pregnancy and weight monitoring: A feasibility study of weight charts and midwife support

Abstract Around half of pregnant women in the United Kingdom are overweight or obese. The antenatal period provides an opportunity for encouraging women to adopt positive lifestyle changes, and in recent years, this has included development of strategies to support women in avoiding excessive gestational weight gain. The objective of this interventional cohort study was to incorporate individualised gestational weight monitoring charts supported by motivational interviewing (MI)‐based conversations into midwifery‐led antenatal care and assess potential of the intervention for further development and evaluation. The study setting was a community midwifery team within a large maternity unit. The study explored the facilitators and barriers to engagement with the intervention as experienced by women and midwives; 52 women were recruited, of whom 48 were included in the analysis. A single training session was found adequate to prepare midwives to use antenatal weight charts but was insufficient to result in the incorporation of motivational interview techniques into clinical practice. We did not find sufficient evidence to recommend effectiveness testing of this intervention, and there is currently insufficient evidence to support reintroducing regular weighing of pregnant women into UK antenatal care. Given the public health importance of reducing rates of obesity, future interventions aimed at controlling gestational weight gain should continue to be developed but need to include innovative strategies particularly for women who are already obese or gain weight above that recommended.


| INTRODUCTION
Rates of obesity amongst women of child-bearing age in developed countries have increased steadily since the 1980s, and the public health concern regarding gestational weight gain has shifted from the postwar concern of inadequate nutrition to one of excess weight gain.
In the United Kingdom, around half of women commence pregnancy overweight or obese (Euro-Peristat Project, 2018), with the United Kingdom having the highest rates of maternal obesity in Europe (Devlieger et al., 2016). Women who are obese (with a body mass index [BMI] of 30 or over) are at a greater risk of complications in the antenatal, intrapartum and postnatal periods (Bakun, Karatieieva, Semenenko, Yurkiv, & Berbets, 2018), and excess gestational weight gain is associated with postnatal weight retention (Begum, Colman, McCargar, & al., 2012;Endres et al., 2015) and longer term adverse maternal health effects (Valgeirsdottir et al., 2019).
The development of interventions to help women avoid excessive gestational weight gain is a UK public health priority (National Institute for Health and Clinical Excellence, 2010). Women also expect their weight to be monitored during pregnancy (Daley et al., 2015) and believe it to be beneficial (Allen-Walker et al., 2017). Global recommended practice on the regularity of weighing pregnant women varies (Scott et al., 2014). Since 1992, US guidance has identified recommended gestational weight gain ranges based on early pregnancy BMI (Institute of Medicine, 1992Medicine, , 2009) (American College of Obstetricians and Gynecologists, 2013) and encourages regular antenatal weight monitoring. In contrast, in the United Kingdom (National Institute for Health and Clinical Excellence, 2003), regular antenatal weighing is not recommended due to a lack of evidence of effectiveness. Instead, care is focused on providing women with information on the risks of obesity and excess gestational weight gain, together with information on healthy diet and exercise (Denison et al., 2018; National Institute for Health and Clinical Excellence, 2010).

Antenatal interventions targeting diet and exercise in pregnancy
have demonstrated modest effectiveness in supporting women to avoid excess gestational weight gain (Muktabhant, Lawrie, Lumbiganon, & Laopaiboon, 2015) and are worthy of further exploration. Weight charts, supported by information on healthy diet and exercise in pregnancy, have been shown to be feasible in the context of US (Aguilera, Sidebottom, & McCool, 2017) and UK (Daley et al., 2015) antenatal care, but a recent high-quality randomised trial did not demonstrate effectiveness in influencing gestational weight gain (Daley et al., 2019).
A systematic review in a UK service context (Johnson, 2013) highlighted the need for good quality midwifery communication skills in order for a collaborative conversation to take place. Women reported struggling to make sense of the inconsistent and vague information they were given relating to gestational weight gain, and midwives who are themselves overweight may find this as a barrier to them discussing weight with women (Foster & Hirst, 2014).
One approach to enhancing communication is the use of motivational interviewing (MI), a client-centred approach to communication, which can help engage people with making positive behavioural changes (Miller & Rollnick, 2012). Dealing with ambivalence about behaviour change and building motivation are central to MI, and health care professionals have found it helpful when communicating with obese pregnant women around weight-related issues (Lindhardt et al., 2015). Brief interventions around weight control have been effective in primary care settings (Aveyard et al., 2016), which have similar time restriction barriers to potential public health interventions as antenatal clinics (Daley et al., 2015).
The existing evidence indicates that further enhancement of interventions is still required to support more women avoid excess gestational weight gain. In this study, we aimed to contribute to this goal by creating an innovative intervention, which combined individualised weight charts with supportive MI conversations with community midwives, focused on monitoring gestational weight in a way that was sensitive to the woman's needs.

| Aim
The study's aim was to incorporate individualised gestational weight monitoring charts supported by MI-based conversations into midwifery-led antenatal care and assess if the intervention is worthy of further development and evaluation.

