Large study finds no link between mRNA COVID vaccine in pregnancy and autism

This pivotal study, conducted by researchers within the Maternal-Fetal Medicine Units Network, offers robust evidence that further solidifies the safety profile of mRNA COVID-19 vaccines for expectant mothers and their offspring. The results are poised to significantly reinforce public health messaging, address lingering parental concerns, and combat widespread misinformation regarding vaccine efficacy and safety during gestation. The investigation focused on 434 toddlers, meticulously evaluating their neurodevelopmental outcomes to ascertain any potential association between maternal vaccination and developmental conditions.

Reinforcing Public Health Guidance Amidst Evolving Challenges

The United States currently recommends two primary types of COVID-19 vaccines: messenger ribonucleic acid (mRNA) vaccines, such as those developed by Pfizer-BioNTech and Moderna, and protein subunit vaccines, like Novavax. Both categories have been consistently deemed safe and effective during all stages of pregnancy by leading health organizations, including the Centers for Disease Control and Prevention (CDC) and the American College of Obstetricians and Gynecologists (ACOG). These recommendations are rooted in extensive data demonstrating the vaccines’ capacity to safeguard both maternal and infant health by reducing the risk of severe COVID-19 disease, hospitalization, and adverse pregnancy outcomes.

Prior to the comprehensive findings presented at the SMFM 2026 Pregnancy Meeting, numerous studies had already established the short-term safety of COVID-19 vaccination in pregnancy, showing no increased risks of miscarriage, preterm birth, or other immediate adverse events. However, concerns about long-term neurodevelopmental effects in children, though largely unfounded by scientific consensus, have persisted among some segments of the population. This new research directly addresses those specific, often emotionally charged, anxieties, providing critical long-term data that underscores the safety of these crucial public health interventions.

The Genesis of a Global Health Crisis and Vaccine Innovation

The emergence of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in late 2019 and its rapid global spread ushered in an unprecedented era of public health crisis. The subsequent COVID-19 pandemic quickly overwhelmed healthcare systems worldwide, leading to millions of deaths and profound societal disruption. In response, the scientific community embarked on an extraordinary race to develop effective vaccines, culminating in the rapid authorization and deployment of several vaccine platforms, most notably the novel mRNA technology.

mRNA vaccines represented a paradigm shift in vaccinology. Unlike traditional vaccines that introduce weakened or inactivated pathogens, mRNA vaccines deliver genetic instructions to human cells, teaching them to produce a harmless piece of the virus’s spike protein. This triggers an immune response, preparing the body to fight off future infections. The speed of their development, while a testament to scientific prowess, also contributed to public skepticism and fueled concerns, particularly regarding their use in vulnerable populations such as pregnant individuals.

Initially, pregnant individuals were often excluded from primary clinical trials due to ethical considerations and a cautious approach. This necessary prudence, however, created a vacuum of specific data that was quickly filled by real-world evidence and subsequent observational studies. Public health bodies worldwide, including the World Health Organization (WHO), began issuing guidance recommending vaccination for pregnant individuals as evidence mounted regarding the severe risks of COVID-19 in pregnancy, which included higher rates of intensive care unit (ICU) admission, mechanical ventilation, preterm birth, and stillbirth compared to non-pregnant individuals.

Addressing Misinformation and Vaccine Hesitancy

The public discourse surrounding COVID-19 vaccines has been heavily influenced by a deluge of misinformation and disinformation, particularly concerning their impact on fertility, pregnancy, and child development. False claims linking vaccines to autism, a narrative that regrettably gained traction decades ago with the thoroughly debunked MMR vaccine controversy, resurfaced with the advent of COVID-19 vaccines. This persistent myth, despite overwhelming scientific refutation, has contributed significantly to vaccine hesitancy among expectant parents.

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition characterized by challenges with social interaction, communication, and repetitive behaviors. According to the U.S. Centers for Disease Control and Prevention (CDC), approximately 1 in 36 children (or 2.8%) were identified with ASD in 2020. The causes of autism are multifactorial, involving a combination of genetic and environmental factors, none of which have been scientifically linked to vaccines. The current study specifically targeted this area of concern, understanding its potential to sway parental decisions regarding vaccination. By directly investigating the association between maternal mRNA COVID-19 vaccination and neurodevelopmental outcomes in toddlers, the researchers aimed to provide definitive data to counter these unfounded fears.

Methodology: A Rigorous Approach to Child Neurodevelopment

The investigation, conducted by the esteemed Maternal-Fetal Medicine Units Network, was a prospective, multi-center, and observational study that spanned from May 2024 to March 2025. This design allowed researchers to follow a cohort of children from early life, minimizing recall bias and ensuring a high quality of data collection. The study population comprised 434 children, aged between 18 months and 30 months, a critical window for identifying early signs of autism and other developmental concerns.

A meticulous comparative approach was employed to ensure the accuracy and reliability of the findings. The cohort was evenly divided: 217 children were born to mothers who had received at least one dose of an mRNA COVID-19 vaccine either during pregnancy or within 30 days prior to conception. The remaining 217 children constituted the control group, born to mothers who did not receive an mRNA vaccine during or within 30 days prior to pregnancy.

