The X-Files S06 E07 Terms of Endearment

"The truth is out there."

After a scan of a couple's unborn child is found to have strange growths protruding from the head and back, the fetus is taken from inside the mother by a demon creature while she is asleep. Mulder heads to investigate after Agent Spender dismisses the claims, and discovers that the father is actually a demon who wants to have a normal child.