Definitely goes hand in hand with any breeding scene in a game. I personally like it more as an aftermath of that. A sort of "look what you did" but not in a bad way. Of course there's whole pregnancy/birthing games out there but those aren't really my cup of tea. I feel like i love it most when it's in a sequence of breeding scene(with the whole impregnated ovum imagery)->positive pregnancy test image->image of pregnant heroine. Also a petite frame with a big belly is definitely on top
I appreciate the option, the execution isnt always the best. I thibk my favorite was Sisterly Lust, given nearly all the characters had pregnancy options.
Not a fan of sandbox games that make it a chance based system though, personally.
I enjoy it when it plays into and affects the story. If it's one of those where the character gets pregnant at the end of the game and then it ends, I don't care for it.