Taking acetaminophen – known in the US by the brand name Tylenol – during pregnancy has no effect on later autism diagnoses, according to a sweeping new study from Denmark published on Monday.
The Trump administration has targeted Tylenol use in pregnancy as a major cause of autism in children, which appears to have led to a drop in pregnant people taking the pain reliever.
Through Denmark’s robust national healthcare system, researchers were able to track more than 1.5 million children born between 1997 and 2022 in the national health registry, including 31,098 children who were exposed to Tylenol in utero.
Autism was diagnosed in 1.8% of children who were exposed to Tylenol and 3% of those who weren’t, according to the study, which was published in Jama Pediatrics. A similar 2024 study in Sweden found a marginal link that disappeared after taking siblings into account, suggesting that autism is strongly genetic, which has already been demonstrated in other studies.
A US review of existing studies in 2025 found a potential relationship, but it wasn’t clear whether confounders were at play. For instance, if pregnant autistic people take Tylenol more often than neurotypical pregnant people because of higher pain levels.
Health officials announced in September 2025 that the US Food and Drug Administration (FDA) would initiate a label change for acetaminophen, warning of a potential link to autism. Trump cautioned several times against taking the pain reliever during pregnancy.
“If you’re pregnant, don’t take Tylenol,” Trump said at a press conference at the time. “Don’t take Tylenol. Don’t have your baby take Tylenol.” He said the medication was “not good” and taking Tylenol during pregnancy was associated with “a very increased risk of autism”.
Trump added that in some “medically necessary” cases, acetaminophen might still be recommended in pregnancy. “That’s, for instance, in cases of extremely high fever that you feel you can’t tough it out,” he said.
Tylenol is safe to take during pregnancy and can play a key role in relieving pain and bringing down fevers. Yet after the September announcement, Tylenol orders for pregnant women in emergency rooms dropped by 16% in the initial study period, according to a Lancet study published last month.
Health officials’ “words are affecting behavior”, said Jeremy Faust, a co-author of that Lancet study Jeremy Faust who is an emergency physician at Mass General Brigham and a health services researcher at Harvard Medical School.
The rate of emergency orders of Tylenol dropped as low as 20% three weeks after the announcement before it began drifting to a 10% reduction, as the news cycle changed and respiratory virus season ramped up, he said. There was no change for Tylenol order rates among women of the same age who were not pregnant, and no declines in orders for other medications, like IV fluids or opioids.
Tylenol is one of the few medications people may take during pregnancy. “It’s the safest option for pain control and fever reduction,” Faust said. Non-steroidal anti-inflammatory drugs like ibuprofen, Aleve or Motrin usually are not recommended because of bleeding risks and potential placenta issues.
“Pain is, in itself, a problem,” Faust said. He was relieved to see that doctors’ orders for opioids, which can also manage pain, did not increase in the study period.
At the same September press conference, officials announced that leucovorin, a B vitamin, could be used to treat autism. That claim was quietly walked back earlier this year.
