Safety of COVID-19 vaccination in pregnant women: A study of the adverse perinatal outcomes.

Objective: To compare adverse perinatal outcome among coronavirus disease 2019 (COVID-19)-vaccinated and -unvaccinated pregnant women.

Method: Retrospective equivalence cohort study comparing 930 women who received at least one BNT162b2 (Pfizer/BioNTech) COVID-19 vaccine during the second or third trimester of pregnancy and 964 unvaccinated women. The primary outcome was a composite adverse perinatal outcome including at least one of the following: preterm delivery <35 weeks of gestation, intrauterine fetal death >23 weeks of gestation, intrauterine growth restriction defined as birth weight < 10th percentile, 5-min APGAR score ≤ 7, and neonatal care unit admission.

Results: The authors found no effect of the COVID-19 vaccine on the rate of the individual adverse perinatal outcomes. At least one adverse perinatal outcome was found in 108 (11.25%) of unvaccinated women versus 82 (8.82%) of vaccinated pregnant women (P = 0.080). The observed proportion difference (unvaccinated minus vaccinated) was 0.024. In the equivalence analysis with a margin of 0.05, the 90% confidence interval (0.01-0.05) was entirely within the equivalence zone (-0.05 to 0.05) with a P value of 0.032.

Conclusion: The present study demonstrated an equivalent rate of adverse perinatal outcomes among vaccinated and unvaccinated women, thus supporting vaccine safety during the second and third trimesters of pregnancy. The authors believe this information is useful in counseling pregnant women regarding COVID-19 vaccination during pregnancy.