On Sept. 22, President Trump and Health and Human Services Secretary Robert F. Kennedy, Jr. held a press conference strongly urging against Tylenol (acetaminophen) use during pregnancy. They associated its use with the development of autism and other childhood neurodevelopmental disorders.
Trump rambled off script, declaring that “we found the cause of autism,” repeatedly advising against the use of Tylenol during pregnancy, and saying, “just tough it out.” He continued by stating that babies should also not receive Tylenol and then ventured into questioning current childhood vaccination schedules.
The press conference was chaotic and reckless, resulting in misinformation and confusion. Trump’s conclusion that Tylenol use during pregnancy was “very high risk” and “strongly associated with autism” goes well beyond what the scientific evidence supports. Studies have found an inconsistent association, and no studies support a causative relationship.
Association is not causation. It’s impossible to conduct prospective placebo-controlled studies (the “gold standard” for demonstrating causation) for Tylenol use during pregnancy for obvious ethical reasons. All studies are retrospective and observational.
Observational studies are burdened with confounding variables that may make an association appear causative. For example, the senior author of an April 2024 Journal of the American Medical Association study, widely considered the definitive research on Tylenol use during pregnancy, offers this scenario: Eating ice cream in the summer is statistically associated with the risk of drowning. It’s actually hot weather that increases both ice cream consumption and swimming (which would increase the likelihood of drowning).
Similarly, conditions that prompt Tylenol use, such as fever and infection during pregnancy, have been linked to autism and other neurodevelopmental conditions if left untreated. These could plausibly be the actual causative factors.
Observational studies can indicate causation, but only when there is an enormous amount of irrefutable evidence over time. Smoking causing lung cancer is an example. Tylenol use during pregnancy is very far from this level of evidence. A recent review in Environmental Health of 46 studies demonstrated conflicting results regarding an association. Some studies finding an association were criticized for a lack of scientific rigor and study design.
The aforementioned JAMA article was a Swedish study of 2.4 million children over 24 years. The study actually demonstrated an association between Tylenol use and autism, but that association disappeared when applying sibling controls who were not exposed to Tylenol during pregnancy. The sibling controls accounted for genetic and other environmental factors. Additionally, no escalating dose-response outcome was found, as would be expected with a causative agent. A Japanese study of over 200,000 children with sibling controls also yielded the same conclusions.
Federal health officials selectively cite and misinterpret studies to support Kennedy’s agenda. It’s noteworthy that the American Psychiatric Association, the American College of Obstetricians and Gynecologists, the Society for Maternal-Fetal Medicine, the American Academy of Pediatrics, and others consider judicious use of Tylenol safe during pregnancy.
Despite the press conference’s rhetoric and a safety warning to be added to Tylenol’s label, the Federal Food and Drug Administration’s recommendation is that the lowest effective dose be used for the shortest possible duration. Good advice for most medications used during pregnancy. Nothing new here.
Under pressure, Kennedy has since admitted that he doesn’t have sufficient evidence to support a causative link – yet.
Women should feel safe prudently using Tylenol during pregnancy. It’s one of the few options available to treat pain and fever. Consult your physician for advice and cast a critical eye on whatever Kennedy or Trump may advise medically.
Richard D. Feldman, M.D. is an Indianapolis family physician and former Indiana State Health Commissioner who served in the administration of Governor Frank O’Bannon.