Objective To determine the effect of increasing maternal obesity, including superobesity (body mass index [BMI] >= 50 kg/m(2)), on perinatal outcomes in women with diabetes. Study Design Retrospective cohort study of birth records for all live-born nonanomalous singleton infants >= 37 weeks' gestation born to Missouri residents with diabetes from 2000 to 2006. Women with either pregestational or gestational diabetes were included. Results There were 14,595 births to women with diabetes meeting study criteria, including 7,082 women with a BMI > 30 kg/m(2) (48.5%). Compared with normal-weight women with diabetes, increasing BMI category, especially superobesity, was associated with a significantly increased risk for preeclampsia (adjusted relative risk [aRR] 3.6, 95% confidence interval [CI] 2.5, 5.2) and macrosomia (aRR 3.0, 95% CI 1.8, 5.40). The majority of nulliparous obese women with diabetes delivered via cesarean including 50.5% of obese, 61.4% of morbidly obese, and 69.8% of superobese women. The incidence of primary elective cesarean among nulliparous women with diabetes increased significantly with increasing maternal BMI with over 33% of morbidly obese and 39% of superobese women with diabetes delivering electively by cesarean. Conclusion Increasing maternal obesity in women with diabetes is significantly associated with higher risks of perinatal complications, especially cesarean delivery.