To create the most accurate comparison possible, vaccinated mothers were carefully paired with unvaccinated mothers based on a series of crucial demographic and obstetric factors. These matching criteria included the delivery location (e.g., hospital, birth center), the exact date of delivery, insurance status, and race. This rigorous matching process helped to control for potential confounding variables that could otherwise influence developmental outcomes, thereby isolating the effect of vaccination.

Certain pregnancies were deliberately excluded from both groups to maintain the study’s focus and integrity. These exclusions included pregnancies that concluded before 37 weeks of gestation (preterm births), those involving multiple babies (twins, triplets, etc.), and cases where the child was diagnosed with a major congenital malformation. These exclusions ensured that the study primarily examined healthy, singleton, full-term births, where any developmental concerns could be more clearly attributed or disassociated from maternal vaccination.

Comprehensive Assessment of Developmental Milestones

When the children reached the age range of 1.5 to 2.5 years, a period crucial for developmental screening, researchers employed a multi-faceted assessment strategy. The primary screening tool utilized was the Ages and Stages Questionnaire Version 3 (ASQ-3). This widely recognized, parent-completed screening tool systematically measures progress in five key developmental areas: communication, gross motor skills, fine motor skills, problem-solving abilities, and personal-social interaction. The ASQ-3 is known for its ability to identify children who may be at risk for developmental delays, prompting further evaluation.

To further enrich the developmental assessment, the research team also reviewed results from several other established tools. These included the Child Behavior Checklist (CBCL), which assesses behavioral and emotional problems in children; the Modified Checklist for Autism in Toddlers, Revised, with Follow-up (M-CHAT-R/F), a highly sensitive screening tool specifically designed to identify young children at risk for autism spectrum disorder; and the Early Childhood Behavior Questionnaire (ECBQ), which measures temperament in young children. The combination of these instruments provided a comprehensive picture of each child’s neurodevelopmental and behavioral patterns, allowing for a thorough comparison between the vaccinated and unvaccinated groups.

Expert Endorsements and Broader Implications

Dr. George R. Saade, MD, a senior researcher on the study and a distinguished Professor and Chair of Obstetrics and Gynecology, and Associate Dean for Women’s Health, at Macon & Joan Brock Virginia Health Sciences at Old Dominion University in Norfolk, VA, emphasized the study’s reassuring findings. "Neurodevelopment outcomes in children born to mothers who received the COVID-19 vaccine during or shortly before pregnancy did not differ from those born to mothers who did not receive the vaccine," Dr. Saade stated. His statement highlights the direct and unambiguous nature of the results, offering a clear answer to a critical public health question.

Echoing this sentiment, Dr. Brenna L. Hughes, MD, MSc, Edwin Crowell Hamblen Distinguished Professor of Reproductive Biology and Family Planning and Interim Chair of the Department of Obstetrics and Gynecology at Duke University in Raleigh, NC, underscored the study’s methodological rigor and its significance. "This study, conducted through a rigorous scientific process in an NIH clinical trials network, demonstrates reassuring findings regarding the long-term health of children whose mothers received COVID-19 vaccination during pregnancy," Dr. Hughes remarked. Her reference to the NIH clinical trials network lends significant credibility to the study’s design and execution, reassuring both the scientific community and the general public.

These findings carry profound implications for public health. They provide robust scientific data that can be used by healthcare providers, public health officials, and policymakers to confidently recommend mRNA COVID-19 vaccination to pregnant individuals. This evidence directly addresses a major area of vaccine hesitancy, potentially increasing vaccination rates among expectant mothers, thereby protecting both them and their infants from the severe consequences of COVID-19. Increased vaccination rates translate to fewer hospitalizations, reduced strain on healthcare systems, and ultimately, healthier maternal and infant populations.

Funding, Dissemination, and Future Directions

The study was made possible through funding from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), a component of the National Institutes of Health (NIH). The authors clarified that while the study was funded by NIH, the conclusions presented are their own and do not necessarily reflect the official views of the National Institutes of Health. This standard disclosure ensures academic independence and transparency.

The full details of the study, specifically oral abstract #8 titled "Association between SARS-CoV-2 vaccine in pregnancy and child neurodevelopment at 18-30 months," are slated for publication in the February 2026 issue of PREGNANCY, the official peer-reviewed medical journal of the Society for Maternal-Fetal Medicine. Publication in such a prestigious, peer-reviewed journal ensures that the findings have undergone rigorous scrutiny by experts in the field, further solidifying their scientific validity and facilitating their widespread dissemination within the medical community.

Looking ahead, while this study provides crucial long-term reassurance, ongoing surveillance and research remain vital. Continued monitoring of child development, potentially extending into school-age years, could offer even more comprehensive data, although the current findings are already highly robust for early childhood. Furthermore, research into the efficacy and safety of new vaccine technologies and formulations, as well as their long-term effects across various populations, will continue to be a cornerstone of public health science. This study represents a significant milestone in ensuring that evidence-based recommendations guide clinical practice and public health policy, ultimately fostering trust and improving health outcomes for all.