Optimal gestational weight gain: prepregnancy BMI specific influences on adverse pregnancy and infant health outcomes

OBJECTIVE: The Institute of Medicine (IOM) 2009 gestational weight gain (GWG) guidelines are based on prepregnancy body mass index (BMI) categories. We intended to refine optimal GWG for each prepregnancy BMI unit in relation to the risk of small- and large-for-gestational-age (SGA and LGA) births, cesarean section (C-section) and infant death. STUDY DESIGN: We used data from 836,841 Ohio birth records from 2006 to 2012, and applied generalized additive models to calculate optimal GWG by prepregnancy BMI unit. RESULTS: The suggested optimal GWG was generally similar to 10M 2009 GWG guidelines for prepregnancy BMIs < 25 kg m(-2), but higher for prepregnancy BMIs 25 to 32 kg m(-2) and lower for BMIs 38 to 50 kg m(-2). The suggested optimal GWG was 14 to 18.5, 13 to 17, 11.5 to 16, 8.5 to 12.5, 4 to 10, 3 to 7, 1.5 to 6 and 1.5 to 4.5 kg for prepregnancy BMIs 15, 20, 25, 30, 35, 40, 45 and 50 kg m(-2), respectively. CONCLUSION: This research suggests that GWG recommendations may be refined at individual prepregnancy BMI levels.