Increased breast-feeding during the first months of life appears to raise a child's verbal IQ, according to a study of nearly 14,000 children released Monday.
The study in Archives of General Psychiatry found that 6-year-olds whose mothers were part of a program that encouraged them to breast-feed had a verbal IQ that was 7.5 points higher that children in a control group.
The researchers said their findings suggested that the longer an infant is fed exclusively breast milk, the greater the IQ improvement.
The results echo smaller previous studies that found children and adults who were breast-fed tend to have higher IQs than whose who were not.
Lead author Dr. Michael Kramer, a professor of pediatrics at McGill University in Montreal, said the IQ improvements were modest and might not be noticeable on an individual basis. But he added that the increase could have a significant effect on society as a whole.
"We're not talking about making a child who has trouble in school and is dropping out into a genius," he said. "But if we can increase IQ by three to four points in the whole population, we can have fewer children at the low end and more Einsteins at the high end."
The latest study tracked breast-fed infants born between June 1996 and December 1997 in Belarus. Half the infants and mothers were assigned to an experimental program designed to promote breast-feeding while the remaining infants and mothers received regular pediatric and follow-up medical care.
The World Health Organization and the American Academy of Pediatrics recommend that infants receive only breast milk during the first six months of life. Children who are breast-fed are believed to have health advantages, including fewer gastrointestinal problems.
Last week, the national Centers for Disease Control and Prevention reported that breast-feeding in the U.S. was at an all-time high, with 77 percent of new mothers saying they breast-fed their children compared with 60 percent on 1993-1994.