Birth weight is associated with body composition in a multiethnic pediatric cohort.

Several studies have indicated that birth weight is associated with increased risk for excess fat accumulation later in life. Our objective was to evaluate the association between birth weight and body composition measures in a multiethnic pediatric population while controlling for environmental factors previously associated with increased adiposity. Dual-energy x-ray absorptiometry was performed on 256 European-American, African-American, and Hispanic-American boys and girls. Body composition measurements were adjusted by height to create a fat mass index, fat-free mass index, and trunk fat mass index. After adjusting for age, pubertal status, sex, race/ethnicity, socioeconomic status, and physical activity, we found that higher birth weights were associated with significant increases in all three body composition indices (P < 0.05). After adjusting for physical activity in analysis of covariance, the relationship between birth weight and the fat-free mass index was no longer significant. This study suggests that higher birth weight is a risk factor for later unfavorable body composition changes in children, and that current environment and physical activity habits can affect these outcomes.