Resident Milf the Game. Was pleasantly surprised by animations, QTE are unexpectedly fit quite well, MILF character(too few games have mature women as MC), choices in scenes, it's noticeable that Dev putting effort in it.
Saw people asking to add pregnancy, as pregnancy fan Myself, I would like it to be added too, but recommend Author to do what He wants and thinks is best.
Talking about pregnancy implementation in this game, well, it's obviously not human pregnancy with all these monsters and viruses, so fast-gestating monster pregnancy(cause science), eggs(from tentacles and frogs), womb parasites or inflation. Parasites like larva or maggots from human zombies, which grow inside her womb and don't leave willingly, and she has to squeeze them out, inflation for those who don't want pregnancy but want to see her with big belly.
To let people choose if they don't want to see preg content add story event where she needs monster spawn to pass through automatic gates of laboratory, so she either needs to fight dangerous monster to get inside or inject herself with mutagen to be able to get pregnant from monsters, also a scene where she thinks about past when her husband creampied her with a choice: she really loved it(inflation in game) or not.
To make it more relevant for gameplay, larva and eggs can be used for crafting, instead of green, red and yellow herbs in RE games, to make healing items or items to stun or distract enemies, to balance ability to craft healing items on pregnancy route, after using mutagen all monsters will start to deal much bigger damage to her(cause her body is weakened by adaptation to mutation).
But All these stuff is just idea mumbling, cause with pregnancy every art will need several versions and with animations amount of work will triple, and most importantly, pregnancy is very specific genre so it's hard to work on it if Author not into this kink.
I like that Author wants to make an interesting game, not simply porn scenes collection, wish You health and luck.
P.S. Watch NullStudio videos to see if You want to add something like this in Your game.