Azara Blog: Another study which claims that breastfeeding raises IQ

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Date published: 2008/05/06

The BBC says:

More evidence is being put forward that breastfed babies eventually become more intelligent than those who are fed with formula milk.

Canada's McGill University found breastfed babies ended up performing better in IQ tests by the age of six.

But the researchers were unsure whether it was related to the breast milk itself or the bond from breastfeeding.

The study of nearly 14,000 children is the latest in a series of reports to have found such a positive link.

However, one problem has been that some of the research has struggled to identify whether the findings were related to the fact that mothers from more affluent backgrounds were more likely to breastfeed and it was factors related to the family circumstances that was really influencing intelligence.

But the latest study attempted to take this into account by following the progress of children born in hospitals in Belarus, some of which ran breastfeeding promotion schemes to boost rates across all groups.

They found that those who breastfed exclusively for the first three months - with many also continuing to 12 months - scored an average of 5.9 points higher on IQ tests in childhood.

Unfortunately this is just another classic confusion between correlation and causation. The hospitals might have promoted the schemes "across all groups" but it does not say that the take-up was the same across all groups. And indeed, the fact that some mothers were more willing to take this up could be taken as prima facie evidence that they were more motivated in the first place, hence might be better mothers, completely independently of whether they breastfed their children or not. So it is misleading to state that it is unclear whether this result "was related to the breast milk itself or the bond from breastfeeding". It could just be related to the fact that correlation is not the same thing as causation. The only way to do this study properly would be to randomly select which mothers breastfeed and which do not. Needless to say, that study will (probably) never be done.

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