Bariatric surgical procedures reduce the absorption of micronutrients needed for fetal development, increasing the risk of neonatal complications. ASMBS recommends that women avoid conception for 12-18 months after bariatric surgical procedures, yet few studies examine whether maternal and neonatal outcomes differ by time since surgery.


A 6-center prospective cohort study enrolled 135 US adult women (median age, 30 years, BMI, 47.2 kg/m2) who underwent bariatric surgery (2006-2009; 80.7% Roux-en-Y gastric bypass) and reported >=1 post-surgical pregnancy within 7 years. Differences in maternal and neonatal outcomes by conception date (0-<18 versus >=18 months post-surgery) were assessed.


Thirty-nine of 189 of pregnancies occurred <18 months post-surgery. C-section (42.5%) and preterm labor or rupture of membranes (40.9%) were the most common maternal complications, with similar prevalence by postoperative period (see table for outcomes by timeframe). Severe vomiting (13.0%) and pre-term delivery (27.2%) were less common 0-<18 versus >=18 months. The most common neonatal complications were miscarriage (22.6%), large for gestational age (LGA, 23.0%), NICU admission (12.2%), and small for gestational age (SGA, 11.5%). SGA was more common, while LGA and NICU admissions were less common <18 versus >=18 months post-surgery.


Among a large cohort of US women who underwent bariatric surgery, most maternal and neonatal complications were not more common <18 months post-surgery. However, a larger sample size is required to evaluate more refined early post-surgery timeframes and additional factors, such as maternal age and weight changes leading up to and during pregnancy, associated with these complications.