For more than a decade, scientists have asked whether acetaminophen — the active ingredient in the painkiller Tylenol — could affect fetal brain development, causing problems in children like autism and A.D.H.D. Some studies have suggested that there is a link; others have found none.

Now the latest study, a scientific review by researchers at Harvard’s T.H. Chan School of Public Health and the Icahn School of Medicine at Mount Sinai, has been swept into a larger debate about the causes of autism, spurred in part by the views of Robert F. Kennedy Jr., the Health and Human Services secretary.

There has been speculation that Mr. Kennedy may cite Tylenol use during pregnancy, among other environmental factors, as a potential cause of autism in an upcoming report.

The review that began the latest round of controversy, which examined 46 existing studies, eight of them looking specifically at autism, found there was evidence for a connection between acetaminophen use during pregnancy and neurodevelopmental disorders.

But the researchers who conducted the review cautioned that their conclusion did not mean acetaminophen caused autism, which mainstream scientists overwhelmingly agree is a result of a complex mix of genetic and environmental factors.

And the findings, other experts said, would not alter the advice doctors routinely give pregnant patients about acetaminophen use.