Limiting antenatal weight gain improves maternal health outcomes in severely obese pregnant women: findings of a pragmatic evaluation of a midwife-led intervention

Background Antenatal obesity in pregnancy is associated with complications of pregnancy and poor obstetric outcomes. Although most guidance on pregnancy weight is focused on the prepregnancy period, pregnancy is widely viewed as a period where women are open to lifestyle change to optimise their health. Methods The hospital‐based Bumps and Beyond intervention invited all pregnant women with a body mass index (BMI) >35 kg m−2 to take part in a programme of health education around diet and exercise, accompanied by one‐to‐one guidance and monitoring of dietary change. This service evaluation compares 89 women who completed at a programme of seven sessions with healthy lifestyle midwives and advisors (intervention) versus a group of 89 women who chose not to attend (non‐intervention). Results Mean (SD) weight gain in the intervention group [4.5 (4.6) kg] was less than in the non‐intervention group [10.3 (4.4) kg] between antenatal booking and 36 weeks of gestation (< 0.001). This was associated with a 95% reduction in the risk of gestational hypertension during pregnancy and a general reduction in pregnancy complications. There was no effect of the intervention upon gestational diabetes or complications in labour other than post‐partum haemorrhage (reduced by 55%). The impact of the intervention on gestational weight gain was greater in women with BMI >40 kg m−2 at booking. There were no adverse effects of the intervention, even though 21% of the intervention group lost weight during their pregnancy. Conclusions Intensive, personalised weight management intervention may be an effective strategy for the prevention of hypertensive disorders during pregnancy.