A study today finds no increase in autism rates in babies born to mothers who received COVID-19 vaccines just before or during pregnancy, compared with children of unvaccinated moms.
The authors of the study, who presented their findings at the Society for Maternal-Fetal Medicine 2026 Pregnancy Meeting, told CIDRAP News they hope the research will help dispel myths about COVID-19 vaccines, which multiple studies have found to be safe and effective during pregnancy.
Half of the 434 children in the study, conducted at 14 medical facilities from May 2024 to March 2025, were born to mothers who received at least one dose of an mRNA vaccine during or within 30 days before pregnancy. The other half of the children in the study were born to mothers who weren’t vaccinated before or during pregnancy.
Researchers evaluated toddlers between the ages of 18 months and 30 months for signs of autism using four standard screenings: the Ages and Stages Questionnaire Version 3 (ASQ-3), the Child Behavior Checklist, the Modified Checklist for Autism in Toddlers, and the Early Childhood Behavior Questionnaire. None of these measures are used to make a definitive diagnosis of autism, but they can indicate a need for further testing.
When the researchers compared the scores on all four screening assessments, they found no significant differences between the children born to vaccinated mothers and those born to unvaccinated mothers.
“The fact that there were no differences on all four of these outcomes is evidence that COVID vaccination does not result in developmental concerns for most children,” said Alycia Halladay, PhD, chief science officer at the Autism Science Foundation, who was not involved in the new study. “For people who are worried that taking the COVID vaccine during pregnancy may cause autism, the study is pretty clear, convincing evidence that it does not.”
The authors of the study said its results are reassuring.
“We found no evidence in our study or in other studies that [the COVID] vaccine causes harm to the children,” said George R. Saade, MD, the new study’s first author and professor and chair of obstetrics and gynecology at Virginia Health Sciences at Old Dominion University.
Findings consistent with earlier research
A growing number of studies show that COVID-19 vaccines are safe for women who want to start a family.
In January, a study of nearly 60,000 Swedish women found no difference between vaccinated and unvaccinated women in the rates of later pregnancy or miscarriage.
Multiple studies also show that vaccines help protect pregnant women from serious complications of COVID-19. In December, a study found that pregnant women vaccinated against COVID-19 were less likely than unvaccinated women to be hospitalized or give birth prematurely.
The new study is being presented as Health and Human Services Secretary Robert F. Kennedy Jr, who espouses the debunked notion that vaccines cause autism, is sowing doubts about COVID-19 vaccines and other immunizations.
Kennedy falsely claimed the COVID-19 vaccine was the "deadliest vaccine ever made” in 2021. Kennedy also blames vaccines for the growing number of autism diagnoses in recent decades. Among eight-year-old children in 2022, one in 31 had autism, according to the Centers for Disease Control and Prevention (CDC).
Under Kennedy’s leadership, in November the CDC altered its website to falsely claim, “studies have not ruled out the possibility that infant vaccines cause autism.” The Food and Drug Administration last month took down a web page warning families of dangerous, unproven autism treatments.
But experts say the increase in autism cases reflects greater awareness and changing definitions of autism to include milder forms of the condition, as well as increased access to screening. Some families are more motivated to go through the testing process today because insurance plans often require a formal diagnosis before covering services, and schools frequently require a diagnosis before providing supportive services, Halladay said.
Limitations of the new study
Although specialists can reliably diagnose autism by age two years, the average age of diagnosis is four to five years old.
Because authors of the new study only followed children until they were 2½ years old, it’s possible that they missed some diagnoses, which could be made later as children age, said Robert H. Hopkins, Jr., MD, a pediatrician and medical director of the National Foundation for Infectious Diseases, who was not involved in the new study.
Hopkins commended the study authors for following up on the children studied as long as they did, which is difficult to do in the United States’ fragmented health system. He described the study as being a “decent size,” but noted he would like to see additional research.
COVID-19 infections put moms, babies at risk
While vaccines are safe for pregnant women, infection with COVID-19 is not, Hopkins said.
Research shows that pregnant women who contract COVID-19 are seven times more likely to die than pregnant women who aren’t infected. Infants of women infected with COVID-19 are also more likely than other babies to be admitted to an intensive care unit.
“The overall message is that COVID-19 continues to cause significant disease in pregnant women and in very young children,” Hopkins said. “If I had to balance the risk between getting the vaccine or getting COVID, I would strongly recommend the vaccine.”
Population-based studies have long linked maternal infections in general with increased rates of autism and schizophrenia in their children.
Studies of pregnant women infected with COVID-19 have produced mixed results. Although one study found no increased risk of autism in babies whose moms were infected while pregnant, others suggest that babies exposed to COVID-19 in the womb are more likely to develop autism or other neurodevelopmental conditions by age three years.
By preventing infection in pregnant women, it’s possible that COVID-19 vaccines could reduce the risk of babies developing neurodevelopmental challenges, Halladay said.
This study, funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development, will be published in the February 2026 issue of Pregnancy, the peer-reviewed medical journal of the Society for Maternal-Fetal Medicine.
