Maternal obesity, associated complications and risk of prematurity

Objective: We aimed at (a) examining the rates of obesity over a 12-year period; (b) studying the effect of obesity and morbid obesity on gestational age and birth weight and (c) determining the influence of race on the association between maternal obesity and the gestational age of a newborn. Study Design: We conducted a retrospective analysis using data from the perinatal data set of mothers delivering at the George Washington University between 1992 and 2003. We stratified mother/infant pairs (n - 14 183) into three groups on the basis of maternal prepregnancy body mass index (BMI): not obese (BMI<30), obese (BMI 30 to 39) and morbidly obese (BMI >= 40). We identified all spontaneous and induced preterm deliveries in each group. Bivariate and multivariate analyses were conducted to control for significant differences between groups. Result: We identified obesity in 1707 (12%) and morbid obesity in 415 (3%) of the mothers. Obesity and morbid obesity increased over time during the study period. In crude analysis, mothers with obesity and morbid obesity were more likely to deliver prematurely (16.7 and 20.3%, respectively) when compared with nonobese women (14.5%), and were also more likely to have other complications including smoking, anemia, hypertension, diabetes and cesarean delivery. When controlling for these complications in a logistic regression model, obesity and morbid obesity were not associated with prematurity. Conclusion: There is no direct link between obesity and prematurity. Prematurity is more likely caused by medical complications that frequently occur in obese women. Further studies are needed on this growing population to test whether providing adequate prenatal care can control the associated medical conditions and subsequently ameliorate the rate of prematurity. Journal of Perinatology (2010) 30, 447-451; doi: 10.1038/jp.2009.117; published online 20 August 2009