The longer an infant is breast-fed the higher they are likely to score on intelligence tests as adults. Previous studies on young children show an association between breast-feeding and cognitive development in early and middle childhood. The present study was done to determine the association between duration of infant breast-feeding and intelligence in young adulthood. The researchers at the Copenhagen University Hospital conducted IQ (intelligence quotient) tests for more than 3,000 people all of whom were born in Copenhagen, Denmark, between October 1959 and December 1961. They were divided into different categories based on the duration of breast-feeding. In this study, those who were breast fed less than one month as infants scored a mean of 99.4 on an IQ test, with progressively higher scores correlating to the longer duration of breast-feeding. Those breastfed between seven and nine months scored a mean 106 on the test. However after nine months of breast-feeding, adult scores dipped to 104. The results showed that being breastfed for up to nine months conferred a long-lasting intellectual benefit. Test scores rose in tandem with the duration of breast feeding for up to nine months, regardless of the parents' social status and education, the mother's weight gain during pregnancy, the individual's birth weight, and other factors that may affect cognitive development. This study demonstrates a strong link between the duration of breast-feeding and adult intelligence. Breast-feeding is known to play an important role in development by providing various nutrients and antibodies that might not be present in infant formula or cow's milk. There is no doubt that breast milk is the best milk for babies. Not only does it provide maximum emotional satisfaction to both the mother and the child creating a bond between the two, it also has various other advantages.
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JAMA May 2002, Vol. 287(18)