Neonatal Outcomes of Pregnancy Following Roux-en-Y Gastric Bypass: a Matched Case-Control Study.

PURPOSE: To compare perinatal outcomes and to assess the predictors of birth weight (BW) after Roux-en-Y gastric bypass (RYGB) to those women unexposed to bariatric surgery. MATERIALS AND METHODS: Singleton births from women submitted to RYGB (BSG) were matched to two control births by maternal age, delivery year, and gender. Control group 1 (CG1) and control group 2 (CG2) were selected according to the prepregnancy body mass index (BMI) /= 35 kg/m(2), respectively, without previous bariatric surgery. RESULTS: Fifty-eight pregnancies were evaluated in each group (n = 174). Neonates born after RYGB presented lower BW compared to CG1 (mean difference - 182.3 g; 95% CI - 333; - 31, P = 0.018) and CG2 (mean difference - 306.6 g, 95% CI - 502; - 111, P = 0.02). Although gestational age (GA) was similar (P = 0.219), fetal growth rate (in grams) per gestational week was higher in CG2 (beta = 196.27, P /= 35 kg/m(2) who had never undergone RYGB.