Gestational weight gain and postpartum weight retention after bariatric surgery: data from a prospective cohort study

Background It is unknown whether international guidelines on gestational weight gain can be used in pregnancies after bariatric surgery. Objectives To investigate gestational weight gain, intrauterine growth, and postpartum weight retention in postbariatric women. Setting 8 Belgian hospitals. Methods Prospective data from 127 postbariatric pregnancies from September 2014 through October 2018. Patients were grouped according to achievement of 2009 Institute of Medicine (IOM) guidelines. Results In 127 patients with a mean age of 30.2 years (standard deviation [SD], 4.7), the mean gestational weight gain was 12.5 kg (SD, 6.7). Of these patients, 24% (30 of 127) showed insufficient weight gain, 20% (26 of 127) showed adequate weight gain, and 56% (71 of 127) showed excessive weight gain. Of 127 patients, 27 (21%) had small-for-gestational-age infants. This peaked in the group with insufficient weight gain (47%; 95% confidence interval [CI], 29%–65%; P < .001). The prevalence of large-for-gestational-age infants was comparable between groups, although highest in the group with excessive weight gain (0% in those with insufficient weight gain, 4% in those with adequate weight gain, and 8% in those with excessive weight gain). Preterm births were recorded more in patients with insufficient weight gain (23%; 95% CI, 8%–38%; P = .048). The mean amounts of postpartum weight retained were 4.0 kg (SD, 7.4) at 6 weeks and 3.0 kg (SD, 9.1) at 6 months. Weight retention at 6 weeks (7.1 kg; 95% CI, 5.5–8.7; P < .001) and 6 months (8.3 kg; 95% CI, 4.5–12.2; P < .001) was highest in women gaining excessive weight. Conclusion Achievement of IOM guidelines is low in postbariatric pregnancies. Insufficient weight gain increases the risk for small-for-gestational-age babies. Excessive weight gain increases weight retention after delivery and could precipitate weight regain. After bariatric surgery, women should be encouraged to achieve IOM recommendations.