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Oral Presentation

Vaccines

Session: Evaluating the Vaccines Against the Nasty Bugs: Safety First Round II

COVID-19 Vaccination During Pregnancy and Risk of Preterm Birth, Small-for-gestational-age Birth, and Stillbirth

Sunday, August 28, 2022

1:30 PM – 1:45 PM CEST

Location: C1M1

Publication Number: 271

Background: Concern about safety of COVID-19 vaccination during pregnancy remains a potential obstacle to achieving high coverage in this population.

Objectives: To assess the risk of preterm birth, small-for-gestational-age (SGA) at 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 (overall; spontaneous preterm birth; very preterm birth < 32 weeks), 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 eligible births during the study period, 33,295 (47.8%) were born to individuals who had received ≥1 dose of COVID-19 vaccine during pregnancy. The cumulative 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 there any increased risk of spontaneous preterm birth or very preterm birth. 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: In this large population, COVID-19 vaccination during pregnancy was not associated with a higher risk of preterm birth, SGA birth, or stillbirth.

Presenting Author(s)

Deshayne B. Fell

Dr.
University of Ottawa
Ottawa, Ontario, Canada

Co-Author(s)

SD

Sheryll Dimanlig-Cruz, n/a

BORN Ontario, Canada
AR

Annette Regan

Annette Regan
SH

Siri Haberg, n/a

Norwegian Institute of Public Health, Norway
CG

Christopher Gravel, PhD

Assistant Professor
University of Ottawa, Canada
LO

Laura Oakley, n/a

London School of Hygiene and Tropical Medicine, United Kingdom
GA

Gilian Alton, n/a

BORN Ontario, Canada
TD

Tavleen Dhinsa, n/a

BORN Ontario, Canada
ET

Eszter Torok, n/a

BORN Ontario, Canada
PS

Prakesh Shah, n/a

Department of Pediatrics, Mount Sinai Hospital and University of Toronto, Canada
DE

Darine El-Chaar

15 Department of Obstetrics and Gynecology, University of Ottawa, Canada
MW

Mark Walker, n/a

15 Department of Obstetrics and Gynecology, University of Ottawa, Canada
JB

Jon Barrett, n/a

15 Department of Obstetrics and Gynecology, McMaster University, Canada
AS

Ann Sprague, n/a

BORN Ontario, Canada
NO

Nanette Okun, n/a

Sunnybrook Health Sciences Centre and University of Toronto, Canada
SB

Sarah Buchan, n/a

Public Health Ontario and University of Toronto, Canada
JK

Jeff Kwong

ICES, Canada
SW

Sarah Wilson, n/a

Public Health Ontario and University of Toronto, Canada
SD

Sandra Dunn, n/a

BORN Ontario, Canada
KW

Kumanan Wilson, n/a

Department of Medicine, University of Ottawa, Canada
SM

Shannon MacDonald, n/a

Faculty of Nursing, University of Alberta, Canada
SD

Shelley Dougan, n/a

BORN Ontario, Canada