscultation
Perinatal mortality (primary outcome) Study population RR 0.86
(0.59 to 1.24)
33513
(11 studies)
⊕⊕⊝⊝
low 1,2
 
3 per 1000 3 per 1000
(2 to 4)
Moderate
4 per 1000 3 per 1000
(2 to 5)
Neonatal seizures (primary outcome) Study population RR 0.5
(0.31 to 0.8)
32386
(9 studies)
⊕⊕⊕⊝
moderate 3
 
3 per 1000 1 per 1000
(1 to 2)
Moderate
4 per 1000 2 per 1000
(1 to 3)
Cerebral palsy (primary outcome) Study population RR 1.75
(0.84 to 3.63)
13252
(2 studies)
⊕⊕⊝⊝
low 4,5
 
3 per 1000 4 per 1000
(2 to 9)
Moderate
39 per 1000 68 per 1000
(33 to 142)
Caesarean section (primary outcome) Study population RR 1.63
(1.29 to 2.07)
18861
(11 studies)
⊕⊕⊝⊝
low 6,7
 
36 per 1000 59 per 1000
(47 to 75)
Moderate
66 per 1000 108 per 1000
(85 to 137)
Instrumental vaginal birth (primary outcome) Study population RR 1.15
(1.01 to 1.33)
18615
(10 studies)
⊕⊕⊝⊝
low 8,9
 
102 per 1000 118 per 1000
(103 to 136)
Moderate
222 per 1000 255 per 1000
(224 to 295)
Cord blood acidosis (primary outcome) Study population RR 0.92
(0.27 to 3.11)
2494
(2 studies)
⊕⊝⊝⊝
very low 10,11,12
 
24 per 1000 22 per 1000
(6 to 74)
Moderate
24 per 1000 22 per 1000
(6 to 75)
Any pharmacological analgesia (primary outcome) Study population RR 0.98
(0.88 to 1.09)
1677
(3 studies)
⊕⊕⊝⊝
low 13,14
 
754 per 1000 739 per 1000
(663 to 822)
Moderate
805 per 1000 789 per 1000
(708 to 877)
*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. 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; RR: Risk ratio;
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.

Background

The baby's heart beat was first thought to be heard in utero in the middle of the seventeenth or eighteenth century (Grant 1989a; Gibb 1992), but it was not until the early nineteenth century that de Kergeradee suggested that listening to the baby's heartbeat might be clinically useful (Grant 1989a). He proposed that it could be used to diagnose fetal life and multiple pregnancies, and wondered whether it would be possible to assess fetal compromise from variations in the fetal heart rate (FHR). Since then, various methods of listening to the fetal heart have been developed and introduced into maternity care (see Table 1), each with the aim of improving outcomes for babies and reducing the heartache for mothers and families when a baby dies or suffers long-term disability. Today, monitoring the fetal heart during labour, by one method or another, appears to have become a routine part of care during labour, although access to such care varies across the world.

Table 1. Methods of fetal heart rate monitoring
MethodDescription
Fetal stethoscope (Pinard) - for intermittent monitoring (IA)This is a trumpet-shaped device, which is placed on the mother's abdomen and the caregiver listens for the heart beat at the other end. This is a simple instrument of relatively low cost.
Hand-held Doppler ultrasound monitor - for intermittent monitoring (IA)The device is placed on the mother's abdomen with gel smeared on the underside of the ultrasound transducer. This allows the ultrasound beam to travel from the fetal heart to the transducer without interruption.
External cardiotocography - for continuous or intermittent monitoringThe fetal heart rate and the activity of the uterine muscle are detected by two transducers placed on the mother's abdomen (one above the fetal heart and the other at the fundus). Doppler ultrasound provides the information which is recorded on a paper strip known as a cardiotocograph (CTG).
Internal cardiotocography - for continuous monitoringAn electrode is placed directly on the baby's presenting part to detect the fetal ECG signal. Again the signals are recorded on a paper strip (CTG). This method can only be used if membranes (fore-waters) have ruptured either spontaneously or artificially.

Description of the condition

The incidence of neonatal morbidity and mortality varies around the world, although direct comparisons may be difficult because of varying definitions and classifications. Nevertheless, large differences are reported between high-income countries with average neonatal mortality rates (NMR) of four per 1000 live births) and low/middle-income countries with average NMRs of 33 per 1000 births) (Lawn 2005). Although the majority of perinatal morbidity and mortality may not be prevented by improved fetal monitoring in labour (Nelson 1996), failure in identifying abnormal FHR patterns and lack of appropriate actions are considered to be significant contributing factors (MCHRC 1997; MCHRC 1998; MCHRC 1999).

Description of the intervention

The baby's heart rate can be monitored either intermittently (at regular intervals during labour) or continuously (recording the baby's heart rate throughout labour, stopping only briefly, e.g. for visits to the toilet) as follows.

(1) Fetal stethoscope (Pinard) and hand-held Doppler

Intermittent monitoring can be undertaken either by listening to the baby's heart rate using a fetal stethoscope (Pinard), or with a hand-held Doppler ultrasound device, and by palpating the mother's uterine contractions by hand. This is known as 'intermittent auscultation'.

(2) Cardiotocograph (CTG)

The baby's heart rate and the mother's uterine contractions can be recorded electronically on a paper trace known as a cardiotocograph. This is done by using a Doppler ultrasound transducer to monitor the baby's heart rate and a pressure transducer to monitor uterine contractions, both of which are linked to a recording machine. This is known as external cardiotocography (external CTG). This is usually undertaken continuously in labour, although occasionally it is used intermittently (intermittent CTG). In most units, external CTG requires the mother to wear a belt across her abdomen while monitoring is being conducted, which restricts her mobility. An alternative means of monitoring the baby's heart rate with the CTG machine is to attach an electrode directly to the baby's presenting part, usually its head. This form of continuous monitoring is known as 'internal CTG' and requires a ruptured amniotic sac (either spontaneously or artificially) and a scalp electrode (clip) attached to the baby's head. This also restricts the woman's mobility.

The term 'electronic fetal monitoring' (EFM) is sometimes used synonymously with CTG monitoring, but is considered to be a less precise term because (1) CTG monitoring also includes monitoring the mother's contractions, and (2) other forms of fetal monitoring might also be classed as 'electronic', e.g. fetal ECG, fetal pulse oximetry.

Intermittent auscultation was the predominant method of monitoring during labour until CTGs became widely used in the latter part of the twentieth century (Enkin 2000). Although there is a lack of empirical evidence on the optimal frequency of intermittent auscultation, there is a consensus in the guidelines from professional bodies that the fetal heart should be auscultated at least every 15 minutes in the first stage of labour and at least every five minutes in the second stage of labour (ACOG 1995; Liston 2002; NCCWCH 2008; RANZCOG 2002) with each auscultation lasting at least 60 seconds (Liston 2002; NCCWCH 2008). It appears that these auscultation protocols were developed initially in the context of clinical trials and were based on 'common sense' rather than research evidence. Compliance with these guidelines, whilst maintaining contemporaneous records, poses a significant challenge for caregivers during labour who usually have multiple tasks to fulfil simultaneously.

Information and interpretation

Both intermittent auscultation and CTG provide information on the baseline heart rate (usually between 110 and 160 beats per minute in the term fetus), accelerations (transient increases in the FHR) and decelerations (transient decreases in the FHR). It is known that some aspects of labour will cause natural alterations in FHR patterns. For example, the baby's sleep FHR pattern is different from the FHR pattern when the baby is awake. External stimuli, like uterine contractions and the mother moving, can cause FHR changes, as can the administration of opiates to the mother. Some of these changes are subtle and can only be detected by continuous CTG, e.g. baseline variability, temporal shape of decelerations. Consideration needs to be given to whether such information improves detection and outcome of those babies who are truly compromised and if there are disadvantages with the technology for those who are not compromised.

Sensitivity and specificity

While specific abnormalities of the FHR pattern on CTG are proposed as being associated with an increased risk of cerebral palsy (Nelson 1996), the specificity of CTG for prediction of cerebral palsy is low with a reported false positive rate as high as 99.8%, even in the presence of multiple late decelerations or decreased variability (Nelson 1996).

FHR pattern recognition, including the relationship between the uterine contractions and FHR decelerations, are fundamental to the use of continuous CTG monitoring. Algorithms have been developed to assess and record what is normal, what requires more careful attention and what is considered abnormal requiring immediate delivery of the baby (NCCWCH 2008). However, CTG traces are often interpreted differently by different caregivers (inter-observer variation) and even by the same caregiver interpreting the same record at different times (intra-observer variation) (Devane 2005). Such variation in interpretation of CTG tracings may result in inappropriate interventions, or false reassurance and lack of appropriate intervention. Although we were unable to locate studies that sought to investigate inter- and intra-observer variation in intermittent auscultation, it would seem reasonable to suggest that intermittent auscultation is not immune to similar problems caused by inter- and intra-observer variation. However, given that the FHR parameter of interest in intermittent auscultation is the baseline FHR, it is likely that inter- and intra-observer variation is less in intermittent auscultation than that found in CTG interpretation where other aspects of FHR patterns including variability and assessment and deceleration classification require interpretation.

Additional tests

Fetal blood sampling is a procedure whereby a small amount of blood is taken from the baby, usually from the scalp. Performing fetal blood sampling and then measuring the parameters of acid-base balance (pH, base excess/deficit, etc) seeks to identify those babies who are truly compromised and need to be born immediately from those who are not truly compromised. It is important to establish the value of this test as an adjunct to CTG. This question is addressed by a subgroup analysis in this review.

Other methods have been considered as additional tests, but there is little evidence to support their use, for example, vibroacoustic stimulation (East 2013). Several other methods of fetal monitoring have been proposed, either as an adjunct or an alternative to CTG, e.g. pulse oximetry (Carbone 1997; East 2007), near-infrared spectroscopy (Mozurkewich 2000), fetal ECG (Neilson 2012), ST segment analysis of the fetal ECG (Luttkus 2004) and fetal stimulation tests (Skupski 2002).

Possible advantages of CTG

  • More measurable parameters related to FHR patterns (see above).

  • The CTG trace gives a continuous recording of the FHR and uterine activity. This is a physical record, which can be examined at anytime in labour, or subsequently if required. The examples where physical records may be useful include clinical audits, counselling parents if there has been as adverse outcome, and medico-legal situations.

Possible disadvantages of CTG

  • The complexity of FHR patterns makes standardisation difficult.

  • CTG prevents mobility and restricts the use of massage, different positions and/or immersion in water used to improve comfort, control and coping strategies during labour.

  • Shifting staff focus and resources away from the mother may encourage a belief that all perinatal mortality and neurological injury can be prevented.

Specific situations that may influence the effectiveness or otherwise of CTG

  1. Continuous CTG is generally recommended for women who are regarded as being at increased risk of perinatal morbidity and mortality (Liston 2002; NCCWCH 2008; RANZCOG 2002). This review addresses the issue of differential effects of CTG in terms of risk status.

  2. Induction of labour is primarily performed where it is anticipated that the outcome for the mother and/or infant would be improved were labour to be induced. Given that induction of labour includes iatrogenic stimulation of uterine activity, which puts the baby at greater risk, we determined to perform a subgroup analysis by induction of labour (RCOG 2001b).

  3. Preterm birth is associated with an increased risk of mortality and neurological morbidity and these babies might benefit from being monitored more intensively. Further, there is debate about what is normal for the different parameters of the CTG for preterm infants at varying gestational ages. Therefore, we performed a preterm subgroup analysis.

  4. Twin pregnancies carry a higher perinatal mortality rate than singleton pregnancies (RCOG 2001b), thus we conducted a subgroup analysis by twin pregnancy.

Women's and professional views

Some studies looking at women's preferences found that the support that women received from staff and labour companions was more important to them than the type of monitoring used (Garcia 1985; Killien 1989). A more recent study of women's views of routine continuous CTG in labour in the UK identified a lack of discussion about the need for, and appropriateness of CTG. In addition, women felt that CTG limited their mobility and led to an acceptance of the machine's place as the focus of attention for the women and her partner (Munro 2004).

In a synthesis of 11 studies on professionals’ views of monitoring the FHR during labour, Smith 2012 identified that, despite an absence of evidence, maternity care professionals perceive the CTG as offering 'proof' of the compromised baby and that this minimises their exposure to criticism and potential litigation. Nevertheless, professionals also recognised that the CTG offered a false sense of security.

How the intervention might work

Through monitoring FHR changes during labour, it is hoped to identify those babies who may be compromised, or potentially compromised, by a shortage of oxygen (fetal hypoxia). If the shortage of oxygen is both prolonged and severe, babies are at risk of being born with a disability (physical and/or mental), or of dying during labour or shortly thereafter. When alterations in the FHR during labour suggest that the baby is hypoxic, or at risk of hypoxia, additional methods of assessment of fetal well-being (e.g. fetal blood sampling) may be used. Sometimes FHR alterations trigger delivery by caesarean section or by an instrument such as forceps or vacuum extractor even without recourse to additional diagnostic tests.

Why it is important to do this review

Concerns have been raised about the efficacy and safety of routine use of continuous CTG in labour (Thacker 1995). The apparent contradiction between the widespread use of continuous CTG with claims of its effectiveness in lowering early neonatal mortality and morbidity (Chen 2011) and recommendations to limit its routine use on all women (NCCWCH 2008), indicates that a regular reassessment of this practice is warranted.

Several other Cochrane reviews have addressed other methods for assessing the condition of the fetus during labour including fetal electrocardiogram/ECG (Neilson 2012); fetal pulse oximetry (East 2007); near-infrared spectroscopy (Mozurkewich 2000) and vibroacoustic stimulation (East 2013). Also, the comparison of cardiotocography versus intermittent auscultation of fetal heart as an admission test on arrival to labour ward is assessed elsewhere (Devane 2012).

Objectives

The objective of this review is to evaluate the effectiveness and safety of continuous cardiotocography (CTG) when used as a method to monitor fetal well-being during labour.

Methods

Criteria for considering studies for this review

Types of studies

All randomised trials and quasi-randomised studies comparing continuous CTG during labour, with and without fetal blood sampling, with (a) no fetal monitoring, (b) intermittent auscultation of the fetal heart rate with a Pinard stethoscope or hand-held Doppler ultrasound device, or (c) intermittent CTG. Sensitivity analysis was undertaken for studies graded as low risk of bias based on sequence generation and allocation concealment. .

Types of participants

Pregnant women in labour and their babies.

Types of interventions

The main intervention of interest is continuous CTG during labour.

For the purpose of this review, the intervention is defined as an attempt to produce a continuous and simultaneous hard-copy recording of the fetal heart rate and uterine contractions in real-time throughout the woman's labour. As a guide, continuous CTG should be discontinued only for short periods (for example, visits to the toilet) and the CTG should be used for clinical decision making during labour.

Control groups of interest include: (a) no fetal monitoring, (b) intermittent auscultation of the fetal heart rate with a Pinard stethoscope or hand-held Doppler ultrasound device, or (c) intermittent CTG.

Types of outcome measures

Primary outcomes
  1. Perinatal mortality;

  2. seizures in the neonatal period, either apparent clinically or detected by electro-encephalographic recordings;

  3. cerebral palsy;

  4. caesarean section;

  5. instrumental vaginal birth;

  6. cord blood acidosis (low pH/low base excess as defined by trialists; where report included a range of pH values we have used cord pH less than 7.10 as a cut off for acidosis);

  7. use of all forms of pharmacological analgesia during labour and birth (including epidural but excluding anaesthesia for caesarean section).

