Do COVID-19 vaccines present any pregnancy risks?

covid pregnancy risks study results
Photo via Frank de Kleine/Flickr (CC BY 2.0)

For expectant mothers who are wondering whether to get the COVID-19 vaccine, there’s some reassuring news from a preliminary study assessing pregnancy risks. 

Researchers at the Centers for Disease Control and Prevention, according to the New York Times, have found no evidence that either the Pfizer/BioNTech or Moderna vaccines put pregnant people at risk.

“The findings are preliminary and cover just the first 11 weeks of the U.S. vaccination program,” the article notes. “But the study, which included self-reported data on more than 35,000 people who received one of the vaccines during or shortly before pregnancy, is the largest yet on the safety of the coronavirus vaccines in pregnant people.” 

Pregnant people were left out of clinical trials as the vaccines were being readied for FDA approval, making this study the first widescale test of how those who are pregnant were affected by the vaccine. 

“There’s a lot of anxiety about whether it’s safe and whether it would work and what to expect as far as side effects,” said Dr. Stephanie Gaw, a maternal-fetal medicine specialist at the University of California, San Francisco.

Gaw observed, “A lot of pregnant people are getting the vaccine, there isn’t a significant increase in adverse pregnancy effects at this point, and that side effect profiles are very similar to nonpregnant people.” She went on to characterize that as reassuring and helpful in public health campaigns to encourage vaccination. 

The study only examined the two vaccines reliant on mRNA technology, CNN pointed out, and therefore doesn’t assess the Johnson & Johnson and AstraZeneca vaccines that have come under scrutiny recently.  

The study, published April 21 in the New England Journal of Medicine, relied on self-reported data from the CDC’s “v-safe after vaccination health checker” surveillance system, the v-safe pregnancy registry, and the Vaccine Adverse Event Reporting System (VAERS). It involved 35,691 v-safe participants 16-54 years of age who identified as pregnant. 

Of those enrolled in the pregnancy registry, which involved nearly 4,000 women, 827 had completed their pregnancies, 86% of which resulted in a live birth. Key data—including rates of miscarriage, prematurity, low birth weight, and birth defects—were consistent in those who participated compared to those reported in pregnant women before the pandemic. 

The study is far from conclusive, however. For instance, as the New York Times observed, “There is not yet any data on pregnancy outcomes from people who were vaccinated during the first trimester of pregnancy.” 

“I think we can feel more confident about recommending the vaccine in pregnancy, and especially with pregnant people that are at risk of COVID,” Gaw said. “But we do need to wait for more data for complete pregnancy outcomes from vaccines early in pregnancy.”

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Sources: New York Times, CNN, New England Journal of Medicine

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