President Donald Trump boasted that his administration may have discovered the “answer to autism” in a link to the use of acetaminophen by pregnant mothers — but such a link is not the “holy grail” and requires more research, a top researcher told Newsweek.
Ann Bauer, an epidemiologist and co-author of research linking the active ingredient in Tylenol to increased incidence of neurodevelopmental disorders, said her research published last month in the journal Environmental Health found a “strong and consistent association” between prenatal use and offspring diagnosed with autism, attention-deficit/hyperactivity disorder and other developmental delays.
Bauer and her co-authors reviewed 46 prior studies and found 27 of them included significant links between prenatal acetaminophen use, compared to nine that found no significant link and four that found negative associations or protective effects.
“Part of this framework is to evaluate the quality of the studies,” Bauer told Newsweek ahead of Trump’s scheduled afternoon press conference on the matter. “And we found that the higher the quality of the study, the stronger the link.”
Many of the studies found more frequent and sustained use of acetaminophen correlated to higher risk of children later being diagnosed with neurodevelopmental disorders, Bauer said.
As the most common over-the-counter pain and fever medication worldwide, more than half of pregnant women use acetaminophen to manage everything from fever to back pain. Still, Bauer cautioned that “correlation is not causation” and recommended that additional research be completed before declaring a public victory regarding autism.
“We obviously need more definitive studies than we have, but what we do know is acetaminophen has many of the hallmarks of an environmental toxicant,” she said, potentially leading to oxidative stress and hormone disruption.
Bauer and her colleagues advised “judicious” acetaminophen use among pregnant women in their findings last month, suggesting the lowest possible dose be taken for the shortest period of time. That recommendation still stands today, she said.
“While there’s still uncertainty, we think there’s enough evidence that we should take a precautionary approach while we continue to do research,” she said.
The recommendation is nuanced, Bauer said, because untreated fever can also pose serious risks to developing fetuses, such as neural tube defects or preterm birth.
“We have to have this balanced approach,” Bauer said. “Alternate pain medications — aspirin and ibuprofen — are not advised for pregnant women, particularly in the third semester, so they’re not an option.”
Additional research could lead to a better painkiller for pregnant women, but acetaminophen is still “best option” for some patients.
“There are going to be times when acetaminophen is the best option,” Bauer said. “I think what we’re trying to express is — at this point — women should try to seek other non-pharmaceutical methods to deal with nuisance-type pain, discomfort. But for anything severe or for fever, they should probably have a consultation with their doctor.”
Expecting mothers should then decide the best path forward with their physicians, Bauer said.
“But I think women need this information to make informed decisions,” she said. “We think that being cautious is prudent.”
Still, she added: “Research suggests that one-off use probably isn’t very harmful. t’s prolonged use that’s more concerning.”
Federal health officials, including HHS Secretary Robert F. Kennedy, Jr., are expected to raise concerns about pregnant women using acetaminophen during a White House press conference scheduled for 4 p.m. Monday.
Trump and Kennedy are expected to warn pregnant women against using Tylenol unless they have a fever, the Washington Post reported.
Trump previewed Monday’s announcement at a memorial Sunday for Charlie Kirk at State Farm Stadium in Glendale, Arizona.
“I think you’re going to find it to be amazing,” he told tens of thousands in attendance. “I think we found an answer to autism.”
Kenvue, which manufactures Tylenol, said in a statement Monday that “independent, sound science clearly shows” that taking acetaminophen does not cause autism.
“We strongly disagree with any suggestion otherwise and are deeply concerned with the health risk this poses for expecting mothers,” the company told Newsweek in a statement. “Acetaminophen is the safest pain reliever option for pregnant women as needed throughout their entire pregnancy. Without it, women face dangerous choices: suffer through conditions like fever that are potentially harmful to both mom and baby or use riskier alternatives.”
Bauer, a visiting scholar at the University of Massachusetts Lowell’s Department of Public Health, said she’s cautiously optimistic that Trump and his administration will communicate the science linking acetaminophen and neurodevelopmental disorders “carefully and accurately,” she said.
Bauer outlined precautionary steps for women using acetaminophen in 2021, citing a “growing body of evidence” that the medication may alter fetal development and increase the risk of neurological disorders.
Other possible causes of neurodevelopmental disorders like autism include air pollution, pesticides, genetics and environmental factors, Bauer said.
“They may have identified a potential risk factor,” she said. “Of course, genetics plays a huge role, but there are other environmental factors out there. I think it’s a contributing factor, but that’s all.”
Bauer stressed that more research is needed to definitively link acetaminophen to autism.
“We have not identified the holy grail at this point,” she said. “We need more research.”