The biggest thing that struck me after reading this thread is the ole saying kept rolling through my mind...."stupid people shouldn't breed". OP, I don't believe she wants the dick, and think its just her excuse to spend the next several months leaving you out in the cold expecting you to pamper her without any reciprocation.
If she really DID want the cock, and is this fucking ignorant about the facts of life out of the blocks.... why wouldn't she ask the doctors and nurses during her pre-natal visits if it was OK? Just tell her if she really is this timid (and dumb), then her mouth better be ready, willing and able to give some of the greatest blowjobs of her life for several months.
I actually do hope something does happen to the fetus and she loses it, because again....STUPID PEOPLE SHOULDN'T BREED!