The risk of miscarriage following COVID-19 vaccination: a systematic review and meta-analysis.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis composed predominantly of observational studies (16 observational studies, 5 randomized trials)
PubMed 36794918 · doi:10.1093/humrep/dead036
What was done
Authors conducted a systematic review and meta-analysis searching MEDLINE, EMBASE, and Cochrane CENTRAL from inception through June 2022. They included randomized trials and observational studies evaluating any COVID-19 vaccine against placebo or no vaccination in pregnant women. Primary outcomes assessed were miscarriage, ongoing pregnancy, and live birth rates.
What was found
Twenty-one studies (5 randomized trials and 16 observational studies) encompassing 149,685 women were analyzed. The pooled rate of miscarriage among vaccinated women was 9% (n = 14,749/123,185; 95% CI 0.05-0.14). Compared to placebo or no vaccination, COVID-19 vaccination was not associated with an increased risk of miscarriage (risk ratio [RR] 1.07, 95% CI 0.89-1.28; I² = 35.8%) and showed comparable rates of ongoing pregnancy or live birth (RR 1.00, 95% CI 0.97-1.03; I² = 10.72%).
Why it matters
This review provides quantitative reassurance that COVID-19 vaccination during or near pregnancy does not elevate the risk of miscarriage or compromise pregnancy continuation.
Limits
The evidence base relies predominantly on observational studies (16 of 21) rather than randomized trials, introducing potential confounding. The authors noted high heterogeneity and variable risk of bias across included studies, and the abstract does not report outcomes stratified by specific vaccine platforms, gestational timing of exposure, or prior pregnancy history.
Cited by
- supports In the phase 3 trials for Pfizer, Moderna, AstraZeneca, and Johnson & Johnson COVID-19 vaccines, there were no statistically significant differences in pregnancy rates or miscarriages between the vaccinated and control groups.