Infancy: mental and motor development.

In a prospective cohort study of 196 infants from birth to age 15 mo, the relationship of iron status to psychomotor development, the effect of a short-term trial of oral iron or placebo, and the effect of longer-term oral iron therapy was assessed. Development was assessed with the Bayley Scale of Infant Development in anemic, nonanemic, iron-deficient, and control children. Anemic infants had significantly lower indices than did control or nonanemic, iron-deficient infants. Control infants and nonanemic, iron-deficient infants performed comparably. No difference between the effect of oral administration of iron or placebo was noted after 10 d or 3 mo of iron therapy. A hemoglobin concentration of less than 105 g/L and anemia duration greater than 3 mo were correlated with significantly lower motor and mental scores, suggesting that when iron deficiency progresses to anemia, adverse influences in the performance of developmental tests appear and persist, despite iron therapy.