JAMA Netw Open

No link found between first-trimester mRNA COVID-19 vaccination and birth defects

October 17, 2025

Study details: This nationwide, population-based cohort study analyzed 527,564 live-born infants in France, using data from the Mother-Child EPI-MERES Register. The study assessed 75 major congenital malformations (MCMs), grouped by 13 organ systems, using standardized diagnostic criteria and adjusted for confounders via propensity score–based weighting.

Results: Among the cohort, 130,338 individuals (24.7%) received at least one dose of an mRNA COVID-19 vaccine during the first trimester of pregnancy. Prevalence of MCMs was similar between exposed (176.6 per 10,000) and unexposed (179.4 per 10,000) infants. No increased risk was observed overall (weighted odds ratio [OR], 0.98; 95% confidence interval [CI], 0.93–1.04), by organ system (weighted ORs ranging from 0.84 [95% CI, 0.68-1.04] for digestive system MCMs to 1.20 [95% CI, 0.75-1.91] for abdominal wall defects), or for any individual MCM. Sensitivity analyses—including timing of exposure and maternal characteristics—confirmed the findings.

Clinical impact: These results provide reassurance that mRNA COVID-19 vaccination during the first trimester isn’t associated with teratogenic effects. Physicians can confidently recommend vaccination to pregnant patients, supporting maternal and neonatal protection without increasing congenital anomaly risk.

Source:

Bernard C, et al. (2025, October 15). JAMA Netw Open. First-Trimester mRNA COVID-19 Vaccination and Risk of Major Congenital Anomalies. https://pubmed.ncbi.nlm.nih.gov/41091463/