Department of Epidemiology, University of Washington, 325 Ninth Ave, Box 359909, Seattle, WA 98104-2499, USA. jbaeten@u.washington.edu
OBJECTIVES: This study examined the associations between prepregnancy weight and the risk of pregnancy complications and adverse outcomes among nulliparous women. METHODS: We conducted a population-based cohort study with 96,801 Washington State birth certificates from 1992 to 1996. Women were categorized by body mass index. Multivariate logistic regression was performed. RESULTS: The rate of occurrence of most of the outcomes increased with increasing body mass index category. Compared with lean women, both overweight and obese women had a significantly increased risk for gestational diabetes, preeclampsia, eclampsia, cesarean delivery, and delivery of a macrosomic infant. CONCLUSIONS: Among nulliparous women, not only prepregnancy obesity but also overweight increases the risk of pregnancy complications and adverse pregnancy outcomes.