Infant Mortality by Maternal Prepregnancy Body Mass Index: United States, 2017-2018.

Objective-This report presents 2017-2018 infant mortality rates in the United States by maternal prepregnancy body mass index, and by infant age at death, maternal age, and maternal race and Hispanic origin. Methods-Descriptive tabulations of infant deaths by maternal and infant characteristics are presented using the 2017-2018 linked period birth/infant death files; the linked period birth/infant death file is based on birth and death certificates registered in all states and the District of Columbia. The 2017 linked birth/infant death file is the first year that national data on maternal prepregnancy body mass index were available. Results-Total infant, neonatal, and postneonatal mortality rates were lowest for infants of women who were normal weight prepregnancy, and then rose with increasing prepregnancy body mass index. Total, neonatal, and postneonatal rates were higher for infants of women who were underweight prepregnancy compared with infants of women who were normal or overweight before pregnancy. Mortality rates for infants of underweight women were generally, but not exclusively, lower than those of infants born to women with obesity. Infants born to women of normal weight generally had lower mortality rates than infants born to women who had obesity prepregnancy for all maternal age and race and Hispanic-origin groups.