[It’s worth sharing here, before I explain the problem, that I have been accused by some of missing the point because I am a social scientist by training (PhD in psychology) whilst ignoring that I also trained in quantitative methods (a combination of statistics and research methodology). It was a graduate minor I completed while doing my PhD. Part of what we learned was that too often the “harder” sciences fail to grasp the effect of groupings or the problems with variable assessment because in their fields the measures are typically clear-cut and they extend that to areas that are not as clear-cut, but may seem so. Breastfeeding research is the perfect example of this problem and one that is ignored by far too many people.]
Although many of the outcome measures associated with breastfeeding are health related and thus clear-cut (e.g., obesity, diabetes), the assessment of breastfeeding seems to be clear cut, but it isn’t. The problem has been that many researchers, and thus most of the breastfeeding research, has treated breastfeeding in a dichotomous way. It has been treated as all-or-none – you breastfeed or you don’t – without understanding the nuances in feeding methods and the potential implications of this to various outcomes.
Just as vaccines were created with a specific use in mind, breastfeeding has evolved biologically in a specific way; biologically, it is something that is to be done exclusively for approximately six months and then continued, along with solids, until the child weans, typically after age 2, though in some cases beforehand. Any research that fails to take this into account is grouping their participants erroneously and potentially masking any effects. (There are also other problems in that mixed groups may lump together babies who had formula for one week with those who breastfed for one week, treating them the same, but that’s yet another methodological grouping issue that masks any possible effects.) People are now using this research to try and claim that breastfeeding is “oversold”.
It’s not. Really.
What if we look at the research that doesn’t make this mistake? Although there is no research that truly has what we could call a “biological” or “evolutionary” breastfeeding group (i.e., exclusive breastfeeding for six months followed by complementary breastfeeding with solids until a minimum of two years), there is research that has started to examine exclusivity and/or duration of breastfeeding as an additional factor in their analyses. When we look at that data, we see that breastfeeding has hardly been oversold. In fact, we may be underselling it.
Take breastfeeding and obesity, for example. Although data has been mixed, when exclusivity or duration is examined (along with controlling for other known confounders such as parental BMI, SES, and the child’s lifestyle behaviours), we can see a dose-effect with those children who were breastfed for less time or who had formula the majority of the time having a greater risk of being obese. The same can be said for analyses examining the relationship between breastfeeding and IQ, despite some researchers suggesting no relationship (even though, in some cases,their own analyses showing significant dose-effects), which is likely explained by the paucity of studies that have actually included appropriate assessment of breastfeeding duration or exclusivity. Most recently, research suggests a dose effect of breastfeeding on IQ, even after controlling for parental IQ (a confound that has previously been ignored), and declares previous null results may be in part due to the type of IQ test used. In Denmark, a large prospective study using two samples and two different measures of IQ examined the relationship to breastfeeding duration (but not exclusivity) while controlling for myriad confounds (including those typically claimed to be the cause of any relationship, such as SES and parental education) and found a significant dose-effect of breastfeeding on later IQ (assessed in adulthood). In perhaps the most persuasive study – the PROBIT study, which is a randomized controlled trial in Belarus – both duration and exclusivity were assessed and it was found that with greater duration and exclusivity (controlling for confounds), clear evidence of a positive relationship to intelligence emerged.
Even more importantly than links to obesity and IQ, when we look at biological or evolutionary breastfeeding we can see strong evidence of the risks of not breastfeeding in this manner to more serious health conditions such as childhood cancer and SIDS. In the cancer research, we still face the issue of exclusivity being ignored with only duration being considered, yet significant results remain. (You can read more on the breastfeeding-childhood cancer research here.) In the SIDS research, exclusivity and duration were examined and found to have a greater effect than any breastfeeding at all, though any breastfeeding was also related to a “reduced risk” of SIDS.
We have to ask ourselves: how much more significant would these findings be if we actually were able to assess biological breastfeeding in its entirety?
Of course none of this is to say that formula shouldn’t be available or that women should lack choice, but rather to say that this push to say the science doesn’t support breastfeeding is not only misguided, but is hurting women’s ability to make an informed choice when it comes to how they feed their babies. (Yes, as hard as it may be to hear, choosing formula is accepting risk. Trying to pretend it’s not doesn’t help anyone. Just remember that we all accept risk, just in different areas.) It also affects the likelihood that society gets its proverbial shit together to better support new mothers in breastfeeding so that 60% of moms don’t report not being able to meet their own breastfeeding goals thanks to the numerous traps set up for them.
It is equally important to make sure people understand that increased or decreased risk does not equal certainty. Too often people bring up anecdotes of people that don’t “fit” the research and take it to mean the research needs to be thrown out; sadly, this is an effect of a science-illiterate population and one that needs to be addressed. Increased or decreased risk simply refers to the chances and does not dictate individual outcomes. It gives us information about general or population-level outcomes, but does not say a given individual will or will not face that specific effect, only their chances based on patterns in a larger group.
In closing, if we are going to talk about breastfeeding research, let’s make sure we do it correctly. Breastfeeding hasn’t evolved to be done partially or even for shorter durations; the biological norm is for a period of exclusive breastfeeding followed by continued complementary breastfeeding for a significant time period. If we are to look at any outcomes of breastfeeding, this is the standard to which it needs to be held. Then we can start to see the effects of deviating away from this and figure out the best way to support all parents in their feeding choices (yes, knowing the risks means we can also help minimize them when people don’t reach this biological norm for any reason). Once we have this information, then parents can make the decisions about what kind of risk they are willing to accept and how to minimize it, for then they will have the appropriate data to make such a conclusion.
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