Objective: To examine whether women who varied from recommended gestational weight gain guidelines by the Institute of Medicine (IOM, now known as the National Academy of Medicine) were at increased risk of severe maternal morbidity during delivery hospitalization compared with those whose weight gain remained within guidelines.
Methods: We conducted a retrospective cohort study using linked 2008-2012 New York City discharge and birth certificate data sets. Cases of severe maternal morbidity were identified using International Classification of Diseases, 9th Revision, Clinical Modification codes based on the Centers for Disease Control and Prevention criteria, which consists of 21 indicators of possible life-threatening diagnoses, life-saving procedures, or death. Multivariable logistic regression was used to evaluate the association between gestational weight gain categories based on prepregnancy body mass index (BMI) and severe maternal morbidity adjusting for maternal demographics and socioeconomic status. The analysis was stratified by prepregnancy BMI categories.
Results: During 2008-2012, there were 515,148 term singleton live births in New York City with prepregnancy weight and gestational weight gain information. In 24.8%, 35.1%, 32.1%, and 8.0% of these births, women gained below, within, 1-19 lbs above, and 20 lbs or more above the IOM guidelines, respectively. After adjusting for maternal demographic and socioeconomic characteristics, women who had gestational weight gain 1-19 lbs above (adjusted odds ratio [AOR] 1.08, 95% CI 1.02-1.13) or 20 lbs or more above the IOM recommendations (AOR 1.21, 95% CI 1.12-1.31) had higher odds of overall severe maternal morbidity compared with women who gained within guidelines. Although the increased odds ratios (ORs) were statistically significant, this only resulted in an absolute rate increase of 2.1 and 6 cases of severe maternal morbidity per 1,000 deliveries for those who gained 1-19 and 20 lbs or more above recommendations, respectively. Women with gestational weight gain 20 lbs or more above recommendations had significantly higher ORs of eclampsia, heart failure during a procedure, pulmonary edema or acute heart failure, transfusion, and ventilation.
Conclusion: Women whose gestational weight gain is in excess of IOM guidelines are at increased risk of severe maternal morbidity, although their absolute risks remain low.