University of Edinburgh: No increased miscarriage risk due to vaccine

The results bolster previous findings that Covid-19 vaccines are safe to have before and during pregnancy, experts say.

Researchers from the University of Edinburgh and Public Health Scotland analysed data from more than half a million pregnancies in Scotland – 24.1 per cent were during the pandemic, with the rest from the pre-pandemic period.

Miscarriage
Some 18,780 women were vaccinated just before conception or in early pregnancy, 9.1 percent of whom had a miscarriage. This compares with a 9.9 per cent miscarriage rate for unvaccinated women pre-pandemic and 10 per cent for unvaccinated women during the pandemic.

Some 3,025 women had a confirmed SARS-CoV-2 infection during the same period in pregnancy – the team did not find any evidence that women are at higher risk of miscarriage after being infected.

Ectopic pregnancy
The team also did not find any evidence that either vaccines or infections increase the risk of an ectopic pregnancy – when a fertilised egg implants itself outside the womb and fails to proceed to a full pregnancy.

In the 10,570 women who had a vaccine in the early days of pregnancy, 1.2 per cent had an ectopic pregnancy. This compares to 1.2 per cent for unvaccinated women pre-pandemic and 1.1 per cent for unvaccinated women during the pandemic.

The Pfizer-BioNTech Covid-19 vaccine was the most commonly received vaccine by pregnant women in Scotland.

Vaccine safety
These findings are part of the COPS study, which tracks levels of Covid-19 infection and vaccine uptake in pregnant women in Scotland, and conducts rigorous analyses including assessing the safety of vaccination in pregnancy.

COPS is an offshoot of the EAVE II project, which uses anonymised linked patient data in Scotland to track the pandemic and the vaccine roll out in real time.

The findings have been published in Nature Communications. This work was funded by Wellcome and the charity Tommy’s and supported by the charity Sands.

This study provides reassurance that COVID-19 vaccines are safe in early pregnancy.

Professor Sarah Stock
COPS co-lead at University of Edinburgh’s Usher Institute and consultant obstetrician