In a Sept. 22 press conference that he had billed as “one of the biggest [medical] announcements … in the history of our country,” President Donald Trump touted an unproven link between autism and the use of Tylenol, or acetaminophen, during pregnancy.
- Trump repeatedly told pregnant women not to take Tylenol and to “tough it out,” due to an association between the medication and autism. But the medication has not been established to cause autism, and some research indicates it likely doesn’t. Untreated pain or fever during pregnancy can be harmful to both mother and child.
- Food and Drug Administration Commissioner Dr. Marty Makary claimed the dean of Harvard University’s public health school said “there is a causal relationship” between Tylenol and autism. The dean did say that in written testimony for a lawsuit in 2023, but in a statement issued before the press conference he only said that a causal relationship was a possibility.
- Trump advised, “Don’t give Tylenol to the baby after the baby’s born.” Research hasn’t shown a causal link to autism for that, either. The American Academy of Pediatrics says that acetaminophen is “safe for children when taken, or dosed, correctly and under the guidance of a child’s pediatrician.”
Months ago, Health and Human Services Secretary Robert F. Kennedy Jr. had promised a press conference like this one pinpointing the causes of autism. In an Aug. 26 Cabinet meeting, Kennedy said that the administration will “have announcements, as promised, in September. We’re finding interventions, certain interventions now, that are clearly, almost certainly causing autism.”
But the press conference didn’t identify clear causes of autism. The administration’s suggestions about the role of acetaminophen go beyond what the research has shown.
The hourlong press conference also included several false and misleading claims from Trump and Kennedy about autism and vaccines, which we addressed in a separate article.
Tylenol During Pregnancy
Trump repeatedly urged pregnant women not to take Tylenol, citing an association between the medication and autism. The FDA will be telling doctors that taking Tylenol, or acetaminophen, “during pregnancy can be associated with a very increased risk of autism,” Trump said. “So taking Tylenol is not good. All right, I’ll say it. It’s not good.”
“Don’t take Tylenol. Don’t take it. … Fight like hell not to take it,” he said later in the press conference, during which he urged women to “tough it out” and repeated the phrase “don’t take Tylenol” around a dozen times.
But acetaminophen during pregnancy is far from having been established to cause autism, as we have written previously, and there is evidence indicating it likely does not. Moreover, there are limited treatments available for pregnant people experiencing pain or fever, and failing to treat these problems can have risks, expert organizations say.
“As far as the evidence goes, it points towards no causal association between acetaminophen use during pregnancy and risk of neurodevelopmental disorders, including autism,” Brian Lee, a professor of epidemiology at Drexel University’s Dornsife School of Public Health, told us in an interview for a previous story.
In observational research, it can be difficult to tell whether one thing that is associated with another actually causes that outcome. People with greater genetic risk for neurodevelopmental conditions, such as autism, are also known to take more acetaminophen in pregnancy, Lee said. So in this case, genetics could explain both why someone might use more acetaminophen and why that person might be more likely to have a child with autism.
Concern about acetaminophen during pregnancy is not new, nor did Trump or others present new research into the topic at the press conference. Several studies have shown an association between acetaminophen use and neurodevelopmental disorders, including autism and attention-deficit/hyperactivity disorder. But some recent studies, including a large one by Lee and colleagues, have found that associations go away when comparing siblings. This suggests that acetaminophen is not causing autism or ADHD.
“Today’s announcement by HHS is not backed by the full body of scientific evidence and dangerously simplifies the many and complex causes of neurologic challenges in children,” Dr. Steven J. Fleischman, president of the American College of Obstetricians and Gynecologists, said in a Sept. 22 statement.
“Despite assertions to the contrary, a thorough review of existing research suggesting a potential link between acetaminophen use during pregnancy and an increased risk of autism and attention deficit and hyperactivity disorder (ADHD) in children has not established a causal relationship,” a statement from the Society for Maternal-Fetal Medicine also said on the same day.
