President Donald Trump will likely announce Monday that use of Tylenol in pregnancy causes autism. He said Tylenol was "a very big factor" in autism risk.

President Donald Trump returns to the White House after the funeral of slain conservative activist Charlie Kirk Sunday. He's expected to announce Monday that Tylenol use during pregnancy causes autism. Photo by Jim Lo Scalzo/UPI UPI

Sept. 22 (UPI) -- President Donald Trump likely will announce Monday that use of Tylenol in pregnancy causes autism, according to media reports.

Trump told reporters Sunday night that he believed Tylenol was "a very big factor" in autism risk, despite a recent study finding that taking acetaminophen, the active ingredient in Tylenol, during pregnancy was not tied to autism spectrum disorder.

When asked to confirm reports that he planned to tie Tylenol to increased risk of autism, Trump said, "We're going to see tomorrow. We're going to do it tomorrow, but I think it's a very big factor."

An announcement is scheduled for 4 p.m. EDT with Health and Human Services Secretary Robert F. Kennedy Jr. and Dr. Mehmet Oz, administrator of the Centers for Medicare and Medicaid Services.

Tylenol maker Kenvue disputes the tie to ASD.

"We believe independent, sound science clearly shows that taking acetaminophen does not cause autism," Kenvue said in a statement. "We strongly disagree with any suggestion otherwise and are deeply concerned with the health risk this poses for expecting mothers."

"The facts are that over a decade of rigorous research, endorsed by leading medical professionals and global health regulators, confirms there is no credible evidence linking acetaminophen to autism," the statement said.

Trump also criticized vaccines.

"Vaccines are very interesting," Trump told reporters. "They can be great, but when you put the wrong stuff in them, and, you know, children get these massive vaccines, like you'd give to a horse, like you'd give to a horse. And I've said for a long time, I mean, this is no secret."

Autism diagnoses in the United States have increased significantly since 2000. By 2020, the U.S. autism rate in 8-year-olds was 1 in 36, or 2.77%, up from 0.66% in 2000, according to the Centers for Disease Control and Prevention.

Research spanning decades hasn't found firm answers on what contributes to autism, but many scientists believe genetics and environmental influences play a role. Kennedy has argued the country has an "autism epidemic" fueled by "environmental toxins."