A landmark study involving more than half a million infants has found that receiving an mRNA-based COVID-19 vaccine during the first trimester of pregnancy does not increase the risk of birth defects.
The findings, published in JAMA Network Open, reinforce earlier research showing that COVID-19 vaccination is safe for pregnant women and their babies.
Researchers analyzed data from more than 530,000 infants, of whom roughly one in four were exposed to at least one dose of an mRNA COVID-19 vaccine while in utero.
Their conclusion was unequivocal: there was no increase in risk for any of 75 major congenital malformations, whether considered as a whole or by individual organ systems.
Reassuring Results Amid Political Rollbacks
The study arrives as the Trump administration moves to roll back vaccination recommendations, including guidance that had previously encouraged pregnant women to receive the COVID-19 shot.
Health and Human Services Secretary Robert F. Kennedy Jr. led the decision to withdraw the federal recommendation earlier this year, despite mounting scientific evidence that vaccination is safe—and that infection poses real dangers during pregnancy.
“This large-scale study shows no teratogenic effects from mRNA-based COVID-19 vaccines,” the researchers wrote, using the medical term for conditions that cause birth defects.
The results provide reassurance for expectant parents at a time when vaccine guidance has become increasingly politicized.
The Risks of Infection During Pregnancy
While the administration’s new policy has generated controversy, medical experts continue to emphasize the risks of COVID-19 infection during pregnancy.
According to the Centers for Disease Control and Prevention (CDC), pregnant women who contract COVID-19 face a higher likelihood of serious complications, including hospitalization, intensive care, or the need for a ventilator.
“Severe COVID-19 illness can lead to death,” the CDC warns. The virus can also harm the baby, increasing the risk of preterm birth, stillbirth, and other adverse outcomes. The new study’s authors argue that withholding or discouraging vaccination could therefore endanger both mothers and infants.
Expert Support for Vaccination
Dr. Mahmoud Zureik, one of the study’s authors, told The New York Times that the findings strongly support maintaining access to COVID-19 vaccination for all pregnant women.
“This research supports COVID vaccines being widely available to all women who wish to be vaccinated during pregnancy,” Zureik said.
He noted that the sheer size of the study—spanning hundreds of thousands of pregnancies—makes it one of the most comprehensive analyses of its kind. “Our data are consistent across all subgroups and provide robust reassurance about the absence of risk,” he said.
A Contrast Between Policy and Science
Public health experts have voiced concern that the administration’s rollback of vaccine guidance undermines scientific consensus.
Numerous studies, including those by the CDC, World Health Organization, and American College of Obstetricians and Gynecologists, continue to endorse COVID-19 vaccination during pregnancy as both safe and beneficial.
Dr. Debra Houry, former CDC chief medical officer, recently warned that changing vaccine policy without scientific justification could erode public trust. “When we ignore large bodies of data in favor of political messaging, we put people’s health at risk,” she said.
Looking Ahead
The new study adds to growing evidence that the COVID-19 vaccine poses no measurable risk to fetal development. For expectant mothers, the findings offer reassurance that vaccination remains a safe and effective way to protect both parent and baby from serious illness.
Public health officials say that while individual decisions should be made in consultation with a healthcare provider, the science is clear: the benefits of vaccination during pregnancy far outweigh any theoretical risks.
As Zureik put it, “Pregnancy should not be a barrier to protection from a virus that continues to pose real risks to maternal and infant health.”
