Beautiful study, ugly reporting

A new study from The American Journal of Medicine strengthens the link between breastfeeding and diabetes prevention. In looking at 2,233 Californian women, ages 40-78, from a single health plan (Kaiser), the researchers discovered a signficantly higher rate in the women who had children but never breastfed (405 of the women), compared to those who either hadn’t given birth (703 of the women) or who had nursed or pumped exclusively for at least a month (1,125 of the women).

The breakdown of those who developed Type 2 diabetes later in life was as follows (copied from WebMD):

  • 17.5% of the women who hadn’t given birth.
  • 17% of the women who breastfed all their children for a month or longer.
  • 20.3% of those who breastfed, but not all children for a month or longer.
  • 26.7% of moms who didn’t breastfeed.

Of those, 405 were not mothers, 1,125 were mothers who breastfed for at least a month, and 703 were mothers who had never breastfed.

You might expect that I’m going to pick apart this study, explaining that it was impossible to control for all confounding factors, lamenting the fact that the results relied on the (personal, and therefore likely flawed) recollections of women who’d been in their childbearing stages up to 50 years prior…. but I’m not. It’s a beautiful study, mostly because the authors are judicious in their analysis, and don’t hide behind “breast is best” rhetoric to disguise shaky results. I can’t copy and paste from the PDF of the entire paper here, but I did link to it, and I’d highly suggest reading the “Discussion” section, which outlines the advantages and flaws of a study such as this. The authors are also responsible enough to point out that the mechanisms behind their findings are completely unknown – in other words, while breastfeeding for even a short duration seems to have some protective effect against later development of Type 2 diabetes, they aren’t sure how this protective effect is conferred. Some have hypothesized that the type of fat lost more easily by lactating women may be the reason, or the apparent ability of lactation to alter insulin resistance. But the really important thing to acknowledge here is that once again, this could be a simple case of chicken and egg. Some of the same factors that may increase the risk of diabetes later in life – insulin resistance and obesity – are also significantly linked to shorter breastfeeding duration and lactation complications. So the same women who developed diabetes in this study could have refrained from breastfeeding for the same reasons that contributed to their later development of the disease… make sense?

Regardless, it’s an interesting finding, and I have no problem with it. I’m happy to see a study that examines the benefit of breastfeeding to mothers, rather than just focusing on what it can do for babies. It takes two to tango, after all. Plus, a month of breastfeeding, for those who physically/emotionally can handle it, doesn’t sound so daunting. Considering most U.S. maternity leaves are approximately 6 weeks, this could indeed be possible for women without having to deal with pumping, engorgement, etc, at work.

But I wouldn’t be the FFF if I didn’t find something to get all hot and bothered about with this news byte, would I? This time, it’s the media that I want to skewer. Because let’s face it – most folks are not going to read the entire study, cover to cover, and draw their own conclusions; they’re not going to see the sensitive discussion and thorough analysis the researchers did. They will probably just read about it in, oh, say, the Los Angeles Times, where reporter Shari Roan treats us to this little nugget of wisdom:

Breastfeeding a newborn for even one month will lower a woman’s lifetime risk of developing Type 2 diabetes, according to a study published Friday. Other research has also linked breastfeeding to a reduced risk of diabetes among women, but the new study establishes the strength of the association to a much greater degree…The question now is, why wouldn’t every new mother breastfeed for at least one month? 

Oh, Shari. Shari, Shari, Shari. If you’ve got 10 minutes, I’d be more than happy to answer that burning question for you. And while we’re at it, a little basic math might be useful, considering you write:

Researchers found that 27% of the mothers who did not breastfeed developed Type 2 diabetes. These women were almost twice as likely to develop the disease compared with women who had breastfed or who had never given birth. Among the women who breastfed for one to six months, 19% developed Type 2 diabetes compared with 16% among women who breastfed for six months or more.

Um, where did you get these numbers? I’m craptastic at math, so if any FFFs feel like picking through the actual study and figuring out why her numbers are off from the ones cited by Web MD, I’d be grateful. Either way though, unless I am even worse at number crunching than I thought (not bloody likely, as I believe I’m borderline LD on math stuff), last I checked 19% (the percentage of diabetes cases in those who had ever breastfed, which I’m assuming this writer is referring to by “compared to women who had breastfed”)x2= 38%. That’s significantly more than 27%, isn’t it? Not exactly “doubling”. Even if we use WebMD’s numbers (and I honestly can’t tell you who is right, although I’m assuming WebMD has a review board which is more familiar with accurate assessment of studies, so I’m leaning towards them), 17%x2= 34%, and again, the statistic for parous (meaning “having given birth”) women who never breastfed was 26.7%. Closer, but still no cigar.

