A longitudinal study of infant feeding and obesity throughout life course.

BACKGROUND: The Centers for Disease Control and Prevention and the US Department of Health and Human Services promote breastfeeding as a strategy for reducing childhood overweight. We evaluated the relation between infant feeding and the development of overweight and obesity throughout life course.

METHODS: We investigated the association between infant feeding and obesity among 35,526 participants in the Nurses' Health Study II who were followed prospectively from 1989 to 2001. Mothers of participants provided information by mailed questionnaires on the duration of breast- and bottle-feeding, as well as the type of milk or milk substitute in the bottle. Information on body shape at ages 5 and 10, weight at age 18, current weight between 1989 and 2001, and height was reported by the participants.

RESULTS: The duration of breastfeeding, including exclusive breastfeeding, was not related to being overweight (25< or = body mass index (BMI) <30 kg/m(2)) or obese (BMI> or =30 kg/m(2)) during adult life. Women who were exclusively breastfed for more than 6 months had a risk of 0.94 (95% confidence interval (CI) 0.83-1.07) of becoming obese as adults compared with women who were not breastfed. Exclusive breastfeeding for more than 6 months was associated with leaner body shape at age 5 (odds ratio (OR)=0.81; 95% CI 0.65-1.01 for the highest vs the lowest category of body shape) compared to women who were not breastfed or breastfed for less than 1 week, but this association did not persist during adolescence or adulthood.

CONCLUSIONS: We did not find that having been breastfed was associated with women's likelihood of becoming overweight or obese throughout life course. Although breastfeeding promotes the health of mother and child, it is unlikely to play an important role in controlling the obesity epidemic.