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Breastfeeding for stroke prevention? Kudos to heart association for clarifying that study doesn’t show cause-and-effect

Breastfeeding may help protect mothers against stroke

Our Review Summary

breastfeedingThe release focuses on a prospective cohort study, one of the strongest types of observational studies, that identified a correlation between breastfeeding and stroke. Specifically, the study reported that women who nursed at least one child were less likely to have a stroke later in life. The release notes that this was an observational study and, therefore, could not establish a cause-and-effect relationship between breastfeeding and stroke risk.


Why This Matters

Although the incidence and mortality from stroke has been in decline, stroke remains a significant health problem in the United States, affecting hundreds of thousands of men and women every year. Therefore, new information that could help people make lifestyle choices that affect their long-term risk of stroke has the potential to significantly affect the health and quality of life for millions of people. That said, it is important for news release to highlight the limitations of new research — something that this release takes pains to do.


Does the news release adequately discuss the costs of the intervention?

Not Applicable

Breastfeeding is not an option for all mothers, whether because of medical/physical limitations or because of socioeconomic ones. However, breastfeeding is also not a medical intervention that one can easily place a price tag on. As such, we rate this criterion as not applicable.

Does the news release adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

This is a tough one to call. The release clearly lays out the research findings that breastfeeding is associated with reductions in stroke risk, even breaking it down by subgroups. That’s good. However, the release only tells readers about relative reductions in risk, as opposed to absolute reductions in risk. What does that mean? Well, let’s say that the women in a study have a 0.25% risk of getting Disease X. If the study reports that a specific behavior doubles the risk of Disease X, that sounds like a big deal — a 100% increase in risk! But that’s a 100%  relative increase in risk. The absolute risk would go from 0.25% to 0.5%. The difference between relative and absolute risk is something has written about, and it is a key distinction that we feel is important. So, when the release tells us that breastfeeding was associated with a 23% decrease in stroke risk, readers still don’t know what that means in terms of absolute risk. And because the baseline absolute risk numbers aren’t mentioned, savvy readers can’t even do the calculation for themselves.

Does the news release adequately explain/quantify the harms of the intervention?

Not Applicable

Breastfeeding may be “natural,” but it’s not effortless. Breastfeeding can be time-consuming and exhausting, and carries risks of dehydration and breast pain. That said, these are not necessarily medical issues that rise to the level of discussion in a news release about an observational study like this one. As such, we’ll rate this criterion as not applicable.

Does the news release seem to grasp the quality of the evidence?


The release does a pretty solid job here, describing the study fairly well and acknowledging its limitations. But there are a couple of things that could have been slightly better. For example, the release describes the study in the fifth paragraph. It is not until the 10th paragraph that the release explicitly tells readers that “Because the study was observational, it couldn’t establish a cause-and-effect relationship between breastfeeding and lower stroke risk, meaning that it is possible some other characteristic that distinguishes between women who breastfeed and those who don’t is the factor changing the stroke risk.” For example, it’s possible that women who did not breastfeed had higher levels of stress than women who did breastfeed, which may be a contributing factor to stroke. And it is not until the 12th paragraph that the release tells readers that “The study was also limited by the relatively small number of strokes that occurred during the follow-up period (just 3.4 percent of the women experienced a stroke during the study period and 1.6 percent reported having had a stroke prior to the study) and by the Women’s Health Initiative’s exclusion of women who had already had severe strokes at the time of recruitment.”

To be clear, we are very glad that the release includes these valuable qualifiers. However, we think the release would have been stronger if they had not been buried at the bottom of the piece.

Does the news release commit disease-mongering?


No disease mongering here. The release offers context on the incidence of U.S. stroke mortality rates.

Does the news release identify funding sources & disclose conflicts of interest?


The release clearly discloses the source of research funding. The release also notes that “author disclosures [regarding potential conflicts of interest] are on the manuscript.” It would have been much better to simply disclose the conflicts on the release itself by saying: “The authors report no potential conflicts of interest.”

Does the news release compare the new approach with existing alternatives?


The release does a nice job here, stating: “Breastfeeding is only one of many factors that could potentially protect against stroke. Others include getting adequate exercise, choosing healthy foods, not smoking and seeking treatment if needed to keep your blood pressure, cholesterol and blood sugar in the normal range.”

Not all of the alternatives have been proven to protect against stroke but listing them is a worthwhile reminder that lifestyle changes might reduce their risk.

Does the news release establish the availability of the treatment/test/product/procedure?


The release requests that pregnant women make breastfeeding part of their “birthing plan” and to breastfeed for at least six months to receive the most benefits. It’s assumed readers know that breastfeeding is an available option unless there are medical or lifestyle barriers.

Does the news release establish the true novelty of the approach?


The release notes that “This is among the first studies to examine breastfeeding and a possible relationship to stroke risk for mothers.” It would have been helpful to briefly note what the other studies found and whether the results were different or had similar conclusions.

Does the news release include unjustifiable, sensational language, including in the quotes of researchers?


The release uses responsible, cautious language. The recommendation to breastfeed to prevent stroke based on observational research may be an overreach, however.

Total Score: 7 of 8 Satisfactory


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