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Chocolate for preeclampsia prevention? Medical society hints at benefits even though study reports the opposite


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The benefits of chocolate during pregnancy

Our Review Summary

Woman biting a chocolate barJust in time for Valentine’s Day, this PR news release describes a study that evaluated the impact of high-flavanol chocolate in reducing preeclampsia risk.

Having discovered that there are no significant differences between the low-flavanol and high-flavanol group in this respect (and, in fact, with respect to all the other secondary outcomes), the study could only conclude flavanol content cannot explain the observed improvement of the pulsatility index, a surrogate variable for blood velocity in the uterine, placental and fetal circulations. Nonetheless, the news release forges ahead and turns this result into a headline that touts the benefits of chocolate during pregnancy, a claim that is completely unsupported by the underlying study. In addition, the news release is almost a word-for-word regurgitation of the attached study abstract. It adds absolutely nothing besides a quote from one of the investigators of the study.

If they read carefully enough, those who wade through the entire news release will eventually learn that chocolate doesn’t in fact help prevent pre-eclampsia. But many will be misled by the headline and vague lead sentence that appear to tout benefits. We can’t even tell what characterizes the women included in the study besides that they “had double-notching on uterine artery Doppler,” again regurgitated with no attempt at explaining its meaning.

The release was issued by the Society for Maternal Fetal Medicine in advance of that organization’s annual meeting, where an abstract of the study was presented. The study findings have not been published in a peer-reviewed journal.


Why This Matters

Preeclampsia is a pregnancy complication characterized by high blood pressure and abnormal amounts of protein in the urine. It occurs in about 3-7% of pregnancies, according to the National Institutes of Health. Severe cases may be accompanied by symptoms like chronic headache, respiratory problems, stomach pain, nausea and vomiting, and vision problems. In rare cases it may be a sign of damage to other organs, primarily the kidneys. The condition usually improves rapidly after delivery of the baby. There has been some back-and-forth discussion in medical literature regarding the role of chocolate consumption and its ability to reduce the risk of preeclampsia. Given this study’s inconclusiveness, it’s difficult to understand why this release is headlined, “The benefits of chocolate during pregnancy.” What benefits? The release offers no explanation of what preeclampsia is but instead adds to the noise surrounding the existing tangle of research on this topic.

The news stories following the issuance of the release illustrates how easy it can be to get some reporters to disseminate and even add to an ill-conceived message.


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

Not Applicable

The release isn’t necessarily pushing specialty high-end dark chocolate since it indicates that any chocolate might be beneficial. People have a rough idea what chocolate costs so we’ll rate this Not Applicable.

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

Not Satisfactory

The news release slings out barely revised terms from the abstract to make it seem like there’s a benefit to eating dark chocolate during pregnancy to prevent preeclampsia. In the end, though, it must get to the quantification, of which there is none. It reads, “The result was that there was no difference in preeclampsia, gestational hypertension, placental weight or birthweight in the two groups; however, the uterine artery Doppler pulsatility index (a surrogate marker of blood velocity in the uterine, placental and fetal circulations) in both groups showed marked improvement that was much greater than expected in general population.”

There is no mention of the meaning or predictive value of the “pulsatility index” named in the release/abstract.

And where’s the data supporting the idea that chocolate “could have a positive impact on placenta and fetal growth and development.”

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

Not Satisfactory

By our calculations, a typical high-flavanol chocolate, better known as dark chocolate, contains about 200 calories per 30 grams, the amount prescribed daily to the study participants. A low-flavanol chocolate, presumably something like white chocolate, is similar in caloric content. It may also be safe to assume there’s quite a bit of sugar present in both kinds of chocolates. Ingesting 30 grams a day (about three-quarters of a Hershey’s chocolate bar) of either type of chocolates seems a little much to us. An examination of these potential, though obvious, “harms” should have been mentioned. After all, obesity is one of several risk factors for preeclampsia.

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

Not Satisfactory

The release tells us that “Researchers conducted a single-center randomized controlled trial of 129 women with singleton pregnancy between 11 and 14 weeks gestation who had double-notching on uterine artery Doppler. The pregnant women selected were randomized to either high-flavanol or low-flavanol chocolate. A total of 30 grams of chocolate was consumed daily for 12 weeks.” The news release failed to improve on the weak scientific message of the study. Its pronouncement that

“…however, the uterine artery Doppler pulsatility index (a surrogate marker of blood velocity in the uterine, placental and fetal circulations) in both groups showed marked improvement that was much greater than expected in general population.”

is simply unfounded. There was no “general population” control group considered in the study. All that can be concluded is that flavanol content cannot alone explain the improvement in the pulsatility index. Also, we are not told what double-notching, flavanol or the pulsativity index are or why they matter.

Does the news release commit disease-mongering?

Not Applicable

We have here the opposite of disease-mongering; we’re not even told what preeclampsia is. In fact, there’s so little information here that we’re hesitant to give credit, which is why we rate this Not Applicable.

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

Not Satisfactory

We’re not told who funded the study although its authors, according to the abstract, are affiliated with research institutions in Quebec, Canada. The abstract, unfortunately, doesn’t address conflicts of interest — now a standard feature in abstracts presented at scientific meetings.

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

Not Applicable

No alternatives to chocolate consumption are mentioned for reducing the risk of preeclampsia, but it’s not clear that there are any effective preventive measures one can take. Once they’ve been diagnosed, some women are advised to have bed rest, drink plenty of water and consume less salt, and some are prescribed blood pressure-lowering medication. That could have been mentioned in the release, but we won’t ding the release for not mentioning these.

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

Not Applicable

We’ll rate this N/A. Chocolate is widely available.

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

Not Satisfactory

The news release mentions that previous studies on this topic show conflicting results regarding the relationship between chocolate consumption and preeclampsia risk. We are made to understand the study aims to evaluate the impact of high-flavanol chocolate. What we are left wondering is how this fits in with the existing literature. Is this the first study to differentiate between high and low-flavanol chocolate? Are there other approaches to reducing the risk of pre-eclampsia being explored? We don’t know because of the lack of context.

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

Not Satisfactory

The release headline — “The benefits of chocolate during pregnancy” — strongly infers there are benefits but the study and even parts of the release itself contradict that claim.

We don’t like to ding a release for quotes that express an expert’s opinion on a treatment claim. However, since we’ve already noted the hype elsewhere we should also highlight a lead author’s comment that “This study indicates that chocolate could have a positive impact on placenta and fetal growth and development and that chocolate’s effects are not solely and directly due to flavanol content.”  It could have, but then again, the study and release don’t make the case.

Total Score: 0 of 6 Satisfactory


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