Secondary outcomes
  1. Hypoxic ischaemic encephalopathy (as defined by trialists);

  2. neurodevelopmental disability assessed at 12 months of age or more. Neurodevelopmental disability, defined as any one or combination of the following: non-ambulant cerebral palsy, developmental delay, auditory and visual impairment. Development should have been assessed by means of a previously validated tool, such as Bayley Scales of Infant Development (Psychomotor Developmental Index and Mental Developmental Index (Bayley 1993);

  3. Apgar less than seven at five minutes;

  4. Apgar less than four at five minutes;

  5. admission to neonatal special care and/or intensive care unit;

  6. fetal blood sampling;

  7. damage/infection to baby's head from scalp electrode or fetal blood sampling;

  8. caesarean section for abnormal fetal heart rate pattern and/or fetal acidosis;

  9. instrumental vaginal birth for abnormal fetal heart rate pattern and/or fetal acidosis;

  10. spontaneous vaginal birth not achieved;

  11. epidural analgesia;

  12. use of non pharmacological methods of coping with labour, e.g. transcutaneous electrical nerve stimulation, hydrotherapy;

  13. amniotomy (artificial rupture of membranes);

  14. oxytocin during labour;

  15. perineal trauma requiring repair (including episiotomy);

  16. inability to adopt preferred position during labour;

  17. dissatisfaction with labour and/or perceived loss of control during labour;

  18. postpartum depression;

  19. exclusively breastfeeding at discharge from hospital;

  20. length of stay in neonatal special care and/or intensive care unit.

Search methods for identification of studies

Electronic searches

We searched the Cochrane Pregnancy and Childbirth Group’s Trials Register by contacting the Trials Search Co-ordinator (31 December 2012). 

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;

  3. weekly searches of EMBASE;

  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.  

For details of additional author searches carried out for the 2006 update of this review, please see Appendix 1. We chose not to repeat these additional searches for the update as they yielded no additional studies in the original search.

Searching other resources

We searched the reference lists of retrieved studies.

We did not apply any language restrictions.

Data collection and analysis

For all included studies in this review we have used the methodology described by Higgins 2011. In previous versions of the review, we used the Cochrane methodology current at the time, with Higgins 2008 being used in the 2008 version and Higgins 2005 being used in the 2006 version, see Appendix 2, (Alfirevic 2006).

Selection of studies

Two review authors independently assessed for inclusion all the potential studies we identified as a result of the search strategy. We resolved any disagreement through discussion or, if required, we consulted the third author.

Data extraction and management

We designed a form to extract data. At least two review authors extracted the data using the agreed form. We resolved discrepancies through discussion or, if required, we consulted the third author. Data were entered into Review Manager software (RevMan 2012) and checked for accuracy.

When information regarding any of the above was unclear, we attempted to contact the authors of the original reports to provide further details.

Assessment of risk of bias in included studies

Two review authors independently assessed risk of bias for each included 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 the third author.

(1) Sequence generation (checking for possible selection bias)

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

We assessed the methods as:

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

  • high risk of bias (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 the allocation sequence in sufficient detail and determine 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 (e.g. open random allocation; unsealed or non-opaque envelopes; alternation; date of birth);

  • unclear risk of bias.   

(3.1) Blinding (checking for possible performance bias)

We described, for each included study, all the methods used, if any, to blind study participants and personnel from knowledge of which intervention a participant received. We have also provided any information relating to whether the intended blinding was effective. We noted where there has been partial blinding (e.g. where it has not been possible to blind participants but where outcome assessment was carried out without knowledge of group assignment). Where blinding was not possible, we assessed whether the lack of blinding was likely to have introduced bias.

We assessed the methods as:

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

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

  • low, high or unclear risk of bias for outcome assessors.

The study was judged to be ‘low risk’ when there was blinding, or where, in our judgement, the outcome or the outcome measurement was not likely to have been influenced by lack of blinding.

(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 considered that studies were at low risk of bias if they were blinded, or if we judged that the lack of blinding could not have affected the results.

We assessed the methods as:· 

  • low risk (no blinding of outcome assessment but the authors judged that the outcome was not likely to be influenced by this); 

  • high risk (no blinding of outcome assessment and the outcome measurement was likely to have been influenced by this);

  • unclear risk (insufficient information to permit judgment; the study did not address this).

(4) Incomplete outcome data (checking for possible attrition bias through withdrawals, dropouts, protocol deviations)

We described for each included study the completeness of outcome data for each main outcome, including attrition and exclusions from the analysis. We stated whether attrition and exclusions were reported, the numbers included in the analysis at each stage (compared with the total randomised participants), reasons for attrition or exclusion where reported, and any re-inclusions in analyses which we undertook.

We assessed the methods as:

  • low risk (e.g. where there were no missing data or where reasons for missing data are balanced across groups);

  • high risk (e.g. where missing data are likely to be related to outcomes or are not balanced across groups, or where high levels of missing data are likely to introduce serious bias or make the interpretation of results difficult);

  • unclear risk of bias (e.g. where there is insufficient reporting of attrition or exclusions to permit a judgement to be made).

(5) Selective reporting bias

We described for each included study how the possibility of selective outcome reporting bias was examined by us 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 sources of bias

We described for each included study any important concerns we have about other possible sources of bias. For example, was there a potential source of bias related to the specific study design? Was the trial stopped early due to some data-dependent process? Was there extreme baseline imbalance? Has the study been claimed to be fraudulent?

We assessed whether each study was free of other problems that could put it at risk of bias:

  • low risk of bias;

  • high risk of bias;

  • unclear risk of bias.

(7) Overall risk of bias

We made explicit judgements about risk of bias for important outcomes both within and across studies. With reference to (1) to (6) above, we assessed the likely magnitude and direction of the bias and whether we considered it was 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 the results as risk ratio (RR) with 95% confidence intervals (95% CI). 

Continuous data

For continuous data, we presented the results as mean difference (MD) with 95% CI. When pooling data across studies we estimated the MD if the outcomes were measured in the same way between trials. We planned to use standardised mean difference to combine trials that measured the same outcome, but used different methods.

Unit of analysis issues

Cluster-randomised trials

We have not identified any cluster trials as yet, and do not anticipate any cluster-randomised trials on this topic. However, should we find any, we will include them using the guidance in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011).

Dealing with missing data

We noted the levels of attrition for included studies. We explored, using sensitivity analysis, the impact of including studies with high levels of missing data in the overall assessment of treatment effect.

Intention-to-treat analysis (ITT)

For all outcomes, we analysed the data, as far as possible, on an intention-to-treat basis, i.e. 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 are known to be missing ('available case' analysis).

We analysed data on all participants with available data in the group to which they are allocated, regardless of whether or not they received the allocated intervention. If in the original reports participants were not analysed in the group to which they were randomised, and there was sufficient information in the trial report, we attempted to restore them to the correct group. 

Assessment of heterogeneity

We assessed statistical heterogeneity in each meta-analysis using the T², I² and Chi² statistics. We regarded heterogeneity as substantial if I² is greater than 50% and either T² is greater than zero, or there is a low P value (less than 0.10) in the Chi² test for heterogeneity. 

Assessment of reporting biases

We investigated reporting biases (such as publication bias) using funnel plots for outcomes with 10 or more studies in the meta-analysis. We assessed funnel plot asymmetry visually. If asymmetry was suggested by a visual assessment, we planned to perform exploratory analyses to investigate it.

Data synthesis

We only synthesised data where we thought it was appropriate, i.e. where trials were examining similar interventions, with similar populations and methods. We used a fixed-effect meta-analysis for combining data. However, where there was clinical or methodological heterogeneity between studies sufficient to suggest that treatment effects might differ between trials, we used random-effects meta-analysis.

Subgroup analysis and investigation of heterogeneity

We carried out the following subgroup analyses:

  1. high risk for perinatal mortality and morbidity (as defined by trialists) versus low risk (absence of identifiable risk factors associated with increased in perinatal mortality and morbidity as defined by trialists);

  2. spontaneous onset of labour versus induction of labour;

  3. preterm (less than 37 + 0 weeks) versus term (greater than 37 + 0 weeks);

  4. singleton pregnancy versus twin pregnancy;

  5. access to fetal blood sampling (FBS) during labour versus no access to FBS during labour;

  6. primiparous versus multiparous.

The review’s primary outcomes were used in subgroup analyses.

We assessed subgroup differences by interaction tests available within RevMan (RevMan 2012). We reported the results of subgroup analyses quoting the χ2 statistic and P values, and the interaction test I² value. We assumed a P value of more than 0.05 indicative that subgroup results are no different from the overall effect. If a P value was less than 0.05 we did not automatically assume that the intervention has a different effect, but planned to interpret the findings in the clinical context and in the context of plausibility.

Sensitivity analysis

We carried out sensitivity analyses to explore the effect of trial quality for the primary outcomes in the review. Where there was risk of bias associated with a particular aspect of study quality (e.g. inadequate allocation concealment), this was explored by sensitivity analyses.

Results

Description of studies

Results of the search

Our search strategy identified 383 citations corresponding to 17 studies for potential inclusion. Of those, 13 studies with 37,715 women participating were included (Athens 1993; Copenhagen 1985; Dallas 1986; Denver 1976; Denver 1979; Dublin 1985; Lund 1994; Melbourne 1976; Melbourne 1981; New Delhi 2006; Pakistan 1989; Seattle 1987; Sheffield 1978) and four were excluded (Harare 1994; Ioannina 2001; Manchester 1982; North America 2000).

Included studies

Twelve studies, with 33,681 women participating, compared continuous CTG with intermittent auscultation (Athens 1993; Copenhagen 1985; Dallas 1986; Denver 1976; Denver 1979; Dublin 1985; Melbourne 1976; Melbourne 1981; New Delhi 2006; Pakistan 1989; Seattle 1987; Sheffield 1978). Five studies compared continuous CTG plus fetal blood sampling versus intermittent auscultation (Copenhagen 1985; Dublin 1985; Melbourne 1976; Pakistan 1989; Seattle 1987), six compared continuous CTG without fetal blood sampling versus intermittent auscultation (Athens 1993; Dallas 1986; Denver 1976; Melbourne 1981; New Delhi 2006; Sheffield 1978) and one study had three groups comparing continuous CTG with and without fetal blood sampling versus intermittent auscultation (Denver 1979). One study compared continuous CTG with fetal blood sampling versus intermittent CTG with fetal blood sampling (Lund 1994).

Participants were assessed as being at low risk of complications in three studies (Dallas 1986; Lund 1994; Melbourne 1981) and outcome data for women at low risk were available for one outcome, neonatal seizures, from one other study (Dublin 1985). Participants were assessed as being at high risk of complications in six studies (Denver 1976; Denver 1979; Melbourne 1976; New Delhi 2006; Pakistan 1989; Seattle 1987) including one study that specifically included women in preterm labour (28 to 32 weeks) and assessed outcomes for babies below 1750 g birthweight (Seattle 1987). The data for neonatal seizures in women at high risk of complications were available from one other study (Dublin 1985). Participants were assessed as mixed risk (mixture of women at high risk and low risk of complications) in four studies (Athens 1993; Copenhagen 1985; Dublin 1985; Sheffield 1978).

Five studies had overall caesarean section rates below 10% (Athens 1993; Copenhagen 1985; Dublin 1985; Melbourne 1981; Sheffield 1978). The highest overall caesarean section rates were reported in Pakistan 1989 (23.5%) and New Delhi 2006 (28%).

Excluded studies

Four studies were excluded (see Characteristics of excluded studies).

Risk of bias in included studies

Included studies were assessed for methodological quality on the basis of selection (sequence generation and allocation concealment) and attrition bias (see 'Methods of the review' above) (Figure 1).

Figure 1.

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

Allocation

Allocation concealment was graded as 'low risk of bias' in three trials (Dublin 1985; Lund 1994; Melbourne 1976), as 'unclear risk of bias' in six trials (Copenhagen 1985; Denver 1976; Denver 1979; New Delhi 2006; Seattle 1987; Sheffield 1978), and as 'high risk of bias' in four trials (Athens 1993; Dallas 1986; Melbourne 1981; Pakistan 1989).

Blinding

Blinding of participants and personnel was assessed as 'high risk of bias' in all 13 studies. Blinding of outcome assessment was assessed as 'unclear risk of bias' in all but one study where it was assessed as 'high risk of bias' (Athens 1993).

Incomplete outcome data

Attrition bias was graded as 'low risk of bias' in eight trials (Athens 1993; Copenhagen 1985; Denver 1976; Denver 1979; Dublin 1985; Lund 1994; New Delhi 2006; Pakistan 1989), as unclear risk of bias in three trials (Dallas 1986; Melbourne 1976; ; Sheffield 1978), as high risk of bias in two trials (Melbourne 1981; Seattle 1987).

Selective reporting

This was assessed as 'unclear risk of bias' in all 13 studies as we did not have access to any of the trial protocols.

Other potential sources of bias

All 13 studies were considered at low risk for other potential sources of bias.

Effects of interventions

See: Summary of findings for the main comparison Continuous CTG versus intermittent auscultation for fetal assessment during labour

Continuous cardiotocography (CTG) versus intermittent auscultation (IA) (Comaprisons 1-8)

A total of 12 randomised trials were included in this comparison with over 33,000 women participating (Athens 1993; Copenhagen 1985; Dallas 1986; Denver 1976; Denver 1979; Dublin 1985; Melbourne 1976; Melbourne 1981; New Delhi 2006; Pakistan 1989; Seattle 1987; Sheffield 1978). Denver 1979 was a three-arm trial comparing continuous CTG alone, versus continuous CTG plus FBS versus intermittent auscultation.

Primary outcomes
For the infant

There was no significant difference in perinatal mortality between the groups. Risk ratio (RR) was 0.86 with, 95% confidence intervals (CIs) ranging from 0.59 to 1.24, n = 33,513, 11 trials, (Analysis 1.1). The funnel plot analysis indicated no missing studies (Figure 2). The quality of the evidence for this outcome was assessed as moderate (Summary of findings table 1).

Figure 2.

Funnel plot of comparison: 1 Continuous CTG versus intermittent auscultation, outcome: 1.1 Perinatal mortality (primary outcome).

The use of continuous CTG monitoring in labour halved the risk of neonatal seizures (RR 0.50, 95% CI 0.31 to 0.80, n = 32,386, nine trials (Analysis 1.2). The funnel plot indicated no missing studies (Figure 3) and the quality of the evidence was assessed as moderate (Summary of findings table 1). This reduction was consistent across the trials and subgroups, although the incidence of neonatal seizures varied considerably between trials. In the two largest trials of 14,618 women (Dallas 1986) and 12,964 women (Dublin 1985), the incidence of neonatal seizures in the intermittent auscultation groups was 0.04% and 0.4% respectively (Analysis 1.2). In the two trials of high quality reporting data for this outcome (Dublin 1985; Melbourne 1976), the risk of neonatal seizures was RR 0.40, 95% CI 0.21 to 0.77 (Analysis 8.2).

Figure 3.

Funnel plot of comparison: 1 Continuous CTG versus intermittent auscultation, outcome: 1.2 Neonatal seizures (primary outcome).

There was no difference in the incidence of cerebral palsy (average RR 1.75, 95% CI 0.84 to 3.63, n = 13,252, two trials, random-effects, (Analysis 1.3). The quality of the evidence was assessed as moderate (Summary of findings table 1). The data on cerebral palsy are heavily influenced by one small trial (Seattle 1987) that randomised only very preterm babies (less than 32 weeks) and assessed outcomes for 173 babies of birthweight less than 1750 g with a cerebral palsy rate of 19.5% in the CTG group compared with 7.7% in the controls (RR 2.54, 95% CI 1.10 to 5.86). The other trial in this comparison (Dublin 1985) showed no significant difference in the incidence of cerebral palsy (RR 1.20, 95% CI 0.52 to 2.79, n = 13,079) with a cerebral palsy rate of 0.18% in the continuously CTG group and 0.15% in the intermittently monitored group.

There was no difference in the incidence of cord blood acidosis between the groups (Analysis 1.6). The quality of the evidence was assessed as very low, mainly due to severe heterogeneity and limitation in design of many of the included studies (Summary of findings table 1).

For the mother

There was a significant increase in the caesarean section rate in the CTG group (average RR 1.63, 95% CI 1.29 to 2.07, 18,861, 11 trials, (Analysis 1.4). However, the quality of this evidence was assessed as low, mainly due to severe heterogeneity and limitation in design of many of the included studies (Summary of findings table 1). Risk difference in the caesarean section rate was 5% (95% CI 2 to 8%), with two-thirds of the data coming from Dublin 1985, where the overall caesarean section rate was 2.3%. In addition, the funnel plot indicated the possibility of missing studies (Figure 4). It appears that the risk of having a caesarean section was not influenced by the quality of trials (Analysis 8.4, interaction test P = 0.31).

