- Objective To compare the perinatal outcomes of women who delivered before with women who delivered after bariatric surgery. Methods A retrospective study was undertaken to compare perinatal outcomes of women who delivered before with women who delivered after bariatric surgery in a tertiary medical center between 1988 and 2006. A multivariate logistic regression model was constructed to control for confounders. Results During the study period, 301 deliveries preceded bariatric surgery and 507 followed surgery. A significant reduction in rates of diabetes mellitus (17.3% vs 11.0; P = 0.009), hypertensive disorders (23.6% vs 11.2%; P < 0.001), and fetal macrosomia (7.6% vs 3.2%; P = 0.004) were noted after bariatric surgery. Bariatric surgery was found to be independently associated with a reduction in diabetes mellitus (OR 0.42, 95% CI 0.26–0.67; P < 0.001), hypertensive disorders (OR 0.38, 95% CI 0.25–0.59; P < 0.001), and fetal macrosomia (OR 0.45, 95% CI 0.21–0.94; P = 0.033). Conclusion A decrease in maternal complications, such as diabetes mellitus and hypertensive disorders, as well as a decrease in the rate of fetal macrosomia is achieved following bariatric surgery.