Thread by @VikiLovesFACS

New data from the V-safe pregnancy registry on the safety of #COVID19 #vaccines in #pregnancy!

👉🏻 2456 people vaccinated before 20 weeks of pregnancy

👉🏻 Followed up to 20 weeks

👉🏻 No increased risk of miscarriage following vaccination.

🧵…

researchsquare.com/article/rs-798…

This is a follow-up to this older study in the same cohort. The older version of the study showed no increased risk of miscarriage following vaccination, but the follow-up time was shorter (10-12 weeks). 2/

nejm.org/doi/full/10.10…

Although the data from this study was reassuring, the limited follow-up time made it difficult to exactly calculate the miscarriage rate following vaccination, so an estimate was used.

I’ve discussed that here… 3/

https://twitter.com/vikilovesfacs/status/1410508758099369984

In the new study, they follow everyone to 20 weeks so we can accurately calculate the miscarriage rate before 20 weeks (because whatever happens after 20 weeks, it can’t be a miscarriage). 4/

But before we get to that, a reminder that across all pregnancies, the miscarriage rate is between 12.5 and 18.7%

5/

thelancet.com/journals/lance…

In this study, doing the simplest possible analysis, the miscarriage rate after vaccination was 14.1% (95% CI: 12.1 - 16.1%).

So within that normal range. 6/

But we know miscarriage rates depend on age, so the authors also do an analysis correcting for that.

The age-adjusted miscarriage rate following vaccination was 12.8% (95% CI 10.8 - 14.8%).

Also within that normal range. 7/

Finally, the authors want to account for 65 people in their cohort who they lost contact with before the end of the first trimester.

They decide to consider the “worst case scenario” that everyone they lost contact with had a miscarriage. 8/

Under this extreme assumption, they get an age-adjusted miscarriage rate of 18.5% (95% CI 16.1 - 20.8%).

It’s really unlikely that everyone they lost contact with had a miscarriage, but even if they did, the rate in this study is still (just!) within the normal range. 9/

So, in a large cohort of people who received the #COVID19 #vaccine in #pregnancy and were followed up to 20 weeks…

… there is *no* increased risk of miscarriage. 10/10

researchsquare.com/article/rs-798…

PS. I hate to be the “please retweet!” person but… please retweet! I suspect this analysis has been put out *specifically* to counter that “83% miscarriage rate post-vax” rumour which I am *still * asked about *all the time*, so let’s spread the word about this new data!

https://twitter.com/vikilovesfacs/status/1410508758099369984