A new study showed a significant decrease in acetaminophen use during pregnancy and a surge in leucovorin prescriptions after a September 2025 announcement that included comments by the president and head of the FDA.
PROVIDENCE, R.I. [Brown University] - A White House briefing in September 2025 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 a new study.
The study 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.
The study was authored by researchers from Brown University's School of Public Health and Harvard Medical School and published in the Lancet.
According to the authors, the usage changes for both drugs are notable because they were specific to the drugs mentioned in the announcement and because they occurred despite no new clinical trial data or formal guideline revisions during that period.
"An important implication of these results is also that it's not just patients who were influenced by the unconventional press conference," said study author Dr. Michael Barnett, a physician and 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 United States. The researchers analyzed weekly prescribing trends before and after the briefing. They compared observed prescribing with expected levels based on prior patterns.
The study notes that during the 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 briefing, which included comments from the president and the head of the Food and Drug Administration, acetaminophen use among pregnant women treated in emergency rooms declined by about 10% compared with what researchers would have expected based on prior trends. In the first month, the decline was 16%, with a low point of 20% below expected levels in the third week.
At the same time, outpatient prescriptions for leucovorin rose substantially among children ages 5 to 17. Overall, leucovorin prescriptions increased approximately 71% above expected levels after the briefing. During the first month, they were up 93%. In the second week, prescribing more than doubled compared with what researchers would have predicted.
Notably, about 72% of the leucovorin prescriptions were written for children with autism diagnoses, a group that accounts for only 4% 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.
"The White House briefing was an extremely unusual mechanism to communicate medical information and bypassed many standard checks on ensuring accurate messaging," Barnett said. "The results show just how much political leaders can steer health behavior even when there has been no change in the evidence for these therapies."
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, the observed associations are significant, they said.
"The results were astounding to me," said study author Dr. Jeremy Samuel Faust, an emergency physician at Brigham and Women's Hospital and 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."
