Observational studies suggest that minimal gestational weight gain (GWG) may optimize pregnancy outcomes for obese women. This trial tested the efficacy of a group-based weight management intervention for limiting GWG among obese women.


One hundred and fourteen obese women (BMI [mean ± SD] 36.7 ± 4.9 kg/m2) were randomized between 7 and 21 weeks' (14.9 ± 2.6) gestation to intervention (n = 56) or usual care control conditions (n = 58). The intervention included individualized calorie goals, advice to maintain weight within 3% of randomization and follow the Dietary Approaches to Stop Hypertension dietary pattern without sodium restriction, and attendance at weekly group meetings until delivery. Control participants received one-time dietary advice. Our three main outcomes were maternal weight change from randomization to 2 weeks postpartum and from randomization to 34 weeks gestation, and newborn large-for-gestational age (birth weight >90th percentile, LGA).


Intervention participants gained less weight from randomization to 34 weeks gestation (5.0 vs. 8.4 kg, mean difference = −3.4 kg, 95% CI [-5.1-1.8]), and from randomization to 2 weeks postpartum (−2.6 vs. +1.2 kg, mean difference = −3.8 kg, 95% CI [-5.9-1.7]). They also had a lower proportion of LGA babies (9 vs. 26%, odds ratio = 0.28, 95% CI [0.09-0.84]).


The intervention resulted in lower GWG and lower prevalence of LGA newborns.