Abstract
Objective. To study the magnitude and timing of changes in body mass index (BMI) and height percentiles in four groups of children defined by overweight status in early childhood and adolescence: nonoverweight-nonoverweight (N-N), nonoverweight-overweight (N-O), overweight-nonoverweight (O-N), and overweight-overweight (O-O). The aim was to determine if monitoring percentile changes can provide early warnings about risk for adolescent overweight before a chronic pattern of overweight is established. Methods. Data on 3 408 children from the US based National Longitudinal Survey of Youth's Child-Mother file were used. Each child was interviewed on average 5.7 times, with a total of 19 470 person/year observations. BMI and height percentiles were estimated as polynomial functions of age in months for each of the four groups using fixed coefficients and random coefficients models. The models were compared using the Aikake information criterion. Results. There was significant transition between initial and final weight states. Children who transitioned to overweight experienced larger increases in BMI percentile points at 2–6 years than at 7–10 years of age. N-O girls, but not boys, had significantly larger increases in height percentile than N-N girls, with the largest increases occurring by age 7. The height percentiles curves for N-O and O-O girls converged by age 8 years. O-N children experienced steeper declines in BMI percentile over longer periods of time than O-O children. Conclusions. Monitoring changes in BMI and height percentiles can give early warnings about children at risk for adolescent overweight while there is ample time for intervention.