Figure 4.

Funnel plot of comparison: 1 Continuous CTG versus intermittent auscultation, outcome: 1.4 Caesarean section (primary outcome).

Although numbers needed to treat to benefit or harm (NNTB/NNTH) analyses remain controversial in the context of meta-analysis and should be interpreted with caution, we have calculated that there will be one additional caesarean section for every 44 women monitored continuously (95% CI 26 to 96). This calculation is based on the pooled caesarean section rate of 3.6% (337/9313) in the IA group from this meta-analysis. However, in most settings caesarean section rates are likely to be much higher. Assuming a caesarean section rate with intermittent auscultation of around 15%, there would be an additional CS for every 11 women monitored (95% CI 7 to 23).

Continuous CTG was also associated with an increase in instrumental vaginal birth (Analysis 1.5). The funnel plot indicated that some studies might be missing (Figure 5). The quality of this evidence was assessed as low, mainly due to severe heterogeneity and limitation in design of many of the included studies (Summary of findings table 1). There was no difference identified in the use of any pharmacological analgesia (Analysis 1.7), with the quality of the evidence assessed as low (Summary of findings table 1).

Figure 5.

Funnel plot of comparison: 1 Continuous CTG versus intermittent auscultation, outcome: 1.5 Instrumental vaginal birth (primary outcome).

Secondary outcomes
For the infant

There was no evidence of any other benefit or harm for the babies in terms of hypoxic Ischaemic encephalopathy (Analysis 1.8), Apgar scores (Analysis 1.10), or admission to neonatal intensive care unit (Analysis 1.12).

For the mother

Women in the continuous CTG group were more likely to have a caesarean section for abnormal fetal heart rate and/or acidosis (Analysis 1.15) and less likely to have a spontaneous vaginal birth, Analysis 1.17).There was no difference in the use of epidural analgesia (Analysis 1.18). The use of fetal blood sampling was reported in two trials (Copenhagen 1985; Dublin 1985) with significantly more sampling tests performed in the continuous CTG group (Analysis 1.13). There were no reported data suitable for analysis for the use of non-pharmacological methods for coping with labour, amniotomy, perineal trauma, inability to adopt preferred position in labour, dissatisfaction in labour and postpartum depression.

Overall findings

Notwithstanding the caution regarding NNTB/NNTH calculations, when the risk of neonatal seizures is around 3 per 1,000, 667 women have to be continuously monitored during labour to prevent one such seizure (95% CI 484 to 1667). There is an opposite effect on caesarean section. Assuming a 3.6% caesarean section rate with IA, there would be 15 more caesarean sections in this cohort associated with preventing one neonatal seizure. However, if caesarean section with IA is higher (15%), 61 extra caesarean sections would be associated with preventing one neonatal seizure.

Continuous CTG versus IA (Subgroup: pregnancy risk status - high/low/unclear or both - Comparison 2)

Of the 12 studies that compared continuous CTG with intermittent auscultation, six included women at increased risk of complications (Denver 1976; Denver 1979; Melbourne 1976; New Delhi 2006; Pakistan 1989; Seattle 1987), three included women at low risk of complications (Dallas 1986; Melbourne 1981; Sheffield 1978) and three studies included both groups of women or did not specify (Athens 1993; Copenhagen 1985; Dublin 1985). There was a significant difference in the impact of CTG monitoring on caesarean section rate depending on the risk status of women (P = 0.004; I2 = 81.6%), although the heterogeneity can be attributed to the group with combined risk rather than to the subgroups where the risk was clearly defined. There were no other statistically significant differences between the subgroups for any other primary outcomes.

Subgroups analysis by onset of labour (spontaneous/induced/unclear or both - Comparison 3)

None of the included trials provided separate data for spontaneous and induced labours. Hence, there is no information to determine if there might be a difference in the impact of CTG for women in spontaneous labour compared with those with induction of labour.

Subgroup analysis by gestational age (preterm/term/unclear or both - Comparison 4)

Of the 12 studies that compared continuous CTG with intermittent auscultation, one included only preterm labours (Seattle 1987). Three studies included only term labours (Copenhagen 1985; Melbourne 1981; Sheffield 1978) and eight studies included both or did not specify (Athens 1993; Dallas 1986; Denver 1979; Denver 1979; Dublin 1985; Melbourne 1976; New Delhi 2006; Pakistan 1989). We found no evidence of a difference between the subgroups.

Subgroup analysis by number of babies being monitored (singleton/twin pregnancy/unclear or both - Comparison 5)

Eight studies included only singleton pregnancies (Athens 1993; Dallas 1986; Denver 1976; Melbourne 1981; New Delhi 2006; Pakistan 1989; Seattle 1987; Sheffield 1978) and four included both singleton and twin pregnancies or did not specify (Copenhagen 1985; Denver 1979; Dublin 1985; Melbourne 1976). There was a significant subgroup effect for the rate of neonatal acidosis (P = 0.04; I2 = 77%) with more acidosis in CTG monitored singletons and less in CTG monitored twins. There was also a subgroup difference in the use of pharmacological analgesia (P = 0.02; I2 = 83%), but the data were only available for singletons and mixed group with no data for twins only. There were no subgroup difference for the other primary outcome.

Subgroup analysis by access to fetal blood sampling (FBS) during labour (Comparison 6)

Six studies offered FBS alongside the CTG (Copenhagen 1985; Dublin 1985; Melbourne 1976; Melbourne 1981; Pakistan 1989; Seattle 1987), five studies did not use FBS (Athens 1993; Dallas 1986; Denver 1976; New Delhi 2006; Sheffield 1978) and one study randomised to three groups, CTG with FBS, CTG alone and IA (Denver 1979).

There was a significant subgroup effect on instrumental vaginal birth with apparently more instrumental deliveries (P = 0.04; I2 = 77%), but less neonatal acidosis (P = 0.04; I2 = 76.5%), in the FBS subgroup. However, there were no subgroup differences for the other primary outcomes.

Subgroups by parity (primiparous/multiparous women/unclear or both - Comparison 7)

None of the studies included only primiparous women, one study included only multiparous women (New Delhi 2006) and 11 studies included both primiparous and multiparous women (Athens 1993; Copenhagen 1985; Dallas 1986; Denver 1976; Denver 1979; Dublin 1985; Melbourne 1976; Melbourne 1981; Pakistan 1989; Seattle 1987; Sheffield 1978). As only one of these studies reported results based on the parity of the women involved, so it was no possible to perform a meaningful subgroup analysis.

Continuous CTG versus IA (Subgroup: high/low/unclear quality of studies - Comparison 8)

Of the 12 studies that compared continuous CTG with intermittent auscultation, two were considered to be of high methodological quality (Dublin 1985; Melbourne 1976), four studies where considered to be of low methodological quality (Athens 1993; Dallas 1986; Melbourne 1981; Pakistan 1989) and for six studies the methodological quality was unclear (Copenhagen 1985; Denver 1976; Denver 1979; New Delhi 2006; Seattle 1987; Sheffield 1978). It appears that in a high-quality trial, there was less neonatal acidosis compared with low-quality trials (P = 0.04; I2 = 76.5%). There was a significant subgroup heterogeneity for instrumental vaginal birth (P = 0.007; I2 = 79.9%), but no clear difference between high- and low-risk subgroups. We found no other subgroups differences for the other primary outcomes.

Continuous CTG versus intermittent CTG (Comparison 9)

Lund 1994 involved 4044 high-risk pregnant women and found no significant differences in any of the eight outcomes specified in this meta-analysis.

Discussion

Summary of main results

The main reason for the introduction of continuous intrapartum cardiotocography (CTG) monitoring in clinical practice was a belief that it would reduce rare but devastating outcomes - perinatal death and neonatal hypoxic brain injury in otherwise healthy babies. However, this review found no statistically significant difference in perinatal deaths between pregnancies monitored during labour with continuous CTG compared to those monitored those intermittent auscultation. The overall quality of evidence that underpins this conclusion has been judged as 'moderate' (Summary of findings table 1). It does, however, seem unrealistic to expect that any intrapartum intervention in modern maternity care will result in a statistically significant improvement in perinatal deaths. In order for a trial to test a realistic hypothesis that continuous CTG can prevent one death in one thousand births (0.1%), more than 50,000 women would have to be randomised. It is, therefore, more logical to concentrate on short- and long-term childhood morbidity. Unfortunately, very few clinically relevant neonatal outcomes have been reported consistently in all trials.

For decades, low Apgar scores have been used as a surrogate measure for birth asphyxia and subsequent adverse neurodevelopmental outcomes. Recent evidence has confirmed a strong association between low Apgar score and cerebral palsy in both low and normal birthweight infants (Lie 2010). This review found no evidence that use of continuous intrapartum CTG monitoring has an impact on Apgar score. However, there were very few babies with clinically significant low Apgar scores in studies that assessed this outcome. Therefore, potentially important differences between the two groups cannot be ruled out.

Hypoxic ischaemic encephalopathy, a more robust measure of hypoxic brain injury, was only reported in one study (Athens 1993). In the absence of any meaningful long-term follow-up data, the impact of continuous CTG monitoring on a neonate can only be evaluated based on the data from two clinically important outcomes, i.e. neonatal seizures and cerebral palsy.

For both neonatal seizures and cerebral palsy, the majority of data are provided by Dublin 1985. At first glance, the data appear contradictory. There is a significant reduction in neonatal seizures in the continuous CTG group, but no impact on cerebral palsy. If anything, the rates of cerebral palsy appear to be higher in the continuous CTG group, although the pooled result did not reach statistical significance. This apparent increase in cerebral palsy in children monitored by CTG comes from Seattle 1987. However, the results from this study, the only study of CTG monitoring during preterm labour, are not statistically significant using 99% confidence intervals. In addition, this study excluded infants with a birthweight of more than 1750 grams (34% of randomised cohort) which may be a source of bias. Given that all other outcomes in this trial, including caesarean section rates, neonatal seizures and deaths were almost identical this may have been a chance finding and should be interpreted with caution.

It is now generally accepted that cerebral palsy is more often caused by antepartum, rather than intrapartum, events (Palmer 1995). It may, therefore, be unrealistic to expect that intrapartum interventions will have the capacity to achieve a significant reduction in cerebral palsy. There are, clearly, some cases of cerebral palsy that are a direct consequence of intrapartum hypoxic injury. These cases are very rare, and even systematic reviews of randomised trials are unlikely to have sufficient power to test intrapartum CTG as a method to reduce cerebral palsy caused by acute and avoidable intrapartum events.

The reduction in seizures associated with continuous CTG monitoring is important, but has to be interpreted cautiously in the absence of good quality long-term follow-up data. It has been suggested that seizures may be a "sentinel event" of a peripartum adversity that does not necessarily always manifest itself as hypoxic encephalopathy (Dennis 1978; Derham 1985, Keegan 1985; Lien 1995; Spellacy 1985). When asphyxia, infection, brain malformations and metabolic causes are excluded, some neonatal seizures are associated with cerebral infarction or neonatal stroke (Estan 1997; Lien 1995). Although the underlying causes are not well understood, neonatal seizures may have long-term consequences other than cerebral palsy. One longitudinal study found that some babies who had neonatal seizures were classified as normal at five years and had normal overall intelligence in adolescence as assessed by IQ tests, but had some abnormal results on detailed neuropsychological testing (Temple 1995). Clearly, there is a need for comprehensive long-term follow-up of the randomised cohorts that is not limited to extreme adverse outcomes such as cerebral palsy, but also includes more subtle neuropsychological assessment.

The results of this review demonstrate that continuous CTG monitoring leads to an increase in caesarean sections. Such an effect of continuous CTG is clinically plausible as CTG monitoring leads to more interventions (e.g. fetal blood sampling, amniotomy) and more diagnoses of presumed fetal compromise for which emergency caesarean section is seen as the only safe management option. However, the overall quality of evidence for this outcome was judged as 'low' (Summary of findings table 1) and, therefore, the observed increase has to be interpreted cautiously. It is noteworthy that size and direction of the effect on caesarean section was consistent for pre-specified subgroups, including high quality trials and trials where clinicians had access to intrapartum fetal blood sampling. Subgroup interaction test was only significant (I2 = 81.6%) for studies in low-risk, high-risk and mixed-risk status, but the heterogeneity comes from a mixed group. The impact of CTG monitoring on caesarean section in low-risk and high-risk populations appears to be virtually identical, which is contrary to recommendations from many professional bodies providing guidance on intrapartum fetal monitoring.

There was some evidence that labour was more painful in the continuous CTG group, but the statistically significant increase in the 'need for any analgesia' included general anaesthesia. It is, therefore, likely that this difference was caused by an increase in the number of caesarean sections, rather than necessarily more painful labour. Women do report more pain when lying on their backs during labour. At the times when the studies in this review were undertaken (between 1976 and 1994), women in the intermittent auscultation group may well also have been on their backs and not using mobility and positions to help them with their labours. There were no data from the trials included in the review to allow any analysis of this potential confounder.

We have prespecified several subgroups that could have been expected to influence the direction and size of the differences compared with results when all trials are considered together. We were conscious that any differences between subgroups and overall results would have to be interpreted with extreme caution (Rothwell 2005). With this proviso, we found no subgroup differences of clinical importance, but the number of trials and women in subgroups was relatively small.

Overall completeness and applicability of evidence

Clearly, the lack of long-term follow-up data and inadequate reporting of the data according to the clinically important subgroups is regrettable and limits the applicability of the evidence.

Quality of the evidence

The overall quality of the evidence can be best described as low to moderate and has been summarised in the Summary of findings table 1.

Potential biases in the review process

Our selection of outcomes in general and primary outcomes in particular might have been influenced by our knowledge of the published literature and the first Cochrane review on this topic (Thacker 2001).

Agreements and disagreements with other studies or reviews

Some large cohort studies suggest much more profound benefit on neonatal morbidity and mortality (Chen 2011). Some observational data also suggest the benefit of fetal blood sampling during labour in cases of suboptimal CTG, (Stein 2006) but we found no evidence that the increase in caesarean section rate was greater if fetal blood sampling was unavailable; nor did access to fetal blood sampling influence the difference in neonatal seizures or any other prespecified outcome.

Authors' conclusions

Implications for practice

Translating the evidence from this review into clinical practice poses significant challenges. One would hope that the quality of CTG equipment, interpretation and training have improved over the years making the external validity of much of the data included in this review questionable. In most studies included in this review, intermittent auscultation was carried out according to the strict protocols in a hospital setting with quick recourse to continuous monitoring and intervention if required. In some trials, most notably the Dublin trial (Dublin 1985), intact fetal membranes were ruptured at the earliest opportunity to confirm absence of meconium and women were provided with one-to-one care from a midwife. This monitoring package differs significantly from practices in some modern birth settings (including, for example, stand alone midwifery units) where artificial rupture of membranes is avoided as long as possible and where mobilisation and normality are promoted. In addition, one-to-one care by a midwife, or a nurse-midwife, seems hard to implement in many healthcare settings and is likely to be an important contributory factor for effectiveness (or lack of it) of both types of fetal heart rate monitoring.

With this proviso, women should be informed that continuous CTG during labour is associated with a reduction in the incidence of neonatal seizures, has no obvious impact on cerebral palsy or perinatal mortality but is associated with an increase in the incidence of caesarean section and instrumental vaginal births. The adverse affects of operative births are well described albeit that longer term morbidity data are less available than shorter term morbidity data. The possible long-term effects of preventable neonatal seizures remain unknown. Women also need to be informed of the loss of mobility associated with the use of continuous CTG in labour.

Women, practitioners and policy makers should consider carefully the absence of evidence that continuous CTG monitoring has a different impact on caesareans section and neonatal seizures in low- and high-risk populations and that there is an absence of evidence from trials included in this review of a beneficial effect for fetal blood sampling.