Another strange piece of journalism comes out of the UK’s Daily Mail, which either misquotes lead study author Eleanor Bimla Schwarz, or Dr. Schwarz has changed her tune since writing the original paper:

“We have seen dramatic increases in the prevalence of type 2 diabetes over the last century,” said Eleanor Bimla Schwarz, M.D., M.S., assistant professor of medicine, epidemiology, and obstetrics, gynecology and reproductive sciences at the University of Pittsburgh. “Diet and exercise are widely known to impact the risk of type 2 diabetes, but few people realize that breastfeeding also reduces mothers’ risk of developing the disease later in life by decreasing maternal belly fat.”

Huh. That’s interesting, considering in the actual study, the authors discuss the possibility that belly fat might be the reason for this breastfeeding advantage, but are also quick to add that “further studies are needed to identify the pathways and mechanisms through which lactation reduces subsequent risk of diabetes.” Again, not a huge deal, but these little soundbytes have a way of spreading like swine flu through society – and even more dangerously, through science and medicine – and before you know it, you’ll be seeing every breastfeeding study citing this study as definitive proof that breastfeeding lowers diabetes risk by reducing belly fat. This is sadly how these things work (For a great breakdown on this phenomenon, I highly recommend reading Jules Law’s definitive paper, The Politics of Breastfeeding.)

Anyway, this quote is also used in CBS’s report on the study, which, like the LA Times, has to throw in its own clever digs to bottle feeders. First, the headline:

Breast-Feeding Protects Moms from Diabetes, Study Shows: Why Use a Bottle?

And then, the classic snappy ending:


“Our study provides another good reason to encourage women to breastfeed their infants, at least for the infant’s first month of life,” said Dr. Schwarz.
As if moms needed another reason.

Thanks, David W. Freedman. There’s a free seat in my lecture about why moms might choose a bottle, right next to your colleague from the LA Times. I’ll even throw in some free coffee and donuts.

About the Author:

Suzanne Barston is a blogger and author of BOTTLED UP. Fearless Formula Feeder is a blog – and community – dedicated to infant feeding choice, and committed to providing non-judgmental support for all new parents. It exists to protect women from misleading or misrepresented “facts”; essentialist ideals about what mothers should think, feel, or do; government and health authorities who form policy statements based on ambivalent research; and the insidious beast known as Internetus Trolliamus, Mommy Blog Varietal.

Suzanne Barston – who has written posts on Fearless Formula Feeder.


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11 thoughts on “Beautiful study, ugly reporting

  1. Ugh…I share your frustration. I agree that it's a nice study, and that as the authors blatantly state, more research needs to be done to find out what, if any, link exists between BFing and diabetes. But then you point out that various media sources have already taken this information and misquoted or twisted it to suit their agendas.
    Of course, that happens with any medical information that gets out to the public at large. Maybe some laypeople don't like elitist scientists, or get angry because they can't understand the science. But when the media twists and falsifies information, with the result that the general public is even more ill-informed than before, the scientists are probably just as angry at the media for failing to report the study accurately.
    So, a huge communication breakdown, between science and the public, which gets muddied even more by the media = angry lactivists, depressed women who can't BF,measles outbreaks in the US, etc.

    Other studies have shown a definite link between insulin resistance/diabetes and reproductive failure. As has been discussed here before, many PCOS women are IR/diabetic and there is a theory that BFing can be impaired in PCOS women. Whether that's all connected to the IR or not is not yet clear. It does seem pretty clear that once one endocrine factor is out of whack (too high or too low) it often affects other factors, as they tend to work in loops or groups.

  2. Ugh. I think I've mentioned that I had gestational diabetes, even though I began my pregnancy at 105 lbs, and gained a total of 20 lbs during the pregnancy. When I was diagnosed, the doctors made a big point of telling me that my lifetime risk of developing type 2 diabetes had now increased due to have diabetes during my pregnancy. What they failed to tell me, and I later read in a study in a magazine, is that women who have GD are twice as likely to end up with PPD as women who don't have it. As we all know, many women with PPD also find it difficult or impossible to continue breastfeeding. So, for them, their risk of developing type 2 diabetes is already increased, as is their risk of PPD, which could cause them to stop breastfeeding early. It all seems to go hand-in-hand to me.

  3. Stopping (or not) breastfeeding actually makes PPD worse, so it is very important that the breastfeeding relationship be preserved, not discontinued, if PPD is diagnosed.

  4. @Anonymous

    That is great in theory, but how would you do that in practice? As far as I understand, many if not all of the meds for PPD are not recommended for breastfeeding Mom's. And PPD is serious stuff that can have a huge impact on the mother-child bond. So how do treat PPD and keep breastfeeding?

