Since we are in 100% shit on the Dev mode here, I'll contribute.
The way this game handles pregnancy is laughably bad, except its not funny, not at all. As in, it is guilty of the greatest sin a video game can commit, not being enjoyable. Don't get me wrong, I'm not saying it has to be fun. I'm sure not all of us were having 'fun' when Joel's daughter died in our arms in 'The Last of Us' or when Alma Wade was chasing us through shadowed buildings in 'F.E.A.R'. But those games were enjoyable, and so were those moments.
SS punishes you for getting girls pregnant. It talks up a warning that pregnancy in the game is 'serious' and you'll notice the effects. Except it isn't and you won't. The only effect is that it takes viable women OUT of the game (removes content) which is a mortal sin by anyone's estimation. But after you simply wait (you don't even have to visit the kid at the hospital or ever even ACT as a parent) the girl comes back and is slutting it up for you again, ready and willing to push out another bastard.
Two possibilities exist for this absurd dichotomy. Either the Dev hates Preg content and wants as little to do with it as possible, including not allowing pregnant sex (which is insane, and does a disservice, many of us, men and women, WANT to sleep with our LI while pregnant, both in the game and IRL) and barely allowing any special interaction at all, they aren't given different content, they aren't allowed to keep their old content, they're just stripped of basically anything they had while you wait for them to bounce back, and their kid to disappear into nursery school, never to be mentioned again.
The other possibility (the more accurate one, I expect) is the Dev is fucking lazy as hell. Doesn't want to make multiple models or modify existing sex scenes (what a fucking loser, watching some of these girls ride the MC with a bump, would be hot as hell) or make any effort at all. All under the guise of 'pregnancy has consequences'.
TLDR. The Dev is pretty lazy and it shows in their work. He also tries to cover this fact up with excuses.