Objective: To estimate the prevalence of obesity in 5 major racial/ethnic groups in 4-year-old US children.
Design: Cross-sectional secondary data analysis.
Setting: Nationally representative sample of US children born in 2001.
Participants: Height and weight were measured in 2005 in approximately 8550 children who participated in the Early Childhood Longitudinal Study, Birth Cohort.
Main exposure: Racial/ethnic group.
Outcome measure: Prevalence of obesity, defined as body mass index at or above the 95th percentile for age of the sex-specific Centers for Disease Control and Prevention growth charts.
Results: Obesity prevalence among 4-year-old US children (mean age, 52.3 months) was 18.4% (95% confidence interval [CI], 17.1%-19.8%). Obesity prevalence differed by racial/ethnic group (P < .001): American Indian/Native Alaskan, 31.2% (95% CI, 24.6%-37.8%); Hispanic, 22.0% (95% CI, 19.5%-24.5%); non-Hispanic black, 20.8% (95% CI, 17.8%-23.7%); non-Hispanic white, 15.9% (95% CI, 14.3%-17.5%); and Asian, 12.8% (95% CI, 10.0%-15.6%). All pairwise differences in obesity prevalence between racial/ethnic groups were statistically significant after a Bonferroni adjustment (P < .005) except for those between Hispanic and non-Hispanic black children and between non-Hispanic white and Asian children.
Conclusions: Racial/ethnic disparities in obesity are apparent in 4-year-old US children. The highest prevalence is in American Indian/Native Alaskan children, in whom obesity is twice as common as in non-Hispanic white or Asian children.