Growth, Maturation, and Weight Status: Insights from a Longitudinal Cohort of Nebraska Youth

Pediatric obesity continues to be a major public health concern in the United States, with well-known short-term and long-term consequences. In efforts to combat pediatric obesity and identify children at high-risk for potential health problems, physicians and health professionals widely practice screening and classifying weight status using age-and-sex-specific body mass index (BMI) percentiles. However, some studies suggest the use of BMI for establishing weight status in relation to health risk in youth is problematic, especially during the period of the adolescent growth spurt. More importantly, maturation-related misclassification may result in overestimations of overweight prevalence among early-maturing youth, and underestimations of overweight prevalence among later-maturing youth. Longitudinal data from 646 youth whose body mass and stature were measured from ages 8-14 during school health screenings were used for analysis. Age-and-sex specific BMI percentiles were calculated, and weight status was determined based on CDC growth charts. Height velocities (i.e. growth rates) were calculated to determine somatic maturity (biological age) based on age at peak height velocity. Overall, growth in stature, body mass, and BMI was described amongst weight status categories, while weight categorization was compared using standard procedures versus an approach adjusted for maturation. As expected, children get taller and heavier with age, and significant differences in growth rate exist according to weight classification. Overall, 8.5% of children were re-classified into a lower weight category, with 22 (30.6%) overweight or obese boys and 14 (20.3%) overweight or obese girls reclassified into a lower weight category when adjusting for maturation. Children grow and mature at different rates, and while the overall effects of maturational adjustment are relatively small, it should be considered when assessing adolescents in particular. Weight status assessments should be modified during the age range when maturational events occur.