Association Between Antenatal COVID-19 Vaccination and Neonatal Outcomes

COVID-19 vaccines are essential public health tools for prevention and control the pandemic. There is still misinformation regarding their safety in pregnant women, particularly in countries with widely used heterologous vaccination. This study investigated the association between maternal COVID-19 vaccination during pregnancy and important neonatal outcomes.

A retrospective cohort study was conducted involving 4032 pregnant women at King Chulalongkorn Memorial Hospital, Thailand, between September 2021 and December 2023. Demographics, vaccination characteristics and adverse neonatal outcomes were collected. The analysis was done by using descriptive statistics and logistic regression.

Of 4032 participants, 1657 (41.1%) received COVID-19 vaccines during pregnancy, mostly mRNA vaccines (60.6%). Vaccination was significantly associated with a lower rate of stillbirth [adjusted odds ratio (aOR): 0.41, 95% CI: 0.16-0.97] and SGA (aOR: 0.27, 95% CI: 0.08-0.90). Vaccination during the second or third trimester was specifically associated with a lower rate of abortion, stillbirth, SGA, and low 5-minute Apgar scores compared with unvaccinated pregnancies. Adequately vaccinated individuals had significantly fewer overall adverse neonatal outcomes compared with partially vaccinated individuals. In addition, mRNA vaccination was associated with a lower abortion and stillbirth rate compared with no vaccination.

Maternal COVID-19 vaccination during pregnancy was not associated with increased adverse neonatal outcomes and was associated with lower rate of stillbirth and small for gestational age. More favorable associations were observed for vaccination in the second or third trimester and for adequate vaccination, and mRNA vaccination showed a lower rate of abortion and stillbirth compared with no vaccination, supporting the safety of vaccination in pregnancy.