Does amount of weight gain during pregnancy modify the association between obesity and cesarean section delivery?

BACKGROUND Two-thirds of reproductive-aged women in the United States are overweight or obese and at risk for numerous associated adverse pregnancy outcomes. This study examined whether the amount of weight gained during pregnancy modifies the prepregnancy body mass index (BMI)-cesarean delivery association. METHODS A total of 2,157 women aged 18-45 who participated in the 2008-2009 North Carolina Pregnancy Risk Assessment Monitoring System had complete information on prepregnancy BMI, maternal weight gain, and mode of delivery on infant birth certificates. Logistic regression was used to obtain odds ratios (ORs) and 95 percent confidence intervals (CIs) to model the association between prepregnancy BMI and cesarean delivery, and a stratified analysis was conducted to determine whether maternal weight gain was an effect modifier of the prepregnancy BMI-cesarean delivery association. RESULTS Obese women had 1.78 times the odds of cesarean delivery as compared with women with a normal BMI (95% CI: 1.44-2.16). When adjusted for race/ethnicity, live birth order, household income, and education, the association increased in magnitude and remained statistically significant (OR = 2.01, 95% CI: 1.63-2.43). In stratified analyses, the obesity-cesarean delivery association persisted and remained statistically significant among all maternal weight gain categories. CONCLUSIONS Health care practitioners should stress the importance of achieving a healthy prepregnancy weight and gaining an appropriate amount of weight during pregnancy to reduce the risk of cesarean delivery and other adverse pregnancy outcomes.