The risk benefit debate will continue to focus on caesarean section and neonatal seizures. Given the perceived conflict between the risk for the mother (increased caesarean section and instrumental vaginal delivery rate) and benefit for the baby (decreased incidence of neonatal seizures), it is difficult to make quality judgments as to which effect is more important. The issue of effectiveness is particularly important. CTG advocates will continue to argue that lack of clear long-term benefit for the child is not proof that intermittent auscultation is safe. However, it would seem reasonable to base clinical decisions on the evidence we currently have rather than on unknown risks of unknown quantity. Obviously, the risk-benefit assessment will vary between individuals, policy makers and healthcare settings. The real challenge is how best to convey this uncertainty to women and help them to make an informed choice without compromising the normality of labour.

Implications for research

The question remains as to whether future randomised trials should measure efficacy (the intrinsic value of continuous CTG in trying to prevent adverse neonatal outcomes under optimal clinical conditions) or effectiveness (the effect of this technique in routine clinical practice).

Along with the need for further investigations into the long-term effects of operative births for women and babies, much remains to be learned about the causation and possible links between antenatal or intrapartum events, neonatal seizures and long-term neurodevelopmental outcome, bearing in mind the changes in clinical practice over the intervening years (one-to-one-support during labour, caesarean section rates). The large number of babies randomised in this review will now have reached adulthood, and could potentially provide us with a unique opportunity to clarify if a reduction in neonatal seizures is something inconsequential that should not greatly influence women's and clinicians' choices, or if seizure reduction leads to long-term benefits for babies. Defining meaningful neurological and behavioural outcomes that could be measured in large cohorts of young adults poses huge challenges.

Data should also be collected from this cohort of women and babies, whilst the medical records still exist, to describe, where possible, the women's mobility and positions during labour and birth, to clarify if these might impact on outcomes. Research should also address the possible contribution of the supine position to adverse outcomes for the baby, and address the question of whether the use of mobility and positions can reduce the already low incidence of neonatal seizures and improve psychological outcomes for women.

Acknowledgements

The review authors would like to acknowledge the support of Mrs Sonja Henderson, Review Group Co-ordinator, and Ms Lynn Hampson, Review Group Trials Search Co-ordinator, in the preparation of this review. We wish to acknowledge the contribution from Mark Turner, Neonatologist from The University of Liverpool, for contributing to the discussion on the importance of adverse neonatal outcomes.

We acknowledge S Thacker, D Stroup and M Chang, who prepared the first version of this Cochrane review under the tItle 'Continuous electronic heart rate monitoring for fetal assessment during labor' (Thacker 2001).

The National Institute for Health Research (NIHR) is the largest single funder of the Cochrane Pregnancy and Childbirth Group. The views and opinions expressed therein are those of the authors and do not necessarily reflect those of the NIHR, NHS or the Department of Health.

Data and analyses

Download statistical data

Comparison 1. Continuous CTG versus intermittent auscultation
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Perinatal mortality (primary outcome)1133513Risk Ratio (M-H, Fixed, 95% CI)0.86 [0.59, 1.24]
2 Neonatal seizures (primary outcome)932386Risk Ratio (M-H, Fixed, 95% CI)0.50 [0.31, 0.80]
3 Cerebral palsy (primary outcome)213252Risk Ratio (M-H, Random, 95% CI)1.75 [0.84, 3.63]
4 Caesarean section (primary outcome)1118861Risk Ratio (M-H, Random, 95% CI)1.63 [1.29, 2.07]
5 Instrumental vaginal birth (primary outcome)1018615Risk Ratio (M-H, Random, 95% CI)1.15 [1.01, 1.33]
6 Cord blood acidosis (primary outcome)22494Risk Ratio (M-H, Random, 95% CI)0.92 [0.27, 3.11]
7 Any pharmacological analgesia (primary outcome)31677Risk Ratio (M-H, Random, 95% CI)0.98 [0.88, 1.09]
8 Hypoxic ischaemic encephalopathy11428Risk Ratio (M-H, Fixed, 95% CI)0.46 [0.04, 5.03]
9 Neurodevelopmental disability at at least 12 months of age1173Risk Ratio (M-H, Fixed, 95% CI)3.88 [0.83, 18.17]
10 Apgar score < 7 at 5 minutes64137Risk Ratio (M-H, Fixed, 95% CI)0.95 [0.71, 1.27]
11 Apgar score < 4 at 5 minutes31919Risk Ratio (M-H, Fixed, 95% CI)1.80 [0.71, 4.59]
12 Neonatal ICU admissions1033167Risk Ratio (M-H, Random, 95% CI)1.01 [0.86, 1.18]
13 Fetal blood sampling213929Risk Ratio (M-H, Fixed, 95% CI)1.24 [1.05, 1.47]
14 Damage/infection from scalp electrode or scalp sampling1200Risk Ratio (M-H, Fixed, 95% CI)3.0 [0.12, 72.77]
15 Caesarean section for abnormal FHR pattern and/or acidosis1133379Risk Ratio (M-H, Fixed, 95% CI)2.38 [1.89, 3.01]
16 Instrumental vaginal birth for abnormal CTG or fetal acidosis112964Risk Ratio (M-H, Fixed, 95% CI)2.54 [1.95, 3.31]
17 Spontaneous vaginal birth1118861Risk Ratio (M-H, Random, 95% CI)0.91 [0.86, 0.96]
18 Epidural analgesia817630Risk Ratio (M-H, Fixed, 95% CI)1.00 [0.90, 1.12]
19 Use of non pharmacological methods of coping with labour00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
20 Amniotomy00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
21 Oxytocin during 1st and/or 2nd stage of labour53683Risk Ratio (M-H, Random, 95% CI)1.08 [0.86, 1.37]
22 Perineal trauma needing repair00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
23 Inability to adopt preferred position in labour00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
24 Dissatisifaction with labour and/or perceived loss of control00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
25 Postpartum depression00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
26 Exclusive breastfeeding at discharge00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
27 Length of stay on NICU1206Mean Difference (IV, Fixed, 95% CI)0.20 [-1.17, 1.57]
Analysis 1.1.

Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 1 Perinatal mortality (primary outcome).

Analysis 1.2.

Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 2 Neonatal seizures (primary outcome).

Analysis 1.3.

Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 3 Cerebral palsy (primary outcome).

Analysis 1.4.

Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 4 Caesarean section (primary outcome).

Analysis 1.5.

Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 5 Instrumental vaginal birth (primary outcome).

Analysis 1.6.

Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 6 Cord blood acidosis (primary outcome).

Analysis 1.7.

Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 7 Any pharmacological analgesia (primary outcome).

Analysis 1.8.

Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 8 Hypoxic ischaemic encephalopathy.

Analysis 1.9.

Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 9 Neurodevelopmental disability at at least 12 months of age.

Analysis 1.10.

Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 10 Apgar score < 7 at 5 minutes.

Analysis 1.11.

Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 11 Apgar score < 4 at 5 minutes.

Analysis 1.12.

Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 12 Neonatal ICU admissions.

Analysis 1.13.

Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 13 Fetal blood sampling.

Analysis 1.14.

Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 14 Damage/infection from scalp electrode or scalp sampling.

Analysis 1.15.

Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 15 Caesarean section for abnormal FHR pattern and/or acidosis.

Analysis 1.16.

Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 16 Instrumental vaginal birth for abnormal CTG or fetal acidosis.

Analysis 1.17.

Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 17 Spontaneous vaginal birth.

Analysis 1.18.

Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 18 Epidural analgesia.

Analysis 1.21.

Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 21 Oxytocin during 1st and/or 2nd stage of labour.

Analysis 1.27.

Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 27 Length of stay on NICU.

Comparison 2. Continuous CTG versus IA (pregnancy risk status - high/low)
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Perinatal mortality1133513Risk Ratio (M-H, Fixed, 95% CI)0.86 [0.59, 1.24]
1.1 High risk51974Risk Ratio (M-H, Fixed, 95% CI)1.04 [0.62, 1.74]
1.2 Low risk316049Risk Ratio (M-H, Fixed, 95% CI)0.87 [0.29, 2.58]
1.3 Risk status - mixed or not specified315490Risk Ratio (M-H, Fixed, 95% CI)0.68 [0.38, 1.24]
2 Neonatal seizures932386Risk Ratio (M-H, Fixed, 95% CI)0.50 [0.31, 0.80]
2.1 High risk54805Risk Ratio (M-H, Fixed, 95% CI)0.67 [0.36, 1.24]
2.2 Low risk325175Risk Ratio (M-H, Fixed, 95% CI)0.36 [0.16, 0.79]
2.3 Risk status - mixed or not specified22406Risk Ratio (M-H, Fixed, 95% CI)0.18 [0.01, 3.80]
3 Cerebral palsy213252Risk Ratio (M-H, Fixed, 95% CI)1.74 [0.97, 3.11]
3.1 High risk1173Risk Ratio (M-H, Fixed, 95% CI)2.54 [1.10, 5.86]
3.2 Low risk00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
3.3 Risk status - mixed or not specified113079Risk Ratio (M-H, Fixed, 95% CI)1.20 [0.52, 2.79]
4 Caesarean section1118861Risk Ratio (M-H, Random, 95% CI)1.63 [1.29, 2.07]
4.1 High risk62069Risk Ratio (M-H, Random, 95% CI)1.91 [1.39, 2.61]
4.2 Low risk21431Risk Ratio (M-H, Random, 95% CI)2.06 [1.24, 3.45]
4.3 Risk status - mixed or not specified315361Risk Ratio (M-H, Random, 95% CI)1.14 [0.95, 1.36]
5 Instrumental vaginal birth1018615Risk Ratio (M-H, Random, 95% CI)1.15 [1.01, 1.33]
5.1 High risk51823Risk Ratio (M-H, Random, 95% CI)1.02 [0.82, 1.27]
5.2 Low risk21431Risk Ratio (M-H, Random, 95% CI)1.09 [0.77, 1.54]
5.3 Risk status - mixed or not specified315361Risk Ratio (M-H, Random, 95% CI)1.33 [1.20, 1.49]
6 Cord blood acidosis22494Risk Ratio (M-H, Fixed, 95% CI)1.16 [0.72, 1.89]
6.1 High risk00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
6.2 Low risk00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
6.3 Risk status - mixed or not specified22494Risk Ratio (M-H, Fixed, 95% CI)1.16 [0.72, 1.89]
7 Any pharmacological analgesia31677Risk Ratio (M-H, Fixed, 95% CI)0.99 [0.93, 1.04]
7.1 High risk21173Risk Ratio (M-H, Fixed, 95% CI)1.01 [0.96, 1.06]
7.2 Low risk1504Risk Ratio (M-H, Fixed, 95% CI)0.92 [0.79, 1.07]
7.3 Risk status - mixed or not specified00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
Analysis 2.1.

Comparison 2 Continuous CTG versus IA (pregnancy risk status - high/low), Outcome 1 Perinatal mortality.

Analysis 2.2.

Comparison 2 Continuous CTG versus IA (pregnancy risk status - high/low), Outcome 2 Neonatal seizures.

Analysis 2.3.

Comparison 2 Continuous CTG versus IA (pregnancy risk status - high/low), Outcome 3 Cerebral palsy.

Analysis 2.4.

Comparison 2 Continuous CTG versus IA (pregnancy risk status - high/low), Outcome 4 Caesarean section.

Analysis 2.5.

Comparison 2 Continuous CTG versus IA (pregnancy risk status - high/low), Outcome 5 Instrumental vaginal birth.

Analysis 2.6.

Comparison 2 Continuous CTG versus IA (pregnancy risk status - high/low), Outcome 6 Cord blood acidosis.

Analysis 2.7.

Comparison 2 Continuous CTG versus IA (pregnancy risk status - high/low), Outcome 7 Any pharmacological analgesia.

Comparison 3. Continuous CTG versus IA (onset of labour - spontaneous/induced)
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Perinatal mortality1133513Risk Ratio (M-H, Fixed, 95% CI)0.86 [0.59, 1.24]
1.1 Spontaneous labour00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
1.2 Induction of labour00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
1.3 Onset of labour - not specified1133513Risk Ratio (M-H, Fixed, 95% CI)0.86 [0.59, 1.24]
2 Neonatal seizures932386Risk Ratio (M-H, Fixed, 95% CI)0.50 [0.31, 0.80]
2.1 Spontaneous labour00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
2.2 Induction of labour00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
2.3 Onset of labour - not specified932386Risk Ratio (M-H, Fixed, 95% CI)0.50 [0.31, 0.80]
3 Cerebral palsy213252Risk Ratio (M-H, Fixed, 95% CI)1.74 [0.97, 3.11]
3.1 Spontaneous labour00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
3.2 Induction of labour00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
3.3 Onset of labour - not specified213252Risk Ratio (M-H, Fixed, 95% CI)1.74 [0.97, 3.11]
4 Caesarean section1118861Risk Ratio (M-H, Fixed, 95% CI)1.43 [1.25, 1.64]
4.1 Spontaneous labour00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
4.2 Induction of labour00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
4.3 Onset of labour - not specified1118861Risk Ratio (M-H, Fixed, 95% CI)1.43 [1.25, 1.64]
5 Instrumental vaginal birth1018615Risk Ratio (M-H, Fixed, 95% CI)1.21 [1.12, 1.31]
5.1 Spontaneous labour00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
5.2 Induction of labour00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
5.3 Onset of labour - not specified1018615Risk Ratio (M-H, Fixed, 95% CI)1.21 [1.12, 1.31]
6 Cord blood acidosis22494Risk Ratio (M-H, Fixed, 95% CI)1.16 [0.72, 1.89]
6.1 Spontaneous labour00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
6.2 Induction of labour00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
6.3 Onset of labour - not specified22494Risk Ratio (M-H, Fixed, 95% CI)1.16 [0.72, 1.89]
7 Any pharmacological analgesia31677Risk Ratio (M-H, Fixed, 95% CI)0.99 [0.93, 1.04]
7.1 Spontaneous labour00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
7.2 Induction of labour00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
7.3 Onset of labour - not specified31677Risk Ratio (M-H, Fixed, 95% CI)0.99 [0.93, 1.04]
Analysis 3.1.

Comparison 3 Continuous CTG versus IA (onset of labour - spontaneous/induced), Outcome 1 Perinatal mortality.

Analysis 3.2.

Comparison 3 Continuous CTG versus IA (onset of labour - spontaneous/induced), Outcome 2 Neonatal seizures.

Analysis 3.3.

Comparison 3 Continuous CTG versus IA (onset of labour - spontaneous/induced), Outcome 3 Cerebral palsy.

Analysis 3.4.

Comparison 3 Continuous CTG versus IA (onset of labour - spontaneous/induced), Outcome 4 Caesarean section.

Analysis 3.5.

Comparison 3 Continuous CTG versus IA (onset of labour - spontaneous/induced), Outcome 5 Instrumental vaginal birth.

Analysis 3.6.

Comparison 3 Continuous CTG versus IA (onset of labour - spontaneous/induced), Outcome 6 Cord blood acidosis.

Analysis 3.7.

Comparison 3 Continuous CTG versus IA (onset of labour - spontaneous/induced), Outcome 7 Any pharmacological analgesia.

