Because most philosophies that frown on reproduction don't survive.

Friday, July 09, 2021

No, COVID Vaccines Are Not Causing First Trimester Babies to Miscarry

There's a meme going around claiming to summarize results from a New England Journal of Medicine study, and warning that receiving the COVID vaccines during the first trimester is causing 90% of pregnant mothers to miscarry.  However, this meme is based on a serious misunderstanding of the data.  I read the study (which you can find here), and here's what it really says.

The study, entitled "Preliminary Findings of mRNA Covid-19 Vaccine Safety in Pregnant Persons" examines data collected about women who both were enrolled in a pregnancy data program called the v-safe pregnancy registry and who also received the Moderna or Pfizer COVID vaccine during the study period of December 14, 2020 to February 28, 2021.  (Seeing as this was very early in the vaccination push, 94% of these were healthcare personnel.  Based on these criteria, the study identified 3958 subjects and then tracked their experiences to see if they had unusual side effects during the study period.

To understand how the meme appears to quote the study and yet is totally deceptive, we turn to Table 4 which records pregnancy loss and other neonatal outcomes.  Here's an image:

In the first line of the table, it notes that 104 out of 827 "completed pregnancies" ended in a miscarriage.  Then in a footnote, it says that 96 of the 104 miscarriages occurred during the first thirteen weeks of pregnancy.  This is where the meme gets the claim "827 women get the jab".  827 is not, however, the number of women who "get the jab" in the study.  827 is the number of women in the study who reached a "completed pregnancy" during the 2.5 month time period of the study.  Recall, a pregnancy lasts nine months, so it's not surprising that in a study lasting 2.5 month, only 827 out of 3958 women completed their pregnancy.  The other 3131 women were still pregnant at the end of the study.

This is also where the meme gets the numbers 104 and 96, but as we shall see, it misattributes what those numbers are.  104 is the total number of women who lost their baby to miscarriage.  It is not the number of women in the study who were in their first trimester when they received their vaccination.  Table 3 shows how many women were in each trimester at the time of vaccination.  The number of women who were in their first trimester when vaccinated was 1132.

The 96 number quoted in the meme is the number of miscarriages which occurred during the first trimester.  So to restate the meme with correctly identified data:

3958 women received a COVID vaccine (I refuse to use the odious phrase "get the jab".)  Of those 1132 were in the first trimester at the time of vaccination.  104 out of 3958 women (2.6%) suffered a miscarriage.  Of those 104, 96 were among the 1132 women vaccinated during their first trimester.  This means that the miscarriage rate for women vaccinated during their first trimester was 8.5%.  According to the Mayo Clinic, 10%-20% of pregnancies end in miscarriage prior to 20 weeks, most of those during the first trimester, so that 8.5% rate is below average.  However, these women were mostly health care professionals, and so it's likely that they were getting better than average care.  I don't thin there's a reason to conclude that the COVID vaccine was associated with lower than average miscarriage, but there's certainly no reason to conclude it was associated with higher than average miscarriage.

And indeed, the study itself states it's conclusion as: 
Preliminary findings did not show obvious safety signals among pregnant persons who received mRNA Covid-19 vaccines. However, more longitudinal follow-up, including follow-up of large numbers of women vaccinated earlier in pregnancy, is necessary to inform maternal, pregnancy, and infant outcomes.

And this points us to the very mischievous thing which has been done by this meme.  It has taken real numbers from a real study that it cites, but it has presented them in a clearly misleading and false way.  I personally find it hard to see how the creator of this meme was not purposefully lying in order to deceive those who would be mislead by the citation of a real NEJM study into believing the alarming  claim that 90%+ of mothers receiving the COVID vaccine while in their first trimester of pregnancy were suffering miscarriages.

This is, to be blunt, a lie.  And if I am right that it was crafted intentionally to deceive others who would share it with only brief checks to see that there was indeed such an article, it is a very wicked lie crafted with the intention of misleading people to fear that the vaccine which is in fact likely to keep mothers and their babies safe would instead kill the baby in 90% of cases.

Please do not be deceived by this lie, and do feel free to share this when people share this deceptive meme.


mandamum said...

Thank you for doing the detail work on this. That's pretty blatant mistreatment of the #s.

Agnes said...

I'd think that if they wanted to see what happens to pregnant women being vaccinated against Covid, they would follow (as many of them as possible) through the pregnancy. I suppose they wanted some information out as soon as possible (if they had waited another half year that time would be lost for vaccinating before an eventual n-th wave of the pandemic). In that case, however, it shold be the authors and NEJM protesting against misquoting and misusing their results to the effect opposite the one they supposedly intended.

Anonymous said...

Interesting to see how well this aged