A new study conducted by researchers from the Karolinska Institutet explored the safety of COVID-19 vaccines during pregnancy. According to their findings, these vaccines aren't likely to increase the risk of complications for pregnant women.
“The results are reassuring and can hopefully make pregnant individuals more willing to get vaccinated,” said researcher Dr. Anne Örtqvist Rosin.
Few risks for pregnant women and infants
For the study, the researchers analyzed data from nearly 160,000 pregnancies from the Pregnancy Registry in Sweden and the Medical Birth Registry of Norway between January 2021, and January 2022. The team evaluated how the Pfizer, Moderna, and AstraZeneca vaccines impacted pregnancy complications, including growth retardation, preterm birth, and the need for neonatal intensive care.
Overall, 18% of the women had received the COVID-19 vaccine during pregnancy. The researchers learned that they were not associated with an increase in pregnancy-related complications. When looking at key indicators of newborn’s health -- preterm birth, stillbirth, small for gestational age, and low Apgar score (which tests heart rate and muscle tone after birth) -- there were few differences between babies born to women who were vaccinated and those born to mothers who were unvaccinated.
“We’re still seeing that vaccination rates are lower than in the rest of the population, so it’s likely that there’s some concern about how the vaccines affect the pregnant individual and the fetus,” said Dr. Örtqvist Rosin. “When the vaccines were produced, pregnant women were not included in the large clinical studies, and until now there have been no population-based data about any risk there might be to them.”
Passing antibodies to newborns
The researchers explained that the pregnant women who had received the vaccine did so after the 12-week mark, and 95% of them had received an mRNA vaccine. These findings held up regardless of whether the women received one or two doses of the vaccine.
The study revealed that the women were able to pass COVID-19 antibodies onto their infants after receiving a vaccine, which helped protect them from the virus. The team’s next goal is to investigate infants’ virus protection in the womb.
“We’re now planning to study how long this protection lasts, and if SARS-CoV-2 infection or vaccination during pregnancy has any other lasting effects on the child’s health,” said researcher Olof Stephansson.