Breastfeeding effect on IQ questioned….

The results of a number of research studies over the past 2 or 3 decades suggest that breastfeeding, particularly for more than four months, improves the cognitive performance of children.

This is a difficult research question to answer, due to the many confounding variables. Breastfeeding mothers tend to be more educated and of higher socioeconomic status. In addition, many parents who use bottles for feeding tend to “prop” the bottle, or leave the infant unattended while he or she drinks the formula, like the little one in the picture below. Given the frequency of feeding for young infants, the cumulative difference in “face time” between the breastfed and bottle fed (and propped) infants becomes large very quickly. Consequently, the breastfed infant has had substantially more eye contact, touching, and other positive social interactions with the mother.

Nonetheless, previous studies have suggested that breastfeeding, especially for low birthweight babies and others with risk factors, can have a positive impact on cognitive development.

Geoff Der and his colleagues published a new study in the online British Medical Journal based on data from over 5000 children of 3000 American mothers. The data set included sibling pairs in which one child was breast fed, while the other was bottle fed. Based on these data, Der et al. concluded that previous reports of breastfeeding enhancing IQ were erroneous. Instead, the higher IQ of breastfed babies was likely due to their having smarter mothers.

Obviously, there are many other benefits to breastfeeding that have nothing to do with IQ. The researchers do point out that they excluded low birth rate and “at risk” infants from their sample, and the benefits of breastfeeding may be particularly important to these groups.

Somewhat lost in the discussion of these results is the fact that the Der et al. data provide one more piece to a growing body of evidence suggesting that whatever IQ is, it is very heritable.