COVID-19 mRNA vaccination during pregnancy not linked to developmental delays in toddlers

Clinical takeaway: Reassure pregnant patients that COVID-19 mRNA vaccination during or immediately before pregnancy was not associated with adverse neurodevelopmental outcomes in children assessed at 18 to 30 months of age. The findings add to a growing body of evidence supporting the safety of COVID-19 mRNA vaccination during pregnancy.

Concerns about potential developmental effects have contributed to vaccine hesitancy among some pregnant patients. While prior studies have demonstrated favorable maternal, fetal, and pregnancy outcomes with COVID-19 vaccination, data on longer-term child neurodevelopment after in utero exposure to mRNA vaccines have remained limited. Children in this study were assessed at a mean age of more than 25 months, a developmental stage when delays can be identified more reliably than during infancy.

In this multicenter prospective cohort study, investigators from the Eunice Kennedy Shriver National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network evaluated 217 matched pairs of children aged 18 to 30 months. Their mothers either received at least one COVID-19 mRNA vaccine dose during pregnancy or within 30 days before conception, or remained unvaccinated during the same period. Among vaccinated participants, nearly half (46%) received their first dose during the first trimester, while 13% were vaccinated in the month before pregnancy; the remainder were vaccinated during the second or third trimester.

The primary outcome, the Ages and Stages Questionnaire, Third Edition (ASQ-3) total score, was virtually identical between groups, with median scores of 255 among in utero vaccine-exposed children and 260 among unexposed children. No meaningful differences were observed across developmental domains, including communication, gross and fine motor function, problem-solving, and personal-social skills.

Secondary analyses likewise found no differences in behavioral outcomes, temperament measures, or autism screening results. Positive autism screens occurred in 5% of vaccine-exposed children and 6% of unexposed children.

The authors concluded that their findings provide reassurance regarding the neurodevelopmental safety of mRNA COVID-19 vaccination during pregnancy and support current vaccination recommendations.

Source: Hughes BL, et al. (2026 Nov 2) JAMA Pediatrics. SARS-CoV-2 mRNA Vaccination in Pregnancy and Child Neurodevelopment at 18 to 30 Months