Breastfeeding Helps Explain Racial and Socioeconomic Status Disparities in Adolescent Adiposity

Abstract

OBJECTIVES. Studies suggest that breastfeeding is protective for later obesity; however, this association has not held among all racial and socioeconomic status groups. Racial and socioeconomic status differences in breastfeeding behavior have also been noted. In this study, we formally test whether breastfeeding mediates the relationship between race and socioeconomic status with adolescent adiposity. METHODS. Data were analyzed from 739 black and white 10- to 19-year-old adolescents who participated in a large, school-based study. Parents provided information on parental education, used to measure socioeconomic status, and whether the child was breastfed as an infant. BMI was used to measure adolescent adiposity and was analyzed as a continuous measure (BMI z score) using linear regression and categorically (BMI ≥85th and ≥95th percentile) using logistic regression. RESULTS. Black adolescents and those without a college-educated parent were less likely to have been breastfed for >4 months. Race and parental education were each independent predictors of BMI z score and of having BMI ≥85th percentile or BMI ≥95th percentile. When added to the model, being breastfed for >4 months was also independently associated with lower BMI z score and lower odds of having BMI ≥85th percentile or BMI ≥95th percentile. Inclusion of being breastfed for >4 months resulted in a 25% decrease in racial and parental education differences in adolescent BMI z score, supporting partial mediation. CONCLUSIONS. Having been breastfed for >4 months was associated with lower adolescent BMI z score and lower odds of having a BMI ≥85th percentile or BMI ≥95th percentile, independent of race or parental education. Furthermore, these analyses suggest that being breastfed for >4 months partially explains the relationship between social disadvantage and increased adiposity. Increasing breastfeeding duration could result in lower adolescent adiposity for all racial and socioeconomic status groups and potentially minimize socioeconomic disparities in adiposity.