Darine El-Chaâr (Canada)
University of Ottawa Obstetrics and GynecologyAuthor Of 1 Presentation
COVID-19 VACCINATION DURING PREGNANCY AND RISK OF PRETERM BIRTH, SMALL-FOR-GESTATIONAL-AGE BIRTH, AND STILLBIRTH IN ONTARIO, CANADA
Abstract
Backgrounds:
Emerging evidence suggests COVID-19 vaccination during pregnancy may reduce risk of newborn SARS-CoV-2 infection; however, safety concerns remain a potential obstacle to achieving high coverage during pregnancy. This study aimed to assess the risk of preterm birth, small-for-gestational-age (SGA) birth, and stillbirth after COVID-19 vaccination during pregnancy.
Methods:
We used provincial databases in Ontario, Canada to identify all live and stillbirths ≥20 weeks’ gestation (birth registry), linked to COVID-19 vaccination data (vaccine registry) for May 1 to November 30, 2021. Using Cox regression, we estimated adjusted hazard ratios (aHR) and 95% confidence intervals (CI) for preterm birth, SGA birth (<10th percentile), and stillbirth treating COVID-19 vaccination as a time-varying exposure. Models were adjusted for calendar time, COVID-19 illness, sociodemographic factors, health behaviours, and pregnancy-related factors.
Results:
Among 69,650 births, 33,295 (47.8%) were born to individuals who received ≥1 dose of COVID-19 vaccine during pregnancy. The incidence of preterm birth was 6.5% among those who received ≥1 dose of COVID-19 vaccine during pregnancy and 7.0% among unvaccinated. The risk of preterm birth was not associated with COVID-19 vaccination during pregnancy (adjusted HR [aHR] 0.96, 95% CI, 0.91 to 1.02), nor was spontaneous preterm birth or very preterm birth (<32 weeks). Similarly, there was no increased risk of SGA birth in vaccinated vs. unvaccinated individuals (8.7% vs. 9.2%; aHR, 1.00; 95% CI, 0.95 to 1.05) or stillbirth (1.6 vs. 2.8 per 1000; aHR, 0.64; 95% CI, 0.46 to 0.90). Results did not differ by trimester of vaccination, mRNA vaccine product, or number of doses received during pregnancy.
Conclusions/Learning Points:
In this large population, COVID-19 vaccination during pregnancy was not associated with a higher risk of preterm birth, SGA birth, or stillbirth.