Study Affirms Safety: First-Trimester mRNA COVID-19 Vaccination Shows No Link to Structural Birth Defects

In the multisite cohort study, the researchers found no association between first-trimester mRNA COVID-19 vaccine exposure and an increased risk for selected major structural birth defects among live-born infants.

The results affirm the safety of administering COVID-19 vaccines to pregnant women during their first trimester.

Throughout pregnancy, COVID-19 vaccination is recommended to prevent pregnancy complications and adverse birth outcomes linked with COVID-19 disease. Data on birth defects following vaccination during the first trimester are scarce. To fill this knowledge gap, Elyse O. Kharbanda, HealthPartners Institute, Minneapolis, Minnesota, and colleagues aimed to evaluate the associated risks for selected major structural birth defects among live-born infants after first-trimester receipt of a messenger RNA (mRNA) COVID-19 vaccine.

For this purpose, the research team conducted a retrospective cohort study of singleton pregnancies with estimated last menstrual period (LMP) between 2020 and 2021 and ending in live births from 2021 to 2022. They included data from 8 health systems in Oregon, California, Colorado, Washington, Minnesota, and Wisconsin in the Vaccine Safety Datalink.

The exposures include receiving 1 or 2 doses of mRNA COVID-19 vaccine during the first trimester as part of the primary vaccination series.

Certain significant structural birth anomalies in live-born infants were identified through electronic health records using validated algorithms, with neural tube defects specifically verified through medical record examination.

The study led to the following findings:

• Among 42 156 eligible pregnancies (mean maternal age, 30.9 years), 18.1% received an mRNA COVID-19 vaccine in the first trimester. Of 34 524 pregnancies without a first-trimester COVID-19 vaccination, 5.9% were vaccinated before pregnancy, 39.1% during the second or third trimester, and 55.0% were unvaccinated before or during pregnancy.
• Compared with pregnant people unvaccinated in the first trimester, those vaccinated in the first trimester were older (mean age, 32.3 years vs 30.6 years) and differed by LMP date.
• After applying stabilized inverse probability weighting, differences in baseline characteristics between vaccinated and unvaccinated pregnant persons in the first trimester were negligible.
• Selected major structural birth defects occurred in 1.48% of infants after first-trimester mRNA COVID-19 vaccination and 1.41% of infants without first-trimester vaccine exposure; the adjusted prevalence ratio was 1.02.
• There were no significant differences between infants vaccinated or unvaccinated in the first trimester in secondary analyses, with major structural birth defect outcomes grouped by organ system.

"First-trimester mRNA COVID-19 vaccine exposure was not associated with an increased risk for selected major structural birth defects among live-born infants," the researchers wrote.

Reference:

Kharbanda EO, DeSilva MB, Lipkind HS, et al. COVID-19 Vaccination in the First Trimester and Major Structural Birth Defects Among Live Births. JAMA Pediatr. Published online July 01, 2024. doi:10.1001/jamapediatrics.2024.1917