London - Breast-feeding has no impact on a child's intelligence, according to research published on Wednesday.
Although breast-feeding has many advantages for children including reducing infections, respiratory illnesses and diarrhoea, enhancing a child's intelligence does not appear to be among them.
"Breast-feeding has little or no effect on intelligence in children," Geoff Der of Britain's Medical Research Council, said in a report published online by the British Medical Journal.
The researchers found that although breast-fed children scored higher on IQ tests this was because their mothers tended be more intelligent, better educated and provided a more stimulating environment at home.
Der and scientists from the University of Edinburgh in Scotland analysed data on 5 475 children and 3 161 mothers in the United States.
Scientists have been looking at possible links between breast-feeding and intelligence for decades. Der said the key to understanding a child's IQ was the intelligence of the mother.
"A rough generalisation is that in studies that factor in the mother's IQ, there isn't much difference between breast-fed and non-breast-fed babies," Der said in an interview.
"But if you don't count the mother's IQ, that tends to double breast feeding's apparent effect and is likely to overestimate a children's IQ."
The researchers also looked at siblings who had been breast-fed and bottle-fed.
"The ones that were breast-fed should have been more intelligent, but there was no significant difference," Der said.
Although the study did not find a link to intelligence, the authors stressed breast feeding had many other advantages for mothers and children.
Previous studies have shown that when babies are breast-fed for the first six months of life they grow better without getting too fat.
Researchers have also shown that breast-feeding has a beneficial impact on blood pressure and cholesterol levels later in life which reduces the risk of heart attack or stroke.