Early Pregnancy Outcomes following COVID-19 Vaccination and SARS-COV-2 Infection in Pregnant Women
October 2022: Research published in Nature Communications looks at potential links between COVID-19 vaccines, SARS-CoV-2 infections, and miscarriage or ectopic pregnancy.
- Video: Does COVID-19 vaccination or SARS-CoV-2 infection impact early pregnancy outcomes?
- New findings from the COVID-19 in Pregnancy in Scotland (COPS) study show that COVID-19 vaccines and SARS-CoV-2 infection do not increase the risk of miscarriage or ectopic pregnancy in pregnant women. The paper was released on 17 October 2022 in Nature Communications. Access to the paper as well as a full summary in plain English can be found at: https://edin.ac/3SKTRpX
A population-based matched cohort study of early pregnancy outcomes following COVID-19 vaccination and SARS-CoV-2 infection
Calvert, C; Carruthers, J; Denny, C; Donaghy, J; et. al.
Published online on: 17 October 2022
Available online at: https://doi.org/10.1038/s41467-022-33937-y
Summary in Plain English
On 16 April 2021, the UK’s Joint Council for Vaccination and Immunisation (JCVI) recommended that pregnant women should be offered COVID-19 vaccines, at the same time as non-pregnant people of the same age and health risk.
On 16 December 2021, the JCVI identified pregnant women as a priority group for vaccination.
Although 78% of women who gave birth in Scotland in July 2022 had received at least one dose of a COVID-19 vaccination prior to delivery, this number is still below the level of vaccine uptake seen among the general population of women who are of reproductive age.
Why did we carry out this research?
We have shown previously that unvaccinated pregnant women were more likely to be seriously ill with COVID-19 than vaccinated women.
There is growing evidence that there is no link between COVID-19 vaccines and complications in late pregnancy. This includes stillbirth and premature (pre-term) birth.
However, studies using high-quality data on early pregnancy are very limited.
We wanted to explore any links between COVID-19 vaccines and early pregnancy complications. We also looked at coronavirus (SARS-CoV-2) infections and early pregnancy.
This research can help policy-makers, healthcare professionals and members of the public to make evidence-based decisions about vaccines in pregnancy.
What data did we use?
To carry out this study, we used data held in the COVID-19 in Pregnancy in Scotland (COPS) dataset. This contains information from the health records of all women in Scotland who were pregnant on or after 1 January 2015.
We looked at pregnancies with a likely conception date up to 28 September 2021. We observed these up to 31 January 2022.
We linked this data to the mother’s SARS-CoV-2 infection and COVID-19 vaccination records held by Public Health Scotland.
We looked at links between vaccination or infection and:
- Miscarriage: An early pregnancy loss, defined here as the first 20 weeks of gestation;
- Ectopic pregnancy: When a fertilised egg implants itself outside the womb, most commonly in the fallopian tubes. It’s not possible to continue an ectopic pregnancy.
We included women who had a vaccine or confirmed infection during early pregnancy (up to 20 weeks gestation), or up to six weeks before they became pregnant. We compared each pregnancy with pre-pandemic data from similar pregnancies. This removed any influence from undiagnosed infections in the pandemic period, starting on 1 March 2020. We also checked the results against unvaccinated and uninfected pregnant women during the pandemic.
What did we find?
Our study included information on 526,608 pregnancies. Of these, 24.1% were during the pandemic, with the rest from the pre-pandemic reference period.
A total of 18,780 women in our study had a COVID-19 vaccine up to six weeks before pregnancy, or up to 20 weeks gestation.
By 20 weeks gestation, the proportion of miscarried pregnancies was:
- 9.1% for vaccinated women
- 9.9% for unvaccinated women pre-pandemic
- 10.0% for unvaccinated women during the pandemic.
We did not find any evidence of higher risk of miscarriage following vaccination.
A total of 3,025 women had a confirmed SARS-CoV-2 infection in the same window. Again, we did not find any evidence that women are at higher risk of miscarriage after being infected.
A total of 10,570 women in our study had a COVID-19 vaccine up to six weeks before, or up to three weeks after, the start of the gestation period.
By the end of the observation period, the proportion of ectopic pregnancies was:
- 1.2% for vaccinated women
- 1.2% for unvaccinated women pre-pandemic
- 1.1% for unvaccinated women during the pandemic.
We did not find any evidence that either vaccines or infections increase the risk of an ectopic pregnancy.
Why is this research important?
This study is the first of its kind to look at early pregnancy complications for women, following vaccination or infection, for a national population.
It shows that having a COVID-19 vaccine does not put women at higher risk of either miscarriage or ectopic pregnancy. The same is true of SARS-CoV-2 infection, but our estimates for this are less precise.
Our results add to the growing body of evidence that COVID-19 vaccines are safe to have during or before pregnancy. Vaccines remain the safest way for pregnant women to protect themselves and their babies from COVID-19.