Comparison 4. Continuous CTG versus IA (preterm/term labour)
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Perinatal mortality1133513Risk Ratio (M-H, Fixed, 95% CI)0.86 [0.59, 1.24]
1.1 Preterm labour1246Risk Ratio (M-H, Fixed, 95% CI)0.96 [0.52, 1.77]
1.2 Term labour32409Risk Ratio (M-H, Fixed, 95% CI)0.82 [0.22, 3.03]
1.3 Both or gestation not specified730858Risk Ratio (M-H, Fixed, 95% CI)0.81 [0.50, 1.32]
2 Neonatal seizures932386Risk Ratio (M-H, Fixed, 95% CI)0.50 [0.31, 0.80]
2.1 Preterm labour1246Risk Ratio (M-H, Fixed, 95% CI)1.02 [0.37, 2.81]
2.2 Term labour21482Risk Ratio (M-H, Fixed, 95% CI)0.33 [0.01, 8.08]
2.3 Both or gestation not specified630658Risk Ratio (M-H, Fixed, 95% CI)0.42 [0.24, 0.72]
3 Cerebral palsy213252Risk Ratio (M-H, Fixed, 95% CI)1.74 [0.97, 3.11]
3.1 Preterm labour1173Risk Ratio (M-H, Fixed, 95% CI)2.54 [1.10, 5.86]
3.2 Term labour00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
3.3 Both or gestation not specified113079Risk Ratio (M-H, Fixed, 95% CI)1.20 [0.52, 2.79]
4 Caesarean section1118861Risk Ratio (M-H, Fixed, 95% CI)1.43 [1.25, 1.64]
4.1 Preterm labour1246Risk Ratio (M-H, Fixed, 95% CI)1.02 [0.57, 1.82]
4.2 Term labour32400Risk Ratio (M-H, Fixed, 95% CI)1.84 [1.25, 2.69]
4.3 Both or gestation not specified716215Risk Ratio (M-H, Fixed, 95% CI)1.41 [1.21, 1.63]
5 Instrumental vaginal birth1018615Risk Ratio (M-H, Fixed, 95% CI)1.21 [1.12, 1.31]
5.1 Preterm labour00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
5.2 Term labour32400Risk Ratio (M-H, Fixed, 95% CI)1.18 [1.01, 1.37]
5.3 Both or gestation not specified716215Risk Ratio (M-H, Fixed, 95% CI)1.22 [1.11, 1.34]
6 Cord blood acidosis22494Risk Ratio (M-H, Fixed, 95% CI)1.16 [0.72, 1.89]
6.1 Preterm labour00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
6.2 Term labour00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
6.3 Both or gestation not specified22494Risk Ratio (M-H, Fixed, 95% CI)1.16 [0.72, 1.89]
7 Any pharmacological analgesia31677Risk Ratio (M-H, Fixed, 95% CI)0.99 [0.93, 1.04]
7.1 Preterm labour00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
7.2 Term labour1504Risk Ratio (M-H, Fixed, 95% CI)0.92 [0.79, 1.07]
7.3 Both or gestation not specified21173Risk Ratio (M-H, Fixed, 95% CI)1.01 [0.96, 1.06]
Analysis 4.1.

Comparison 4 Continuous CTG versus IA (preterm/term labour), Outcome 1 Perinatal mortality.

Analysis 4.2.

Comparison 4 Continuous CTG versus IA (preterm/term labour), Outcome 2 Neonatal seizures.

Analysis 4.3.

Comparison 4 Continuous CTG versus IA (preterm/term labour), Outcome 3 Cerebral palsy.

Analysis 4.4.

Comparison 4 Continuous CTG versus IA (preterm/term labour), Outcome 4 Caesarean section.

Analysis 4.5.

Comparison 4 Continuous CTG versus IA (preterm/term labour), Outcome 5 Instrumental vaginal birth.

Analysis 4.6.

Comparison 4 Continuous CTG versus IA (preterm/term labour), Outcome 6 Cord blood acidosis.

Analysis 4.7.

Comparison 4 Continuous CTG versus IA (preterm/term labour), Outcome 7 Any pharmacological analgesia.

Comparison 5. Continuous CTG versus IA (singleton/twin pregnancy)
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Perinatal mortality1133513Risk Ratio (M-H, Fixed, 95% CI)0.86 [0.59, 1.24]
1.1 Singleton718406Risk Ratio (M-H, Fixed, 95% CI)0.77 [0.49, 1.21]
1.2 Twins00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
1.3 Both or singleton/twins not specified415107Risk Ratio (M-H, Fixed, 95% CI)1.04 [0.55, 1.97]
2 Neonatal seizures932386Risk Ratio (M-H, Fixed, 95% CI)0.50 [0.31, 0.80]
2.1 Singleton517279Risk Ratio (M-H, Fixed, 95% CI)0.69 [0.32, 1.46]
2.2 Twins00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
2.3 Both or singleton/twins not specified415107Risk Ratio (M-H, Fixed, 95% CI)0.41 [0.22, 0.76]
3 Cerebral palsy213252Risk Ratio (M-H, Fixed, 95% CI)1.74 [0.97, 3.11]
3.1 Singleton1173Risk Ratio (M-H, Fixed, 95% CI)2.54 [1.10, 5.86]
3.2 Twins00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
3.3 Both or singleton/twins not specified113079Risk Ratio (M-H, Fixed, 95% CI)1.20 [0.52, 2.79]
4 Caesarean section1118861Risk Ratio (M-H, Fixed, 95% CI)1.43 [1.25, 1.64]
4.1 Singleton73888Risk Ratio (M-H, Fixed, 95% CI)1.58 [1.30, 1.93]
4.2 Twins00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
4.3 Both or singleton/twins not specified414973Risk Ratio (M-H, Fixed, 95% CI)1.33 [1.11, 1.59]
5 Instrumental vaginal birth1018615Risk Ratio (M-H, Fixed, 95% CI)1.21 [1.12, 1.31]
5.1 Singleton63642Risk Ratio (M-H, Fixed, 95% CI)1.13 [1.00, 1.28]
5.2 Twins00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
5.3 Both or singleton/twins not specified414973Risk Ratio (M-H, Fixed, 95% CI)1.25 [1.13, 1.38]
6 Cord blood acidosis22494Risk Ratio (M-H, Fixed, 95% CI)1.16 [0.72, 1.89]
6.1 Singleton11419Risk Ratio (M-H, Fixed, 95% CI)1.58 [0.89, 2.81]
6.2 Twins00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
6.3 Both or singleton/twins not specified11075Risk Ratio (M-H, Fixed, 95% CI)0.45 [0.16, 1.29]
7 Any pharmacological analgesia31677Risk Ratio (M-H, Fixed, 95% CI)0.99 [0.93, 1.04]
7.1 Singleton2987Risk Ratio (M-H, Fixed, 95% CI)0.93 [0.86, 1.01]
7.2 Twins00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
7.3 Both or singleton/twins not specified1690Risk Ratio (M-H, Fixed, 95% CI)1.06 [1.00, 1.12]
Analysis 5.1.

Comparison 5 Continuous CTG versus IA (singleton/twin pregnancy), Outcome 1 Perinatal mortality.

Analysis 5.2.

Comparison 5 Continuous CTG versus IA (singleton/twin pregnancy), Outcome 2 Neonatal seizures.

Analysis 5.3.

Comparison 5 Continuous CTG versus IA (singleton/twin pregnancy), Outcome 3 Cerebral palsy.

Analysis 5.4.

Comparison 5 Continuous CTG versus IA (singleton/twin pregnancy), Outcome 4 Caesarean section.

Analysis 5.5.

Comparison 5 Continuous CTG versus IA (singleton/twin pregnancy), Outcome 5 Instrumental vaginal birth.

Analysis 5.6.

Comparison 5 Continuous CTG versus IA (singleton/twin pregnancy), Outcome 6 Cord blood acidosis.

Analysis 5.7.

Comparison 5 Continuous CTG versus IA (singleton/twin pregnancy), Outcome 7 Any pharmacological analgesia.

Comparison 6. Continuous CTG versus IA (access to FBS during labour - yes/no)
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Perinatal mortality1133513Risk Ratio (M-H, Fixed, 95% CI)0.85 [0.59, 1.23]
1.1 Continuous CTG plus FBS716131Risk Ratio (M-H, Fixed, 95% CI)0.97 [0.64, 1.47]
1.2 Continuous CTG alone - no FBS517382Risk Ratio (M-H, Fixed, 95% CI)0.57 [0.26, 1.24]
2 Neonatal seizures932386Risk Ratio (M-H, Fixed, 95% CI)0.50 [0.31, 0.80]
2.1 Continuous CTG plus FBS515004Risk Ratio (M-H, Fixed, 95% CI)0.49 [0.29, 0.84]
2.2 Continuous CTG alone - no FBS517382Risk Ratio (M-H, Fixed, 95% CI)0.51 [0.18, 1.44]
3 Cerebral palsy213252Risk Ratio (M-H, Fixed, 95% CI)1.74 [0.97, 3.11]
3.1 Continuous CTG plus FBS213252Risk Ratio (M-H, Fixed, 95% CI)1.74 [0.97, 3.11]
3.2 Continuous CTG alone - no FBS00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
4 Caesarean section1118861Risk Ratio (M-H, Fixed, 95% CI)1.43 [1.25, 1.64]
4.1 Continuous CTG plus FBS716001Risk Ratio (M-H, Fixed, 95% CI)1.34 [1.14, 1.58]
4.2 Continuous CTG alone - no FBS52860Risk Ratio (M-H, Fixed, 95% CI)1.63 [1.30, 2.06]
5 Instrumental vaginal birth1018615Risk Ratio (M-H, Fixed, 95% CI)1.21 [1.12, 1.31]
5.1 Continuous CTG plus FBS615755Risk Ratio (M-H, Fixed, 95% CI)1.27 [1.16, 1.39]
5.2 Continuous CTG alone - no FBS52860Risk Ratio (M-H, Fixed, 95% CI)1.05 [0.90, 1.22]
6 Cord blood acidosis22494Risk Ratio (M-H, Fixed, 95% CI)1.16 [0.72, 1.89]
6.1 Continuous CTG plus FBS11075Risk Ratio (M-H, Fixed, 95% CI)0.45 [0.16, 1.29]
6.2 Continuous CTG alone - no FBS11419Risk Ratio (M-H, Fixed, 95% CI)1.58 [0.89, 2.81]
7 Any pharmacological analgesia31677Risk Ratio (M-H, Fixed, 95% CI)0.99 [0.93, 1.04]
7.1 Continuous CTG plus FBS2849Risk Ratio (M-H, Fixed, 95% CI)0.98 [0.90, 1.07]
7.2 Continuous CTG alone - no FBS2828Risk Ratio (M-H, Fixed, 95% CI)0.99 [0.92, 1.05]
Analysis 6.1.

Comparison 6 Continuous CTG versus IA (access to FBS during labour - yes/no), Outcome 1 Perinatal mortality.

Analysis 6.2.

Comparison 6 Continuous CTG versus IA (access to FBS during labour - yes/no), Outcome 2 Neonatal seizures.

Analysis 6.3.

Comparison 6 Continuous CTG versus IA (access to FBS during labour - yes/no), Outcome 3 Cerebral palsy.

Analysis 6.4.

Comparison 6 Continuous CTG versus IA (access to FBS during labour - yes/no), Outcome 4 Caesarean section.

Analysis 6.5.

Comparison 6 Continuous CTG versus IA (access to FBS during labour - yes/no), Outcome 5 Instrumental vaginal birth.

Analysis 6.6.

Comparison 6 Continuous CTG versus IA (access to FBS during labour - yes/no), Outcome 6 Cord blood acidosis.

Analysis 6.7.

Comparison 6 Continuous CTG versus IA (access to FBS during labour - yes/no), Outcome 7 Any pharmacological analgesia.

Comparison 7. Continuous CTG versus IA (primiparous/multiparous women)
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Perinatal mortality1133513Risk Ratio (M-H, Fixed, 95% CI)0.86 [0.59, 1.24]
1.1 Primaparous women00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
1.2 Multiparous women00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
1.3 Both or parity not specified1133513Risk Ratio (M-H, Fixed, 95% CI)0.86 [0.59, 1.24]
2 Neonatal seizures932386Risk Ratio (M-H, Fixed, 95% CI)0.50 [0.31, 0.80]
2.1 Primaparous women00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
2.2 Multiparous women00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
2.3 Both or parity not specified932386Risk Ratio (M-H, Fixed, 95% CI)0.50 [0.31, 0.80]
3 Cerebral palsy213252Risk Ratio (M-H, Fixed, 95% CI)1.74 [0.97, 3.11]
3.1 Primaparous women00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
3.2 Multiparous women00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
3.3 Both or parity not specified213252Risk Ratio (M-H, Fixed, 95% CI)1.74 [0.97, 3.11]
4 Caesarean section1118961Risk Ratio (M-H, Fixed, 95% CI)1.44 [1.26, 1.64]
4.1 Primaparous women00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
4.2 Multiparous women1100Risk Ratio (M-H, Fixed, 95% CI)1.55 [0.81, 2.96]
4.3 Both or parity not specified1118861Risk Ratio (M-H, Fixed, 95% CI)1.43 [1.25, 1.64]
5 Instrumental vaginal birth1018715Risk Ratio (M-H, Fixed, 95% CI)1.21 [1.12, 1.30]
5.1 Primaparous women00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
5.2 Multiparous women1100Risk Ratio (M-H, Fixed, 95% CI)0.33 [0.04, 3.10]
5.3 Both or parity not specified1018615Risk Ratio (M-H, Fixed, 95% CI)1.21 [1.12, 1.31]
6 Cord blood acidosis22494Risk Ratio (M-H, Fixed, 95% CI)1.16 [0.72, 1.89]
6.1 Primaparous women00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
6.2 Multiparous women00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
6.3 Both or parity not specified22494Risk Ratio (M-H, Fixed, 95% CI)1.16 [0.72, 1.89]
7 Any pharmacological analgesia31677Risk Ratio (M-H, Fixed, 95% CI)0.99 [0.93, 1.04]
7.1 Primaparous women00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
7.2 Multiparous women00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
7.3 Both or parity not specified31677Risk Ratio (M-H, Fixed, 95% CI)0.99 [0.93, 1.04]
Analysis 7.1.

Comparison 7 Continuous CTG versus IA (primiparous/multiparous women), Outcome 1 Perinatal mortality.

Analysis 7.2.

Comparison 7 Continuous CTG versus IA (primiparous/multiparous women), Outcome 2 Neonatal seizures.

Analysis 7.3.

Comparison 7 Continuous CTG versus IA (primiparous/multiparous women), Outcome 3 Cerebral palsy.

Analysis 7.4.

Comparison 7 Continuous CTG versus IA (primiparous/multiparous women), Outcome 4 Caesarean section.

Analysis 7.5.

Comparison 7 Continuous CTG versus IA (primiparous/multiparous women), Outcome 5 Instrumental vaginal birth.

Analysis 7.6.

Comparison 7 Continuous CTG versus IA (primiparous/multiparous women), Outcome 6 Cord blood acidosis.

Analysis 7.7.

Comparison 7 Continuous CTG versus IA (primiparous/multiparous women), Outcome 7 Any pharmacological analgesia.

Comparison 8. Continuous CTG versus IA (high-quality studies vs lower-quality studies)
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Perinatal mortality1133513Risk Ratio (M-H, Fixed, 95% CI)0.86 [0.59, 1.24]
1.1 High-quality trials213434Risk Ratio (M-H, Fixed, 95% CI)1.00 [0.49, 2.05]
1.2 Low-quality trials417173Risk Ratio (M-H, Fixed, 95% CI)0.58 [0.28, 1.18]
1.3 Quality of trials unclear52906Risk Ratio (M-H, Fixed, 95% CI)1.00 [0.58, 1.71]
2 Neonatal seizures932386Risk Ratio (M-H, Fixed, 95% CI)0.50 [0.31, 0.80]
2.1 High-quality trials213434Risk Ratio (M-H, Fixed, 95% CI)0.40 [0.21, 0.77]
2.2 Low-quality trials216046Risk Ratio (M-H, Fixed, 95% CI)0.26 [0.04, 1.60]
2.3 Quality of trials unclear52906Risk Ratio (M-H, Fixed, 95% CI)0.83 [0.38, 1.81]
3 Cerebral palsy213252Risk Ratio (M-H, Fixed, 95% CI)1.74 [0.97, 3.11]
3.1 High-quality trials113079Risk Ratio (M-H, Fixed, 95% CI)1.20 [0.52, 2.79]
3.2 Low-quality trials00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
3.3 Quality of trials unclear1173Risk Ratio (M-H, Fixed, 95% CI)2.54 [1.10, 5.86]
4 Caesarean section1118861Risk Ratio (M-H, Random, 95% CI)1.63 [1.29, 2.07]
4.1 High-quality trials213314Risk Ratio (M-H, Random, 95% CI)1.27 [0.88, 1.83]
4.2 Low-quality trials32555Risk Ratio (M-H, Random, 95% CI)1.77 [0.92, 3.41]
4.3 Quality of trials unclear62992Risk Ratio (M-H, Random, 95% CI)1.81 [1.34, 2.44]
5 Instrumental vaginal birth1018615Risk Ratio (M-H, Fixed, 95% CI)1.21 [1.12, 1.31]
5.1 High-quality trials213314Risk Ratio (M-H, Fixed, 95% CI)1.26 [1.13, 1.42]
5.2 Low-quality trials32555Risk Ratio (M-H, Fixed, 95% CI)1.39 [1.17, 1.64]
5.3 Quality of trials unclear52746Risk Ratio (M-H, Fixed, 95% CI)1.00 [0.87, 1.16]
6 Cord blood acidosis22494Risk Ratio (M-H, Fixed, 95% CI)1.16 [0.72, 1.89]
6.1 High-quality trials11075Risk Ratio (M-H, Fixed, 95% CI)0.45 [0.16, 1.29]
6.2 Low-quality trials11419Risk Ratio (M-H, Fixed, 95% CI)1.58 [0.89, 2.81]
6.3 Quality of trials unclear00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
7 Any pharmacological analgesia31677Risk Ratio (M-H, Fixed, 95% CI)0.99 [0.93, 1.04]
7.1 High-quality trials00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
7.2 Low-quality trials00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
7.3 Quality of trials unclear31677Risk Ratio (M-H, Fixed, 95% CI)0.99 [0.93, 1.04]
Analysis 8.1.

