Do parents have to pay the medical bills of deceased children?

If they are minors or dependants of the parents, yes. I'm sorry for your loss if that's the case. If they are adults, no, and there should be an estate opened for this very reason, so the debts can be resolved.
If they are minors or dependants of the parents, yes. I'm sorry for your loss if that's the case. If they are adults, no, and there should be an estate opened for this very reason, so the debts can be resolved.