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

This significant finding, emerging from a prospective, multi-center observational study conducted by researchers within the esteemed Maternal-Fetal Medicine Units Network, directly addresses a prevalent concern among expectant parents and healthcare providers worldwide. The study, which meticulously evaluated 434 children aged between 18 months and 30 months, offers robust evidence that the benefits of maternal mRNA COVID-19 vaccination are not offset by adverse neurodevelopmental outcomes in offspring.

Addressing a Global Health Concern

The COVID-19 pandemic presented unprecedented challenges, particularly for vulnerable populations, including pregnant individuals. Early in the pandemic, data suggested that pregnant people with COVID-19 were at an increased risk of severe illness, including intensive care unit admission, mechanical ventilation, and even death, compared to non-pregnant individuals. Furthermore, COVID-19 during pregnancy was associated with an elevated risk of adverse pregnancy outcomes such as preterm birth and stillbirth. These risks underscored the urgent need for effective protective measures, leading to the recommendation of COVID-19 vaccines for pregnant individuals by major public health organizations globally, including the Centers for Disease Control and Prevention (CDC), the American College of Obstetricians and Gynecologists (ACOG), and the World Health Organization (WHO).

In the United States, two primary types of COVID-19 vaccines have been recommended: the messenger ribonucleic acid (mRNA) vaccine (Pfizer-BioNTech and Moderna) and a protein subunit vaccine (Novavax). Both are widely considered safe and effective during all stages of pregnancy, playing a critical role in safeguarding both maternal and infant health by reducing the risk of severe disease in the mother and potentially providing passive immunity to the newborn through the transfer of maternal antibodies. However, despite these recommendations and a growing body of real-world safety data, vaccine hesitancy, often fueled by misinformation, persisted, particularly regarding long-term effects on child development. The current study directly confronts these concerns with rigorous scientific inquiry.

The Rigorous Study of 434 Toddlers

The investigation, which spanned from May 2024 to March 2025, meticulously compared developmental outcomes in two carefully matched groups of children. Half of the participants (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 before conception. The remaining 217 children served as the control group, born to mothers who did not receive an mRNA vaccine during or within 30 days prior to pregnancy. This study design allowed for a direct comparison, aiming to isolate any potential developmental differences attributable to maternal vaccination status.

To ensure the highest degree of accuracy and minimize confounding variables, the researchers employed a meticulous matching protocol. Vaccinated mothers were paired with unvaccinated mothers based on several critical factors: the location of delivery (e.g., hospital, birth center), the exact date of delivery, insurance status, and racial demographics. This granular matching strategy is crucial in observational studies to control for socio-economic and demographic factors that could independently influence child development. Furthermore, certain pregnancies were explicitly excluded from both groups to maintain the homogeneity and focus of the study. These exclusions included pregnancies that ended before 37 weeks of gestation (preterm births), those involving multiple babies (twins, triplets, etc.), or those that resulted in a child diagnosed with a major congenital malformation. These exclusions aimed to remove known factors that could independently impact neurodevelopmental outcomes, thereby strengthening the validity of the comparison between vaccinated and unvaccinated groups.

Expert Endorsement of Findings

Dr. George R. Saade, MD, a distinguished senior researcher on the project, 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, underscored the clarity of the 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, providing a definitive conclusion that offers substantial reassurance to the medical community and the public. His statement directly addresses the primary objective of the study, confirming no discernible link between maternal mRNA COVID-19 vaccination and adverse neurodevelopmental outcomes in early childhood.

Comprehensive Assessment of Developmental Milestones

The assessment of children’s development was thorough and multi-faceted, leveraging widely recognized and validated screening tools. When the children reached 1.5 to 2.5 years of age, researchers employed the Ages and Stages Questionnaire Version 3 (ASQ-3). The ASQ-3 is a widely used, parent-completed developmental screening tool that measures progress in five crucial areas:

1. Communication: Including babbling, vocalizing, and understanding words.
2. Gross Motor Skills: Such as sitting, crawling, walking, and running.
3. Fine Motor Skills: Involving hand-eye coordination, manipulating small objects, and drawing.
4. Problem Solving: Related to understanding cause and effect, and basic cognitive functions.
5. Personal-Social Interaction: Encompassing self-help skills, playing with others, and expressing emotions.

The use of ASQ-3 provided a broad overview of developmental progress across key domains. To further enrich the evaluation and capture a more nuanced picture of behavioral and developmental patterns, the research team also reviewed results from several other specialized instruments:

• The Child Behavior Checklist (CBCL): A comprehensive tool used to identify behavioral and emotional problems in children.
• The Modified Checklist for Autism in Toddlers, Revised with Follow-up (M-CHAT-R/F): A screening tool specifically designed to identify young children at risk for autism spectrum disorder.
• The Early Childhood Behavior Questionnaire (ECBQ): Which assesses temperament dimensions in young children, providing insights into their personality and emotional regulation.

This comprehensive battery of assessments ensured that any potential subtle differences in development or behavior would be detected, lending significant weight to the study’s conclusions. The absence of significant differences across these multiple, validated measures strongly supports the safety profile of mRNA COVID-19 vaccination during pregnancy.

Dr. Brenna L. Hughes, MD, MSc, the 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, further emphasized the scientific rigor behind these findings. "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 noted. Her statement highlights not only the positive outcomes but also the credibility derived from the study’s affiliation with a National Institutes of Health (NIH) clinical trials network, signifying adherence to high standards of research ethics and methodology.

The Evolution of Vaccine Safety in Pregnancy: A Timeline

The journey to confidently recommend vaccines during pregnancy has been a long one, marked by scientific advancement and careful monitoring.

