COVID-19 Vaccination During Pregnancy and Major Structural Birth Defects.

Background and objectives: COVID-19 vaccination is recommended during pregnancy; however, evidence on the prevalence of major structural birth defects born to people vaccinated early in pregnancy (≤20 weeks of gestation) is limited. We compared the prevalence of major structural birth defects by COVID-19 vaccination status and key strata: insurance provider, clinically diagnosed SARS-CoV-2 infection during pregnancy, and concomitant administration of other maternal vaccines. We also compared, head-to-head, the prevalence of birth defects by brand (Moderna mRNA-1273 vs Pfizer-BioNTech BNT162b2).

Methods: A claims-based cohort study captured pregnancies ending in a live birth among people with an estimated last menstrual period between August 15, 2021, and December 24, 2021. Prevalence ratios comparing birth defects by exposure to COVID-19 vaccines were estimated using binomial regression with inverse probability treatment weights.

Results: Among 78 052 pregnancies, we identified 1248 major structural birth defects (1049 [160.6 per 10 000 live births] among unvaccinated people and 199 [156.4 per 10 000 live births] among vaccinated people). No differences in the prevalence of major structural birth defects were observed given COVID-19 vaccination (adjusted prevalence ratio [aPR], 0.96; 95% CI, 0.81-1.13). Findings were unchanged by insurance provider, SARS-CoV-2 infection during pregnancy, and concomitant of other maternal vaccines. No differences in the prevalence of birth defects were observed among vaccinated people by brand (aPR, 1.02; 95% CI, 0.77-1.37).

Conclusions: COVID-19 vaccination during early pregnancy is not associated with an increased prevalence of major structural birth defects in infants. These results support the safety of COVID-19 vaccination in early pregnancy.