Abstract
OBJECTIVE: Assessment of the joint and independent relationships of gestational weight gain and prepregnancy body mass index (BMI) on risk of infant mortality was performed. METHODS: This study used Pennsylvania linked birth-infant death records (2003-2011) from infants without anomalies born to mothers with prepregnancy BMI categorized as underweight (n = 58,973), normal weight (n = 610,118), overweight (n = 296,630), grade 1 obesity (n = 147,608), grade 2 obesity (n = 71,740), and grade 3 obesity (n = 47,277). Multivariable logistic regression models stratified by BMI category were used to estimate dose-response associations between z scores of gestational weight gain and infant death after confounder adjustment. RESULTS: Infant mortality risk was lowest among normal-weight women and increased with rising BMI category. For all BMI groups except for grade 3 obesity, there were U-shaped associations between gestational weight gain and risk of infant death. Weight loss and very low weight gain among women with grades 1 and 2 obesity were associated with high risks of infant mortality. However, even when gestational weight gain in women with obesity was optimized, the predicted risk of infant death remained higher than that of normal-weight women. CONCLUSIONS: Interventions aimed at substantially reducing preconception weight among women with obesity and avoiding very low or very high gestational weight gain may reduce risk of infant death.