President Donald Trump and federal health officials claimed in a news conference Monday that there was an established link between Tylenol use during pregnancy and autism. Trump administration officials have leaned heavily on Baccarelli’s research in pushing the idea, citing him in the news conference, posting on social media and championing him in a television interview as a highly credentialed expert backing the evidence for an autism-acetaminophen link.
Scientists have researched a potential link for years, but the studies have yielded inconclusive results, with some finding increased risk among pregnant women who took acetaminophen and some finding no connection between the drug and autism.
Baccarelli was the senior author on a recent scientific review that he conducted with collaborators at the Icahn School of Medicine at Mount Sinai and other universities. The study was cited during Monday’s White House press conference.
Baccarelli declined a request for an interview Tuesday. A spokesperson for Harvard’s public health school, Stephanie Simon, said that Baccarelli “confirmed that his testimony in the deposition was accurate and that his work on the case culminated in the deposition; he worked just a handful of additional hours following the deposition.”
Baccarelli said in a statement Monday that he had discussed his team’s “scientific findings and this recommendation from our review article” with Health Secretary Robert F. Kennedy Jr. and the director of the National Institutes of Health, Dr. Jay Bhattacharya, in recent weeks. He said he appreciated “their interest in this study.”
The scientific review did not produce new data on birth outcomes but evaluated 46 existing studies that examined whether acetaminophen use during pregnancy was linked to a higher risk of neurodevelopmental disorders in children, including autism spectrum disorder and attention deficit hyperactivity disorder. The review concluded that there was an “association between exposure to acetaminophen during pregnancy” and the risk of neurodevelopmental disorders in children.
During the deposition, Baccarelli was asked how much he had been paid for his work on the lawsuits, which included preparing expert reports.
“I work for more than 200 hours, so it’s about $150,000,” Baccarelli said in the deposition. The all-day deposition was conducted at a Manhattan law firm on Aug. 14, 2023.
At the time of the deposition, Baccarelli was a professor in the department of environmental health sciences at the Columbia Mailman School of Public Health. He became the dean of the public health school at Harvard in 2024.
The litigation in which Baccarelli served as an expert witness involved hundreds of lawsuits filed by families who claimed that their children were given diagnoses of autism or ADHD after Tylenol use during pregnancy.
Kenvue, which has been the maker of Tylenol since it was spun off from Johnson & Johnson in 2023, along with major retailers that sell generic versions of acetaminophen, was named as a defendant in the litigation.
In the decision to dismiss the lawsuits, the judge, Denise Cote, agreed with lawyers for the defendants that Baccarelli had “cherry-picked and misrepresented study results” in his testimony and was therefore “unreliable.”
The main law firm representing the plaintiffs, Keller Postman, did not immediately respond to a request for comment. A spokesperson and lawyers for Kenvue declined to comment.
In Monday’s news conference, the Food and Drug Administration commissioner, Dr. Marty Makary, cited the findings of the scientific review by Baccarelli and his collaborators.
“Four weeks ago, a Mount Sinai-Harvard study reviewed all the existing literature and found the overwhelming body of evidence points to an association,” Makary said. “Sure, you’ll be able to find a study to the contrary; that’s how science works.
“But, 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.’”
In a statement Monday night, Baccarelli slightly distanced himself from Makary’s description of his view, saying, “Further research is needed to confirm the association and determine causality, but based on existing evidence, I believe that caution about acetaminophen use during pregnancy — especially heavy or prolonged use — is warranted.”
In his 2023 expert report for the lawsuit, however, Baccarelli wrote that “substantial evidence supports a strong, positive, causal association between acetaminophen” and neurodevelopmental disorders, particularly autism and ADHD.
In the deposition, Baccarelli said he began to grow concerned about the use of acetaminophen in pregnancy in 2021. As he reviewed more of the scientific literature on the issue, he said, “Gradually, I came to the realization that this was a big issue. I believed this was real. This was happening. This was causal.”
The August 2025 scientific review disclosed Baccarelli’s work as an expert witness in the litigation, saying, in a disclaimer, “This involvement may be perceived as a conflict of interest regarding the information presented in this paper on acetaminophen and neurodevelopmental outcomes.”
It continued, “Dr. Baccarelli has made every effort to ensure that this current work — like his past work as an expert witness on this matter — was conducted with the highest standards of scientific integrity and objectivity.”