New findings provide assurance regarding the safety profile of COVID-19 vaccinations administered during gestation. This research, unveiled at the 2026 Pregnancy Meeting of the Society for Maternal-Fetal Medicine (SMFM), concludes that mRNA vaccine exposure during pregnancy does not adversely affect a young child's cognitive growth. The investigation revealed no discernible disparities in developmental benchmarks between children born to immunized mothers and those whose mothers did not receive the vaccine.
The efficacy and safety of vaccines during gestation have been a paramount concern for expecting parents since the inception of COVID-19 immunizations. Messenger RNA (mRNA) vaccines operate by delivering genetic instructions to the body's cells, prompting them to synthesize a particular protein. This protein subsequently activates the immune system, leading to the production of antibodies against the virus.
Despite public health organizations endorsing these vaccines to mitigate severe maternal illness, comprehensive data on long-term infant outcomes has been progressively amassed. A common apprehension among parents is that maternal immune activation could potentially disrupt the intricate processes of fetal brain development.
To address these specific anxieties, a research cohort examined the neurodevelopmental trajectories of children aged 18 to 30 months. This study was spearheaded by George R. Saade of Eastern Virginia Medical School at Old Dominion University and Brenna L. Hughes of Duke University School of Medicine. Their collaborative efforts were conducted under the auspices of the Maternal-Fetal Medicine Units Network, a collective of research facilities supported by the Eunice Kennedy Shriver National Institute of Child Health and Human Development.
The researchers implemented a prospective observational study design, tracking a group of participants over time to observe outcomes without direct intervention or experimentation. They identified women who had received at least one dose of an mRNA SARS-CoV-2 vaccine. For inclusion in the vaccinated group, mothers must have received the vaccine either during their pregnancy or within 30 days prior to conception.
This cohort was then compared against a control group of mothers who had not received the vaccine within the same timeframe. To ensure scientific validity, a matching technique was employed, wherein each vaccinated mother was paired with an unvaccinated mother sharing critical characteristics. These matching criteria included the specific medical facility of delivery, the delivery date, insurance status, and racial background. Such a meticulous matching process is vital in observational research to control for confounding variables like healthcare access or socioeconomic status that could independently influence a child's development.
Strict exclusion criteria were applied to isolate the vaccine's effect. The study excluded women who delivered their babies before 37 weeks of gestation, as prematurity is a recognized cause of developmental delays and could have skewed the results. Multifetal pregnancies and children with significant congenital malformations were also excluded.
Ultimately, the study encompassed 217 matched pairs, totaling 434 children. The primary assessment tool for development was the Ages and Stages Questionnaire, Third Edition (ASQ-3), a widely used standardized pediatric screening instrument. This questionnaire relies on parental observations and reports across five developmental domains: communication (language comprehension and expression), gross motor skills (large bodily movements), fine motor skills (small hand and finger movements), problem-solving, and personal-social interaction (play and social engagement).
Statistical equivalence was the benchmark for data analysis, with a defined margin of 10 points on the ASQ-3 scale. If the average score difference between the vaccinated and unvaccinated groups fell within this 10-point threshold, the outcomes were deemed practically identical. The results consistently indicated equivalent neurodevelopmental outcomes. The median total ASQ-3 score for the vaccinated group was 255, while for the unvaccinated group, it was 260. After accounting for various factors, the adjusted difference was -3.4 points, well within the 10-point equivalence margin, signifying no meaningful developmental difference between the cohorts.
Beyond general developmental scores, the researchers utilized several supplementary screening instruments to detect specific conditions. The Modified Checklist for Autism in Toddlers was employed to evaluate autism spectrum disorder risk, revealing no statistical differences. Approximately 5% of children in the vaccinated group screened positive for potential autism risk, mirroring the 6% in the unvaccinated group. These figures suggest vaccination status had no bearing on the likelihood of an autism diagnosis. The Child Behavior Checklist was also used to assess behavioral and emotional challenges, including internalizing behaviors (e.g., anxiety, withdrawal) and externalizing behaviors (e.g., aggression). Scores for both internalizing and externalizing behaviors were virtually identical across both groups. For instance, 93% of vaccinated children exhibited normal total behavioral problems, precisely matching the percentage in the unvaccinated group.
Finally, temperament was evaluated using the Early Childhood Behavior Questionnaire, measuring traits like "surgency" (positive emotional reactivity, high energy) and "effortful control" (attention focus, impulse inhibition). Across all psychological domains, the study identified no correlation between maternal vaccination and adverse developmental outcomes. While the two groups were largely similar due to the matching process, some demographic variations persisted. Vaccinated mothers were more frequently nulliparous (never having given birth prior to the studied pregnancy). Additionally, vaccinated children were marginally younger at the time of assessment (median age 25.4 months vs. 25.9 months for unvaccinated children). Statistical models were applied to adjust for these minor discrepancies, yet the conclusion of equivalent developmental outcomes remained robust.
“Children born to mothers who received the COVID-19 vaccine during or shortly before pregnancy exhibited neurodevelopmental outcomes that were indistinguishable from those born to unvaccinated mothers,” stated Saade. While these findings are encouraging, certain contextual factors and limitations warrant consideration. The observational nature of the study, while rigorous, cannot establish causation with the same certainty as a randomized controlled trial, which is often ethically impractical for widely recommended vaccines. Furthermore, the reliance on parent-reported data via tools like ASQ-3 introduces a degree of subjectivity. The study also focused on children up to 30 months of age, meaning that some subtle neurodevelopmental issues might only manifest later in childhood, particularly when faced with school-related demands. Despite these limitations, the robust matching methodology and the application of multiple standardized screening tools instill high confidence in the results for the toddler age group. This study effectively addresses a critical knowledge gap concerning the safety of mRNA technology for the next generation. “This research, meticulously conducted within an NIH clinical trials network, offers reassuring evidence regarding the long-term well-being of children whose mothers received COVID-19 vaccination during gestation,” remarked Hughes. The study, titled “Association Between SARS-CoV-2 Vaccine in Pregnancy and Child Neurodevelopment at 18–30 Months,” co-authored by George R. Saade and Brenna L. Hughes, is slated for publication in the February 2026 issue of PREGNANCY.