A White House briefing last fall that raised concerns about acetaminophen use during pregnancy and promoted the drug leucovorin as a potential autism treatment was followed by sharp changes in how doctors prescribed those medications nationwide, according to new research.
The Lancet study, by Brown and Harvard researchers, shows that after the Sept. 22, 2025, briefing, acetaminophen orders for pregnant women in emergency rooms fell markedly while prescriptions for leucovorin for children dramatically increased. These changes occurred despite no new clinical trial data or formal guideline revisions during that period, the authors point out.
“An important implication of these results is also that it’s not just patients who were influenced by the unconventional press conference,” says study author Michael Barnett, MD, Sorensen Family Provost’s Professor of Health Services, Policy, and Practice at Brown. “Their doctors were either influenced themselves or pushed by patients to adopt a new practice.”
The findings are based on data from Cosmos, a large electronic health record database that includes information from more than 1,600 hospitals and 37,000 clinics across the US. The researchers analyzed weekly prescribing trends before and after the briefing.
At the September briefing, administration officials claimed that acetaminophen use during pregnancy may be linked to an increased risk of autism. They also suggested that leucovorin, a folate-based drug approved for certain cancer-related uses and metabolic conditions, could be used to treat autism. Though leucovorin has been studied in small clinical trials for autism with mixed and still preliminary results, it is not included in standard autism treatment guidelines.
After the press conference, which included comments from the president and the head of the US Food and Drug Administration, acetaminophen use among pregnant women treated in emergency rooms declined by about 10 percent compared with what researchers would have expected based on prior trends. In the first month, the decline was as low as 20 percent below expected levels.
At the same time, outpatient prescriptions for leucovorin rose approximately 71 percent among children ages 5 to 17; during the first month, they as much as doubled compared with what researchers would have predicted. Almost three-quarters of the leucovorin prescriptions were written for children with autism diagnoses, a group that accounts for only 4 percent of the pediatric population in the dataset.
The authors say the findings highlight the broader impact of public health communications and illustrate how high-profile federal messaging can influence clinical decision-making across the country.
Because of the design of the study, the authors note that the analysis does not prove that the White House briefing caused the prescribing changes, nor did the research assess whether patients experienced better or worse outcomes as a result. Still, they say, the findings are significant.
“The results were astounding to me,” says study author Jeremy Samuel Faust, MD, an assistant professor at Harvard Medical School. “It can take years, even decades, for high-quality research to finally reach clinicians. Here, by using the White House, it was done overnight. Unfortunately, they’re claiming breakthroughs that simply haven’t occurred.”