If I didn’t hate conspiracy theories so much, I’d start this post out reminding you that a recent systematic review from the World Health Organization (WHO) had the nerve to be realistic about the health benefits of breastfeeding. The results shouldn’t have been surprising to any of you who read this blog regularly; basically, they found that most infant feeding studies show modest benefits to breastfeeding, and are bogged down by research pitfalls like endless confounding factors, self-reported data marred by poor recall, and the impossibility of conducting the double blind, randomized, controlled experiments we need to make absolutely sure we aren’t confusing causation with correlation. But considering that this analysis came from WHO, an organization that has been fundamental in the popularization of breastfeeding advocacy and research, it must have ruffled a lot of feathers.
So, one could argue that the media push of three rather sloppy studies is simply a flurry of flapping wings, trying to distract from the presumably disappointing WHO statement. But one won’t, because one gets seriously annoyed when one hears people engaging in similar conspiracy theories about Big Formula. Although one could also argue that viewing these studies as a ploy would be a less offensive interpretation than assuming people actually think they are worth spreading around. One is also very exhausted after a 4-am wake-up from one’s two-year-old and one is discussing oneself in a grammatically incorrect, rather disturbing third-person. Let’s move on, shall one?
The three studies include one about metabolic function and gut microbiome; one about maternal deaths attributed to not breastfeeding; and one about child cognitive function. We’ll start with the the metabolic/gut microbe study, Early Diet Impacts Infant Rhesus Gut Microbiome, Immunity, and Metabolism, because it involves rhesus monkeys and they are just so damn adorable.
For this study, the researchers fed rhesus monkeys either breastmilk or infant formula, and concluded that “metabolic and gut microbiome development of formula-fed infants is different from breast-fed infants and that the choice of infant feeding may hold future health consequences”. I don’t think it’s even worth explaining what the implications of this finding are in humans, because, well, these were monkeys. They were presumably fed monkey breastmilk and human infant formula, or human breastmilk and monkey formula, or some other combination of the two. But no matter what, they were comparing apples to oranges. Or humans to monkeys, as the case may be. True, rhesus monkeys are considered a great stand-in for human subjects, but if monkey milk was that similar to human milk, I expect we’d see the WHO hierarchy of infant feeding change to include “rhesus money milk” after human donor milk, ahead of formula. (I wonder if anyone has ever looked into this, come to think of it… ) To quote some of my favorite lactivist memes, cow’s milk is for cow babies. Human milk is for human babies. Therefore, wouldn’t feeding monkeys either human milk or formula made to emulate human (as opposed to monkey) milk confuse the results?
Consensus: not worth worrying about unless you are super concerned about the metabolic and gut function of rhesus monkeys being used as lab rats. (If you are, contact your local animal right’s group, because frankly I think using innocent animals for this sort of “research” is on par with using them to test mascara.)
Next up, we have a study from the same researcher who brought you the infamous “Burden of Suboptimal Breastfeeding” study which was the direct cause of a permanent dent in the master bedroom wall of our old house that bears an uncanny resemblance to the shape of my forehead. This new study, Cost Analysis of Maternal Disease Associated With Suboptimal Breastfeeding, uses the same type of statistical model as its ugly stepsister and reports:
If observed associations between breastfeeding duration and maternal health are causal, we estimate that current breastfeeding rates result in 4,981 excess cases of breast cancer, 53,847 cases of hypertension, and 13,946 cases of myocardial infarction compared with a cohort of 1.88 million U.S. women who optimally breastfed. Using a 3% discount rate, suboptimal breastfeeding incurs a total of $17.4 billion in cost to society resulting from premature death $733.7 million in direct costs, and $126.1 million indirect morbidity costs.
All you need to know about this study is in the abstract (something I never thought I’d hear myself say). This is not a study, but an elaborate guesstimate, based on “modeling cases” of specific diseases the authors believe to be caused by not breastfeeding “using literature on associations between lactation and maternal health”.