| Objectives
The study objectives were to

Key messages
• Brief MI training for midwives is insufficient to result in incorporation of discussions of maternal weight into antenatal care.
• Weight charts are acceptable to women but currently lack evidence as an effective method of supporting women achieve a healthy gestational weight gain.
• More complex interventions aimed at supporting pregnant women maintain a healthy weight are required, including interventions appropriate for women who have obesity and pregnant women who gain more weight than recommended.

| Intervention
The intervention combined (a) an individualised weight chart for use by participants at home or in the clinic with (b) support from their community midwife who had received training in an MI approach for engaging in conversations relating to monitoring and managing weight gain during pregnancy. The weight chart intervention was developed in conjunction with a lay advisory group of six recently pregnant women who informed the chart design and content. The study was approved by the National Health Service (NHS) Ethics Committee 16/ WA/0221.

| Sample size
An a priori sample size of 50 women was calculated to enable the study to estimate a chart usage rate to 36 weeks gestation of 80% to within 95% confidence interval of ±11%. An estimated attrition rate of 20% to 36 weeks gestation was based on a rate of 6% premature births (Office of National Statistics, 2015) and the remainder being those without a recorded weight at or beyond 36 weeks. A sample of 50 women would allow us to estimate the proportion of women who had gained an appropriate amount of gestational weight at 36 weeks, identified as a primary outcome for a future effectiveness trial.

| Recruitment and participation
Women registering their pregnancy with their general practitioner between 27 January and 7 June 2017 and who would receive care from a single community midwifery team received written information about the study when they first attended the surgery.
Women were eligible for inclusion if they were aged over 18 years, had a singleton viable pregnancy of ≤16 weeks gestation confirmed on ultrasound scan, were able to provide informed consent and could communicate clearly in English. Women were ineligible to participate if they were receiving current treatment for a mental health disorder or had an existing medical or obstetric condition that required hospital-based antenatal care.
Community-based midwives discussed the study with women at their initial antenatal booking appointment. At around 10-12 weeks gestation, women attended a hospital-based appointment including an ultrasound scan, baseline weighing and calculation of BMI. Interested women were provided with a further opportunity to ask questions prior to providing written informed consent obtained by a study midwife. An individualised weight chart was printed and incorporated into the woman's hand-held maternity notes, and women were instructed by a study midwife on its use, including how to record weight on the table and graph.
The weight charts included information on usage. The text suggested participants to record their weight on the chart or table up to once a week. A table was also provided for women to record their weight for later plotting by their midwife. A standard set of bathroom scales was offered to all participants.

| Data collection: Quantitative
Once the participant gave birth, the weight chart was copied for analysis, including the number of weight entries and whether the woman, at 36 weeks gestation was within the recommended healthy weight range. The following socio-economic and obstetric baseline data were extracted from maternity notes of participants following birth: ethnicity, age, gestational age at recruitment, weight, height, BMI, comorbidities and parity. Comparative characteristics of all women receiving care at the recruitment site were extracted from the maternity information system.

| Interviews with women
From 36 weeks gestation, women who had consented to being contacted were invited by phone to participate in an interview to discuss their views on the intervention. Prior to the telephone contact, a midwife researcher checked if the woman had given birth and whether there were any serious pregnancy complications an interviewer should be made aware of. Appointments were made to interview the participant at a convenient time and location. Written consent, including for audio recording and the incorporation of direct quotes in reporting, was obtained prior to interviews. Interviews were conducted either face to face or by telephone by experienced qualitative researchers.

| Focus group with midwives
A focus group was conducted with participating community midwives to explore their experiences of the charts and in engaging in MI conversations with women around weight gain in pregnancy, led by an experienced qualitative researcher (SC). Views on the utility, feasibility and acceptability of the weight chart were explored, and any training or preparation needs were identified. Written consent, including for audio recording and the incorporation of direct quotes in reporting, was obtained from midwives before participation.

| Data analysis
Quantitative data were analysed using SPSS version 25. Participant characteristics were described using summary statistics: number and proportion and mean alongside standard deviation. Chart usage and the proportion of women reaching 36 weeks gestation within a healthy weight gain was described.
Interviews were transcribed verbatim by independent professional transcribers. The analysis of participant interview data was subjected to thematic analysis and coded, supported by Nvivo software, by an experienced qualitative researcher not involved in data collection (EC). Themes and codes were subsequently collated to form a comprehensive picture of collective experiences and views regarding the intervention. A random selection of transcripts was coded by a second researcher to check for consistency. The analytical process was undertaken in a way that ensured that the integrity of the original transcripts remained intact.
Data from the focus group were subjected to thematic analysis using the same methods and this provided details of midwives' views on the utility, acceptability and impact of the intervention and how the intervention might be adapted for more routine clinical use and any additional training needs required.

