Prenatal,Perinatal, Early Life,and Sociodemographic Factors Underlying Racial Differences in the Likelihood of High Body Mass Index in Early Childhood

Objectives. We investigated early childhood disparities in high body mass index (BMI) between Black and White US children.Methods. We compared differences in Black and White children’s prevalence of sociodemographic, prenatal, perinatal, and early life risk and protective factors; fit logistic regression models predicting high BMI (≥ 95th percentile) at age 4 to 5 years to 2 nationally representative samples followed from birth; and performed separate and pooled-survey estimations of these models.Results. After adjustment for sample design–related variables, models predicting high BMI in the 2 samples were statistically indistinguishable. In the pooled-survey models, Black children''s odds of high BMI were 59% higher than White children''s (odds ratio OR] = 1.59; 95% confidence interval CI]= 1.32, 1.92). Sociodemographic predictors reduced the racial disparity to 46% (OR = 1.46; 95% CI = 1.17, 1.81). Prenatal, perinatal, and early life predictors reduced the disparity to nonsignificance (OR = 1.18; 95% CI = 0.93, 1.49). Maternal prepregnancy obesity and short-duration or no breastfeeding were among predictors for which racial differences in children’s exposures most disadvantaged Black children.Conclusions. Racial disparities in early childhood high BMI were largely explained by potentially modifiable risk and protective factors.Over recent decades, as the prevalence of high body mass index (BMI; defined as at or above the Centers for Disease Control and Prevention 95th percentile1) has increased dramatically among all children,2,3 racial disparities have been documented in nationally representative samples of children at very young ages.4–7 Reviews and prevalence studies highlight the need for a better understanding of the predictors of these disparities in BMI and other indicators of childhood obesity,8,9 especially in early childhood.7Previous research on high BMI in early childhood with racially and ethnically diverse samples has identified risk and protective factors at multiple developmental stages. In the prenatal and perinatal period, risks include higher birth weight,10–13 maternal prepregnancy BMI,14 and maternal smoking during pregnancy.14,15 In infancy and early life, risks include maternal employment,11 especially among highly educated women,12,16 nonparent child care,13,17,18 and television viewing hours.12,19–21 Protective factors include breastfeeding10,12,14 and family meals.12,21,22Studies have shown that young racial/ethnic minority children are exposed to more of these risks and fewer of these protections.23,24 Nevertheless, in analyses of nationally representative samples, high BMI remains more common among Black than White children even after adjusting for sociodemographic characteristics and risk and protective factors.6,11,12,14,16 We suspect that the persistence of racial disparities in these studies might be attributable to omitted predictors or less detailed measurement of the age and duration of children’s exposures. This type of comprehensive assessment is methodologically challenging because of the number of variables and observations required to draw statistically valid inferences.We employed a novel 2-survey methodological design to overcome these challenges. We used data from 2 nationally representative samples of US children followed from birth to age 4 to 5 years in separate and pooled-survey analyses to identify prenatal, perinatal, early life, and sociodemographic factors that may explain Black–White disparities in early childhood high BMI. The separate analyses in 2 surveys that cover a historical period of more than 10 years increased the robustness of our findings to differences in sample design, measurement protocols, and period variability in unobserved confounders. The pooled-survey analyses enhanced the statistical power of our study and thereby strengthened our conclusions about which factors explain Black–White disparities in early childhood high BMI.