No significant associations between breastfeeding practices and overweight in 8-year-old children.

Aim: The aim was to examine if breastfeeding practices were associated with body mass index (BMI) and risk of overweight or obesity in third grade (8 years) of elementary school.

Methods: In a regional cohort, we related BMI z-scores and presence of overweight or obesity at 8 years of age with ever being breastfed and with duration of exclusive and partial breastfeeding after adjusting for potential confounders. Parents completed questionnaires on breastfeeding and sociodemographic and lifestyle factors at school entry, and public health nurses measured height and weight. For non-participants, the nurses anonymously reported these measurements together with sex and age.

Results: 90% of participants had been breastfed. In adjusted analyses, BMI z-scores were not significantly related to whether or not the child had been breastfed (P = .64), or to the duration of exclusive (P = .80) or partial breastfeeding (P = .94). Logistic regression also showed no significant association between breastfeeding measures and overweight or obesity.

Conclusion: This study on 8-year-old Norwegian children did not support a commonly held notion that breastfeeding reduces the risk of overweight or obesity.