| Ethical considerations
The PRAM study was approved by the NHS Ethics Committee 16/WA/0221.

| Quantitative results
During the recruitment period, 218 women booked for maternity care with the participating team of community midwives, of whom 52 (24%) were recruited into the study at a mean of 12.3 weeks gestation (range 10-16 weeks, SD = 1.2), with a mean BMI of 29.51 (SD = 5.13).  Four women were withdrawn from the study as they moved out of the area (n = 2) or due to mid-trimester pregnancy loss (n = 2) ( Figure 1)

| Qualitative findings
Individual interviews were conducted with 15 participants, at which time no new issues were being raised and no further participants were invited to interview. Participants were satisfied with study information and appreciated the relaxed approach taken by recruiting midwives. Women cited several reasons for taking part: self-interest in their gestation weight gain, altruistic reasons, the lack of burden involved and the incentive of weighing scales.

| Weight management
Women were asked about gestational weight gain including motivators and the barriers that restricted healthy eating and exercise.
Some participants chose a healthy diet during pregnancy to provide the baby with the 'best start in life'. Other participants were motivated to limit risk factors for pregnancy-related conditions such as gestational diabetes and to be within eligibility criteria for a midwife-led birth centre. Others expressed a fear of gaining excessive gestational weight gain due to a history of struggles with personal weight.

| Practicalities of using the chart
Most women valued the visual aspect of the chart, but some experienced difficulties in accurately marking their weight and others would have preferred the charts to have used imperial rather than metric units. The

| Chart as a motivator
The extent to which the weight chart acted as a motivator or reassurance varied between women, some stating that study participation impacted their health behaviours and others using the information to inform family members.
I was more careful in what I was eating, because I didn't want to put on a lot in a week and I didn't want to see myself going higher and higher and higher, so yeah definitely, I was definitely more mindful about what I was eating. (93) And when I've got my mum nagging me, telling me, "Oh, you shouldn't eat that, you're going to put on weight," I can say, "Well actually, I don't think I'm putting on an unreasonable amount of weight." (49) Women suggested that in addition to monitoring weight gain on the chart, incorporating it into an app or providing additional support, such as a physical activity intervention, would be beneficial.
I guess I would have been interested if there had been some classes or something I probably would have come along for a bit more physical activity. (18) I think when it comes to mapping it on the chart, if it was done in an app or online, that would be quite nice.
Because it would be that bit easier than having to kind of map it out. (08)

| Weight management as a component of antenatal care
Although some midwives monitored whether participants were weighing themselves and recording their weights on the study charts, discussions regarding gestational weight gain in pregnancy appeared to be initiated by the participants or prompted when women were weighed as part of routine antenatal care at 36 weeks gestation.
According to the women, most midwives appeared not to assume their study role in initiating discussions regarding weight gain. Of the discussions that women reported, which followed excess gestational weight, midwives appeared to take on a reassuring rather than advisory role.
How's it going with the PRAM study? Are you still weighing yourself? …So she's asked me those questions but she hasn't really discussed weight with me.

| Midwives' views
To explore midwives' experiences of the intervention, a focus group was conducted with six of the nine of the midwives, who were able to attend at the prearranged time. An additional midwife, who was unable to attend the focus group, was interviewed separately.
Future randomised trials need to incorporate other potential ways of making midwifery-led discussion around antenatal weight more effective. Also, to increase confidence to start weight-related discussions, midwives need ways to identify excess fat gain separate from oedema (Widen & Gallagher, 2014) and access to evidence-based interventions to recommend to women gaining above that recommended.
Weight management, both within and outside of pregnancy, is multifactorial (National Institute for Health and Clinical Excellence, 2010), and it is likely that having a range of options available to woman to provide support prior to, during or following birth may have the greatest overall effect in reducing pregnancy-related excess weight gain on a population level.
This study had important limitations: the 3-h MI training session was designed to be deliverable within an NHS service, represented minimal training on the subject and may have been ineffective for this reason. Although the weight chart was incorporated into the notes of participants at recruitment, some participants opted to remove the chart for home use, reducing the opportunity for review and discussion of weight gain by midwives during antenatal check-ups.

| CONCLUSION
We found antenatal weight charts to be acceptable to women, but a single MI training session was insufficient to result in the incorporation of motivational interview techniques into antenatal care. Previous trials with differing approaches to the use of gestational weight charts have not demonstrated effectiveness (Brownfoot et al., 2016;Fealy et al., 2017;Jeffries et al., 2009;McCarthy et al., 2016), and results of this study did not suggest that the brief MI training provided to midwives, when added to the intervention of gestational weight charts, would be sufficient to yield more positive results. Although there is currently insufficient evidence to support reintroducing regular weighing of pregnant women into UK antenatal care, given the public health importance of reducing rates of obesity, future interventions aimed at controlling gestational weight gain should continue to be developed. Future interventions should include innovative strategies for women who commence pregnancy obese or gain weight above that recommended.