i think the pregnancy mechanic is bugged? i'm stuck in early stage :,(
I think it takes a random amount of time before your character enters the final stage of pregnancy.
How long is your character in the early stage of pregnancy?
P.S.: Once your character has delivered the baby, you can no longer put on any lower underwear. If you try, a loading-error-message will pop up saying that the game failed to load the image of your character wearing the lower underwear, because the game still thinks that your character is pregnant. (at least thats how it is in the version r27.1)