Effect of Second-Trimester and Third-Trimester Rate of Gestational Weight Gain on Maternal and Neonatal Outcomes

OBJECTIVE: To estimate the effect of second- and third-trimester rate of gestational weight gain on pregnancy outcomes using the revised Institute of Medicine guidelines. METHODS: This is a retrospective cohort study of singleton live births in upstate New York between January 2004 and December 2008. Women were grouped by prepregnancy body mass index (BMI) and rates of second- and third-trimester gestational weight gain were calculated. Women were then classified as having less than, within, or greater than recommended rates of gain. Maternal and neonatal outcomes were assessed based on rate of weight gain within each BMI class. RESULTS: Of 73,977 women meeting inclusion criteria, 4% were underweight, 48% normal weight, 24% overweight, and 24% obese: 13% class I, 6% class II, and 5% class III, respectively. After controlling for potential confounding variables, less than recommended rates of second- and third-trimester weight gain were associated with increased odds of small-for-gestational-age neonates in all BMI groups except obese classes II and III. Greater than recommended rates of weight gain were associated with increased odds of large-for-gestational-age neonates in all BMI groups and increased odds of cesarean delivery in all BMI groups with the exception of underweight and obese class III women. CONCLUSION: Suboptimal second-and third-trimester rates of gestational weight gain in the most obese women, even with net weight loss, do not increase the odds of small-for-gestational-age neonates. Excessive rates of gestational weight gain increase the odds of large-for-gestational-age neonates regardless of BMI.