Context: It has been suggested that breastfeeding is protective against children becoming overweight, and that there is a dose-dependent effect of its duration.
Objective: To determine whether breastfeeding and its duration are associated with a reduced risk of being overweight among young children in the United States.
Design and setting: Data on infant feeding and child overweight status were taken from the third National Health and Nutrition Examination Survey (NHANES III), a cross-sectional health examination survey conducted from 1988-1994.
Subjects: Sample of 2685 US-born children between the ages of 3 and 5 years, with birth certificates, height and weight measures, and information on infant feeding.
Main outcome measures: A body mass index (BMI) between the 85th and 94th percentile was considered at risk of overweight and a BMI in the 95th percentile or higher was considered being overweight.
Results: After adjusting for potential confounders, there was a reduced risk of being at risk of overweight for ever breastfed children (adjusted odds ratio [AOR], 0.63; 95% confidence interval [CI], 0.41-0.96) compared with those never breastfed. There was no reduced risk of being overweight (AOR, 0.84; 95% CI, 0.62-1.13). There was no clear dose-dependent effect of the duration of full breastfeeding on being at risk of overweight or overweight and no threshold effect. The strongest predictor of child overweight status was the mother's concurrent weight. The rate of children being overweight nearly tripled with maternal overweight status (BMI, 25.0-29.9 kg/m(2); AOR, 2.95; 95% CI, 1.35-6.42) and more than quadrupled with maternal obesity status (BMI >/=30.0 kg/m(2); AOR, 4.34; 95% CI, 2.50-7.54).
Conclusions: There are inconsistent associations among breastfeeding, its duration, and the risk of being overweight in young children. Breastfeeding continues to be strongly recommended, but may not be as effective as moderating familial factors, such as dietary habits and physical activity, in preventing children from becoming overweight.