Study: COVID vaccines didn't impact placentas during pregnancy

·3 min read

CHICAGO – New data from researchers who studied women who were vaccinated while pregnant found no evidence that the vaccine affected their placentas.

The new findings, published Tuesday in the Obstetrics & Gynecology journal, may help switch the focus from conversations around whether the vaccine is safe during pregnancy to how getting vaccinated is a way to protect mom and baby.

Co-author Dr. Emily Miller, a Northwestern Medicine maternal fetal medicine physician, said that the study results were reassuring.

“We don’t see any signals that suggest the placenta is getting injured from the vaccine,” Miller said. “This builds upon rapidly emerging data that emphasizes that the vaccine is not dangerous during pregnancy.”

The Obstetrics & Gynecology study adds to the growing evidence that COVID-19 vaccines are safe during pregnancy, researchers said. It is also believed to be the first to examine any effect of COVID-19 vaccines on placentas, which can indicate potential risks and be an early sign of issues.

“The placenta is like the black box in an airplane,” co-author Dr. Jeffery Goldstein, assistant professor of pathology at Northwestern University Feinberg School of Medicine, said in a statement accompanying the research. “If something goes wrong with a pregnancy, we usually see changes in the placenta that can help us figure out what happened.”

From what they saw, he added, “The COVID vaccine does not damage the placenta.”

Dr. Jessica O’Connell was one of the first to get vaccinated while pregnant, with her early eligibility as a Northwestern physician. She delivered her son at Northwestern Medicine Prentice Women’s Hospital in January.

As a physician who understood the science behind the vaccine and was confident in her ability to weigh any risk-benefit scenario, “I never had a doubt,” about getting vaccinated, she said. Seeing this study reinforces her decision.

“It’s always a relief to have actual data that supports your hypothesis,” she said. “Of course I would never want to do anything that could potentially harm my child. To get some data that shows, OK, there doesn’t appear on a cellular molecular level any impact, is a big relief as well.”

Since the vaccines became available, maternal health experts have worked to communicate advice to pregnant women. Pregnant and lactating women were not included in initial COVID-19 vaccine trials, which meant that when vaccines were available, families were making decisions around a new vaccine without data specific to pregnancy to guide them. By listing pregnancy as a health issue that can make people more at risk should they get COVID-19, the Centers for Disease Control and Prevention paved the way toward early access for pregnant women to get vaccines.

“By excluding pregnant people from the original vaccine trials, we have had an uphill battle to try to get the data quickly, to reassure people that it’s OK to get the vaccine in pregnancy,” Miller said.

Data has remained limited enough that Sen. Tammy Duckworth, D-Ill., recently sent a letter to the CDC asking that more information be provided to Congress and to help guide pregnant women’s decisions.

Much misinformation has spread around the vaccine and fertility. Goldstein also noted the internet has amplified concerns that the vaccine might trigger an immunological response causing the mother to reject the fetus, and that these results contradict that.

The study collected placentas from 84 patients who were vaccinated and 116 unvaccinated patients. Most of the vaccinated patients had received the Moderna or Pfizer vaccines during their third trimester (beginning in the 28th week of pregnancy).

What can affect a pregnancy is contracting COVID-19. Pregnant women have been shown to have a higher risk of severe illness should they contract COVID-19. A previous study from Northwestern and Lurie Children’s Hospital researchers found that placentas of women who tested positive for the virus showed evidence of injury, like abnormal blood flow between mother and baby in utero.

Researchers also published a study in April that showed vaccinated pregnant women make COVID-19 antibodies, successfully transferring those to their fetuses. Until infants can get vaccinated, this provides the only way for them to get COVID-19 antibodies.