Breastfeeding and obesity at 21 years: a cohort study.

AIMS To determine the influence of breastfeeding on overweight and obesity, as determined by body mass index in early adulthood. BACKGROUND Obesity is a contemporary epidemic and linked to increased risk of later cardiovascular disease and type 2 diabetes. The success of long-term treatment is modest. Protective factors, such as potentially, and breastfeeding, are few and very important. There are uncertainties as to whether breastfeeding has a protective effect, especially in adults, or whether it is a reflection of other markers of obesity that are more linked to cardiovascular disease and diabetes risk. Some studies suggest that breastfeeding is protective in later life for cardiovascular disease and atherosclerosis. DESIGN Epidemiological analysis of longitudinal data set. METHODS We collected data about breastfeeding duration, body mass index of children at 21 years and confounding variables from an ongoing longitudinal study of a singleton birth cohort of 7223 children in Brisbane. We assessed the duration of breastfeeding at six months and prevalence of overweight and obesity at 21 years by body mass index. Adjustment for potential confounders was by multivariable multinomial logistic regression. RESULTS Data were available for 2553 young adults. In neither the unadjusted or adjusted analysis was longer duration of breastfeeding associated with reduction in obesity at 21 years. CONCLUSIONS Findings of this investigation are consistent with breastfeeding not independently affecting body mass index in young adults. RELEVANCE TO CLINICAL PRACTICE Breastfeeding has a range of important benefits for infants, mothers and families, although duration of breastfeeding may not play a substantial role in preventing adult onset obesity.