Background: Excess gestational weight gain (GWG) is common and has adverse maternal and infant outcomes including increased gestational diabetes. This trial aimed to demonstrate effectiveness of lifestyle intervention on reducing excess GWG and to explore implementation across intervention uptake and adherence in routine care.
Methods: This pragmatic controlled implantation-effectiveness trial was conducted in a tertiary hospital maternity service. Participants included women with pre-pregnancy BMI of 35-43kg/m² at risk of excess GWG, recruited before the 23rd week of gestation. The intervention group attended routine antenatal care with an integrated behavioural lifestyle intervention delivered by a health coach and an endocrinologist in a total of five visits. Women who developed endocrine complications (gestational diabetes, thyroid disease) were treated within the service, simplifying their treatment plan. The comparison group was existing standard of care.
Results: 277 women were studied: 157 in intervention, 120 in standard care. The intervention did not result in a difference in proportion of women who gained excessive GWG above IOM recommendations, 32% of intervention and 33% of standard care exceeding (p=0.91). There was a reduction in total GWG (-1.4 (95% CI -2.6,-0.1),p=0.04 adjusted bootstrap), also significant when excluding for women who developed GDM (-2.0 (95% CI -4.0,-0.2),p=0.03 adjusted). Mean GWG/week was also lower in intervention group (0.32kg/wk vs 0.37 kg/wk, p=0.02, adjusted). Intervention uptake was 95% and 87% attended 4 of 5 sessions.
Conclusion: Lifestyle intervention embedded in routine antenatal care for obese women lowered total GWG and GWG/week, although the proportion of pregnancies with excessive GWG was similar in both groups. Intervention uptake and engagement rates were high. This pragmatic trial of lifestyle implementation into pregnancy care is important in the context of new national guidelines recommending GWG control. Lower intensity intervention studies for non-obese women are underway across multiple services, states and countries, as are cost-effectiveness analyses.