NHS Maternity Care for Women with a Body Mass Index of 30 kg/m2 or Above: Births between 1 April 2015 and 31 March 2017 in England, Wales and Scotland.

Introduction This report focuses on the maternal and neonatal outcomes of pregnant women with body mass index (BMI) of 30 kg/m2 or above who gave birth between 1 April 2015 and 31 March 2017, compared with those of women with BMI in the range 18.5–24.9 kg/m2 . Methods This study uses existing NMPA linked datasets to explore the characteristics and outcomes of women and babies according to category of maternal BMI at booking with the maternity service provider. Women are grouped by BMI according to established World Health Organization (WHO) categories. The association between maternal BMI and each maternal or neonatal measure is represented using line graphs, stratified by maternal parity (nulliparous, multiparous with previous vaginal births only, multiparous with a previous caesarean birth). We also explored the feasibility of stratifying the outcomes according to the woman’s risk status at the time of labour and birth (as defined by the National Institute of Health and Care Excellence (NICE) Intrapartum Care for Healthy Women and Babies guideline). Finally, we described the type of maternity units in which the women gave birth, by maternal BMI. A lay advisory group was involved at all stages of this sprint audit, including discussing the choice of outcomes, interpreting the results, and reviewing the draft report and recommendations.

Key findings For the period 1 April 2015 to 31 March 2017, we estimate that 21.8% of women giving birth had a BMI of 30 kg/m2 or above; however, 16.9% of women did not have a BMI (or height and weight) recorded. The likelihood of a woman experiencing an intrapartum intervention or adverse maternal outcome, or her baby experiencing very serious complications following birth, increases as BMI increases. We do not know whether this is because women with higher BMI are more likely to develop complications requiring intervention or because of differences in the clinicians’ threshold to intervene. However, those women with a BMI of 30 kg/m2 or above who have previously had at least one vaginal birth (and no caesarean births) are almost as likely to have another unassisted vaginal birth as multiparous women with a BMI in the range 18.5–24.9 kg/m2 who have also not previously had a caesarean birth. Babies born to women with a BMI of 30 kg/m2 or above are less likely to receive skin-to-skin contact within 1 hour of birth or breast milk for their first feed than babies born to women with a lower BMI. The proportion of women giving birth in a freestanding midwifery unit, or at home, decreases as BMI increases, although 1.7% of women with a BMI of 35.0–39.9 kg/m2 and 1.1% of women with a BMI of 40 kg/m2 or above did give birth in one of these settings. The lay advisory group requested that we also measure access to birth in water, monitoring of fetal growth by ultrasound, access to perinatal mental health services and prevention of venous thromboembolism in women with a BMI of 30 kg/m2 or above. We currently do not have sufficient information in the NMPA dataset to assess these. Presentation of maternal or neonatal outcomes by maternal BMI, parity and risk status (as assessed at admission for birth) is both feasible and likely to be useful to support informed decision making. It is limited by uncertainty with less common outcomes (particularly those indicating poor condition of the baby at birth), more so when these are estimated in smaller groups of women.

Recommendations R1 Audit local rates of missing data on BMI (or height and weight) before the end of the 2021/22 reporting year, and commence local initiatives to improve electronic recording of this where it is low. (Audience: Maternity service providers) R2 Commence by the end of June 2023 the production of, or include in updates to existing documents, detailed guidance on the antenatal and intrapartum care offered to women who are suspected to have a large-for-gestational-age baby, including whether the guidance should differ for women with a BMI of 30 kg/m2 or above. (Audience: National organisations responsible for publishing guidance on maternity care) R3 Support research and investigation into why women with a BMI of 30 kg/m2 or above have a higher risk of stillbirth, in order to inform clinical care which aims to reduce this risk. (Audience: National Institute for Health Research, Health and Care Research Wales and NHS Research Scotland in consultation with the Royal College of Obstetricians and Gynaecologists and policy makers, service planners/commissioners, service managers and healthcare professionals working for maternity services) R4 Ensure that women with a BMI of 30 kg/m2 or above are given preconception and antenatal information tailored to their individual circumstances (including their BMI and whether this is their first birth or they have previously had a caesarean birth). To support women in their decision making, this should include information from this report on their risk of the following: ● birth interventions ● major postpartum blood loss ● postnatal readmission to hospital ● very serious complications for their baby following birth. (Audience: Healthcare professionals working in maternity services, general practitioners) R5 Identify common causes for readmission to the maternity unit following birth specifically for women with a BMI of 40 kg/m2 or above, and commence local quality improvement initiatives to reduce the risk of readmission. (Audience: Maternity service providers) R6 Support all women and babies to experience skin-to-skin contact with one another within 1 hour of birth should they choose to and regardless of the woman’s BMI, unless it is unsafe to do so because either the woman or baby requires immediate medical attention. (Audience: Healthcare professionals working in maternity services) R7 Offer all women breastfeeding information and support during pregnancy and again shortly after the birth. Women with a BMI of 30 kg/m2 or above may require support to be tailored to their specific needs and to be provided by a healthcare professional who is trained to adapt breastfeeding techniques for women with a higher BMI. (Audience: Healthcare professionals working in maternity services) R8 Incorporate information on antenatal assessment of fetal growth status (suspected SGA or LGA) and on venous thromboembolism risk scores and prophylaxis in future trust/board and national maternity dataset specifications. (Audience: Maternity service providers, the Data and Intelligence Division of Public Health Scotland, the National Welsh Informatics Service) R9 Assess the quality of data on labour or birth in water, and where completeness is low, commence initiatives to improve it. (Audience: Maternity service providers)