Rates of miscarriage in women who had and hadn’t received COVID-19 vaccines
Rates of miscarriage in women who had and hadn’t received COVID-19 vaccines
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Two papers published on Wednesday in The Journal of the American Medical Association (JAMA) and in The New England Journal of Medicine (NEJM) look at rates of spontaneous abortion in women who had and hadn’t received COVID-19 vaccines.
Two papers published on Wednesday in The Journal of the American Medical Association (JAMA) and in The New England Journal of Medicine (NEJM) look at rates of spontaneous abortion in women who had and hadn’t received COVID-19 vaccines.
Publication
Spontaneous Abortion Following COVID-19 Vaccination During Pregnancy
Not peer-reviewed
Peer-reviewed
Receipt of mRNA Covid-19 Vaccines and Risk of Spontaneous Abortion
Not peer-reviewed
Peer-reviewed
What our experts say
Context and background
Resources
Expert Comments:
Prof Penny Ward
The small study published in JAMA used data from large healthcare databases in the USA to compare the odds of receiving a COVID-19 vaccine in the 28 days prior to a spontaneous abortion (miscarriage within the first 20 weeks of pregnancy) compared with the odds of receiving a COVID-19 vaccine in the 28 days prior to index dates for ongoing pregnancies. The comparison found no significant difference between these two groups, suggesting that COVID mRNA vaccine is not associated with miscarriage. Although the ‘point estimate’ (that is the odds of having had a vaccine within 4 weeks prior to a miscarriage) is in general more than 1 (i.e. more likely) when gestational age, maternal age and ongoing antenatal care were adjusted for, the 95% confidence limits cross 1 (i.e. range from less to more than 1) so the finding is not statistically different.
This lack of association between COVID mRNA vaccine and miscarriage is further confirmed by a second report (in the NEJM) from 2456 women enrolled in an ongoing pregnancy registry study assessing cumulative probability of miscarriage in pregnant women that had received a covid vaccine. Pregnancy registries are tried and trusted methods for assessing the impact of medicines on pregnancy outcomes and have been used for many years. This second study confirmed that the cumulative risk of miscarriage in the vaccinated population is the same as that reported from non vaccinated women in earlier work.
Taken together these studies provide reassuring support for the safety of the mRNA vaccines in pregnancy.
