Neonatal Body Composition According to the Revised Institute of Medicine Recommendations for Maternal Weight Gain

Abstract

In 2009, the Institute of Medicine (IOM) released revised pregnancy weight gain guidelines. There are limited data regarding the effect of maternal weight gain on newborn adiposity. The aim of this study was to estimate neonatal fat mass, lean body mass, and percentage body fat according to current Institute of Medicine (IOM) pregnancy weight gain guidelines. This is a secondary analysis of a prospective observational cohort study of neonates delivered at least 36 wk gestation and evaluated for fat mass, lean body mass, and percentage body fat. Women with abnormal glucose tolerance testing and other known medical disorders or pregnancies with known fetal anomalies were excluded. Pregravid body mass index (BMI) was categorized as normal weight (<25 kg/m2), overweight (25-30 kg/m2), or obese (>30 kg/m2). Maternal weight gain was quantified as less than, equal to, or greater than current IOM guidelines. Newborn body composition measurements were compared according to weight gain and BMI categories. A total of 439 maternal-newborn pairs were evaluated; 19.8% (n=87) of women gained less than IOM guidelines; 31.9% (n=140), equal to IOM guidelines; and 48.3% (n=212), greater than IOM guidelines. Significant differences for each component of body composition were found when evaluated by IOM weight gain categories (all ANOVA, P<0.001). When controlling for pregravid BMI, only weight gain for women who were of normal weight before pregnancy remained significant. Maternal weight gain during pregnancy is a significant contributor to newborn body composition, particularly for women who are of normal weight before pregnancy.