Adult Fear: Giving birth in the middle of nowhere because indestructible super-beings are out to take and/or kill your child. And just when you thought you were safe, they gather while you're in labor.
Away in a Manger: William's birth has multiple parallels to the Christ birth story.
Screaming Birth: Scully, though at least half of her screams are directed at the Super Soldiers standing outside.
Sealed with a Kiss: The very last scene of the episode, following an equally heartwarming scene of Mulder and Scully admiring William.
Three-Month-Old Newborn: Averted. Jerry Shiban (son of producer John Shiban) played baby William, and was only a couple weeks old at the time of filming.
Kim Manners, in the DVD commentary for this episode, laughed at the situation of having to re-cast William for season 9. Apparently, all babies don't look alike and having to find one that looked like Jerry was not as easy as it sounded.