A massive study of over 1.5 million children in Denmark has found no link between the use of acetaminophen during pregnancy and later autism diagnoses, according to research published Monday in JAMA Pediatrics.
The findings directly challenge recent claims from the Trump administration that Tylenol use in pregnant women is tied to a significantly increased risk of autism.
Researchers used Denmark’s national health registry to track births between 1997 and 2022. The study included 31,098 children who were exposed to the medication in utero.
Data showed autism was diagnosed in 1.8% of children exposed to Tylenol, compared to 3% of those who were not.
Impact on medical practice
Following a September 2025 announcement by the FDA regarding potential links, Tylenol orders for pregnant women in emergency rooms dropped by 16%, according to a study in The Lancet.
At a press conference last year, Donald Trump cautioned pregnant women against using the pain reliever. “If you’re pregnant, don’t take Tylenol,” Trump said. “Don’t take Tylenol. Don’t have your baby take Tylenol.”
Jeremy Faust, an emergency physician at Mass General Brigham and a co-author of the Lancet study, said the administration's rhetoric is actively changing clinical behavior.
“Health officials’ words are affecting behavior,” Faust said.
In some periods, emergency orders for the medication plummeted by as much as 20% just three weeks after the federal warnings were issued.
Medical experts maintain that acetaminophen remains a primary tool for managing fever and pain during pregnancy.
“It’s the safest option for pain control and fever reduction,” Faust said, noting that alternatives like ibuprofen or Motrin carry risks of bleeding and placental issues.
While a 2025 U.S. review suggested a potential relationship, researchers noted that confounding factors—such as higher pain levels in pregnant individuals who may already be neurodivergent—could influence such data.
