NEW YORK, July 13 (Reuters) - A federal appeals court on Monday revived hundreds of private lawsuits against Kenvue KVUE.N and many pharmacies and retailers, alleging that the Tylenol painkiller causes autism and attention deficit hyperactivity order.

The 2nd U.S. Circuit Court of Appeals in Manhattan said a district court judge improperly excluded testimony from expert witnesses offered by parents who sued over their use of Tylenol, or its active ingredient acetaminophen, during pregnancy.