Effects of Fat Mass on Motor Development During the First 2 Years of Life

Abstract

This study characterized total body fat mass (FM) and motor development during the first 2 years of life in healthy infants. Participants (n = 469) from the Beginnings Study cohort, a prospective, longitudinal study of early infant feeding, were assessed at 3, 6, 9, 12, and 24 months of age for a total of 2231 observations. Growth was evaluated using standard anthropometric techniques, and body composition was assessed using dual-energy X-ray absorptiometry (DXA). Motor development was evaluated using Bayley Scales of Infant Development. Mixed-effects models adjusted for race, sex, gestational age, birth weight, birth length, and maternal education were used for data analyses. Greater weight-for-length Z-scores and overweight status were negatively associated with subsequent psychomotor development index (PDI) scores ( P < .01), and total body FM was negatively associated with concurrent and subsequent PDI scores ( P < .01). The relationship between total body FM and PDI scores was significant starting at 9 months ( −0.18, P = .01) until 24 months ( −0.39, P = .04). Infants with high total body FM ( ≥31%) scored 1.96 points lower on concurrent PDI and 3.05 points lower on subsequent PDI. However, neither anthropometric measures nor total body FM was associated with the clinical diagnosis of delayed motor development, defined by PDI scores below 85. Thus, greater FM and overweight status were significantly associated with lower motor development in early childhood, although average scores remained within the normal range.