Advocates of breastfeeding have long cited that a mother's milk boosts a child's intelligence but findings of a new study suggest that the IQ of breastfed babies is no better than those of bottle-fed babies.

Based on data from King's College London's early development study, which involved nearly 6,000 sets of twins, psychologists Sophie von Stumm and Robert Plomin, from Goldsmith's University in London, found that breastfeeding is neither linked with the IQ level of two year olds nor later gains.

The researchers reported that although breastfeeding appeared to have an advantage to the IQ of girls before 7 years of age, the advantage is gone by the time they reach 16 years old.

For the study, 62 percent of the babies were breastfed for four months and the rest were bottle-fed. Between two and 16 years of age, the twins were tested and compared in terms of their cognitive ability.

At each testing age, the children completed ability tests, which include web-based, parent-administered and phone-based tests.

The researchers found that both of the children who were breastfed and bottle-fed have the same average IQ, which led them to conclude that breastfeeding offers little or no benefit for cognitive development from early age through adolescence.

"Comparatively small events such as breast-feeding are very unlikely to be at the core of something as big and complex as children's differences in IQ," Stumm said. "Instead, IQ differences are better explained by long-term factors, for example, children's family background and their schooling."

Despite their findings, the researchers said that it does not mean that breastfeeding does not have any benefit at all. Breastfeeding, for instance, is known to be beneficial to the development of a child's autoimmune system.

Many experts likewise recommend breastfeeding such that it also strengthens the bond between mother and child. Babies who were exclusively breastfed for the first six months of life also had fewer bouts with diarrhea, respiratory problems and ear infections.

The American Academy of Pediatrics (AAP) urge mothers to breastfeed their babies for at least the first 12 months of their child's life.

Nonetheless, the researchers of the new study, which was in the journal PLOS ONE, said that mothers should know that they are not harming their child if they cannot breastfeed such that being bottlefed early in life won't likely cost a child a university degree when he grows up.