A Stuck Pregnancy refers to a situation in any of the Creatures games where a female creature is physically unable to lay her egg. While not immediately life threatening, it may make the female creature tired or hungry due to the fact that pregnancy consumes a portion of the creature's energy.
The main culprit behind stuck pregnancies is a genetic mutation where the female Creature doesn't produce progesterone during her pregnancy, causing the egg to remain inside her uterus indefinitely unless the player takes action. A good indicator of this mutation in C3/DS is when a female creature gets pregnant but her belly stays flat.
In most cases, the female Creature can be coaxed to lay her egg by giving her a large shot of progesterone. In some rare cases, however, a progesterone injection won't work due to the female's egg-laying receptor mutating, or because her uterus is damaged. This can only be fixed via a third-party COB such as the C-Section available at Norntropolis for Creatures, the Egg Layer for Creatures 2, and the Eggernator for C3/DS. The player can also use the CAOS Code (C3/DS Only), targ norn mesg writ targ 65 to induce a birth.