    More generally, I am with Samantha. There seems to be a such a cycle of things happening that all circle around each other: infertility, PCOS, hormonal imbalance and insulin resistance, diabetes, breastfeeding issues, lives filled with chemicals and sugar. They seem to me to be a tangled web where more needs to be done to understand the issue. It's not just “see, so everyone should just breastfeed then.” As if that will magically solve the problem.

  5. @ Anonymous- You should back statements like that up with research. There are lots of articles here about the reverse position, so it's important to post here with information rather than opinion.

  6. Anonymous,
    PPD is a very multi-faceted issue. If a mother wants to continue breastfeeding and has a good BF relationship or is willing to work on that relationship, then she should definitely be supported. But if, for example, the mother has low supply, or is pumping around the clock while not having enough support and being forced to let her baby cry while she pumps, I don't know if continuing would really help. If the mother is completely sleep deprived to the point of feeling crazed b/c of BF issues, I don't think continuing exclusive BF would help. If a woman is just plain miserable and unable to cope and breastfeeding is driving her over the edge and she wants to quit, I really don't think it makes sense to tell her to keep going.
    Speaking from experience, when you are able to get at least two hours of consecutive sleep, when you can feed your baby without tears because they refuse to latch, when you don't fear doctor's appts. because your baby isn't gaining weight, breastfeeding does not always help PPD. I think breastfeeding should be looked at in light of each individual woman's situation. The reason why PPD is more common in bottlefeeding women is very complex and I think it has more to do with correlation than causation.

    -Woman who was cured of severe PPD partly by stopping breastfeeding

  7. A medical professional told me that PPD is caused by the drastic drop in estrogen and some womens' bodies react negatively to this. This has been the most plausible answer I received. The same goes with bfing. It is not a one-size fits all situation. I know many women who after their 2nd or 3rd child went straight to formula feeding avoided getting PPD all together because they said that bfing caused them PPD with their previous children. Then there are others that tell you the opposite and then many of us here had tried bfing and felt a lot better mentally once we stopped so to generalize something like that is really misguided.

  8. I'm gonna have a look at the study but I am already suspicious of the “conclusion” breastfeeding reduces diabetes risk. There's obviously a big time lag between the breastfeeding and the development of diabetes in a lot of these women, so the larger the window, the more opportunities for other variables to come into play (and thus, the harder to identify and assess confounding variables). And just look at that age gap. What women in their 70s now even breastfeed, I'm amazed they found any. I'm interested in the age spread in the sample. I'm thinking the older the women, the less “average” they probably were, the more health conscious (in terms of their children and own behaviors). So the women in their 60s and 70s are hardly a representative group. Even for the younger women, I am thinking about all the differences between those that breastfeed and those who don't, or don't for month than a month. Those who do are no doubt more health conscious in general, and perhaps as a group healthier. Did they break the study findings down by age group? Why ask? Because if you can't find results within the younger group (say the 40 to 50-somethings) than add the older women who must have been real outliers in terms of healthy behavior to get some significant results. I could be wrong but would be curious to find out…

  9. @ Polly Palumbo Ph.D., you know this one about the diabetes really leaves me skeptical too. Diabetes is now a worldwide problem among men and women. Even cultures with high breastfeeding rates like Latin America have a very high diabetes rate. Hispanics have the highest rates out of a all ethnic groups and yet have the highest breastfeeding rates. I have heard many other reasons that are way more plausible than lack of breastfeeding such as diets too high in starch, but low in complex carbohydrates (worldwide problem now), high fructose corn syrup, genetics , and an overall a more sedentary lifestyle. Families that once never had diabetic relatives are now finding more and more of them.

  10. Awesome! Since I breastfed for 7 weeks, I'm in the clear. Cookies, here I come! What's that? My parents are diabetic? Yeah. I had gestational diabetes? Yeah. I'm a fatty-fat-fatty who doesn't exercise enough and loves cookies way too much? Yeah. But I breastfed for more than a month, so that means I have a 17% chance of developing type 2 diabetes.

    And that “logic” that I just displayed right there is precisely why every time I feel that twinge of mommy guilt over a bottle of formula, I remember that there are *so* many other factors at play in my son's life that will have an impact on his IQ, his short-term health, and his long-term health. Heck, the 5 point increase in IQ from breastfeeding would have been canceled out by the 10 point drop if I hadn't quit breastfeeding and gotten rid of my PPD. Hey, Anonymous #1, that's right, I quit, and it WENT. AWAY. Because the correlation between formula feeding and PPD is just that — a correlation. And I for one believe that it goes both ways. Some women become depressed after they start formula, and others start formula because they are depressed. And Anonymous #2, I couldn't have written it any better than you did.

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