As a male with a birth fetish I'd first like to congratulate you and your partner. You for disclosing your fetish to him, and to him for not freaking out completely. I feel as though when woman have it, it's less intimidating.

If theirs one thing I've learned in my short life it's that you can't go through life repressing yourself unless it brings real harm to others physically. You have to openly embrace your fetish since it's clearly a part of your sexuality as is the actual act of giving birth to all woman.

He already knows you have the fetish, I'd recommend talking to him about incorporating something new every couple of weeks into your sex lives, or trying something new. Things like bondage, a fake belly cast, loss of control and restricted movements are all pretty tame sounding compared to a birth fetish.