Changes in Socioeconomic, Racial/Ethnic, and Sex Disparities in Childhood Obesity at School Entry in the United States.

Changes in Socioeconomic, Racial/Ethnic, and SexDisparities in ChildhoodObesity at School Entry in the United States The National Health and Nutrition Examination Survey data suggest aplateauingof childhoodobesity in theUnitedStates, with no trend among children younger than 11 years since 1999.1,2However, studieshavechallenged this findingandcautioned that the overall static trend masks significant differences across subgroups.3,4 There isnotmuchconsensus about whether and how childhood obesity prevalence has changed for various age, sex, race/ethnicity, and socioeconomic subgroups.2,4Availabledataon2nationally representative cohorts of US kindergarten-aged children 12 years apart provide avaluableopportunity todocumentchanges inweightgainand obesity among young children and underlying sex, socioeconomic, and racial/ethnic disparities between 1998 and 2010. Methods |Sponsoredby theNational Center forEducationStatistics, the Early Childhood Longitudinal Study kindergarten class (ECLS-K) consists of 2 separate nationally representative cohorts recruited as kindergarteners during the 1998 to 1999 and 2010 to 2011 school years (mean age, 5.7 years). Both cohorts first surveyed children in the fall of the kindergarten year, with additional waves in later grades. Only kindergarten data were available at the time of analysis; therefore, our analyses used only the fall kindergarten data from both cohorts. In both cohorts, bodymass index (calculated asweight in kilograms divided by height inmeters squared) was calculatedusingheight andweightmeasurements takenby trained staff using standardized procedures described elsewhere.5,6 Measuresofchildrenwhowereoverweightorobese (bodymass index ≥ 85th percentile) and children who were obese (body mass index ≥ 95th percentile) were computed using the 2000 sexand age-specific Centers for Disease Control and Prevention growth charts.