In the middle of filming, a mother withdrew her baby from the cast during the final run-through of the "cursed-birth" scene. Although a fan of the show, as a devout Catholic she was uncomfortable with her child representing a demon. Director Rob Bowman assured her that the production staff understood her dilemma; the casting staff quickly called down and found a replacement in less than 45 minutes. It was the first time during the filming of the series that a cast member withdrew for religious reasons.
Old friends Bruce Campbell and David Duchovny spent most of the time pranking the cast and crew in their downtime.
This is the first episode in the series to be written by David Amann. His pitch was told not from the expectant mother's point of view but from the demon trying to spawn.
Mulder and Scully don't share a scene until 30 minutes into this episode.