Trump Links Tylenol Use During Pregnancy to Autism. What Does the Science Show?

In a Sept. 22 statement, President Donald Trump said using Tylenol during pregnancy increases the risk of having a child with autism, contradicting the advice of leading obstetrics experts who say the popular drug is very safe during pregnancy.

“Don't take Tylenol. Fight like hell not to take it,” Trump said during a White House briefing.

The president, who was accompanied by U.S. Health and Human Services (HHS) Secretary Robert F. Kennedy Jr. and other Cabinet officials, said pregnant women should not take acetaminophen, the active ingredient in Tylenol, unless they have an “extremely high fever.”

“If you can't stand it, if you can't do it, this is what you're going to have to do,” Trump said.

The American College of Obstetricians and Gynecologists was quick to dispute Trump's claims, saying there was no clear evidence linking acetaminophen use to autism or other risks to fetal development. Other pain relievers and fever reducers, such as ibuprofen and aspirin, carry risks during pregnancy, and acetaminophen is the only over-the-counter drug approved for the treatment of fever during pregnancy.

Trump's statement “is not supported by a full body of scientific evidence and dangerously oversimplifies the multiple and complex causes of neurological problems in children,” ACOG President Dr. Steven Fleischman said in a statement. in the statement. “It is deeply troubling that our federal health agencies are willing to make a statement that will impact the health and well-being of millions of people without the benefit of reliable data.”

Trump said there would be no harm in not treating fevers in pregnant women. “There’s no downside to not taking it,” he said.

Untreated fever during pregnancy is linked to miscarriage, fetal organ defects, cardiovascular complications and even autism, according to a 2021 study. statement from the Society of Maternal-Fetal Medicine.

“The conditions that people use acetaminophen to treat during pregnancy are far more dangerous than any theoretical risks,” Fleischman said.

Several studies over the past decade have examined whether acetaminophen increases the risk of autism and other neurodevelopmental disorders. The results of these studies were mixed, with some showing a possible correlation and others showing no connection. None of them showed a cause-and-effect relationship.

A review of 46 of these studies, published in August in the journal BMC Environmental Hygiene concluded that there is an association between prenatal acetaminophen use and the incidence of neurodevelopmental disorders, including autism and attention-deficit/hyperactivity disorder (ADHD). Dr. Andrea Baccarelli, the senior author, said in a statement emailed to TIME that he had discussed the review findings with Kennedy and National Institutes of Health Director Dr. Jay Bhattacharya in recent weeks.

Baccarelli, dean of the faculty at the Harvard T.H. School of Public Health. T.Ch. Chan School of Environmental Health and professor of environmental health, said that given the review's findings, “caution regarding the use of acetaminophen during pregnancy, especially intensive or long-term use, is warranted.”

Baccarelli acknowledged that he served as an expert witness in a case regarding a potential link between acetaminophen use during pregnancy and neurodevelopmental disorders. “Such participation may be perceived as a conflict of interest,” the review states.

The Trump administration relied in part on that review as the basis for its announcement. However, many obstetrics experts questioned the validity of the review's findings.

Dr. Nathaniel DeNicola, an obstetrician-gynecologist who advises ACOG on environmental health issues, says the problem with the review is that it was based on studies that were largely poorly designed and therefore unreliable. “The studies that claimed a link were so flawed that it was impossible to draw any conclusions,” he says.

For example, several studies have used women's recall to determine whether they took acetaminophen during pregnancy and, if so, how much they took. The women were asked to recall these details weeks, months, and in some cases years later, DeNicola says. “Anyone who has been asked the question, 'What did you have for lunch yesterday?' knows that you tend to misremember things, even things from the recent past,” he says.

Most studies also did not take into account the potential influence of genetics on autism—an indirect oversight given that genetic factors play a significant role in the development of autism, DeNicola said.

Higher-quality studies—especially several that took genetics into account—have found no link between prenatal acetaminophen use and autism risk, DeNicola says. One of these studywhich was published in 2024 in JAMAexamined electronic health records of almost 2.5 million children born in Sweden between 1995 and 2019. In an initial analysis that did not control for genetic factors, the researchers found little association between women who used paracetamol during pregnancy and the incidence of autism, ADHD and intellectual disability. However, when the researchers conducted a follow-up study comparing siblings who were exposed to acetaminophen during the mother's pregnancy with those who were not exposed to the drug, they found no association.

“This tells us that [initial] The association was likely due to genetics, says Brian Lee, a professor of epidemiology at Drexel University and the study's lead investigator.

Research shows that people with autism are more likely to suffer from pain-causing conditions such as headaches and migraines, and are therefore more likely to take painkillers. Therefore, pregnant women with a higher genetic risk for autism may be more likely to take acetaminophen, Lee says.

Asked about a review published in August that included a review of his group JAMA study, Lee says its conclusions were flawed because it was based largely on flawed research. “Garbage in, garbage out,” he says.

It's also correlation that's important, not causation, Lee says. “The example I would like to give is that eating ice cream is statistically associated with drowning. But ice cream does not cause drowning.” It just so happens that in hot weather both the speed of eating ice cream and the number of swimming increases.

During a press briefing, Dr. Marty Macari, head of the U.S. Food and Drug Administration, said Baccarelli, a co-author of the review, said there is a clear cause-and-effect relationship between acetaminophen use during pregnancy and an increased risk of neurodevelopmental disorders. Baccarelli, however, told TIME in no uncertain terms that the review did not find a cause-and-effect relationship and that more research was needed “to confirm the link and determine causation.”

“Because acetaminophen is the only approved medication for reducing pain and fever during pregnancy, it remains an important tool for pregnant patients and their doctors. High fever can pose risks to both mother and fetus, including neural tube defects and preterm birth,” Baccarelli wrote in a statement. “After evaluating the evidence, my colleagues and I recommended a balanced approach based on the precautionary principle: Patients who need fever or pain relief during pregnancy should take the lowest effective dose of acetaminophen for the shortest period of time after consulting with their doctor about an individualized risk-benefit calculation.”

Baccarelli's advice echoes what most doctors already tell their pregnant patients to do.

Kenvue, the parent company of the maker of Tylenol, told TIME in a statement that acetaminophen is “the safest pain reliever option for pregnant women, as needed, throughout pregnancy” and that without it, women face dangerous choices, including suffering from potentially harmful conditions such as fevers or using riskier alternatives.

“We believe that independent, reliable science clearly shows that taking acetaminophen does not cause autism. We strongly disagree with any suggestion to the contrary and are deeply concerned about the health risks and confusion this creates for expectant mothers and parents,” a company spokesperson said in a statement.

Kenvue shares fell to an all-time low on Sept. 22, the day before Trump's announcement. Barrons reported.

Trump said at the briefing that his administration is committed to fighting the “terrible, terrible crisis” of autism. Kennedy said the NIH and other federal health agencies are actively looking into possible causes of autism, including research into potential risks associated with vaccines. Large-scale studies spanning decades have found no link between vaccines and autism.