A new study on breastfeeding challenges its effect on children’s behavioural, linguistic and cognitive development. Researchers studied both breastfed and formula-fed babies and found no statistical differences across 13 behavioural and cognitive outcomes among children beyond age 5. In fact, the only behavioural or cognitive difference researchers found between the two groups was a slightly less hyperactivity at age 3 among babies who had been breastfed for at least six months. This suggests “that the earlier observed benefit from breastfeeding may not be maintained once children enter school,” the study’s authors wrote.

This is notable for a couple of reasons: First, the study, which involved roughly 8,000 families, used a technique of statistical analysis called propensity score matching. Without getting too technical, propensity score matching allows researchers to make sure the outcomes they’re examining – problem behaviours, expressive vocabulary and cognitive abilities at age 3 and again at 5– are actually due to breastfeeding (or, not breastfeeding), rather than any other potential influencers, like say, parent’s income or education level.

Second, it challenges deeply held assumptions about the degree to which breast milk provides an IQ boost to children. While other studies support breast milk’s cognitive benefit, the boost is small (though not insignificant) — 1.76 points among four studies with the least bias.

The study is not, of course, conclusive. And the biological benefits of breastfeeding in terms of nutrition and immunity are undisputed; breast milk is still promoted by experts, including the World Health Organization, as the best, cheapest, and most nourishing food to give babies. (There can also be benefits to the mother.)

But these results may, perhaps, ease the guilt many women feel when they are unable or choose not to breastfeed their babies. With the rise of breastfeeding advocacy globally – a good thing, in its purest aim – has come an inevitable underbelly of judgement that plays out in online forums. Hopefully, this study is the start of a string of research that ends with the conclusion: Rather than parse the biological benefits of breastfeeding to their minutest levels, let’s focus on how to make sure all mothers have the opportunity and resources to breastfeed successfully, if they choose to.