Neonatal body composition according to the revised institute of medicine recommendations for maternal weight gain

Abstract

Background: 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.

Objective: 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.

Design: 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.

Results: 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.

Conclusion: Maternal weight gain during pregnancy is a significant contributor to newborn body composition, particularly for women who are of normal weight before pregnancy.

Figures

Fig. 1.

Comparison of neonatal anthropometric measurements according to the IOM weight gain recommendations. A–C, The primary outcome data for LBM, FM, and %BF by IOM weight gain categories. ANOVA demonstrated significant differences for each component of newborn body composition by IOM weight gain categories. For all subjects, subgroup analyses were performed to evaluate the relationship between weight gain categories and newborn measurements (PLSD). Dark bars represent the median value. A, Neonatal LBM according to maternal weight gain categories. ANOVA, P = 0.0004. Subgroup comparisons (PLSD): <IOM vs. =IOM, P = 0.15; =IOM vs. >IOM, P = 0.01; <IOM vs. >IOM, P = 0.0002. B, Neonatal FM according to maternal weight gain categories. ANOVA, P = 0.0002. Subgroup comparisons (PLSD): <IOM vs. =IOM, P = 0.11; =IOM vs. >IOM, P = 0.01; <IOM vs. >IOM, P < 0.0001. C, Neonatal %BF according to maternal weight gain categories. ANOVA, P = 0.0006. Subgroup comparisons (PLSD): <IOM vs. =IOM, P = 0.07; =IOM vs. >IOM, P = 0.03; <IOM vs. >IOM, P = 0.0002.

Fig. 2.

Comparison of neonatal LBM by maternal pre-pregnancy BMI and weight gain groups. In women who were normal BMI before pregnancy, ANOVA identified significant differences in newborn LBM (P = 0.007) by IOM weight gain groups. Subgroup analysis (PLSD) identified significant differences when comparing normal-weight women with <IOM vs. =IOM weight gain (P = 0.02) and when comparing normal-weight women with <IOM vs. >IOM weight gain (P = 0.002).

Fig. 3.

Estimation of neonatal FM by maternal pre-pregnancy BMI and weight gain groups. In women of normal BMI before pregnancy, ANOVA identified significant differences in newborn FM (P = 0.001) by IOM weight gain groups. Subgroup analysis (PLSD) identified significant differences when comparing normal-weight women with <IOM vs. =IOM weight gain (P = 0.003) and when comparing normal-weight women with <IOM vs. >IOM weight gain (P = 0.0003). In women who were overweight before pregnancy, ANOVA identified significant differences in newborn FM (P = 0.04) by IOM weight gain groups. Subgroup analysis (PLSD) identified significant differences when comparing overweight women with =IOM vs. >IOM weight gain (P = 0.04).

Fig. 4.

Estimation of neonatal %BF by maternal pre-pregnancy BMI and weight gain groups. In women who were normal BMI before pregnancy, ANOVA identified significant differences in newborn %BF (P = 0.001) by IOM weight gain groups. Subgroup analysis (PLSD) identified significant differences when comparing normal-weight women with <IOM vs. =IOM weight gain (P = 0.003) and when comparing normal-weight women with <IOM vs. >IOM weight gain (P = 0.0004).