Effects on postpartum weight retention after antenatal lifestyle intervention - a secondary analysis of a randomized controlled trial.

High weight retention after pregnancy is related to an increased risk of future obesity. The objective was to evaluate if an antenatal intervention, compared to standard care, could reduce postpartum weight retention (PPWR).Women with body mass index >19, age ≥18 years, knowledge of Swedish, and pregnancy ≤16 weeks' gestation were randomized. Standard care was compared to a composite intervention including a personalized weight graph, education on recommended weight gain, prescription of exercise, and monitoring of weight until one year after delivery. Mean (kg) PPWR was compared between the groups and risk estimates (odds ratio) for excessive weight retention were calculated.Of 445 women randomized, 267 remained for analysis at ≤16 weeks postpartum and 168 at one year postpartum. The intervention group had a significantly lower mean PPWR at ≤16 weeks (1.81 kg (standard deviation, SD, 4.52) vs. 3.19 kg (SD 4.77), p=0.016). At one year postpartum, mean retention was still 0.7 kg lower in the intervention group (0.30 kg (SD 5.52) vs. 1.00 kg (SD 5.46)), the difference was not statistically significant (p=0.414). Gestational weight gain above Institute of Medicine recommendations was a significant risk factor for excessive weight retention (>5 kg) one year after delivery (OR 2.44; 95% CI; 1.08-5.52, p=0.029).A composite lifestyle intervention during pregnancy reduced short-term weight retention, but the effect of the intervention did not remain at one year postpartum. A gestational weight gain above Institute of Medicine recommendations increases the risk of excessive long-term weight retention. This article is protected by copyright. All rights reserved.