Infant Weight and Length Growth Trajectories Modeled Using Superimposition by Translation and Rotation Are Differentially Associated with Body Composition Components at 3 and 7 Years of Age.
To evaluate how infant weigh and length growth trajectories associate with body composition at 3 and 7 years because previous studies have noted that rapid infant weight gain increases risk for high body mass index (BMI) in children. There were 322 children enrolled at 3 years of age with dual x-ray absorptiometry body composition data and pediatrician growth data for 0-2 years of age who were included in analysis. Superimposition by translation and rotation modeling was used to characterize infant weight and length trajectories in terms of size, tempo and velocity measures. Associations of these measures with fat mass, lean mass, percent body fat, bone mineral content, BMI z-score, and overweight prevalence at 3 and 7 years of age were determined. Infant growth trajectories differed by sex, race, and breastfeeding status. Higher overall weight size and weight velocity from 0 to 2 years of age were associated positively with all age 3 body composition and anthropometry outcomes. However, longer length size from 0 to 2 years of age was associated independently with higher bone mineral content and lean mass, but lower percent body fat, BMI z-score, and a lower odds of overweight at 3 years of age. By 7 years of age, later than average infant weight tempo was also associated with lower fat mass, lean mass, and BMI z-score. Greater average weight size and greater weight velocity in infancy are markers for greater overall body size at 3 and 7 years of age. However, longer average lengths and later weight gain tempo between 0 and 2 years of age may help to establish a leaner body composition by 3 and 7 years of age.