Table 3. Adjusted Odds Ratios for Receipt of Third COVID-19 mRNA Vaccine in a 28-Day Exposure Window Across 8 Vaccine Safety Datalink Sites, November 1, 2021, to June 12, 2022.
| COVID-19 mRNA vaccine exposure | Ongoing pregnancy-period controls | Spontaneous abortion cases | Adjusted odds ratio (95% CI)a | ||
|---|---|---|---|---|---|
| No. | COVID-19 vaccine booster, No. (%) | No. | COVID-19 vaccine booster, No. (%) | ||
| Primary analysis | |||||
| Third mRNA COVID-19 vaccine in 28-d window | 270 853 | 11 095 (4.1) | 14 226 | 553 (3.9) | 0.94 (0.86-1.03) |
| Secondary analyses | |||||
| Any COVID-19 booster vaccine in 28-d window | 270 853 | 11 952 (4.4) | 14 226 | 592 (4.2) | 0.94 (0.86-1.02) |
| Third mRNA COVID-19 vaccine in 42-d window | 168 699 | 10 808 (6.4) | 13 326 | 861 (6.5) | 0.97 (0.90-1.05) |
| Any COVID-19 vaccine booster in 42-d window | 168 699 | 11 579 (6.9) | 13 326 | 915 (6.9) | 0.96 (0.89-1.04) |
a
Generalized estimating equation models included gestational age group, surveillance period, maternal age group, number of antenatal visits, site, and race and ethnicity factors and accounted for unique pregnancies that included multiple pregnancy-periods.