Comparison 8 Continuous CTG versus IA (high-quality studies vs lower-quality studies), Outcome 1 Perinatal mortality.

Analysis 8.2.

Comparison 8 Continuous CTG versus IA (high-quality studies vs lower-quality studies), Outcome 2 Neonatal seizures.

Analysis 8.3.

Comparison 8 Continuous CTG versus IA (high-quality studies vs lower-quality studies), Outcome 3 Cerebral palsy.

Analysis 8.4.

Comparison 8 Continuous CTG versus IA (high-quality studies vs lower-quality studies), Outcome 4 Caesarean section.

Analysis 8.5.

Comparison 8 Continuous CTG versus IA (high-quality studies vs lower-quality studies), Outcome 5 Instrumental vaginal birth.

Analysis 8.6.

Comparison 8 Continuous CTG versus IA (high-quality studies vs lower-quality studies), Outcome 6 Cord blood acidosis.

Analysis 8.7.

Comparison 8 Continuous CTG versus IA (high-quality studies vs lower-quality studies), Outcome 7 Any pharmacological analgesia.

Comparison 9. Continuous CTG versus intermittent CTG
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Perinatal mortality (primary outcome)00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
2 Neonatal seizures (primary outcome)00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
3 Cerebral palsy (primary outcome)00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
4 Caesarean section (primary outcome)14044Risk Ratio (M-H, Fixed, 95% CI)1.29 [0.84, 1.97]
5 Instrumental vaginal birth (primary outcome)14044Risk Ratio (M-H, Fixed, 95% CI)1.16 [0.92, 1.46]
6 Cord blood acidosis (primary outcome)14044Risk Ratio (M-H, Fixed, 95% CI)1.43 [0.95, 2.14]
7 Any pharmacological analgesia (primary outcome)00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
8 Hypoxic ischaemic encephalopathy00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
9 Neurodevelopmental disability at at least 12 months of age00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
10 Apgar score < 7 at 5 minutes14044Risk Ratio (M-H, Fixed, 95% CI)2.65 [0.70, 9.97]
11 Apgar score < 4 at 5 minutes00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
12 Neonatal ICU admissions14044Risk Ratio (M-H, Fixed, 95% CI)1.34 [0.91, 1.98]
13 Fetal blood sampling00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
14 Damage/infection from scalp electrode or scalp sampling00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
15 Caesarean section for abnormal FHR pattern and/or acidosis14044Risk Ratio (M-H, Fixed, 95% CI)1.19 [0.66, 2.15]
16 Instrumental vaginal birth for abnormal CTG or fetal acidosis00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
17 Spontaneous vaginal birth14044Risk Ratio (M-H, Fixed, 95% CI)0.98 [0.96, 1.00]
18 Epidural analgesia14044Risk Ratio (M-H, Fixed, 95% CI)1.06 [0.92, 1.21]
19 Use of non pharmacological methods of coping with labour00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
20 Amniotomy00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
21 Oxytocin during 1st and/or 2nd stage of labour00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
22 Perineal trauma needing repair00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
23 Inability to adopt preferred position in labour00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
24 Dissatisifaction with labour and/or perceived loss of control00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
25 Postpartum depression00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
26 Exclusive breastfeeding at discharge00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
27 Length of stay on NICU00Mean Difference (IV, Fixed, 95% CI)0.0 [0.0, 0.0]
Analysis 9.4.

Comparison 9 Continuous CTG versus intermittent CTG, Outcome 4 Caesarean section (primary outcome).

Analysis 9.5.

Comparison 9 Continuous CTG versus intermittent CTG, Outcome 5 Instrumental vaginal birth (primary outcome).

Analysis 9.6.

Comparison 9 Continuous CTG versus intermittent CTG, Outcome 6 Cord blood acidosis (primary outcome).

Analysis 9.10.

Comparison 9 Continuous CTG versus intermittent CTG, Outcome 10 Apgar score < 7 at 5 minutes.

Analysis 9.12.

Comparison 9 Continuous CTG versus intermittent CTG, Outcome 12 Neonatal ICU admissions.

Analysis 9.15.

Comparison 9 Continuous CTG versus intermittent CTG, Outcome 15 Caesarean section for abnormal FHR pattern and/or acidosis.

Analysis 9.17.

Comparison 9 Continuous CTG versus intermittent CTG, Outcome 17 Spontaneous vaginal birth.

Analysis 9.18.

Comparison 9 Continuous CTG versus intermittent CTG, Outcome 18 Epidural analgesia.

Appendices

Appendix 1. Search strategies

In the 2006 update of this review, we searched CENTRAL (The Cochrane Library 2005, Issue 4), MEDLINE (1966 to December 2005), CINAHL (1982 to December 2005) and EMBASE (1974 to December 2005) using the search strategies below:

CENTRAL

1. Labor Obstetric/
2. Delivery Obstetric/
2. Fetal Monitoring/
3. intrapartum near monitor*
4. fetal near surveillance
5. 1 or 2
6. 3 or 4 or 5
7. 6 and 7

MEDLINE

1. exp Labor, Obstetric/ or exp Delivery, Obstetric/
2. exp Fetal Monitoring/
3. (intrapartum adj2 monitor$).ti,ab.
4. (fetal adj surveillance).ti,ab.
5. randomized controlled trial.pt.
6. exp Controlled Clinical Trials/
7. controlled clinical trial.pt.
8. 2 or 3 or 4
9. 5 or 6 or 7
10. 1 and 8 and 9

CINAHL

1. exp Clinical Trials/
2. clinical trial.pt.
3. (clinic$ adj trial$1).tw.
4. ((singl$ or doubl$ or trebl$ or tripl$) adj (blind$3 or mask$3)).tw.
5. randomi?ed control$ trial$.tw.
6. exp Random Assignment/
7. random$ allocat$.tw.
8. placebo$.tw.
9. Quantitative studies/
10. allocat$ random$.tw.
11. Placebos/
12. 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11
13. exp Fetal Monitoring/
14. (fetal adj2 monitor$).tw.
15. (intrapartum adj2 monitor$).tw.
16. (labor or labour).tw.
17. exp Childbirth/
18. 13 or 14 or 15
19. 16 or 17
20. 12 and 18 and 19

EMBASE

1. randomization/
2. double blind procedure/
3. crossover procedure/
4. intermethod comparison/
5. single blind procedure/
6. clinical study/
7. controlled study/
8. randomized controlled trial/
9. (clin$ adj2 trial$).tw.
10. ((singl$ or doubl$ or trebl$ or tripl$) adj2 (blind$ or mask$)).tw.
11. exp clinical trial/
12. placebo/
13. placebo$.tw.
14. random$.tw.
15. labour$ or labor or laboring.af.
16. Fetus-Electrocardiography/
17. Fetus-Monitoring/
18. fetal with monitor$
19. fetal adj surveillance
20. 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14
21. 16 or 17 or 18 or 19
22. 20 and 21 and 15

We also searched for grey literature by searching Dissertation Abstracts (1980 to December 2005) and National Research Register (December 2005) databases, using monitoring terms identified above, adapted for each database. We chose not to repeat these additional searches for the update as they yielded no additional studies in the original search.

Appendix 2. Methods used in previous versions

We developed the methods of the review in light of the advice contained in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2005).

Study identification

We considered all identified randomised and quasi-randomised controlled trials involving a comparison of continuous CTG, with and without fetal blood sampling, with (a) no fetal monitoring, (b) intermittent auscultation of the fetal heart rate with a Pinard stethoscope or hand-held Doppler ultrasound device or (c) intermittent CTG.

One review author (Declan Devane (DD)) ran the additional search strategies. Each potentially eligible trial identified by the search strategy was obtained as a full-text article and independently assessed for inclusion by Zarko Alfirevic (ZA) and Gill Gyte (GG). There were no disagreements regarding eligibility for inclusion that needed to be resolved by discussion with DD. We did not encounter problems with language or missing information requiring classification as 'Study awaiting assessment' (RevMan 2003).

Quality assessment of included studies

Two review authors (GG and DD) independently assessed the quality of all included trials, namely selection and attrition bias. With regard to performance bias, due to the differences in the modus operandi of the continuous CTG and intermittent auscultation, it is unlikely that clinicians or women will have been blinded to either intervention. Therefore, lack of blinding was not considered to undermine the validity of studies.

Selection bias

Studies were allocated a grade on the basis of allocation concealment as per criteria outlined in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2005) i.e. (A) adequate, (B) unclear, (C) inadequate or (D) allocation concealment was not used. Approaches to allocation concealment considered to be clearly inadequate include: alternation, the use of case record numbers, dates of birth or day of the week, and any procedure that is entirely transparent before allocation, such as an open list of random numbers.

Attrition bias

Due to inadequacies in reporting how losses of participants (e.g. withdrawals, dropouts, protocol deviations) were handled, the review authors were cautious about implicit accounts of follow-up. Given that study reports on attrition after allocation have not been found to be consistently related to bias, studies were not excluded on the basis of attrition. Studies were, however, graded for completeness of follow-up using the following criteria. For completeness of follow-up:
(A) less than 3% of participants excluded;
(B) 3% to 9.9% of participants excluded;
(C) 10% to 19.9% of participants excluded;
(D) more than 20% of participants excluded.

Data extraction

Two review authors (ZA and DD) independently extracted the data using predesigned data extraction forms, the fields of which had been agreed by all review authors. Study eligibility was verified again at the time of data abstraction or collection.

Additional information was extracted from the included trials by one review author (GG) and recorded in an additional table (Table 2). The data include: (1) one carer to one woman support during labour; (2) labour induction; (3) the use of artificial rupture of membranes (ARM) in labour; (4) the use of oxytocin for augmentation of labour; (5) women's mobility during labour; (6) women's positions for giving birth; (7) women's views of labour and monitoring; (8) social and environmental context of trials; (9) experience of staff in CTG interpretation. These were considered to be factors that might impact on the comparison of outcomes. For example, it is unclear what impact the supine position, ARM and oxytocin use might have on the fetal heart rate patterns, and whether mobility in labour might reduce the use of such interventions.

Table 2. Additional descriptive information from included studies
  1. ARM: artificial rupture of membranes
    CTG: cardiotocography
    EFM: electronic fetal monitoring
    IA: intermittent auscultation
    IV: intravenous

Study1 carer to 1 womanInductionARMOxytocinMobilityBirth positionsWomen's viewsSocial contextExperience of staff
Athens 1993YesInduction - 11% overallNo informationAugmentation - 46% overallNo mobility - all women with IV line insertedSemi-Fowler or lateralNo informationNo informationIA standard practice, EFM intensive training provided
Copenhagen 1985No informationNo informationNo informationNo informationEFM only applied when women no longer wished to walk around.No informationNo informationNo informationNo information
Dallas 19862 women : 1 nurseExcluded women whose labours were inducedNo informationExcluded womenNo informationNo informationNo informationNo informationNo information
Denver 1976IA: yes CTG: no informationIncluded women whose labours were inducedNo informationIncluded women given oxytocin for augmentationNo informationNo informationNo informationNo informationNo information
Denver 1979YesNo specific informationNo information29% of women given oxytocin for augmentationNo informationNo informationNo informationNo informationNo information
Dublin 1985YesIncluded women whose labours were inducedARM within an hour of admission to check liquor23% of women given oxytocin for augmentationIA, probably more mobileNo informationWomen's views sought and published separately.No informationNo information
Lund 1994No informationIncluded women whose labours were inducedNo information48% of women were given ocytocin for induction or accelerationWomen in CTG group offered telemetry if wished mobilityNo informationNo informationNo informationNo information
Melbourne 1976No informationInduction - 42% overallNo information63% of women given oxytocin in labourNo informationNo informationNo informationNo informationExp staff.
Melbourne 1981No informationNo informationARM when in established labour or for obstetric reasonsNo informationNo informationNo informationNo informationNo informationNo information
Pakistan 1989No informationNo informationNo informationNo informationNo informationNo informationNo informationNo informationNo information
New Delhi 2006No informationNo informationNo informationNo informationNo informationNo informationNo informationNo informationNo information
Seattle 1987YesNo informationARM at 7 cm unless clinically indicated prior to 7 cmIncluded women given oxytocinNo informationNo informationWomen's views sought and published separately.No informationNo information
Sheffield 1978No informationIncluded women whose labours were inducedAugmentation with ARM alone or in combination with oxytocin if progress fell below nomogram.Oxytocin was administered to all women as indicatedNo informationNo informationNo informationNo informationNo information

Data analysis

We performed statistical analyses with the Review Manager Software (RevMan 2003). Dichotomous (or binary) outcomes were reported using the 'relative risk' summary statistic and their 95% confidence intervals. Continuous data were reported using the weighted mean differences and their 95% confidence intervals.

Denver 1979 was a three-arm trial with two experimental groups (CTG with and without access to fetal scalp sampling) and one control group (intermittent auscultation). Following statistical advice, we arbitrarily split the data for the controls into two equal groups and assigned them to each experimental arm. This approach ensured that there was no double-counting for controls when overall relative risks were calculated. An arbitrary decision was made when the number needing to be split was not an even number.

We used a fixed-effect model of meta-analysis for summarising the results of studies in the absence of substantial heterogeneity between trials. Where heterogeneity between trials was substantial a random-effects model was used. Measurements of heterogeneity were performed using the I-squared statistic, which is less affected by the number of trials in the analysis than the Chi-squared test. I-square of 30% to 50% suggests mild heterogeneity and more than 50% indicates substantial heterogeneity.

We planned subgroup analyses on the following a priori determined subgroups:
(a) low risk (absence of identifiable risk factors associated with increased in perinatal mortality and morbidity as defined by trialists);
(b) high risk for perinatal mortality and morbidity (as defined by trialists);
(c) spontaneous onset of labour;
(d) induction of labour;
(e) preterm (less than 37 + 0 weeks);
(f) term (greater than 37 + 0 weeks);
(g) singleton pregnancy;
(h) twin pregnancy;
(i) without fetal blood sampling (FBS) during labour;
(j) with FBS during labour;
(k) parity.

Sensitivity analysis

We performed sensitivity analysis based on quality comparing high-quality trials with trials of lower quality. Given that study reports on attrition after allocation have not been found to be consistently related to bias, 'high quality' was, for the purposes of this sensitivity analysis, defined as a trial having allocation concealment classified as 'A' (adequate).

