Interaction between maternal prepregnancy body mass index and gestational weight gain shapes infant growth

Abstract

Objective: To quantify the combined effect of maternal prepregnancy obesity and maternal gestational weight gain (GWG) on the shape of infant growth throughout the first year of life.

Methods: A retrospective cohort of mother-child dyads with children born between January 2007 and May 2012 was identified in a linked electronic medical record. Data were abstracted to define the primary exposures of maternal prepregnancy body mass index (BMI) and GWG, and the primary outcome of infant growth trajectory.

Results: We included 499 mother-child dyads. The average maternal age was 28.2 years; 55% of mothers were overweight or obese before pregnancy, and 42% of mothers had excess GWG, as defined by the Institute of Medicine. Maternal prepregnancy BMI (P < .001) and the interaction between prepregnancy BMI and maternal GWG (P = .02) showed significant association with infant growth trajectory through the first year of life after controlling for breast-feeding and other covariates, while GWG alone did not reach statistical significance (P = .38). Among infants of mothers with excess GWG, a prepregnancy BMI of 40 kg/m(2) versus 25 kg/m(2) resulted in a 13.6% (95% confidence interval 5.8, 21.5; P < .001) increase in 3-month infant weight/length percentile that persisted at 12 months (8.4%, 95% confidence interval 0.2, 16.5; P = .04).

Conclusions: The combined effect of excess maternal GWG and prepregnancy obesity resulted in higher infant birth weight, rapid weight gain in the first 3 months of life, with a sustained weight elevation throughout the first year of life. These findings highlight the importance of the preconception and prenatal periods for pediatric obesity prevention.

Keywords: infants; mothers; obesity; pediatric; pregnancy; weight gain.

Copyright © 2014 Academic Pediatric Association. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1

Study Cohort of Maternal-Infant Dyads

Figure 2

The Interaction between Maternal Pre-Pregnancy BMI and Gestational Weight Gain on Infant Growth. Abbreviations: BMI=Body Mass Index (kg/m2); GWG=Gestational Weight Gain (kg) Representative curves are shown from the adjusted generalized least square model to illustrate that the shape of the infant growth curve is markedly different for infants of mothers who were obese prior to pregnancy. There was a significant 2-way interaction between GWG and maternal pre-pregnancy BMI (p=0.02). This interaction indicates that the effect of maternal GWG on infant growth in the first year is modified by pre-pregnancy BMI. The model was adjusted for estimated gestational age, exclusive breast-feeding for the first 6 months of life, maternal age, number of previous pregnancies, maternal smoking, levothyroxine use, hypertension, depression, insurance type, and gestational diabetes.