Has a scientific study reported an abnormally high number of miscarriages in pregnant women vaccinated against Covid-19? Several readers of 20 minutes asked the “Fake Off” section to verify the results of a study published in the prestigious American journal New England Journal of Medicine last April, and their interpretation by anti-tax accounts.
Widely used in France and abroad, this study entitled “Preliminary research on the safety of mRNA vaccines against Covid-19 for pregnant people” has been the subject of alarming publications on social networks, most often by made of accounts propagating false information. According to them, the impact of vaccination on pregnancy would be terrible, since “82% of pregnant women under 20 weeks have miscarried” after the injection of the vaccine.
And calmly at Moderna, we are launching a study on pregnant women to find out if the vaccine is safe, while 133,000 pregnant women have already had it! 🤡
Reminder of the study already published: 82% of pregnant women under 20 weeks have had a miscarriage 🤡🤡🤡 https://t.co/StyVOVDmph– Laure Gonlézamarres (@LaureGonlezamar) July 15, 2021
A largely overestimated statistic, which does not correspond to the conclusions of the study of New England Journal of Medicine. We explain why.
FAKE OFF
This scientific article, written by members of the US Centers for Disease Control and Prevention (CDC) and peer-reviewed, is based on a sample of 3,958 people who were pregnant at the time of their vaccination and who were contacted about three months ago. later by the CDC, the principal US federal agency responsible for public health. Of these, 712 gave birth to healthy infants, 104 had miscarriages, one gave birth to a stillborn child, and 10 cases of abortion and ectopic pregnancies were reported. The rest of the participants, or 3,100 people, were still pregnant or had not contacted the authors again at the time of publication of the article.
The study concludes that 12.6% of the 827 completed pregnancies were due to a miscarriage, a result comparable to the average rate of miscarriages, estimated at around 15%. The authors stress that their “preliminary results do not show clear red flags among pregnant people who have received anti-Covid messenger RNA vaccines”, while calling for further work to refine the results.
A deliberately biased and “meaningless” statistic
Where does this figure of 82% of miscarriages put forward by anti-tax accounts in their social media posts come from? To obtain it, the latter excluded pregnant people vaccinated during their third trimester of pregnancy, a period when the development of the fetus is advanced, and during which the risk of miscarriage is therefore less common. Out of 827 pregnancies, they excluded 700, keeping only 127 pregnancies to obtain a miscarriage rate of 82%.
Now, as pointed out on Twitter Victoria Male, Associate Professor of Reproductive Immunology at Imperial College London, this statistic is “meaningless” as it only confirms the fact that the only way to end a pregnancy in three months from the first trimester is to miscarry. And to add: “And probably, the only reason why this rate is not 100% is that some people vaccinated at the end of the second trimester ended their pregnancy within 3 months by giving birth. “
By calculating (roughly) the number of first and second trimester miscarriages from the study data, the scientist came up with a rate of 8.5% in the first trimester and 0.5% in the second. These figures are still lower than the average rate of miscarriages occurring during pregnancy.