Combined Effects of Pre-pregnancy Body Mass Index and Weight Gain During Pregnancy on the Risk of Infant Death

More than 28,000 U.S. babies die before their first birthday each year. Programmatic and Policy focus on prematurity and birth weight stem largely from their known relationship to infant mortality and morbidity. A large body of literature exists linking poor gestational weight gain to prematurity and low birth weight, but few studies have examined infant death as an important pregnancy outcome of inadequate gestational weight gain. As a measure of healthy gestational weight gain, the Institute of Medicine (IOM) published guidelines which provide a recommended weight gain for each category of pre-pregnancy Body Mass Index. Using data from the Pregnancy Risk Assessment Monitoring System in 35 states and New York City, we investigated the association between the 2009 IOM guidelines and infant death by maternal pre-pregnancy body mass index (BMI) among 160,111 women who delivered a singleton infant from 2004-2008. Descriptive and logistic regression analyses were used to assess the risk of infant mortality associated with inadequate gestational weight gain compared to normal weight gain. Nearly 25% of women experienced inadequate weight gain. Infants born to women with inadequate gestational weight gain had odds of infant death that were 1.61 times (p<0.0001, 95% Confidence Interval: 1.29, 1.99) the odds for infants born to women with normal weight gain. Increased odds remained after adjustment for gestational age, low birth weight, parity, maternal age, maternal education, prenatal care, maternal race, marital status, diabetes, hypertension, tobacco use, and alcohol consumption. There is a significant association between inadequate gestational weight gain and infant death.