Feedback

Ingemarsson, 30 March 2008

Summary

In this review you comment on the significant reduction in neonatal seizures associated with continuous cardiotocography rather than intermittent auscultation, but then put this in opposition to the increase in caesarean section. Yet, more caesarean sections are performed without clinical indication, on maternal `request' than are performed for threatening fetal hypoxia. Moreover, you stress that continuous cardiotocography is not associated with any beneficial effect on the risk of cerebral palsy, because 80%-85% of cases have an antenatal origin and therefore intrapartum CTG can not be expected to have a great impact on the overall figure.

A recent Swedish study (Lindström 2006) reported outcome at 15-19 years of age after moderate hypoxic-ischemic encephalopathy (Sarnat II with neonatal seizures in most cases). Of 43 children with moderate hypoxic-ischemic encephalopathy, 15 had cerebral palsy. Of the 28 children without encephalopathy, 20 had cognitive problems. Only 8 of the 43 children had no problem later in life. So, a halving in neonatal seizures with continuous cardiotocography seems to me, as an old obstetrician, to be a very good outcome.

(Summary of feedback from Ingemar Ingemarsson, March 2008)

Reply

Thank you for your comments. In our review, we feel we have clearly articulated the perceived conflict between our findings of increased caesarean section and instrumental vaginal birth and decreased incidence of neonatal seizures associated with continuous CTG when compared with intermittent auscultation.

We are unaware of any high quality evidence that demonstrates a higher rate of caesarean sections due to maternal ‘request’ than due to hypoxia. Caesarean sections for maternal ‘request’ is a complex issue and there are those who have argued that it is not a significant influencing factor on caesarean rates (Gamble 2007) Even if such evidence existed, we believe that this is addressing a different question from that in our review. 

The focus of the quoted study by Lindström et al (Lindström 2006) is on neonatal encephalopathy. In our review, we highlighted that much remains to be learned about the causation and possible links between antenatal or intrapartum events, neonatal seizures and long-term neurodevelopmental outcome. Until and unless a causative link is made between neonatal seizures, we believe it reasonable to base clinical decisions on the evidence we currently have. 

Contributors

Zarko Alfirevic
Declan Devane
Gillian Gyte

Panteghini, 30 September 2013

Summary

I have two comments about this review:

1) In the continuously monitored group the relative risk of perinatal mortality is lower rather than in the intermittently monitored group (RR 0.86). This result may be important for women when they choose which method of fetal monitoring to adopt during labour. Is it not more useful to present the absolute and relative risk, so the woman, her midwife and doctor can decide if these are significant to them or not? To consider a result significant only if it is statistically significant (and only if statistically significant at a given level of significance, such as 5%) is an arbitrary decision that needs to be shared with the woman and her clinical team.

2) An interesting question raised by this review is which method of intermittent auscultation is best. The review lumps together different types of intermittent auscultation; for example, auscultation during and after a contraction, and auscultation only after a contraction.

The review assesses the relationship between pH at birth and the method of foetal heart monitoring rate (intermittent or continuous) in two studies (Athens 1993, Dublin 1985), and does not find any difference between the two methods as regards neonatal pH at birth. It is interesting to note that in the Dublin trial, which used intermittent auscultation only after a contraction, the pH at birth was worse for woman allocated intermittent auscultation rather than continuous monitoring (RR 0.45, 95% CI 0.16 - 1.29). In contrast, in the Athens trial, which used intermittent auscultation during and after the contraction, pH at birth was better for woman allocated intermittent auscultation (RR 1.58, 95% CI 0.89 - 2.81).

The importance of decelerations during the contraction and their impact on foetal wellbeing is now well known. Therefore the National Institute for Clinical Excellence (NICE) (1) considers monitoring to be reassuring only if there are no decelerations. Some guidelines advise monitoring the foetal heart after a contraction (2), others during and after (3), and others again do not specify the timing of auscultation in relation to contraction (4). The review is appropriate in not drawing any conclusions about what is the best method of intermittent monitoring. We think that guidelines should state both that the mode of intermittent monitoring and the choice of one method rather than another is a grade C recommendation (personal opinion) (5) as, in the light of this review, we do not know which method of intermittent monitoring is best (although we could suppose that intermittent auscultation during and after a contraction may be better than auscultation only after a contraction for preventing low pH at birth).

References

(1) NICE. Intrapartum care, 2008; p219-220 Tables 13.1, 13.2.

(2) Royal College of Midwives. Evidence based guidelines for midwifery-led care in labour,2012.

(3) American College of Nurse and Midwives. Intermittent Auscultation for Intrapartum Fetal Heart Rate Surveillance. Journal of Midwifery and Women's Health, 2010; 55: 397-403.

(4) Association of Women's Health Obstetric and Neonatal Nurses. Fetal Heart Monitoring, 2008

(5) Danti L, Di Tommaso MR, Maffetti G, Carfagna M. Cardiotocografia. Milano 2010, Piccin editore.

Comment submitted by Marco Panteghini, September 2013

What's new

Last assessed as up-to-date: 31 January 2013.

DateEventDescription
30 September 2013Feedback has been incorporated Feedback 2 received from Marco Panteghini.

History

Protocol first published: Issue 3, 2006
Review first published: Issue 3, 2006

DateEventDescription
31 December 2012New citation required but conclusions have not changedThe inclusion of one new study has not changed the results and conclusions of this review.
31 December 2012New search has been performed

Search updated. Two trial reports identified. One new study has been included (New Delhi 2006) and one is awaiting classification (Greece 2012).

This review is now comprised of 13 included studies (involving over 37,000 women) and four excluded studies.

23 July 2008Feedback has been incorporatedFeedback added with reply from authors.
23 July 2008AmendedConverted to new review format.

Contributions of authors

Zarko Alfirevic (ZA) drafted the protocol. Declan Devane (DD) and Gill Gyte (GG) commented on all its sections.
ZA and GG assessed studies in respect of inclusion and exclusion criteria.
DD ran additional searches. ZA and DD extracted the data independently and double entered them into Review Manager. GG extracted additional descriptive information from included studies. All three authors wrote and agreed the final version of the review.

Declarations of interest

None known.

Characteristics of studies

Characteristics of included studies [ordered by study ID]

Athens 1993

MethodsRCT. Assignment by coin toss on admission. Mothers and obstetricians not blinded; neonatologists collecting data on neonatal outcomes were blinded.
Participants

Inclusion: Mixed-risk. Women with a singleton fetus at 26 or more weeks' gestation admitted in spontaneous labour or for induction of labour.

Total of 1428 women participated.

Exclusion: Women with known fetal congenital or chromosomal abnormalities.

Interventions

Intervention: Continuous CTG without FBS

  • CTG: external unless trace poor when internal CTG used

  • N = 746

Comparison: IA

  • N = 682

Outcomes

Labour onset, oxytocin administration, duration of labour, premature rupture of the membranes, meconium-stained liquor, mode of delivery, analgesia/anaesthesia, 'non reassuring' FHR patterns, length of maternal hospital stay, postpartum maternal morbidity (infection or blood transfusion), duration of 'good quality tracing'.

Presentation at birth, birthweight (< 2500, 2500-4000, > 4000), Apgar score < 7 @ 1 min and @ 5 min, cord arterial pH < 7.10, neonatal resuscitation, NICU admission, assisted ventilation, length of neonatal hospital stay, neonatal complications (none, HIE, intraventricular haemorrhage, seizures, hypotonia, necrotising enterocolitis, respiratory distress, sepsis, hyperbilirubinaemia, hypoglycaemia, congenital anomalies), intrapartum fetal death, neonatal death, perinatal death, perinatal death from hypoxia.

Outcomes analysed: caesarean deliveries, operative vaginal deliveries, 1 minute Apgar < 4 and < 7, neonatal seizures, NICU admissions, length of stay, and perinatal death. Outcomes not analysed: presentation, labour, labour duration, PROM, meconium, maternal infection or blood transfusion.

Overall risk of bias

High risk of bias including high risk of bias for random sequence generation and concealment of allocation.

“C”

Notes

Study period: October 1990 to June 1991.

Subgroups: Mixed risk; mixed onset of labour; mixed gestation; singletons; no FBS; mixed parity; low quality.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)High risk“…assigned on admission by a coin toss...” However, unexplained high imbalance in numbers allocated to groups (746 EFM and 682 IA) suggests a high risk of bias in sequence generation.
Allocation concealment (selection bias)High riskNo information given. The use of coin toss to generate the random sequence without this information suggests there was high risk of bias in allocation concealment.
Blinding of participants and personnel (performance bias)
All outcomes
High riskAlthough not documented, we judged that women and clinicians were not blind to the interventions used.
Blinding of outcome assessment (detection bias)
All outcomes
High riskNeonatologists assessing neonatal outcomes were blinded to allocation. Not stated if other outcomes were assessed blindly but unlikely.
Incomplete outcome data (attrition bias)
All outcomes
Low riskData on all 1428 women were available.
Selective reporting (reporting bias)Unclear riskWe did not assess trial protocol.
Other biasLow riskAppears to be free of other sources of bias.

Copenhagen 1985

MethodsRCT. Weekly allocation to either group by random sampling. Method of randomisation unclear.
Participants

Inclusion: Mixed-risk

Among 1410 women who fulfilled the criteria for entering the study, 349 refused to participate (primarily due to preference for 1 form of monitoring).

Total of 969 women participated. Baseline outcomes collected for non-participating group of women.

3 twins in CTG group and 6 twins in IA group.

Exclusion: Women with diabetes

Interventions

Intervention: Continuous CTG in conjunction with FBS

  • CTG: external or internal

  • N = 482

Comparison: IA

  • N = 487

Outcomes

FHR pattern, corrective procedures for pathological FHR pattern (oxygen, change of maternal position, CS, vacuum extraction), indications for termination of labour (mechanical disproportion, bleeding, cord prolapse, maternal disease, fetal disease, lack of progression, other), presentation at birth, administration of oxytocin, analgesia/anaesthesia.

Apgar score 0-3, 4-6, 7-10 @ 1 min and @ 5 min, gestational age (including appropriate for gestational age, small-for-gestational age, large-for-gestational age), weight, NICU admissions, asphyxia, oxygen/CPAP requirement, intubation, ventilation, post-asphyxia pallor, seizures, irritability, neonatal infection, intrapartum death, antepartum death.

Overall risk of bias

Moderate risk of bias including unclear risk of bias for random sequence generation and concealment of allocation.

“B”

Notes

Study period: January 1981 to January 1982 (date women expected to give birth).

Subgroups: Mixed risk; mixed onset of labour; term; both singletons & twins; FBS; mixed parity; unclear quality.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk“…by random sampling…”
Allocation concealment (selection bias)Unclear riskUnpublished paper refers to ‘The weekly allocation was furthermore selected….’. This suggests that allocation may have been done on a weekly basis but it is unclear.
Blinding of participants and personnel (performance bias)
All outcomes
High riskAlthough not documented, we judged that women and clinicians were not blind to the interventions used.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNo information given.
Incomplete outcome data (attrition bias)
All outcomes
Low riskData on all 969 women available.
Selective reporting (reporting bias)Unclear riskWe did not assess the trial protocol.
Other biasLow riskAppears to be free of other sources of bias (ITT information in the unpublished paper from this study).

Dallas 1986

MethodsQuasi-RCT. Randomisation by alternate months; selective monitoring (policy of using monitoring only in high-risk pregnancies) versus universal monitoring (use of a monitor for every pregnancy in which the fetus was considered viable i.e. irrespective of risk status).
Participants34,995 women included in the study. Data were extracted for 14,618 women with pregnancies at low risk; 7288 in universal monitoring group where all women monitored by CTG, and 7330 in selective monitoring where women at low risk monitored by IA.
Interventions

Intervention: Continuous CTG

  • CTG: no information on external or internal

  • N = 7288

Comparison: IA

  • N = 7330

OutcomesAbnormal FHR pattern, CS, intrapartum fetal deaths, neonatal deaths, assisted ventilation, Apgar score < 5 @ 5 min, NICU admission, seizures.
Overall risk of bias

High risk of bias including high risk of bias for random sequence generation and concealment of allocation.

“C”

Notes

Study period: information not available.

Subgroups: Low risk; mixed onset of labour; mixed gestation; singletons; no FBS; mixed parity; low quality.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)High riskRandomisation by alternate months.
Allocation concealment (selection bias)High riskRandomisation by alternate months.
Blinding of participants and personnel (performance bias)
All outcomes
High riskAlthough not documented, we judged that women and clinicians were not blind to the interventions used.
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 riskWe did not assess trial protocol.
Other biasLow riskThe study appears to be free of other sources of bias.

Denver 1976

MethodsRCT. Randomised sealed envelope with participants with even numbers having CTG while participants with odd numbers had IA.
Participants

Women at high risk on point system rating; in addition those with meconium stained fluid, needing oxytocin or abnormal fetal heart tones during labour were eligible to participate.

Total of 483 women participated.

Interventions

Intervention: Continuous CTG without FBS

  • CTG: internal

  • N = 242

Comparison: IA

  • N = 241

OutcomesFHR pattern, CS, instrumental vaginal deliveries, anaesthesia, umbilical cord pH, mean Apgar scores and Apgar scores <= 7 and > 7 @ 1 min and @ 5 min, NICU admissions, temperate abnormalities, jaundice, lethargy, seizures, jitteriness, spontaneous respiration, intubation, ventilation.
Overall risk of bias

Moderate risk of bias including unclear risk of bias for random sequence generation and concealment of allocation.

“B”

Notes

Study period: information not available.

IA group had a CTG monitor attached, which was turned off at bedside but which was recorded on a covered monitor in the hallway. This CTG was not available to clinicians during the woman's labour.

Subgroups: High risk; mixed onset of labour; mixed gestation; singletons; no FBS; mixed parity; unclear quality

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk‘… previously randomized sealed envelope…’ Women with even number allocated to CTG and women with odd number allocated to bedside monitor turned off.
Allocation concealment (selection bias)Unclear riskInsufficient information provided. Though randomised sealed envelopes were used, it is not clear if they were opaque and sequentially numbered. Also women with even number allocated to CTG and women with odd number allocated to bedside monitor turned off.
Blinding of participants and personnel (performance bias)
All outcomes
High riskAlthough not documented, we judged that women and clinicians were not blind to the interventions used.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNo information provided.
Incomplete outcome data (attrition bias)
All outcomes
Low riskData on all 483 women were reported.
Selective reporting (reporting bias)Unclear riskWe did not assess trial protocol.
Other biasLow riskAppears to be free of other sources of bias.

Denver 1979

MethodsRCT. Allocation by random numbers in sealed envelopes.
Participants

Women at high risk in labour.

Total of 690 women participating with 5 sets of twins (695 infants).

Interventions

Intervention 1: Continuous CTG with FBS

  • CTG: external until internal feasible

  • N = 229

Intervention 2: Continuous CTG without FBS

  • CTG: external until internal feasible

  • N = 230

Comparison: IA

  • N = 231

Outcomes

Pre-eclampsia, amnionitis, FHR patterns, CS, instrumental vaginal deliveries, anaesthesia, maternal postpartum infections, oxytocin administration during labour, meconium.

Gestational age (including appropriate for gestational age, small-for-gestational age, large-for-gestational age), mean Apgar score and Apgar score 0-3, 4-7, 8-10 @ 1 min and @ 5 min, umbilical cord blood gases (pH, pO2, pCO2), respiratory distress, pneumonia, seizures, sepsis, meningitis, NICU admission, required antibiotics, Bayley scales and Milani-Comparetti tests at 9 months of age.

Overall risk of bias

Moderate risk of bias including unclear risk of bias for random sequence generation and concealment of allocation.

“B”

Notes

Study period: July 1975 to July 1977.

Intervention 1 and Intervention 2 - data pooled to provide overall data for CTG.

Subgroups: High risk; mixed onset of labour; mixed gestation; singletons & twins; no FBS; mixed parity; unclear quality

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskNo information reported.
Allocation concealment (selection bias)Unclear risk“…allotted a sealed envelope…” but no information on if opaque or if numbered sequentially.
Blinding of participants and personnel (performance bias)
All outcomes
High riskAlthough not documented, we judged that women and clinicians were not blind to the interventions used.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNo information provided.
Incomplete outcome data (attrition bias)
All outcomes
Low riskSome low levels of attrition for some outcomes but insufficient to impact on outcomes.
Selective reporting (reporting bias)Unclear riskWe did not assess trial protocol.
Other biasLow riskAppears to be free of other sources of bias.

