This is a summary, written by members of the CITF Secretariat, of:

Fell DB, Dhinsa T, Alton GD, Török E, Dimanlig-Cruz S, Regan AK, Sprague AE, Buchan SA, Kwong JC, Wilson SE, Håberg SE, Gravel CA, Wilson K, El-Chaâr D, Walker MC, Barrett J, MacDonald SE, Okun N, Shah PS, Dougan SD, Dunn S, Bisnaire L. Association of COVID-19 Vaccination in Pregnancy With Adverse Peripartum Outcomes. JAMA. Publié en ligne le 24 mars 2022. doi: 10.1001/jama.2022.4255.

The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.

In a paper published in JAMA (Journal of the American Medical Association), CITF-funded researchers Drs. Deshayne Fell and Kumanan Wilson of the University of Ottawa and Dr. Jeffrey Kwong from the University of Toronto and colleagues found that COVID-19 vaccination was not significantly associated with an increased risk of adverse pregnancy outcomes. This study found that COVID-19 vaccines were not significantly associated with increased risk of postpartum hemorrhage, chorioamnionitis, cesarean delivery, admission to neonatal intensive care unit, or low newborn 5-minute Apgar score.

This large population-based study (n=97,590) included information from all births in Ontario between December 14, 2020, and September 30, 2021. Among the participants, over 22,000 individuals received at least one dose of COVID-19 vaccine during pregnancy. Vaccinations received during pregnancy were primarily mRNA vaccines (99.8%) administered in the second and third trimester.

Key findings:

  • Comparing those vaccinated during pregnancy (n=22,660) to those vaccinated after pregnancy (n=44,815), vaccination was not significantly associated with any increased risk of postpartum hemorrhage, chorioamnionitis, cesarean delivery, NICU admission or low 5-minute Apgar score.
  • The results were largely unchanged when stratified according to the number of doses received during pregnancy, vaccine product, or the trimester when dose 1 was received.
  • Findings were qualitatively similar when compared with those individuals who did not receive COVID-19 vaccination at any point (n=30,115) by the end of September 2021.

The results were robust to sensitivity analyses designed to account for potential residual confounding by factors such as maternal age, calendar time, time since vaccination, gestational length, and COVID-19 during pregnancy.