In an announcement on Sept. 22, President Donald Trump said that using Tylenol during pregnancy increases the risk of having a baby with autism, contradicting advice from leading obstetrics experts who say the popular drug is very safe in pregnancy.
“Don’t take Tylenol. Fight like hell not to take it,” Trump said during a White House briefing.
The president, who was flanked by U.S. Health and Human Services (HHS) Secretary Robert F. Kennedy Jr. and other cabinet officials, said pregnant women shouldn’t take acetaminophen, the active ingredient in Tylenol, unless they have an “extremely high fever.”
“If you can’t tough it out, if you can’t do it, that’s 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 that there was no clear evidence linking the use of acetaminophen to autism or other risks to fetal development. Other pain- and fever-reducing medications, such as ibuprofen and aspirin, carry risks during pregnancy, and acetaminophen is the only over-the-counter drug approved to treat fevers during pregnancy.
Trump’s announcement “is not backed by the full body of scientific evidence and dangerously simplifies the many and complex causes of neurologic challenges in children,” said ACOG President Dr. Steven Fleischman in a statement. “It is highly unsettling that our federal health agencies are willing to make an announcement that will affect the health and well-being of millions of people without the backing of reliable data.”
Trump said not treating fevers in pregnant women can’t cause any harm. “There’s no downside in not taking it,” he said.
Untreated fever in pregnancy is associated with miscarriage, fetal organ malformations and cardiovascular complications, and even autism, according to a 2021 statement from the Society for Maternal-Fetal Medicine.
“The conditions people use acetaminophen to treat during pregnancy are far more dangerous than any theoretical risks,” Fleischman said.
Several studies conducted over the past decade have probed whether acetaminophen increases the risk of autism and other neurodevelopmental disorders. The results of these studies have been mixed, with some showing a possible correlation and others showing no link. None has shown a causal connection.
A review of 46 of these studies published in August in the journal BMC Environmental Health concluded that there was a link between prenatal acetaminophen use and the incidence of neurodevelopmental disorders including autism and attention-deficit/hyperactivity disorder (ADHD). Dr. Andrea Baccarelli, a senior author, said in an emailed statement to TIME that he had discussed the findings of the review with Kennedy and National Institutes of Health Director Dr. Jay Bhattacharya in recent weeks.
Baccarelli, dean of the faculty at Harvard T.H. Chan School of Public Health and an environmental health professor, said given the review’s conclusions, “caution about acetaminophen use during pregnancy—especially heavy or prolonged use—is warranted.”
Baccarelli has acknowledged that he served as an expert witness in a case involving potential links between acetaminophen use during pregnancy and neurodevelopmental disorders. “This involvement may be perceived as a conflict of interest,” the review said.
The Trump Administration relied in part on the review as the basis for the announcement. But many obstetrics experts have questioned the validity of the review’s conclusions.
Dr. Nathaniel DeNicola, an ob-gyn who advises ACOG on environmental health issues, says the problem with the review is that it was based on studies that were mostly poorly designed and therefore unreliable. “The studies that have claimed an association were so deeply flawed that you can’t draw any conclusion,” he says.
Several studies, for example, relied on women’s memories to determine if and how much acetaminophen they took during their pregnancy. The women were asked to recall these details weeks, months, and in some cases years after the fact, 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 didn’t take the potential influence of genetics on autism into account, DeNicola says—a consequential oversight given that genetic factors play a significant role in the development of autism.
Higher quality studies—specifically a handful of them that have taken genetics into consideration—have shown no link between prenatal acetaminophen use and autism risk, DeNicola says. One such study, which was published in 2024 in JAMA, looked at the electronic medical records from nearly 2.5 million children who were born in Sweden between 1995 and 2019. In an initial analysis that didn’t control for genetic factors, the researchers found a small association between women who used acetaminophen during pregnancy and the incidence of autism, ADHD, and intellectual disability. However, when the researchers conducted a follow-up study that compared siblings who were exposed to acetaminophen during their mother’s pregnancy to those who weren’t exposed to the drug, they found no link.
“What this tells us is that the [initial] association was most likely due to genetics,” says Brian Lee, a professor of epidemiology at Drexel University and the study’s lead investigator.
Research suggests that people with autism are more likely to suffer from pain-causing conditions such as headaches and migraines and may therefore be more likely to take pain medications. Pregnant women with a higher genetic risk of autism may therefore be more likely to take acetaminophen, Lee says.
Asked about the review published in August, which included his group’s JAMA study, Lee says its conclusions were flawed because it was based on mostly flawed studies. “Garbage in, garbage out,” he says.
Correlation is also, critically, not causation, Lee says. “The example I like to give is: Eating ice cream is statistically associated with drowning. But ice cream doesn’t cause you to drown.” It just so happens that both the rates of eating ice cream and swimming go up in hot weather.
During the press briefing, Dr. Marty Makary, chief of the U.S. Food and Drug Administration claimed that Baccarelli, who co-authored the review, had said there was a clear causal relationship between acetaminophen use during pregnancy and an increased risk of neurodevelopmental disorders. Baccarelli, however, was unequivocal in his statement to TIME that the review didn’t show a causal link and that more research was needed “to confirm the association and determine causality.”
“As the only approved medication for pain and fever reduction during pregnancy, acetaminophen remains an important tool for pregnant patients and their physicians. High fever can pose risks to both the mother and the fetus, including neural tube defects and preterm birth,” Baccarelli wrote in the statement. “After assessing the evidence, my colleagues and I recommended a balanced approach based on the precautionary principle: Patients who need fever or pain reduction during pregnancy should take the lowest effective dose of acetaminophen, for the shortest possible duration, after consultation with their physician about their individual risk-benefit calculation.”
Baccarelli’s advice echoes what most doctors already advise their pregnant patients to do.
Kenvue, the parent company of Tylenol’s manufacturer, told the Wall Street Journal in a piece published before the briefing that the company has “continuously evaluated the science” and believes “there is no causal link between acetaminophen use during pregnancy and autism.” Kenvue’s shares dropped to an all-time low on Sep. 22, ahead of Trump’s announcement, Barron’s reported.
Trump said at the briefing that his administration was dedicated to confronting the “horrible, horrible crisis” of autism. Kennedy said NIH and other federal health agencies were actively searching for possible causes of autism, including probing the potential risks of vaccines. Large-scale studies conducted over decades have shown no link between vaccines and autism.
Researchers say there is no single cause to the range of conditions that fall under the umbrella of autism spectrum disorder. Instead, experts believe that genetics together with myriad environmental factors—including maternal age and health and exposure to pollution and contaminants like heavy metals—play a role.
Following the White House briefing, the FDA announced that it was issuing a notice to physicians highlighting the potential risks of acetaminophen use during pregnancy. The agency said it was also initiating a safety-label change for the drug.
