The relationship of rapid weight gain in infancy to obesity and skeletal maturity in childhood

Objective: Children with birth weight appropriate for gestational age (AGA) who also demonstrate rapid weight gain in infancy have a greater risk of being overweight or obese during childhood. A concurrent advancement in skeletal maturity would account for their greater size and would, therefore, not necessarily pose a threat of greater risk during adolescence and early adulthood. This study aims to determine whether children with rapid weight gain during infancy have advanced skeletal maturity during childhood. Research Methods and Procedures: One hundred and ninety-three African children (boys = 108; girls = 85) of normal birth weight and gestational age were assessed from birth to 9 years. Body composition was assessed at 9 years of age by whole-body DXA, and skeletal maturity was assessed using the Tanner-Whitehouse II technique. Rapid weight gain in infancy was defined as a +0.67 change in weight-for-age Z-score between birth and 2 years. Results: Rapid weight gain was experienced by over 20% of the sample. Children with rapid weight gain were significantly lighter at birth and significantly taller, heavier, and fatter throughout childhood. Chronological age and Tanner-Whitehouse II technique skeletal ages at 9 years were not significantly different between groups or between sexes within groups. Discussion: Because AGA children with rapid weight gain have a greater risk of overweight and obesity but are not advanced in skeletal maturity, later adolescent adjustments toward average weight and fatness values are unlikely. The identification and monitoring of such children is of importance in reducing their risk of morbidity.