Minnesota study finds no increase in miscarriage risk with COVID-19 vaccines

Pregnant women who received COVID-19 vaccines did not experience an increased risk of miscarriage, according to new research on data from Bloomington-based HealthPartners and several large medical centers across the country.

Doctors hope the results will prove reassuring to pregnant women who, as a group in the U.S., have been relatively slow to get vaccinated.

"This is really the first large data analysis of risks of COVID-19 vaccination early in pregnancy," said Dr. Elyse Kharbanda, senior investigator at HealthPartners Institute and lead author on the study. "The research we're presenting is contributing to the evidence out there that the vaccines are safe in pregnancy."

Concerns have been growing throughout the pandemic over the COVID-19 risks for pregnant women due to emerging health data as well as tragic case reports. Yet many have been reluctant to undergo immunization since the original clinical trials of the vaccines excluded pregnant women, meaning there's been a lack of safety data.

Several studies have tried to remedy the information void.

Reports this year, for example, have found that COVID vaccines prompt a strong immune response in pregnant women while not harming the placenta. Last month, the Centers for Disease Control and Prevention (CDC) published data highlighting the safety of COVID-19 vaccines while encouraging pregnant women to get immunized.

In the new study, researchers analyzed data from about 105,000 patients early in their pregnancies between Dec. 15, 2020, and June 28, 2021. They found that women who suffered miscarriages and those with continuing pregnancies had comparable odds of having received a COVID-19 vaccine.

The study, which is being published in the Journal of the American Medical Association, looked at patients who received two-dose mRNA vaccines from Moderna and Pfizer.

"The key finding is really that we did not detect an increased risk" of miscarriage, Kharbanda said. "The odds of COVID-19 vaccine exposure were not increased in the prior 28 days [before miscarriage] compared to women with ongoing pregnancy."

The report draws on data from the Vaccine Safety Datalink, a safety monitoring project funded by the CDC that includes HealthPartners and eight other large medical groups in the U.S.

HealthPartners Institute has received $2 million from the federal government to monitor the safety of new COVID-19 vaccines for pregnant women and their babies.

In June, HealthPartners was part of a national study that found pregnant women were getting vaccinated against the coronavirus at a lower rate than their nonpregnant peers. It also found the uptake was particularly low among those 18 to 24 as well as Black and Hispanic women.

Federal data show that only about 25% of pregnant women in the U.S. have been vaccinated. Researchers at Duke University say the delta variant has been driving increased COVID-related hospitalizations of pregnant women.

Women trying to get pregnant should "absolutely" get the vaccine, Dr. Geeta Swamy, a professor of obstetrics and gynecology at Duke, said Wednesday during a news conference.

"There has been no concern whatsoever that a woman trying to conceive, the vaccine would have any impact on their ability to conceive," Swamy said.

She added: "There is no evidence that vaccination causes early pregnancy loss."