Breast-feeding linked to higher adult IQs. (Duration of 7-9 Months).

Breast-feeding may have long-term positive effects on adult intelligence, reported Erik Lykke Mortensen, Ph.D., of Copenhagen University Hospital, and his colleagues.

In a prospective, longitudinal, birth cohort study involving 3,253 participants, the cognitive development of adults who as infants were breast-fed for 7-9 months surpassed that of adults who were breast-fed for less than 7 months, the investigators said (JAMA 287[18]:2365-71, 2002).

The nutritional composition of breast milk, behavioral considerations, and demographic factors likely contribute to this positive association, the investigators said.

Dr. Ruth Lawrence, chair of the American Academy of Pediatrics Breast-Feeding Task Force, said that the results of this study add an important component to the growing body of literature that examines the relationship between breastfeeding and intellectual development. While several studies have suggested a positive association between breast-feeding and cognitive development in early and middle childhood, the correlation with adult intelligence has been more elusive.

"This study indicates that the positive effects of breast-feeding with respect to intelligence are not short-lived," Dr. Lawrence, also a neonatologist at the University of Rochester (N.Y.), said in an interview.

The observed association is based on analyses of two nonoverlapping subsamples from the Copenhagen Perinatal Cohort, which comprises 9,125 participants born in Copenhagen between October 1959 and December 1961. The first sample included a total of 973 men and women with a mean assessment age of 27.2 years. The second sample included 2,280 men with a mean assessment age of 18.7 years.

The study divided each sample into five ...