A study led by researchers from the University of Edinburgh’s Usher Institute has shed new light on the safety of the COVID-19 vaccines in early pregnancy.
The study is the first of its kind to look at complications in early pregnancy following vaccination or infection, and shows that having a COVID-19 vaccine does not put women at higher risk of either miscarriage or ectopic pregnancy.
On 16 April 2021, the UK’s Joint Council for Vaccination and Immunisation (JCVI) recommended that pregnant women should be offered COVID-19 vaccines, and pregnant women were then identified as a priority group for vaccination in December of that year.
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.
A growing body of evidence has demonstrated the vaccines to be safe and effective for pregnant women, and previous research from the Usher Institute and others has shown that unvaccinated pregnant women are more likely to be seriously ill with COVID-19 than vaccinated women.
Evidence suggests there is no link between COVID-19 vaccines and complications in late pregnancy, including stillbirth and premature birth. However, studies looking specifically at early pregnancy have until now been few and far between.
In this new study, published in the journal Nature Communications, researchers at the Usher Institute looked at information from the health records of all women in Scotland who were pregnant on or after 1 January 2015, and linked this data to the mother’s COVID-19 infection and vaccination records held by Public Health Scotland. In particular, they wanted to see if there was any link between either vaccination or infection and miscarriage or ectopic pregnancy (where a fertilised egg implants itself outside the womb).
They compared data relating to different categories of pregnancy, as follows:
- pregnancies where the mother had a vaccine or confirmed infection during early pregnancy (up to 20 weeks’ gestation), or up to six weeks before they became pregnant
- unvaccinated and uninfected pregnant women during the pandemic
- pregnancies from before the pandemic
Overall, data from 526,608 pregnancies was studied, with 24% of these being pregnancies that took place during the pandemic.
18,780 women included in the study had a COVID-19 vaccine up to six weeks before pregnancy, or during pregnancy up to 20 weeks’ gestation.
In this group, 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
There was no evidence of higher risk of miscarriage following vaccination.
3,025 women had a confirmed COVID-19 infection in the same window. Again, there was no evidence that they were at higher risk of miscarriage after being infected.
10,570 women had a COVID-19 vaccine up to six weeks before, or up to three weeks after the start of their pregnancy.
The proportion of ectopic pregnancies in this group was:
- 1.2% for vaccinated women
- 1.2% for unvaccinated women pre-pandemic
- 1.1% for unvaccinated women during the pandemic
There was no evidence that either vaccines or infections increase the risk of an ectopic pregnancy.
These results add to the growing body of evidence that COVID-19 vaccines are safe during or before pregnancy. Vaccines remain the safest way for pregnant women to protect themselves and their babies from COVID-19.
Click here to read more about the Usher Institute’s previous work in this area
Click here to read the NHS's current guidance on COVID-19 vaccines for pregnant women