• Pre-COVID Era: Vaccines like the influenza vaccine and Tdap (tetanus, diphtheria, and acellular pertussis) have long been recommended for pregnant individuals due to their proven safety and efficacy in protecting both mother and child. Pertussis, for instance, can be deadly for newborns, and maternal vaccination provides critical antibodies.
• Early 2020: The emergence of SARS-CoV-2 and the rapid development of mRNA vaccines (Pfizer-BioNTech and Moderna) marked a new era in vaccine technology. Initial clinical trials for these vaccines did not specifically include pregnant individuals, leading to initial caution in recommendations.
• Late 2020 – Early 2021: As real-world data from vaccinated individuals, including those who became pregnant shortly after vaccination or who were inadvertently vaccinated early in pregnancy, began to accumulate, a clearer picture of safety emerged. Observational studies quickly demonstrated no increased risk of adverse pregnancy outcomes such as miscarriage, preterm birth, or stillbirth.
• Mid-2021: Major health organizations, including the CDC, ACOG, and WHO, officially recommended COVID-19 vaccination for pregnant and lactating individuals, citing mounting evidence of safety and the significant risks of COVID-19 infection during pregnancy.
• 2022-2024: Continued surveillance and numerous studies further solidified the safety profile of COVID-19 vaccines in pregnancy, extending to various outcomes like birth weight, congenital anomalies, and neonatal health. However, long-term neurodevelopmental outcomes remained an area requiring dedicated research.
• May 2024 – March 2025: The current study was conducted, focusing specifically on neurodevelopmental outcomes at 18-30 months of age, directly filling a critical data gap.
• February 2026: The oral abstract #8, "Association between SARS-CoV-2 vaccine in pregnancy and child neurodevelopment at 18-30 months," is slated for publication in PREGNANCY, the official peer-reviewed medical journal of the Society for Maternal-Fetal Medicine. This publication will make the detailed findings accessible to the broader scientific and clinical communities.

Understanding mRNA Vaccines and Dispelling Misinformation

A significant factor contributing to vaccine hesitancy has been a lack of understanding regarding mRNA technology and the persistence of debunked myths, particularly the long-disproven link between vaccines and autism.

• How mRNA Vaccines Work: Messenger RNA (mRNA) vaccines do not contain live virus and do not interact with or alter a person’s DNA. Instead, they deliver genetic instructions to the body’s cells to produce a harmless piece of the SARS-CoV-2 spike protein. This protein then triggers an immune response, teaching the body to recognize and fight off the actual virus if exposed. The mRNA itself is quickly broken down and eliminated by the body. This mechanism is inherently safe for both the pregnant individual and the developing fetus, as the vaccine components do not cross the placental barrier in a way that would directly affect fetal cells or DNA.
• The Autism Myth: The false link between vaccines and autism originated from a fraudulent 1998 study published by Andrew Wakefield, which was subsequently retracted and debunked by numerous large-scale, robust scientific investigations. Wakefield’s medical license was revoked, and the scientific consensus is overwhelmingly clear: vaccines do not cause autism. The current study specifically investigating mRNA COVID-19 vaccines and autism/developmental disorders in children whose mothers were vaccinated during pregnancy serves as a direct, modern reiteration of this fundamental scientific principle in the context of new vaccine technology.

Broader Impact and Implications

The findings presented at the SMFM 2026 Pregnancy Meeting carry profound implications for public health, clinical practice, and the broader societal understanding of vaccine safety.

• Reinforced Public Health Recommendations: These results provide further scientific bedrock for existing recommendations from organizations like the CDC, ACOG, and WHO, strengthening their ability to confidently advise pregnant and lactating individuals to get vaccinated. This data will be invaluable in public health campaigns aimed at increasing vaccine uptake and combating misinformation.
• Empowering Healthcare Providers: Obstetricians, maternal-fetal medicine specialists, pediatricians, and other healthcare providers can now counsel their patients with even greater certainty. They can confidently reassure expectant parents that mRNA COVID-19 vaccination does not pose a risk to their child’s neurodevelopment, directly addressing a common and deeply personal concern.
• Reassurance for Expectant Parents: For individuals who were vaccinated during pregnancy, or those currently pregnant and considering vaccination, these findings offer immense relief and peace of mind. It validates their decision to protect themselves and their babies, confirming that they made a safe choice for their child’s long-term health.
• Building Public Trust: In an era marked by vaccine skepticism and the rapid spread of misinformation, studies of this caliber are vital for rebuilding and maintaining public trust in scientific research and public health initiatives. By rigorously investigating and transparently reporting on safety outcomes, the scientific community demonstrates its commitment to public well-being.
• Future Research Directions: While this study provides crucial early childhood data, the scientific community will continue to monitor the health and development of children over longer periods, as is standard practice for all new medical interventions. This ongoing surveillance ensures that any potential long-term effects, however unlikely, are identified and understood.

Funding and Transparency

The study’s integrity is further underscored by its funding source: the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), a component of the National Institutes of Health. This federal funding signifies the national importance and scientific merit of the research question. The authors also meticulously noted that the conclusions presented are their own and do not necessarily reflect the official views of the National Institutes of Health, a standard disclosure that highlights academic independence and transparency in research reporting.

In conclusion, the research presented at the SMFM 2026 Pregnancy Meeting marks a pivotal moment in understanding the long-term safety of mRNA COVID-19 vaccines in pregnancy. By conclusively demonstrating no link between maternal vaccination and autism or other developmental disorders in early childhood, this study provides vital reassurance, empowers healthcare providers, and strengthens public health efforts to protect mothers and their children from the risks of COVID-19. It stands as a testament to rigorous scientific inquiry in safeguarding public health in the post-pandemic world.