Further Reassurance for COVID-19 Vaccination Safety During Pregnancy

The initial COVID-19 vaccine trials did not include pregnant women, which led to questions about vaccine safety in pregnancy, but early studies were reassuring regarding the safety of mRNA vaccines in pregnant women. Findings from two new studies reinforce those data.

In one study, researchers identified 158,000 singleton pregnancies from Sweden and Norway in linked pregnancy and vaccination databases. In another study, similar linkage was performed for 98,000 Canadian pregnancies. In both studies, vaccination during pregnancy — usually with mRNA vaccines given during the second or third trimester — occurred in about 20% of women. Women who had been vaccinated prior to pregnancy were excluded.

In the Scandinavian study, adverse outcomes (i.e., preterm birth, stillbirth, newborn small for gestational age, low Apgar score, or neonatal intensive care unit [NICU] admission) were similar for patients vaccinated during pregnancy and those vaccinated after pregnancy or not at all. A similar analysis in the Canadian study showed no differences in the rates of postpartum hemorrhage, chorioamnionitis, or cesarean delivery; infants of vaccinated women had lower risk for NICU admission or low Apgar score than did infants of nonvaccinated women. All analyses were adjusted for clinical and demographic factors.