i think that's kinda easy to do? in the start maybe the author can add some choices if we are "fully" transitioned, so, if the player is a trans men, they can decide if they still have a womb, if they are taking the female hormone blocker, if they are taking testosterone, etc, so the game can track if the player is *capable* of getting pregnant.
with trans women is very simple too, i guess?? trans women don't have a womb, so, they can't get pregnant and im pretty sure the game won't add a "add a womb" in the clinic bc it is not realistic, does this mean that trans women are not women? absolutely not, they are! we are just talking about the biologic sides <3
also, in real life, if a trans women is taking the testosterone blocker and it is taking the contraceptive, they CAN still experience PMS (Premenstrual Syndrome) or PMT (Premenstrual tension) wich i think it would be really cool to implement! <33