President Donald Trump on Monday used the platform of the presidency to promote unproven and in some cases discredited ties between Tylenol, vaccines and autism as his administration announced a wide-ranging effort to study the causes of the complex brain disorder.

“Don’t take Tylenol,” Trump instructed pregnant women around a dozen times during the unwieldy White House news conference, also urging mothers not to give their infants the drug, known by the generic name acetaminophen in the U.S. or paracetamol in most other countries. He also fueled long-debunked claims that ingredients in vaccines or timing shots close together could contribute to rising rates of autism in the U.S., without providing any medical evidence.

The rambling announcement, which appeared to rely on existing studies rather than significant new research, comes as the Make America Healthy Again movement has been pushing for answers on the causes of autism. The diverse coalition of supporters of Health Secretary Robert Kennedy Jr. includes several anti-vaccine activists who have long spread debunked claims that immunizations are responsible.

The announcement also sheds light on Trump’s own long-held fascination with autism and his trepidation about the childhood vaccine schedule, even as the president has taken pride in his work to disseminate COVID-19 vaccines during his first term.

Associate professor and the leader of the Early Detection and Intervention research program at the A.J. Drexel Autism Institute Giacomo Vivanti said he was hoping to hear about new research during Trump's news conference.

"Instead, what I heard is about using old data to draw incorrect conclusions from data that already existed," he said.