Dublin 1985

MethodsRCT. Random allocation by opening the next envelope in a series of serially numbered, opaque, sealed envelopes.
Participants

Women at > 28 weeks' gestation, in labour, clear liquor previously demonstrated. Mixed risk.

Total of 12,964 women participated.

Interventions

Intervention: Continuous CTG in conjunction with FBS

  • CTG: internal

  • N = 6474

Comparison: IA

  • N = 6490

OutcomesUse of FBS, scalp pH values, randomisation-delivery interval, oxytocin use, analgesia, CS, operative vaginal deliveries, Apgar score < 3 @ 1 min and @ 5 min, intubation, NICU admission, umbilical cord venous pH values neonatal trauma (e.g. fractured clavicle, facial nerve injury, intrapartum death, neonatal death, seizures, abnormalities of tone and reflexes, primary cause of stillbirths and neonatal deaths, labour length, cerebral palsy at 4 years of age.
Overall risk of bias

Low risk of bias (no limitations for random sequence generation and allocation concealment).

“A”

Notes

Study period: March 1981-April 1983.
Zelen design.

FBS was performed when the duration of labour exceeded 8 hours. This occurred in 77/6474 (1.2%) of women in the CTG arm and 139/6486 (2.1%) of women in the IA arm.

Subgroups: Mixed risk (separated data only available for seizures); mixed onset of labour; mixed gestation; singletons & twins; FBS; mixed parity; high quality.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskThe sequence was generated using a random numbers table, at a central register, to randomly select from the range of permutations available within the balanced blocks. (personal communication from Adrian Grant, 24.04.12).
Allocation concealment (selection bias)Low risk“…serially numbered, sealed, opaque envelopes…”
Blinding of participants and personnel (performance bias)
All outcomes
High riskAlthough not documented, we judged that women and clinicians were not blind to the interventions used.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear risk

No information provided other than other than below:

 

‘All 30 children who had survived after neonatal seizures, and 125

(91%) of the remaining 138 children whose neurological status had been judged to be abnormal, underwent a general physical and detailed neurological examination by an experienced paediatrician who was "blind" both to the trial allocation and to the nature of the neonatal neurological abnormality.’

Incomplete outcome data (attrition bias)
All outcomes
Low riskNo exclusions after randomisation.
Selective reporting (reporting bias)Unclear riskWe did not assess trial protocol.
Other biasLow riskAppears to be free of other sources of bias.

Lund 1994

MethodsRCT. Shuffled opaque envelopes in randomly permuted blocks.
Participants

Women with low to moderate risk factors for complications during labour.

Total of 4044 women participated.

Interventions

Intervention: Continuous CTG with FBS

  • CTG: no information on external or internal

  • N = 2029

Comparison: Intermittent CTG with FBS

  • CTG: no information on external or internal

  • N = 2015

OutcomesFHR pattern, time from admission to delivery, length of labour, duration of CTG, CS, instrumental vaginal deliveries, normal deliveries, umbilical cord arterial pH values, Apgar score <7 @ 1 min and 5 min, NICU admission.
Overall risk of bias

Low risk of bias (unclear risk of bias for random sequence generation and low risk for allocation concealment)

“A”

Notes

Study period: October 1989 May 1991.

Subgroups: these analyses were not undertaken because this study compared continuous with intermittent CTG

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskNo information provided, although possibly random sequence due to reference to ‘…randomly permuted blocks…’.
Allocation concealment (selection bias)Low risk“…opening an opaque envelope from a pack of shuffled envelopes in randomly permuted blocks…”
Blinding of participants and personnel (performance bias)
All outcomes
High riskAlthough not documented, we judged that women and clinicians were not blind to the interventions used.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNo information provided.
Incomplete outcome data (attrition bias)
All outcomes
Low riskNo exclusions after randomisation.
Selective reporting (reporting bias)Unclear riskWe did not assess trial protocol.
Other biasLow riskAppears to be free of other sources of bias.

Melbourne 1976

MethodsRCT. Randomised cards in sealed, consecutively numbered envelopes.
Participants

Women at high risk.

Total of 350 women participated.

Interventions

Intervention: Continuous CTG with FBS

  • CTG: external

  • N = 175

Comparison: IA

  • N = 175

Outcomes

Length of labour, induction-delivery interval, oxytocin use, IV fluid volume use, ketonuria, analgesia, CS, instrumental vaginal deliveries, maternal infection.

Apgar score (mean grouped) 0-3, 4-6, 7-10 (? timing), resuscitation, NICU admission, twitching, apneic episodes, hypotonia, convulsions, tachypnoea, high-pitched cry, hypertonus, neonatal infection, umbilical cord arterial and venous blood gases.

Overall risk of bias

Low risk of bias (no limitations for random sequence generation and allocation concealment).

“A”

Notes

Study period: March 1974 - April 1975.

Subgroups: High risk; mixed onset of labour; mixed gestation; singletons & twins; FBS; mixed parity; high quality.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk“…randomised cards…”
Allocation concealment (selection bias)Low risk“…sealed consecutively numbered envelopes…”
Blinding of participants and personnel (performance bias)
All outcomes
High riskAlthough not documented, we judged that women and clinicians were not blind to the interventions used.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNo information provided.
Incomplete outcome data (attrition bias)
All outcomes
Unclear risk1 of the 8 clinicians removed all the women in his care from the trial, although it is not reported how many women this was. So it is unclear if this may have introduced bias.
Selective reporting (reporting bias)Unclear riskWe did not assess trial protocol.
Other biasLow riskAppears to be free of other sources of bias.

Melbourne 1981

MethodsRCT. Randomised cards; envelopes unsealed; biased randomisation in 1 of the participating hospitals; 62 low-parity women excluded post-hoc to correct for imbalance in randomisation.
Participants

Women at low risk.

Total of 989 women participated.

Randomisation was open and there was a disproportionate number of low-parity women in the monitored group. Numbers were adjusted by random elimination of 62 women. Analysis was undertaken using the corrected figures.

Interventions

Intervention: Continuous CTG without FBS

  • CTG: external until membranes ruptured then internal

  • N = 445

Comparison: IA

  • N = 482

Outcomes

Analgesia, ketonuria, CS, instrumental vaginal deliveries, normal deliveries.

Apgar score 0-3, 4-6, 7-10 @ 1 min, days in 'isolette', days in nursery, phototherapy, neonatal death, neurological signs & symptoms (unspecified).

Overall risk of bias

Moderate risk of bias including high risk of bias for concealment of allocation.

“B

Notes

Study period: no information available.

Subgroups: Low risk; mixed onset of labour; term; singletons; FBS; mixed parity; low quality.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk“…randomization sequences were used…”
Allocation concealment (selection bias)High riskEnvelopes were not sealed at 1 of the hospitals and this created more low-parity women in the monitored group. This was corrected by random elimination.
Blinding of participants and personnel (performance bias)
All outcomes
High riskAlthough not documented, we judged that women and clinicians were not blind to the interventions used.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNo information provided.
Incomplete outcome data (attrition bias)
All outcomes
High riskWomen were randomly excluded from 1 group to balance the difference in parity.
Selective reporting (reporting bias)Unclear riskWe did not assess trial protocol.
Other biasLow riskAppears to be free of other sources of bias.

New Delhi 2006

MethodsRCT but no details on how this was undertaken.
Participants

Women at high risk.

100 women who had had 1 previous low-transverse CS.

For this pregnancy, singleton and cephalic.

Interventions

Intervention: Continuous CTG

  • N = 50

Comparison: IA

  • N = 50

OutcomesVaginal birth; CS; forceps; PPH; infection (fever); mean birthweight; Apgar scores; admission to NICU; assisted ventilation; neonatal morbidity.
Overall risk of bias

Moderate risk of bias including unclear risk of bias for random sequence generation and concealment of allocation.

“B”

Notes

Study period: no information

No good information on study methodology.

Subgroups: High risk; mixed onset of labour; mixed gestation; singletons; no FBS; multiparity; unclear quality

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk“...divided randomly...”
Allocation concealment (selection bias)Unclear risk“...divided randomly...”
Blinding of participants and personnel (performance bias)
All outcomes
High riskAlthough not documented, we judged that women and clinicians were not blind to the interventions used.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNo information provided.
Incomplete outcome data (attrition bias)
All outcomes
Low riskAll 100 women's data were available.
Selective reporting (reporting bias)Unclear riskWe did not assess the trial protocol.
Other biasLow riskAppears to be free of other sources of bias.

Pakistan 1989

MethodsRCT. Randomisation by woman selecting 1 of 200 sealed, opaque, unnumbered envelopes.
Participants

Women at high risk (all participants had meconium stained liquor).

Total of 200 women participated with 100 in the CTG group and 100 in the IA group.

Interventions

Intervention: Continuous CTG with FBS

  • CTG: external

  • N = 100

Comparison: IA

  • N = 100

OutcomesApgar score < 7 @ 1 min and @ 5 min, CS, instrumental vaginal deliveries, normal deliveries, stillbirths, early neonatal deaths.
Overall risk of bias

High risk of bias (including unclear risk of bias for random sequence generation and high risk of bias for concealment of allocation.

"C"

Notes

Study period: 1988-1989.

Data extracted from unpublished trial lodged with the Cochrane Pregnancy and Childbirth Editorial Office in Liverpool, UK.

Subgroups: High risk; mixed onset of labour; mixed gestation; singletons; FBS; mixed parity; low quality.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk“Randomisation was effected by the woman selecting one of two hundred... ...envelopes...”. It is unclear just what this means.
Allocation concealment (selection bias)High risk“Randomisation was effected by the woman selecting one of two hundred sealed, opaque, unnumbered envelopes containing a card indicating the type of monitoring to be employed.”
Blinding of participants and personnel (performance bias)
All outcomes
High risk“…blinding of the allocated intervention was not feasible.”
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNo information provided.
Incomplete outcome data (attrition bias)
All outcomes
Low riskNo women were excluded after randomisation.
Selective reporting (reporting bias)Unclear riskWe did not assess trial protocol.
Other biasLow riskAppears to be free of other sources of bias.

Seattle 1987

MethodsRCT. Randomisation by numbered, sealed envelopes.
Participants

Women at high risk.
Preterm labour (28-32 weeks' gestation), estimated fetal weight 700-1750 g.

Total of 386 women participated with 188 in the CTG group and 188 in the IA group. Assessing birthweights under 1750 g left 122 in the CTG group and 124 in the IA group.

Interventions

Intervention: Continuous CTG with FBS

  • CTG: external until rupture of membranes then internal

  • N = 188 women randomised but 66 excluded from analysis because of low infant birthweight

Comparison: IA

  • N = 188 women randomised but 64 excluded from analyses because of low infant birthweight

Outcomes

Use of tocolytic agents/antenatal glucocorticoids/oxytocin, regional anaesthesia, premature rupture of membranes, CS.

Birthweight, sex of infant, Apgar score 0-3 and 4-10 @ 1 min and @ 5 min, umbilical cord blood gases, intracranial haemorrhage, severe respiratory distress syndrome, seizures, perinatal death.

Overall risk of bias

Moderate risk of bias including unclear risk of bias for random sequence generation and concealment of allocation.

“B”

Notes

Study period: Nov 1981 - Feb 1985.

Subgroups: High risk; mixed onset of labour; preterm; singletons; FBS; mixed parity; unclear quality.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskNo information provided other than ‘Randomization cards’.
Allocation concealment (selection bias)Unclear risk‘ID numbers were consecutive, and to enter a patient the next consecutive envelope was chosen.’ (Luthy 1987).
Blinding of participants and personnel (performance bias)
All outcomes
High riskAlthough not documented, we judged that women and clinicians were not blind to the interventions used.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear risk‘…investigators assessing neurologic development were unaware of the monitoring technique used.’ No information on blinding for other outcomes.
Incomplete outcome data (attrition bias)
All outcomes
High risk130/376 (34%) women were excluded after randomisation because birthweight > 1750 g and authors wished to study babies < 1750 g. Similar proportion of exclusions from each group but we still considered there to be high risk of bias.
Selective reporting (reporting bias)Unclear riskWe did not assess trial protocol.
Other biasLow riskAppears to be free of other sources of bias.

Sheffield 1978

  1. a

    CPAP: continuous positive airways pressure
    CS: caesarean section
    CTG: cardiotocography
    EFM: electronic fetal monitoring
    FBS: fetal blood sampling
    FHR: fetal heart rate
    HIE: hypoxic ischaemic encephalopathy
    IA: intermittent auscultation
    ITT: intention-to-treat
    IV: intravenous
    min: minutes
    NICU: neonatal intensive care unit
    PPH: postpartum haemorrhage
    PROM: preterm rupture of membranes
    RCT: randomised controlled trial

MethodsRCT. Sealed envelopes; randomisation details not described.
Participants

Women with mixed-risk.

Total of 504 women participated.

Interventions

Intervention: Continuous CTG without FBS

  • CTG: internal

  • N = 253

Comparison: IA

  • N = 251

Outcomes

Analgesia/anaesthesia, duration of labour, intra or postpartum pyrexia, length of maternal postpartum stay.

Birthweight, congenital anomalies, length of hospital stay, type of labour onset, CS, instrumental vaginal deliveries, normal deliveries, Apgar score (6 or less @ 1 min), NICU admission (including reasons for admission), hypertonicity, umbilical cord blood gases, perinatal deaths.

Overall risk of bias

Moderate risk of bias including unclear risk of bias for random sequence generation and concealment of allocation.

“B”

Notes

Study period: July 1976 - June 1977.

Subgroups: Low risk; mixed onset of labour; term; singletons; no FBS; mixed parity; unclear quality.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskNo information provided.
Allocation concealment (selection bias)Unclear risk“…allocated a sealed envelope…” It is unclear if these were opaque and numbered sequentially.
Blinding of participants and personnel (performance bias)
All outcomes
High riskAlthough not documented, we judged that women and clinicians were not blind to the interventions used.
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNo information provided.
Incomplete outcome data (attrition bias)
All outcomes
Unclear risk81/565 (14%) of women were excluded but it is unclear if these were before or after randomisation.
Selective reporting (reporting bias)Unclear riskWe did not assess trial protocol.
Other biasLow riskAppears to be free of other sources of bias.

Characteristics of excluded studies [ordered by study ID]

StudyReason for exclusion
  1. a

    CTG: cardiotocography
    EFM: electronic fetal monitoring
    RCT: randomised controlled trial

Harare 1994This randomised study did not include continuous CTG. 4 randomised groups received (i) CTG 10 minutes in every 30 minutes, (ii) Doppler ultrasound monitoring by research midwife, (iii) Pinard stethoscope by research midwife or (iv) routine auscultation by Pinard (last 10 minutes of every 30 minutes).
Ioannina 2001Non-randomised trial; 468 women in labour with cervical dilatation less than 5 cm who were continuously monitored were compared with 346 women in whom CTG monitoring was commenced when cervix was more than 4 cm dilated. According to the trial report the cohort was divided into 2 groups 'according to cervical dilatation'.
Manchester 1982This quasi-RCT of 426 women at low risk was excluded because there were no reported data for the control group.
North America 2000Study design compared CTG with CTG plus continuous fetal pulse oximetry.

Characteristics of studies awaiting assessment [ordered by study ID]

Greece 2012

  1. a

    CTG: cardiotocography
    NICU: neonatal intensive care unit
    RCT: randomised controlled trial

MethodsQuasi-RCT.
ParticipantsWomen in active labour with singleton pregnancy, of at least 36 weeks' gestation, in cephalic presentation.
InterventionsContinuous CTG alone versus continuous CTG plus Doppler.
OutcomesMetabolic acidosis at birth; caesarean section for fetal distress; Apgar score < 7 at 5 minutes; neonatal endotracheal intubation; admission to NICU.
Notes 

Ancillary