Many doctors and scientists were reeling after President Donald Trump went on TV to insist that pregnant women should never take Tylenol and revive debunked theories about vaccines and autism. Trump on Monday went beyond his own health regulators' more modest advice that doctors “should consider minimizing" the painkiller's use during pregnancy because of inconclusive research. Brain experts know there is no single cause of autism and say the rhetoric ignores decades of science into the genetic and environmental factors that can play a role. Autism rates are rising, but largely because of an expanded definition, more awareness and more screening.