The amount of planned content, and the number of possible children for after the time skip, is already so high that I had to take a step back somewhere. That's why monstergirls can't get pregnant. Once everything else is done, I'd like to add those afterwards, but my focus is on finishing all lose ends and planned content first, so that I can move on with the main story, and add more "new" content once the game is in a finished state.