Hm... is pregnancy just an ending for the characters? I've been reading through the thread here and it seems that's exactly how it is. So no actual mechanic then, right?
It's a work in progress as of now, the game is a few updates away from completion-
But partway through your playthrough you'll have the option to opt in or out of the pregnancy route as a whole, and then you'll have further choices for each character, as so far at least, some of the pregnancy options are...morally dubious.
So technically in a gray area if you're asking if it's like a feature like in some games with an impreg mini-game.
If you're thinking "pregnancy chance" then no, it doesn't work like that. It's just "do you want this or no?"
Instead you'll reach a certain event in which pregnancy will become open for all other routes, and you'll basically be paid for every character that gets pregnant.
It doesn't really go further than being a dialog option though.
Though...it might impact the ending, not sure as it's not complete yet.