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A new study suggests breastfeeding produces smarter kids. Except that’s not actually what it says

To me, breastfeeding and formula feeding both possess a kind of magic. But the claims made about breastfeeding stretch credulity

Those who want to breastfeed deserve robust, serious and material support. But so do those who don’t. Photograph: Anastasiia Krivenok
Those who want to breastfeed deserve robust, serious and material support. But so do those who don’t. Photograph: Anastasiia Krivenok

A recent study on breastfeeding out of Oxford has enjoyed extensive media coverage over the last week. The study – which focuses on associations between having been breastfed and performing well in GCSE exams – has spawned many articles suggesting that breastfeeding produces smarter kids.

Many articles praise the study’s methodology for accounting for the fact that breastfed babies are typically from richer and more highly-educated households than non-breastfed babies. This raises concerns about whether good exam performance is better explained by these other factors (since they are so generally impactful). It seems strange that most articles simultaneously praise the study for doing what few studies manage (ie controlling for confounding factors like socioeconomic status and maternal education) and then just go ahead and report the “crude”, non-adjusted results, which is what most newspapers did. Many articles mention at the end that the associations between breastfeeding and good grades diminish drastically after the relevant adjustments, but by then the damage is done.

A better headline might have been “association between breastfeeding and improved exam performance reduces to barely statistically significant (and sometimes not even that) when just two confounding factors accounted for”. And, while it is good to see studies taking confounding factors seriously, there is much scope for improvement. The method used to control for maternal intelligence involved equating cognitive ability with a score on a vocabulary test of just 20 words, conducted when the relevant child is 14. This is not a new metric, but it’s far from ironclad, to say the least. Merciful that most of us do not have our capacities so crudely reduced.

Beyond these limitations, there is every chance that some third control (say, for co-parental intelligence or availability of caregiving support) might reduce the association away entirely. For example, one study that poses a challenge to this whole field of literature is a 2014 study which looked for different outcomes between children from the same families who had been fed differently (so, where the socioeconomic factors can be expected to vary little, but where some children were breastfed and some were not). There, 10 out of 11 classic claims for benefits of breastfeeding almost completely vanish under analysis, and “none reach statistical significance (p<0.05)”.

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The method used to control for maternal intelligence involved equating cognitive ability with a score on a vocabulary test of just 20 words, conducted when the relevant child is 14

Separate from the questionable rigour of a lot of the scientific literature (and the worse state of its reporting) is the ethical issue of when we might be willing to take “no” for an answer on breastfeeding. Nobody who has had any part of maternity services in Ireland will have missed the recommendation that babies be breastfed. It is raised frequently and breastfeeding literature abounds in all maternal spaces.

Why are Ireland’s breastfeeding rates stubbornly low?Opens in new window ]

The rhetoric is also routinely heavy-handed. Until December 2022, the HSE’s webpage dedicated to explaining “types of formula” opened with an information box issuing the following caution: “Breastmilk is the best and most natural food for your baby. Your body makes breast milk that is unique for your baby. The special ingredients are vital for normal growth, development and good health.” Vital for normal development is surely a stretch. Sabina Higgins, an enthusiastic promoter of breastfeeding, opened Breastival 2021 by describing Ireland’s breastfeeding rates as “pathetically low” and in the following terms: “We human beings, as top of the chain of life, have in our personal preferences played no small role in insulting mother nature by ignoring her gift to us.”

We also stigmatise use of infant formula economically by grouping it with cigarettes and alcohol as a commodity for which loyalty points cannot be earned in places like Tesco and Boots, and banning its advertisement in ordinary media.

Despite the vigorous campaign, many Irish families don’t breastfeed. We could continue to frame this scenario – as we so often do – as a consequence of maternal ignorance, manipulation by advertising or anxiety about breastfeeding in a hostile public sphere.

Or we might eventually accept that it is possible that many people make an informed decision not to observe the guidance, and that our lower rates are an accurate reflection of the percentage of the population that thinks it’s the right choice for their family. While I don’t think most people fret over the methodological mayhem of a lot of the scientific reporting on breastfeeding, I think the status quo reveals that at some deep level, many do not trust the veracity of the recommendations or feel they conform with their experience.

‘Women don’t treat breastfeeding or breasts as a sexual thing. It’s mainly males’Opens in new window ]

To me, breastfeeding and formula feeding both possess a kind of magic. Breastfeeding, somehow simultaneously natural and miraculous, connects a life-sustaining practice of modern parenthood with the earliest activities of humanity and back even further into evolutionary ancestry. Formula and bottle feeding take what has almost forever been an operation shared exclusively between mothers and babies, and throws this intimacy open to fathers, same-sex partners and broader caregiving circles, thereby widening the scope for nurturing and enabling more egalitarian distributions of family roles. There is much to celebrate all round here.

We have some genuinely serious issues impacting the very young and vulnerable in this country – housing and homelessness crises, a childcare crisis, a shambolic scenario for parents trying to get school places for children with special needs. Those who want to breastfeed deserve robust, serious and material support. But so do those who don’t, and I know I don’t speak only for myself when I say we could deal with a little less proselytising and misrepresentation.

Dr Clare Moriarty is an Irish Research Council Postdoctoral Fellow at Trinity College Dublin