Abstract
BACKGROUND: We estimated longitudinal trajectories of body mass index (BMI) z-score and percentile, weight for height (WFH) z-score and percentile, and percentage of the 95th BMI percentile (BMIp95) among low-income Hispanic children ages 2-5 years to provide normative data for this population and compare the behavior of different measures. METHODS: Longitudinal height and weight measurements obtained from 18,072 Hispanic children aged 2-5 years enrolled in the Special Supplemental Nutrition Program for Women, Infants and Children in Los Angeles County were analyzed. Trajectories of adiposity-related measures were estimated using mixed models, stratified by sex and BMI percentile at age 2 years. RESULTS: For children in the 5th-85th BMI percentile at age 2 years, all adiposity-related measures rose during ages 2-3.5 years; during ages 3.5-5 years, BMI-based measures increased, BMIp95 decreased, and WFH-based measures were stable. For children exceeding the 85th BMI percentile at age 2 years, measures generally trended downward during ages 2-5 years, except for BMIp95, which had variable trends. CONCLUSIONS: Adiposity measures changed at different rates as children grew during ages 2-3.5 years compared to ages 3.5-5 years, and different measures displayed different trends. Studies should consider examining multiple measures and focusing on change relative to a comparison group. IMPACT: To address the childhood obesity epidemic, information on normative trajectories of adiposity-related measures in at-risk populations of young children is needed. Longitudinal analysis of data collected from low-income Hispanic children during ages 2-5 years revealed different patterns for different adiposity measures and for ages 2-3.5 years versus 3.5-5 years. Child obesity studies should consider examining multiple adiposity measures and focus on change relative to a comparison group to avoid misinterpreting longitudinal patterns.