Most of the academic research on breastfeeding focuses on early-life outcomes—infections, for example, in the time period in which you might actually be breastfeeding. In the popular discourse, however, the focus seems to be much more on the long-term benefits. This is where the guilt stacks up.
The question is, really, whether breastfeeding gives children some small leg up in intelligence. If you believe studies that just compare kids who are breastfed to those who are not, you find that it does. I talked about one example of these studies on page 68, and there are others. There is a clear correlation here—breastfed kids do seem to have higher IQs.
But this isn’t the same as saying that breastfeeding causes the higher IQ. In reality, the causal link is much more tenuous. We can see this by looking carefully at a number of studies that compare children who were breastfed to their siblings who were not. These studies tend to find no relationship between breastfeeding and IQ. The children who were nursed did no better on IQ tests than their siblings who were not.
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