Toddlers whose mothers got a COVID mRNA vaccine in pregnancy developed on par with unexposed peers, JAMA Pediatrics study finds

Children whose mothers received an mRNA COVID-19 vaccine during pregnancy or shortly before it showed equivalent neurodevelopment at 18–30 months compared with children whose mothers were not vaccinated, according to a study published in JAMA Pediatrics on 2 November 2026. The results were first presented at the Society for Maternal-Fetal Medicine meeting in February 2026; this is the peer-reviewed publication.

The study

• Design: multicentre prospective observational cohort conducted in a US NIH-funded maternal-fetal medicine research network, led by Brenna L. Hughes (Duke University).
• Exposure: at least one mRNA vaccine dose during pregnancy or within 30 days before it. Exposed and unexposed mothers were matched by delivery date, site, insurance status and race — 217 pairs (434 children). Preterm births, twins and major congenital malformations were excluded.
• Primary outcome: total score on the Ages and Stages Questionnaire (ASQ-3), with equivalence defined as a difference within 10 points.

Findings

Median ASQ-3 scores were 255 (exposed) vs 260 (unexposed), a median difference of −3.4, within the equivalence margin. Secondary measures — ASQ-3 domains, the Child Behavior Checklist, an autism screening checklist and a temperament questionnaire — showed no significant differences. The authors say the findings support continued recommendations for mRNA vaccination in pregnancy.

Limitations

This was not a randomised trial: vaccinated and unvaccinated families may differ in ways matching did not capture (for example, exposed mothers were more often first-time mothers and their children were more often vaccinated). The ASQ-3 and the other tools are screening questionnaires, not clinical diagnoses; the sample is modest; preterm births were excluded; and follow-up ended at about 2½ years. Questions about vaccination in pregnancy should be discussed with a doctor.