In his remarks, Makary, the FDA commissioner, referred to two studies from 2019 on acetaminophen during pregnancy, including one that showed an association with autism and ADHD and another showing an association with ADHD. “We now have data we cannot ignore,” he said. Neither of the studies, which were both observational, claimed to have established acetaminophen as an autism or ADHD cause.
The study showing an association between acetaminophen and both autism and ADHD, published in JAMA Psychiatry, had significant limitations, as we reported previously. Researchers found an association between the two conditions and the amount of acetaminophen components found in blood from a baby’s umbilical cord. As we wrote, looking at acetaminophen in cord blood only indicates recent use around the time of childbirth, as opposed to use throughout pregnancy. And researchers have pointed out that the sample of children in the study was unusual. All cord blood samples showed at least some acetaminophen exposure, and the children had a very high rate of autism and ADHD.
Makary also mentioned a recent review study, published Aug. 14 in Environmental Health. The study did not present new research. Rather, it reviewed the existing literature on acetaminophen during pregnancy and autism, finding “evidence consistent with an association between acetaminophen exposure during pregnancy and increased incidence” of neurodevelopmental disorders. The study did not do a quantitative analysis of the studies’ findings, but rather described the existing literature, with flexibility for the authors to interpret the quality of the available studies and decide how much to emphasize each. A different review study, published in late 2024, concluded that acetaminophen during pregnancy “is unlikely to confer a clinically important increased risk of childhood ADHD” or autism.
To bolster the administration’s actions, Makary also highlighted remarks from Dr. Andrea Baccarelli, the senior author of the August review. “To quote the dean of the Harvard School of Public Health, there is a causal relationship between prenatal acetaminophen use and neurodevelopmental disorders of ADHD and autism spectrum disorder,” Makary said, referring to Baccarelli.
Makary did something similar later that evening on Fox News when he suggested the paper itself claimed a “causal relationship,” and also said those were the “exact words of the dean of the Harvard School of Public Health.”
The review called a causal relationship “plausible” but said more research was needed to “determine causality.” Other authors of the review study have told news outlets it does not establish that acetaminophen causes autism. Baccarelli, too, has said as much.
A statement from Baccarelli, which an X account for the White House posted and a Harvard spokesperson told us was provided to the White House before the press conference, only said that “biological evidence lends support to the possibility of a causal relationship between prenatal acetaminophen exposure and neurodevelopmental disorders, including autism.”
The statement said that more research is needed “to confirm the association and determine causality” but urged caution in acetaminophen use during pregnancy. It noted that Baccarelli had discussed his findings with Kennedy and National Institutes of Health Director Dr. Jay Bhattacharya in recent weeks.
In the past, however, Baccarelli has made more definitive statements about causation. While at Columbia Mailman School of Public Health, Baccarelli served as an expert witness in a lawsuit against acetaminophen manufacturers. In reports he submitted for the case in 2023, Baccarelli stated his opinion that prenatal acetaminophen use “can cause” ADHD and autism and that “there is a causal relationship,” although in another instance he only said that a causal link was “likely.” The New York Times also reported that in his deposition for the lawsuit, Baccarelli said he became concerned about acetaminophen use during pregnancy in 2021, gradually realizing it “was a big issue” that was “real” and “causal.”
The judge in the case deemed Baccarelli’s expert opinion inadmissible, agreeing with the defendants that his opinions are “unreliable,” in part because he “cherry-picked and misrepresented study results and refused to acknowledge the role of genetics in the etiology of either” autism or ADHD.
Notably, Makary’s new FDA notice to physicians cautioning about acetaminophen use during pregnancy specifically said that a causal relationship “has not been established” and noted that “there are contrary studies in the scientific literature.”
ACOG’s Fleischman said that “not a single reputable study has successfully concluded that the use of acetaminophen in any trimester of pregnancy causes neurodevelopmental disorders in children,” even though the topic has been studied for more than 20 years.
“The studies that are frequently pointed to as evidence of a causal relationship, including the latest systematic review released in August, include the same methodological limitations—for example, lack of a control for confounding factors or use of unreliable self-reported data—that are prevalent in the majority of studies on this topic,” he said.
