Honey if being prego or having a child gets in the way of being who and what you are to/with each other...well then imho he isnt much of a dom to begin with and the two of you were never ment to be anyway.

Of course your child will come first and rightly so, but it shouldnt be a "problem" so much as a new joy in your life together, it shouldnt be any different than it would for any other couple bdsm/vanila or otherwise.

Especially if he does right by you.