You should add snakes that can bite Leah, paralyze her and then have sex with her while she's paralyzed.
I am not the dev of this game. And dont have any of his/her contacts.
I think it sounds cool but probably it like game end scene. Because if Leah be fully paralyzed or just paralyzed as i think that will be neded to add something that can prevent paralyze.
As eroism earlier wrote after she / he add pregrancy it will add more work to him/ her with making scenes if add something that can have sex with Leah in her womb.
So in conclusion its just hard to make it work as best as it able.