Trump’s Advice Carries Risks
Following Trump’s advice to “tough it out” carries risks for the mother and the baby. “There’s no downside … other than a mother will have to, as I say, tough it out a little bit,” Trump said. “There’s no downside to doing this. It’s not like, oh, if you do this, you’re going to die.”
This is inaccurate. Acetaminophen during pregnancy is used to treat conditions that “can create severe morbidity and mortality for the pregnant person and the fetus,” Fleischman said.
“Untreated fever, particularly in the first trimester, increases the risk of miscarriage, birth defects, and premature birth, and untreated pain can lead to maternal depression, anxiety, and high blood pressure,” the Society for Maternal-Fetal Medicine said in a Sept. 5 statement.
The new HHS recommendations on acetaminophen in pregnancy, meanwhile, are not that different from the existing recommendations from expert organizations. HHS said in a news release that doctors should prescribe “the lowest effective dose for the shortest duration when treatment is required.”
Expert organizations have long recommended prudent use of acetaminophen. “ACOG supports the use of acetaminophen in pregnancy when taken as needed, in moderation, and after consultation with a doctor,” an FAQ on the group’s website reads.
Tylenol for Babies
Trump also repeatedly told people not to give Tylenol to babies, often referring to Tylenol given alongside vaccines. “Don’t give Tylenol to the baby after the baby’s born,” he said. “Every time the baby gets a shot … they say, ‘Here, take a cup of Tylenol.’ I’ve heard that for years: ‘Take Tylenol.’ Don’t take Tylenol. Don’t have your baby take Tylenol.”
It is unclear why Trump advised against Tylenol for babies, and the White House did not respond to a question about the evidence behind this recommendation. However, Kennedy suggested that “the safety of acetaminophen against the risk of neurodevelopmental disorders in young children has never been validated.”
“Studies do not point to a causal link between the use of acetaminophen and autism in children or in pregnancy, and extensive research indicates there is no single root cause of autism,” a web page from the American Academy of Pediatrics states. The page also says that acetaminophen is “safe for children when taken, or dosed, correctly and under the guidance of a child’s pediatrician.”
Dr. Paul A. Offit, a vaccine expert at the Children’s Hospital of Philadelphia, told us that “anything done postnatally is probably not going to affect … the incidence of autism,” explaining that risk factors for autism tend to be things that are established before birth.
“There is no robust evidence that giving acetaminophen to children (neonatal/postnatal), or co-administration with vaccines, causes autism,” Dr. Sura Alwan, a clinical teratologist at the University of British Columbia and executive director for PEAR-Net Society, a nonprofit focused on maternal-fetal development, told us in an email.
As we wrote previously, a small 2008 study claiming an association between autism and acetaminophen use after the measles, mumps and rubella vaccine had numerous weaknesses, including that it recruited parents non-randomly and asked them years later about medication use.
“Large epidemiologic and vaccine-safety study designs have not demonstrated a causal link between vaccination and autism; adding acetaminophen to the theory doesn’t change the facts,” Alwan said.
Experts urge moderation in giving children acetaminophen. The medication does come with risks, including liver damage, when people get the dose wrong. Kennedy cited liver toxicity in urging caution in using acetaminophen in young children.
Acetaminophen also isn’t always necessary. Expert guidance recommends holding off on acetaminophen or other pain and fever medications when they aren’t needed, such as for pain after vaccination or a low-grade fever.
“Yes, I think we overuse Tylenol for routine childhood viral infections,” Offit said.
Correction, Sept. 24: After publication, we became aware of earlier comments by Dr. Andrea Baccarelli, the dean of Harvard’s public health school, that support the statement by the FDA commissioner quoting Baccarelli. Also, this week’s statement by Baccarelli said he had “discussed” his work with HHS officials, not that he had “met” with them, as we originally said. He is also the senior author, not first author, of the study. We have updated the story accordingly.
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