No indication of an increased risk of miscarriage after vaccination against COVID-19
This content is archived and will not be updated.
Pregnant women who have been vaccinated against COVID-19 have no apparent increased risk of miscarriage, according to a new study from the Centre for Fertility and Health at the Norwegian Institute of Public Health (NIPH).
“These are reassuring results for pregnant women who were vaccinated in the first trimester,” says Maria C. Magnus, researcher at the NIPH.
Together with colleagues at the NIPH, the National Institute of Environmental Health Sciences in the USA and the University of Ottowa in Canada, she analysed Norwegian registry data. Included in the study are 4,521 women who had a miscarriage, and 13,956 pregnant women who did not experience a miscarriage in the first trimester. There was no difference in the rate of vaccination during pregnancy between those who did and did not experience miscarriage. Among the group of women who experienced a miscarriage during the first trimester, 5.5 per cent had been vaccinated, while 5.1 per cent among those who were still pregnant after the first trimester were vaccinated.
“There is still limited knowledge about COVID-19 vaccination of pregnant women, but none of the studies so far have found an increased risk of pregnancy complications,” explains Magnus.
The researchers also compared the risk of miscarriage between the COVID-19 vaccines offered in the Norwegian immunisation programme, from BioNTech/Pfizer, Moderna and AstraZeneca. They found no indication of an increased risk of miscarriage in the first trimester with any of the vaccines, nor were differences observed between one and two vaccine doses.
Three independent studies concur
As well as this study from the Centre for Fertility and Health, the US Center for Disease Control conducted two studies into COVID-19 vaccination and the risk of miscarriage. They also found no increased risk of miscarriage after COVID-19 vaccination.
One study compared the risk of miscarriage among 2,456 women who were vaccinated while pregnant (miscarriage risk was 13 per cent) with two groups of women who were pregnant before the pandemic (miscarriage risk was 13 and 23 per cent in the two groups, respectively). The second study compared the proportion vaccinated among 13,160 women who had a miscarriage (8.6 per cent vaccinated) and 92,286 women who did not experience a miscarriage (8.6 per cent vaccinated). The researchers find this reassuring.
“Having three independent studies which all indicate that women who are vaccinated do not have an increased risk of miscarriage is reassuring. Finding the same result in different studies from two different countries means that we can be more confident in the findings,” says Magnus.
Planning more studies of vaccination of pregnant women
Pregnant women are usually not included in vaccine trials, so it is extremely important to monitor those who have been vaccinated. There are no indications that vaccination during pregnancy increases the risk of complications, but researchers at the NIPH are collaborating with other Scandinavian countries to compare the risk of different pregnancy complications among vaccinated and unvaccinated people.
“We are planning several studies on pregnancy outcomes after COVID-19 vaccination, for example, the risk of premature birth and low birth weight,” says Magnus.