Breast milk feeding and cognitive ability at 7-8 years

Objective-To examine the association between duration of breast milk feedin g and cognitive ability at 7-8 years in a birth cohort of very low birthwei ght infants. Design-280 survivors from a national birth cohort of 413 New Zealand very l ow birthweight infants born in 1986 were assessed at age 7-8 years on measu res of verbal and performance intelligence quotient (IQ) using the WISC-R. At the same time mothers were questioned as to whether they had elected to provide expressed breast milk at birth and the total duration of breast mil k feeding. Results-Some 73% of mothers provided expressed breast milk and 37% breast f ed for four months or longer. Increasing duration of breast milk feeding wa s associated with increases in both verbal IQ (p < 0.001) and performance I Q (p < 0.05): children breast fed for eight months or longer had mean (SD) verbal IQ scores that were 10.2 (0.56) points higher and performance IQ sco res that were 6.2 (0.35) points higher than children who did not receive br east milk. These differences were substantially reduced after control for s election factors associated with receipt of breast milk. Nevertheless, even after control for confounding, there remained a significant (p < 0.05) ass ociation between duration of breast milk feeding and verbal IQ: children br east fed for eight months or longer had adjusted mean (SD) verbal IQ scores that were 6 (0.36) points higher than the scores of those who did not rece ive breast milk. Conclusions-These findings add to a growing body of evidence to suggest tha t breast milk feeding may have small long term benefits for child cognitive development.