Related Experiment Video
Updated: Jun 9, 2026

Introduction of Intracapsular Rotary-cut Procedures IRCP: A Modified Hysteromyomectomy Procedures Facilitating Fertility Preservation
Published on: January 17, 2019
Miscarriage after SARS-CoV-2 vaccination: A population-based cohort study
Maria P Velez1,2, Deshayne B Fell2,3, Jonas P Shellenberger2
1Department of Obstetrics and Gynaecology, Queen's University, Kingston, Ontario, Canada.
Objective:
To evaluate the risk of miscarriage following SARS-CoV-2 vaccination, while accounting for the competing risk of induced abortion.
Design:
Population-based cohort study.
Setting:
Ontario, Canada.
Participants:
Women aged 15-50 years with a confirmed pregnancy at ≤19 completed weeks' gestation.
Methods:
Exposure to first SARS-CoV-2 vaccination, handled in a time-varying manner, was defined as (i) unvaccinated, (ii) remotely vaccinated >28 days before the estimated conception date or (iii) recently vaccinated ≤28 days before conception and up to 120 days after conception.
Main Outcome Measures:
The outcome was miscarriage, occurring between the estimated date of conception and up to 19 completed weeks of pregnancy. Fine-Grey hazard models, accounting for the competing risk of induced abortion, generated hazard ratios (aHR), adjusted for socio-demographic factors, comorbidities, and biweekly periods.
Results:
Included were 246 259 pregnant women, of whom 34% received a first SARS-CoV-2 vaccination. Miscarriage occurred at a rate of 3.6 per 10 000 person-days among remotely vaccinated women and 3.2 per 10 000 person-days among those recently vaccinated, in contrast to a rate of 1.9 per 10 000 person-days among unvaccinated women, with corresponding aHR of 0.98 (95% confidence interval [CI] 0.91-1.07) and 1.00 (95% CI 0.93-1.08).
Conclusions:
SARS-CoV-2 vaccination was not associated with miscarriage while accounting for the competing risk of induced abortion. This study reiterates the importance of including pregnant women in new vaccine clinical trials and registries, and the rapid dissemination of vaccine safety data.
Related Concept Videos
Vaccinations
Rous Sarcoma Virus (RSV) and Cancer
RSV is a retrovirus that contains two copies of a plus-strand RNA genome. Its genome consists of four main open...
Rous Sarcoma Virus (RSV) and Cancer
RSV is a retrovirus that contains two copies of a plus-strand RNA genome. Its genome consists of four main open...
Teratogenicity
Confounding in Epidemiological Studies
Bias in Epidemiological Studies

