The COVID Vaccine Does Not Increase Risk for Preterm Birth

A new study has further confirmed the safety of the COVID-19 vaccine for pregnant people. According to research published by the Centers for Disease Control and Prevention on January 4, the COVID-19 vaccine does not increase risk for preterm birth or low-birth rate. 

In the study, researchers looked at birth outcomes for over 46,000 pregnant people from eight health systems across the U.S. Of those, over 10,000 had received at least one COVID-19 vaccine at some point during their pregnancy—over 90% of which were Pfizer-BioNTech or Moderna mRNA vaccines. In comparison to the unvaccinated pregnant people, they found that those who had received the COVID-19 vaccine while pregnant showed no increased risk for preterm birth or low-birth rate (both of which can pose developmental and health risks to the baby). Just 6.6% of babies were born prematurely and 8.2% were considered to have low birth weight, the researchers found—rates that matched the birth outcomes of the unvaccinated people. 

Getting infected with COVID-19 during pregnancy, on the other hand, does increase the risk of preterm birth, according to the CDC. Pregnant people who get COVID-19 are more likely to deliver before 37 weeks and face a greater risk of stillbirth, as SELF earlier reported. “I can tell you, anecdotally, that in my practice women who are not vaccinated are for sure getting way sicker,” Heather S. Lipkind, M.D., a maternal fetal medicine specialist at Yale University who led the new research, told the New York Times. “We’re seeing pre-term birth in pregnant women who had COVID and loss of pregnancy. It’s very, very tragic.” 

Existing research backs this up. A large study of over 869,000 pregnant people, including over 18,000 who had COVID-19, found that infected patients were 10 times more likely to die in the hospital. Over 5% were on ventilators during childbirth (compared to 0.9% of COVID-19-free patients) and those with the virus were 40% more likely to have a preterm birth. 

These outcomes are a key driver behind health officials’ recommendation that pregnant people get vaccinated ASAP. On this note, the findings of the new study also suggest that the trimester in which pregnant people are vaccinated likely doesn’t matter. Researchers found no increased risks among pregnant people regardless of when they were vaccinated during their pregnancy. However, almost all of the vaccinated pregnant people in the study received their shot(s) in the second or third trimester, meaning there wasn’t enough data on first trimester vaccinations for definitive conclusions. 

The study is one of the first (and largest) to look at birth outcomes for vaccinated pregnant people, but it joins a growing body of research on the safety of the COVID-19 vaccine—including that it does not pose an increased risk for miscarriage.  

Despite the risks of forgoing the COVID-19 vaccine, many pregnant people remain unvaccinated. The findings of the new study “reinforce the importance of communicating the risks for COVID-19 during pregnancy, the benefits of vaccination, and information on the safety and effectiveness of COVID-19 vaccination during pregnancy,” the authors wrote.