Large study shows effects of Covid vaccine in pregnancy on newborns

It can be worrying to roll up your sleeve for a vaccine in pregnancy, but the benefits of doing so largely outweigh any possible risks—both for you and your developing baby. That’s true for the flu shot and pertussis (Tdap), as well as the Covid vaccine. And now, a large study shows that getting a Covid shot while pregnant is not linked to adverse outcomes in newborns and infants. In fact, it may protect against adverse outcomes in newborns, the research finds. 

If you’re currently expecting or are planning to become pregnant, you’re likely wondering if you should get a Covid vaccine during pregnancy.

The Centers for Disease and Control recommends that all pregnant people eligible for an updated booster or a primary series should receive the vaccine in pregnancy, both to best protect themselves and their developing baby against severe forms of the disease, which can be worse in pregnancy. Because babies under 6 months are not eligible for their own Covid vaccination, getting vaccinated in pregnancy can offer some protection to them after birth. A previous JAMA study showed that vaccination with two doses of an mRNA vaccine during pregnancy resulted in antibody levels in infants that lasted until they were 6 months old at much higher rates than in babies born to unvaccinated, Covid-infected mothers. Antibodies from maternal vaccination have also been found in breast milk.

What to know about the effects of Covid vaccine in pregnancy on newborns

The new study, out Monday in JAMA Pediatrics, examined 142,006 live births in Ontario between May 2021 and September 2022. Of the infants studied, about 60% were exposed to one or more Covid vaccine doses while the mother was pregnant. The researchers included women who received the vaccine in any trimester.

Getting vaccinated while pregnant was linked with lower risks for severe disease during the first 28 days after the babies were born. It was also associated with lower risks of the baby being placed in the neonatal intensive care unit (NICU), the researchers found. 

One month after birth, infants exposed to the shots were 14% less likely to experience severe neonatal morbidity, 53% less likely to die, and 14% less likely to be admitted to the NICU.

Additionally, the researchers didn’t find a link between getting vaccinated while pregnant and being readmitted to the hospital during the first 28 days after birth or six months down the road.

Vaccine uptake among pregnant women has been significantly lower than in nonpregnant women in many regions, the study authors note. “Uncertainty about vaccine safety for the infant is one of the most frequently reported reasons for lack of intent to get vaccinated during pregnancy.” But the study authors created this experiment to report on the safety of infant outcomes after maternal vaccination.

“We assessed the safety of maternal COVID-19 vaccination during pregnancy for newborns and infants and did not find an increase in adverse outcomes,” Sarah Jorgensen, lead author and researcher at the University of Toronto, told Newsweek. “Some of these outcomes were actually improved in infants of mothers vaccinated during pregnancy.”

“These improved outcomes might be because the vaccines protect mothers from severe COVID-19 during pregnancy, which, in turn, is associated with pregnancy complications and harms to the fetus/newborn,” Jorgensen said. “Or it could be because women who get the vaccine are generally from higher-income areas and have other health-related behaviors associated with improved newborn and infant outcomes. Most likely both explanations are somewhat responsible.”