Breastfed babies 'more intelligent'
Breastfeeding your baby gives them a headstart in the classroom, according to research showing that it raises a child's IQ.
The most comprehensive UK study of breastfeeding to date shows that it continues to have an effect on a child's mental ability right through secondary school.
The study of more than 10,000 children from the Bristol area found that those breastfed exclusively for at least the first four weeks of life consistently outperformed those put on the bottle from birth.
Researchers at Oxford University and the Institute for Social and Economic Research (ISER) in Essex made their conclusions after "pairing up" children who in all major respects, such as family circumstances and maternal IQ, were identical.
The only difference was whether or not they were breastfed. They then compared each of these "twin" pairs to gauge the difference made by breastfeeding.
Maria Iacovou, a research fellow at the ISER, said breastfed babies had IQs that were on average between three and five points higher.
The results are from the Avon Longitudinal Study of Parents and Children, which follows the lives of more than 14,000 mothers who gave birth in 1991 and 1992, and their children.
Ms Iacovou said the data show an effect at aged five, seven, 11 and 14.
"We wouldn't have been surprised if the effect faded with time, but it didn't," she said.
She added that other studies showed there was an effect in the pre-school years. They excluded such information from this study, as in the Avon study pre-school ability was assessed by the mothers, who she thought were "probably a little biased".
She said there were two schools of thought on how breastfeeding had an effect: that long-chain fatty acids in breast milk helped the brain develop; and that the act of breastfeeding improved the mother-child bond.
Numerous studies have shown that breastfeeding improves a young child's health. For example, breastfed infants tend to get fewer infections. However, relatively few have looked at its impact on intelligence.
Ms Iacovou said: "This is more evidence that breastfeeding is good for your baby."
However, while she said that increasing numbers of studies were pointing to the conclusion that it aided intelligence, the theory remains controversial. In 2006 a study published in the British Medical Journal showed it had no effect.