Consensus: Not worth worrying about, unless you are taking economics and want to challenge yourself by figuring out how they came to their conclusions, as I expect it would be an interesting exercise. See how I’m looking out for your cognitive development? Which is a great segue to our last study of note…
… Breastfeeding and early white matter development: A cross-sectional study, by Deoni et al, which claims to:
…(P)rovide new insight into the earliest developmental advantages associated with breastfeeding, and support the hypothesis that breast milk constituents promote healthy neural growth and white matter development.
Here, the researchers performed MRIs on a bunch of babies and toddlers who had been breastfed, formula fed, and combo-fed, and found that the exclusively breastfed kids showed more white matter in their brains, as well as a few other differences in brain composition that suggested enhanced cognitive ability. The study is being applauded for doing two important things: showing the advantage of breastmilk on the human brain without having to rely on IQ tests and performance assessments, and for (supposedly) controlling for the ultimate confounding factor of socioeconomic status, or SES. This is because all of the babies they used were born full-term, healthy, and to mothers in the same socioeconomic group, based on the Hollingshead Social Status Index.
Ideally, this would lead people like me to throw up the white flag, as we can’t start arguing that maternal education or income has anything to do with the benefits observed in breastfed babies. If all the mothers were of the same social status, and they controlled for health issues in the babies (which they did) then the breastmilk has to be what’s influencing the results, right?
The trouble is, in this case, the researchers failed to control for what is, arguably, the most important factor of all – maternal and paternal IQ. They try to explain this away, stating that “(w)hile maternal IQ was not specifically measured, the combination of education and SES was believed to provide an adequate alternative.” Now, it could be my sleep-deprived brain (speaking of white matter, I bet if I had an MRI right now the image would look like swiss cheese) but doesn’t this seem rather obtuse for people smart enough to be conducting neurological studies? Having a superior education does not mean that your IQ is high, and if you’re talking about wealth in the same breath, the reality can be even trickier. Enough money can buy you an pretty impressive education – followed by a high-status job. There are extremely smart mechanics and extremely average CEOs. Status begets status, and IQ may beget IQ, but the two don’t necessarily have anything to do with each other.
This is a long way of saying that maternal SES (speaking of which – it really twists my knickers that none of these child cognitive studies ever mention the dad’s role. What about paternal IQ? Paternal SES? Paternal involvement?), while undeniably important when measuring things like access to healthcare, is not an accurate assessment of the quality of the child’s early learning and home environment, or his/her genetics – two important pieces in the intellectual development puzzle. A recent study using similar techniques as the one in question discovered that “the more mental stimulation child gets around the age of four, the more developed the parts of their brains dedicated to language and cognition will be in the decades ahead.” Considering that the Deoni study did not even control for childcare – i.e., whether the child was primarily in daycare, with an in-home but non-parental caregiver, or with a parent (mother or father) – how can we possibly know if their environment had any effect? Women in the U.S. who choose to/are able to exclusively breastfeed for a lengthy amount of time – something that often requires a physical, emotional and in many cases professional/financial burden – might also be more willing to invest in their children in other ways that can affect early learning. Not to mention that EBF women are more likely to be full-time caregivers to their babies - the elephant in the room, especially for a working mom like me who has made a decision to combine career and family. True, I don’t want to hear that staying home with your babies gives them cognitive advantages (and I also think there are plenty of ways to skin a cat or however that horrible saying goes, and there are advantages to having a mother who is professionally fulfilled and satisfied, also) but I also think it’s subliminally sexist not to talk about this- because it certainly doesn’t have to be the woman who stays home. Anyway, I digress… but the point is, this study doesn’t control for what it needed to control for.
Consensus: Given the fact that they didn’t control for much besides health and SES, I don’t think this study “proves” or even “suggests” anything important, except that the people studying these brain scans might want to assess their own critical thinking skills. I wonder if that can be seen on an MRI?