Strongly suggest talking as a vanilla girlfriend about how he feels about the baby, responsibility, sex with a "mother" and other intimacy issues BEFORE talking about how your kitten needs are not being met. I'm not minimizing your needs at all - relationships have ended when they started on a bdsm footing and then someone lost that kinky spark - but I think that should be a small part of a much larger discussion. He might need permission to view you as a sex object, or as a sub, now that you're pregnant.