Abstract
BACKGROUND: American Indians and Alaska Natives have the highest obesity prevalence in the United States, but the influence of early childhood variables on body mass index (BMI; calculated as kg/m(2)) is not well understood. Previous studies have investigated the association between breastfeeding in infancy and offspring BMI, but rarely included American Indians and Alaska Natives. OBJECTIVE: This study investigated the association between breastfeeding in infancy and BMI in American Indians and Alaska Native and non-Hispanic white adolescents and young adults. DESIGN: Longitudinal analysis based on data from the National Longitudinal Study of Adolescent to Adult Health (1994 to 2008). PARTICIPANTS: Adolescent respondents who self-identified as American Indians and Alaska Native or non-Hispanic white, and whose parents completed the parental questionnaire, reported their height and weight. The final sample included 655 American Indians and Alaska Native and 10,305 non-Hispanic white respondents. STATISTICAL ANALYSES PERFORMED: Generalized estimating equations were used to measure the mean differences, 95% CIs, and P values of the association between breastfeeding in infancy and offspring BMI in adolescence, stratifying by race, and adjusting for demographic and socioeconomic variables. RESULTS: The length of breastfeeding was inversely associated with BMI in both populations. American Indians and Alaska Natives that were breastfed for 6 to 12 months or for more than 12 months had a mean BMI of 2.69 (95% CI -3.46 to -1.92; P<0.01) and 1.54 (95% CI -2.75 to -0.33; P<0.05) units lower than those that were never breastfed. Non-Hispanic whites that were breastfed for 3 to 6 months, 6 to 12 months, or more than 12 months had a mean BMI of 0.71 (95% CI -0.93 to -0.50; P<0.01), 0.68 (95% CI -0.87 to -0.50; P<0.01), and 0.85 (95% CI -1.09 to -0.62; P<0.01) units lower than those that were never breastfed. The association between the length of breastfeeding and offspring BMI varied by race (P<0.01). CONCLUSIONS: Breastfeeding in infancy is associated with lower mean BMI. Future research should investigate causal pathways and whether interventions promoting breastfeeding in American Indians and Alaska Natives can prevent increasing BMI.