Rapid Infant Weight Gain and Advanced Skeletal Maturation in Childhood

Objective To test the hypothesis that rapid infant weight gain is associated with advanced skeletal maturity in children from the United States and South Africa. Study design Longitudinal data from 467 appropriate-for-gestational-age infants in the Fels Longitudinal Growth Study (Dayton, Ohio) and 196 appropriate-for-gestational-age infants in the Birth to Twenty birth cohort study (Johannesburg, South Africa) were used. Multiple linear regression models tested the association between internal SD score change in weight from 0 to 2 years and relative skeletal age at 9. years, adjusting for body mass index, stature, and other covariates. Results In both studies, faster infant weight gain was associated with more advanced skeletal maturity (approximately 0.2 years or 2.4 months per SD score) at age 9 years (P <.0001-.005), even when adjusting for the positive associations of both birth weight and body mass index at age 9 years. This effect appeared to be accounted for by the greater childhood stature of subjects with more rapid infant weight gain. Conclusions Relatively rapid infant weight-gain is associated with advanced skeletal development in late childhood, perhaps via effects on stature. (J Pediatr 2009;155:355-61).