Breast feeding and mental and motor development at 12 months in a low-income population in northeast Brazil.

The aim of this prospective study was to investigate the association between breast feeding and mental and motor development at age 12 months, controlling for comprehensive measures of the child's socio-economic, maternal and environmental background, and nutritional status. A cohort of 205 infants born during May-August 2001 in a poor area in the interior of the State of Pernambuco was enrolled, of whom 191 were tested at age 12 months with the Bayley Scales of Infant Development II, and in whom breast-feeding status was measured at days 1, 10, 30, 60, 90, 120, 150, 180, 270 and 360. After adjusting for potential confounders, full breast feeding (i.