It's also worth noting that acetaminophen is pretty much the ONLY OTC painkiller you're allowed to take while pregnant (other than baby aspirin as a preventative if you're high risk for pre-eclampsia), so I strongly suspect a sizeable majority of people end up using it at least once during pregnancy. It's common enough that I'd imagine separating correlation from causation on that one might be especially difficult.

In all likelihood the root cause of ASD is multifactoral and appears to be at least partially genetic.