A retrospective comparative study of antenatal healthy lifestyle service interventions for women with a raised body mass index

Background: Women with obesity are more likely to gain excessive gestational weight; with both obesity and excessive weight gain linked to adverse outcomes for mothers and their infant. Provision of antenatal healthy lifestyle services is currently variable, with uncertainty over the most effective gestational healthy lifestyle interventions. Aim: To compare pregnancy and birth outcomes among women who experienced an antenatal health lifestyle service with a cohort who did not receive this service. Methods: A retrospective comparative cohort study was undertaken in women with a BMI >= 40 kg/m2 attending maternity care in two NHS Trusts. One Trust provided an antenatal healthy lifestyle service, while the comparison Trust provided routine maternity care. Data was collected from medical records. Findings: No differences were observed between the antenatal healthy lifestyle service and comparison cohorts for average gestational weight gain [adjusted mean difference (aMD) - 0.70 kg (95%CI -2.33, 0.93)], rate of weight gain [aMD - 0.02 kg/week (95%CI -0.08, 0.04)] or weight gain in accordance with recommendations. The proportion of women breastfeeding at discharge was higher for the antenatal healthy lifestyle service than the comparison cohort (42.4% vs 29.8%). No other clinical outcomes were enhanced with the antenatal healthy lifestyle service. Conclusion: Internal audit had suggested the antenatal healthy lifestyle service was successful at managing gestational weight gain in women with a BMI >= 40 kg/m2. However, no benefit on gestational weight gain was evident once the service was evaluated against a comparison cohort with adequate adjustment for confounders. It is essential that future services are evaluated against a relevant comparison group.