the Wechsler Abbreviated Scales of Intelligence, and

Context: The evidence that breastfeeding improves cog-nitive development is based almost entirely on observa-tional studies and is thus prone to confounding by subtle behavioral differences in the breastfeeding mother’s be-havior or her interaction with the infant. Objective: To assess whether prolonged and exclusive breastfeeding improves children’s cognitive ability at age 6.5 years. Design: Cluster-randomized trial, with enrollment from June 17, 1996, to December 31, 1997, and follow-up fro