Health and development outcomes in 6.5-y-old children breastfed exclusively for 3 or 6 mo.

BACKGROUND Despite the current World Health Organization recommendation that infants be exclusively breastfed for 6 mo, this practice remains unusual in both developed and developing countries. OBJECTIVE The objective was to compare health and development outcomes at age 6.5 y in children who were exclusively breastfed for 3 mo (EBF3) or for 6 mo (EBF6); in the EBF3 group, the children continued partial breastfeeding for > or =6 mo. DESIGN This was a prospective cohort study nested within a large, cluster-randomized trial of a breastfeeding promotion intervention in the Republic of Belarus. Outcomes compared at 6.5 y included anthropometric measurements, systolic and diastolic blood pressure, intelligence quotient, teachers' ratings of academic performance, parent- and teacher-rated behavior, atopic symptoms, allergen skin-prick tests, and dental caries. All statistical analyses were adjusted for cluster- and individual-level covariates and for clustering of outcomes within the clinics at which the children were examined. RESULTS The 2427 EBF3 and 524 EBF6 children who were followed up represented 84.7% and 89.4%, respectively, of those followed for the first year of life. The only significant differences observed between the 2 groups were in mean body mass index, triceps skinfold thickness, and hip circumference, all of which were higher in the EBF6 group. CONCLUSIONS We observed no demonstrable beneficial or adverse long-term effects on child health of exclusive breastfeeding for 6 mo. Higher adiposity measures in the EBF6 group probably reflect reverse causality rather than a causal effect of prolonged exclusive breastfeeding. Established benefits appear to be limited to the period of exclusive breastfeeding.