Machine
Member
Years ago, probably when I was in middle school, I was sharing a hotel room on a school trip with some friends, and we of course took the opportunity to watch some racy movie on HBO or Cinemax or something. All I can remember are a couple of specifics: the main character was a dark-haired female, she was pregnant with a monstrous child that was going to be dangerous if born and probably wasn't entirely human, she decided to keep the baby at the end, and there was a sex scene (between the pregnant woman and I think her husband) with some mild nudity (I want to say a rocking chair was involved, but I can't be sure). It definitely wasn't Rosemary's Baby, though that fits some of the points very well.
Parts of that sound like Demon Seed. Hard to be sure though.