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.
Bibliographical noteFunding Information:
This study was funded by grants from the National Institutes of Health (R01-HD12252 and R01-HD53685), the Medical Research Council of South Africa, the Anglo-American Chairman's Fund, Child, Youth, and Family Development of the Human Sciences Research Council of South Africa, the Wellcome Trust (United Kingdom), the South African National Research Foundation, and the University of the Witwatersrand. There was no role of the study sponsors in the study design, collection, analysis, or interpretation of the data, writing the report, or the decision to submit the paper for publication.