Well, it's all about having enough time to work on the system. Pregnancies can get complicated, depending on what you decide to do with them. Plus, I had plans for far more limited content related to pregnancies at first, but I got some complaints from a player, and I decided to expand it more, so now it's taking me extra time to fit elements I didn't consider when I first started working on the game.I can only say that I do love some pregnancy, because getting creampied over and over again without anything really happening, is kinda irritating to me. And I guess it kinda makes sense with her being more fertile (? at least thats what I remember from the moomoo thing).
She is more fertile (lore-wise), although for the sake of gameplay, pregnancies are under player's control (and de-activated as a default).