Breastfeeding ‘linked to higher IQ’?

  • Dr Dawn LeemingDr Dawn Leeming has a wide range of research interests in the areas of health and well-being.  In particular her research has focussed on women’s experiences of breastfeeding and the social construction of these.  Here she comments on why we need to be cautious about the recent study which suggests being breastfed longer may lead to higher IQ scores and enhanced income in adulthood.

Breast and the rest

The BBC and other news media have reported a Brazilian study suggesting that being breastfed longer may lead to slightly higher IQ scores and enhanced income in adulthood.  But how relevant is this research to parents and healthcare professionals within the UK?  Is this newsworthy or just good copy on an emotive issue?  

The study by Professor Cesar Victora and colleagues, reported in The Lancet Global Health, is part of an admirable programme of longitudinal research on child health outcomes in a developing country.  The researchers followed up an impressive 3493 participants over 30 years.  Furthermore they included assessment of socioeconomic factors such as parental income and education that might be expected to impact both breastfeeding and IQ scores.  Their analyses suggest that these factors were not responsible for their finding that those who had been breastfed for more than 12 months had higher IQ scores and incomes than those who had been breastfed for less than one month or not at all.

However, there are reasons to be cautious about the findings.  As the authors acknowledge, they did not investigate aspects of the home environment such as parenting style, number of siblings, support with childcare and hence the amount of adult attention available for the baby.  As many new parents will know, these factors can be highly relevant to both continuing breastfeeding and being able to provide stimulating learning experiences.  Such factors could therefore explain, at least partially, the link between longer duration of breastfeeding and enhanced IQ scores.

Moreover, a particular concern about applying the findings to the UK is that, as the authors explain in the full study protocol, the usual alternative to breastfeeding in Brazil is cow’s milk rather than infant formula. This means that the researchers’ comparisons between participants who received more or less breast milk (and hence more or less cow’s milk) cannot be transferred to the UK where unmodified cow’s milk is not generally used to feed infants.

There are other reasons to be circumspect about investigations into IQ and breastfeeding.   Apart from debates about the meaningfulness of IQ scores, extensive research has suggested that cognitive abilities are likely to be influenced by many factors.  These include not only socioeconomic inequalities, but also genetic heritage, parental education and interests, home learning experiences, schooling, timing of schooling, and health and nutrition more generally.  Therefore, it is worth questioning the media focus on just one potential factor – breastfeeding.  Could this be part of a wider social concern with policing and judging the behaviour of mothers?  It is curious that we do not see quite the same interest in potential links between the amount of time fathers spend interacting with their babies and later IQ.

There is certainly value in research that evidences the advantages of human milk for babies.  It is profoundly regrettable the way that commercial and other interests during the last century led to the decline in such a fundamental human activity and there is still work to be done in reversing this trend.

However, further information about the health benefits of breast milk is not what is primarily needed to achieve change – research suggests that today’s mothers already know that ‘breast is best’.  What many don’t know is how to deal with negative responses to feeding their baby when others are around, how to achieve the best position for successful pain-free breastfeeding when they haven’t seen others breastfeeding and how to feel good about using their breasts in this manner when our society fetishizes female breasts.  Moreover, our own and others’ research has illustrated just how distressing some new mothers find their initial struggle to establish breastfeeding when they are led to believe that the alternative – infant formula – is almost toxic to babies.

Therefore, we do actively need to promote the value, normality and visibility of breastfeeding, and improved understanding of how human milk may benefit infants is an important part of this.  However, producing news headlines that suggest your child will be less intelligent and less affluent if you do not breastfeed them is probably not the best way to move our society forwards.

The original report of the study:

Victora, C. G., Horta, B. L., Loret de Mola, C., Quevedo, L., Tavares Pinheiro, R., Gigante, D. P., Gonçalves, H., & Barros, F. C. (2015). Association between breastfeeding and intelligence, educational attainment, and income at 30 years of age: a prospective birth cohort study from Brazil. The Lancet Global Health , Volume 3 , Issue 4 , e199 – e205.

Read the full story on the BBC News website.

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>