In the Afterbirth expansion for Rebirth, they can be also encountered in Dank Depths.
Babies slowly float towards Isaac, occasionally shooting a single blood shot. They also have the ability to teleport to anywhere in the room, occasionally close to Isaac. They usually teleport after a shot. The only random element is the shooting, and they have no specific cue to indicate incoming attacks.
- Version 1.33 from the original game introduced a bug called "Psy Baby" which was fixed in 1.4
- Babies always spawn in pairs or fours. The lowest spawning babies in each room were always the psychic ones, whether normal or angel. This also applied to Isaac and ??? spawning 2 Angelic Babies; each time they were spawned, the lower one of the two would be psychic.
- From both the original game and Rebirth remake, Babies use the same death sounds as gooballs from the game World of Goo.
- Babies's sounds, along with Angelic Babies, from the original game while attacking are much high-pitched than from Rebirth.
- From the original game, if Isaac touch the baby right when it reappears (after disappearing to teleport), he'll take no damage.