COVID-19 mRNA vaccines not linked to increased risk of miscarriage, new data show

The research, led by HealthPartners Institute, adds to existing data that suggest COVID-19 vaccines are safe for people who are pregnant.

Bloomington, Minn. – New surveillance data published in JAMA show that mRNA vaccines administered during pregnancy did not increase the risk of miscarriage. The research, led by HealthPartners Institute, adds to existing data that suggest COVID-19 vaccines are safe for people who are pregnant.

“Our data adds to a growing body of research that should give pregnant people confidence to get vaccinated against COVID-19, if they haven’t already,” said Elyse Kharbanda, MD, senior investigator at HealthPartners Institute and lead author on the study. “It’s especially important for pregnant people to protect themselves against the virus because COVID-19 infections may impact them more severely and lead to birth complications.”

Kharbanda and collaborators analyzed data from about 105,000 patients who were early in their pregnancies, the time when miscarriages can occur. Data was gathered between Dec. 15, 2020 and June 28, 2021. The researchers compared the odds of having received a COVID-19 vaccine in the 28 days prior to miscarriage to the odds of having received a COVID-19 vaccine in the 28 days prior to pregnancy that did not end in miscarriage across similar gestational ages.

They found that after adjusting for maternal age and other important risk factors, the proportion of miscarriages to ongoing pregnancies among those who were vaccinated was nearly identical to the proportion of miscarriages to ongoing pregnancies among those who were unvaccinated (an odds ratio of 1.02). This suggests that vaccines had no impact the miscarriages.

The pregnancy data came from HealthPartners and eight other large health systems. Collectively these health systems make up the Vaccine Safety Datalink (VSD), a research network funded by the Centers for Disease Control and Prevention that conducts post-marketing surveillance of vaccines licensed and used in the United States. The network has additional studies underway looking at birth outcomes and maternal complications.

Earlier research published in JAMA showed that COVID-19 vaccines prompt a strong immune response in people who are pregnant, and likely provide protective benefits to babies, too. Data published in the Journal of Obstetrics and Gynecology has also shown that the mRNA vaccines do not harm the placenta.

The CDC and other leading medical groups now recommend that people who are pregnant get vaccinated against COVID-19.