Robert F Kennedy Jr will reportedly claim that autism is caused by taking Tylenol during pregnancy.

Donald Trump’s health secretary launched an inquiry into the neurological condition, which is widely believed to be at least partially influenced by genetics.

The report into the apparent causes of autism, likely to be published this month by the US Department of Health and Human Services, will also point to low levels of the vitamin folate in pregnant women, insiders told the Wall Street Journal (WSJ).

The folate known as folinic acid, or leucovorin, is largely used in the treatment of chemotherapy side effects and parasitic diseases.

The active ingredient in Tylenol is acetaminophen – sold in the UK under the name paracetamol.

Speaking during a lengthy cabinet meeting last month, Mr Kennedy said: “We’re finding interventions, certain interventions now that are clearly, almost certainly causing autism.

“And we’re going to be able to address those in September.”

Mr Trump responded by citing a rise in autism diagnoses, adding: “There has to be something artificially causing this, meaning a drug or something ... we’re going to do some things.”

In July 2023, Mr Kennedy, then a Democratic presidential hopeful, told Fox News: “I do believe that autism comes from vaccines.”

The link between the MMR vaccine and autism was first drawn by Andrew Wakefield, a British medical researcher. His 1998 study was later found to be fraudulent, and he was barred from practising medicine in the UK.

A spokesman for Kenvue, the parent company of McNeil Consumer Healthcare, which makes Tylenol, said: “Nothing is more important to us than the health and safety of the people who use our products.

“We have continuously evaluated the science and continue to believe there is no causal link between acetaminophen-use during pregnancy and autism.”