Breastfeeding Medicine

Physicians blogging about breastfeeding

Arthur Eidelman deconstructs the latest breastfeeding-and-IQ study

with 7 comments

Would you do a study that “analyzed” the relationship of breastfeeding and IQ based on data obtained from mothers who retrospectively reported at 18 months postpartum if they did or did not breastfeed? Would you conclude anything if the data base was a yes or no answer, with no distinction made if it was exclusive breastfeeding or partial (of any degree) and with absolutely no data provided as to duration of the breastfeeding? Believe or not that was the basis for the “conclusion” by researchers in England that was published in the open access journal PLOS/one, widely reported the lay press and trumpeted gleefully by the disparagers of breastfeeding.

No less than these glaring methodological deficiencies, is the misreading by the “public” of what the authors themselves studied. As they stated, the study was NOT on IQ per se, but rather on IQ growth trajectories. Or to put it simply, if breastfeeding increased a child’s IQ as measured by the initial IQ test and the child maintained that degree of increased IQ as compared to children who did not breastfeed, there would be no increased growth trajectory.

Thus, extrapolating from trajectory data to absolute levels of IQ and concluding that breastfeeding has no impact on IQ is just plain wrong (let alone ignoring the wealth of articles in literature that support the conclusion that breastfeeding does increase IQ : see the most recent review: Effects of Breastfeeding on Obesity and Intelligence: Causal Insights From Different Study Designs. Smithers LG, Kramer MS, Lynch JW. JAMA Pediatr. 2015 Aug)

Given this combination of the basic limitations of methodology coupled with the misinterpretation of the study results, one must conclude that in no way does this study contradict what is a given: breastfeeding is critical quantitative positive variable in the cognitive development of all children. Furthermore, as a measure of the limited value of the study, one should note that authors did not even cite the issue of the lack of data as to the quantity of breast milk that the infants ingested over time in their list of the limitations of the study, let alone, did they indicate the lack of data as to major confounders such as maternal IQ and quality of home environment.

Bottom line is that this study should be discounted in any serious discussion as to the relationship of breastfeeding and IQ!

Dr. Arthur I Eidelman is a Professor of Pediatrics at Shaare Zedek Medical Center, Jerusalem, Israel. He is the Editor-in-Chief of Breastfeeding Medicine, past president of ABM, and a Fellow of the Academy of Breastfeeding Medicine.

Posts on this blog reflect the opinions of individual ABM members, not the organization as a whole.

Written by aeidelmanmd

October 8, 2015 at 5:05 pm

7 Responses

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  1. I share your concerns about treating breastfeeding as a dichotomous variable. I’m also curious about the impact of the twin sample. We’ve known for years that mothers of multiples draw from the same fatty acid reserves to supply more than one baby, and that this demand makes a difference in cord blood EFA levels. I’m curious about the impact of this depletion on lactation. A preliminary search didn’t turn up anything conclusive on this question, but there’s an intriguing 2001 study on language outcomes: they reported a breastfeeding effect for singletons, but not for twins. (Could be lots of other factors in play besides EFAs, of course, like exclusivity.)

    I’ve also been chewing on their choice to control for gestational age. We’ve known since Lucas et al. in 1992 that breastfeeding is especially important for cognition in premies, so isn’t it going to obscure an important relationship if you partial out gestational age? This is a messy question, since prematurity is tangled up with both cognitive outcomes and breastfeeding duration/exclusivity outcomes, but I think it’s an important one.


    October 8, 2015 at 6:01 pm

  2. Breast is best, plain and simple. Everyone should stop arguing that some chemically concocted mess made in a lab compares. The only time formula is better is when breastfeeding cannot be performed and that is another debate altogether.


    October 9, 2015 at 10:44 am

  3. The author of this post feels that this study can not contribute to the discussion of whether or not breastfeeding can boost IQ. He writes that there is a wealth of articles that show that breastfeeding is a “critical quantitative positive variable in the cognitive development of all children”

    One of the authors’ main issues with the study was that they did not control of confounders like maternal IQ and home environment. — Isn’t a twin study a pretty good way to do this? Where else can you find children raised in the same household with the same parents?

    I would be interested in knowing the his thoughts on some other studies that did not find that breastfeeding played a critical role in IQ.

    Like the 2007 AHRQ report (and oldie, but a goodie)
    “There was no relationship between breastfeeding in term infants and cognitive performance”

    Or this study that factored out whether or not children were read to? 2013
    “little-to-no relationship between infant feeding practices and the cognitive development of children..”

    Or the 2014 sibling study?

    Or the 2013 WHO meta analysis that found a only 2.2 point increase when high quality studies were taken into account? (Is a 2 points statisitcally significant?)

    Or any of these studies?
    “Breastfeeding was not associated with any crude IQ advantage or difference in neurological soft signs in children at 9 years” 2013 .
    “…The results suggest that parental education and maternal IQ are major predictors of IQ” 2013 .
    “…little or no effect of breastfeeding exclusivity and duration on key child outcomes”.

    The opinion piece by Smithers and Kramer did conclude that breastfeeding did effect IQ, but did acknowledge that sibling studies found no difference and that some analyses found a very small increase. The authors of this paper did not say how much they felt that breastfeeding increased IQ.

    This article also concludes that breastfeeding has no effect on obesity. It would be interesting to know the author’s thoughts on this as well . In table 2 of the AAP policy statement, which was co-written by him states that breastfeeding can reduce the risk of obesity by 24%.

    Anne Risch

    October 12, 2015 at 8:20 am

    • BAM. Bring it.


      October 19, 2015 at 3:34 pm

    • Here is recent study on breastfeeding and IQ that looks well done to me, although I have not read the full text. I would assume that Dr. Eidelman and others at the ABM have read it in its entirety.

      I would be interested in hearing what ABM members think about this study.
      It is associated with Harvard and has several coauthors.
      Results: “In linear regression models adjusted for sociodemographics, maternal intelligence, home environment, early child care, and maternal depression, longer breastfeeding duration was not associated with substantially better executive function, behavior, or social-emotional development.”

      Anne Risch

      December 16, 2015 at 7:56 am

  4. This is one more study that should be added to meta-analyses rather than interpreted on its own. Readers are invited to refer to “Breastfeeding and intelligence: systematic review and meta-analysis”, Horta BL, de Mola CL, Victora CG. Acta Paediatrica 2015 July 27 doi: 10.1111/apa.13139. [Epub ahead of print]

    James Akre

    October 22, 2015 at 2:14 pm

  5. Breastfeeding is not best. And breastfeeding cannot raise IQ. Breastfeeding is physiological. It is its substitutes that should be examined for their effect on IQ I would like to see a study that compares children who received only formula; varying, specified amounts of formula; and no formula, that treats breastfeeding without substitutes, as the control.


    April 12, 2016 at 2:30 pm

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