Differing intensities of a midwife-led antenatal healthy lifestyle service on maternal and neonatal outcomes: A retrospective cohort study.

Introduction Maternal obesity and excessive gestational weight gain are associated with adverse maternal and neonatal outcomes. There is uncertainty over the most effective antenatal healthy lifestyle service, with little research determining the impact of different lifestyle intervention intensities on pregnancy outcomes. Method This retrospective cohort study compared pregnancy and birth outcomes in women with a body mass index of 40 or above who were offered a low intensity midwife-led antenatal healthy lifestyle service (one visit) with women who were offered an enhanced service (three visits). The primary outcome was gestational weight gain. Results There were no differences between the two healthy lifestyle service intensities (N=682) in the primary outcome of mean gestational weight gain [adjusted mean difference (aMD) -1.1kg (95% CI -2.3 to 0.1)]. Women offered the enhanced service had lower odds of gaining weight in excess of Institute of Medicine recommendations [adjusted odds ratio (aOR) 0.63 (95% CI 0.40-0.98)] with this reduction mainly evident in multiparous women. Multiparous women also gained less weight per week [aMD -0.06kg/week (95% CI -0.11 to -0.01)]. No overall beneficial effects were seen in maternal or neonatal outcomes measured such as birth weight [aMD 25g (95% CI -71 to 121)], vaginal birth [aOR 0.87 (95% CI 0.64-1.19)] or gestational diabetes mellitus [aOR 1.42 (95% CI 0.93-2.17)]. However, multiparous women receiving the enhanced service had reduced odds of small for gestational age [aOR 0.52 (95% CI 0.31-0.87)]. This study was however underpowered to detect differences in some outcomes with low incidences. Discussion Uncertainty remains over the best management of women with severe obesity regarding effective interventions in terms of intensity. It is suggested that further research needs to consider the different classes of obesity separately and have a particular focus on the needs of nulliparous women given the lack of effectiveness of this service among these women.