I agree that correlation is often confused with causation, and has been particularly in discussions of breastfeeding. However I read the actual study, which is linked and they included maternal education, income level, smoking, maternal age, maternal pre pregnancy body mass index, gestational age, type of delivery, and birth weight in their study and took them into account. They also did the study in Brazil because breastfeeding was not positively associated with family income. The difference in IQ is seen even within income, as seen in figure 1 of the study. The authors of the study admit the study does not answer the question of whether this difference in IQ is attributable to the biological component of breastmilk, mother infant bonding, or intellectual stimulation, but this study goes much further than any previous study.Okay, fine, maybe it is more convincing than other studies.
But what seemed curious to me was how NPR was eager to convince people that breastfeeding is good for the baby, but a lack of breastfeeding is not necessarily bad:
STEIN: Horta and Lawrence agree that babies raised on formula can turn out to be just fine, but they say everything should be done to help women breast-feed if they can. Rob Stein, NPR News.Saying that breastfed babies are better off, on average, is the same as saying that formula-fed babies are worse off.
I guess they want to shame the moms who could breastfeed and choose not to, and not shame the moms who are unable to breastfeed. Are NPR listeners really eager to shame someone after hearing a story like this?