If you are not positive on your DH's blood group get him to get a blood test to see. If he is + then you'll need to have an anti-d injection either during the pregnancy or at birth. If he is -, like you are, then you won't need it.
My OB does not care what blood type DH is. He may very well be Negative like me (and then I wouldn't need the injections) ... but you know why the OB doesn't care? Because he can't be sure that DH is the father! Can you believe that?! It makes sense though I suppose. I could be lying to DH and the OB. Too bad if DH tested as Negative like me but the father of the baby was someone who was Positive. I guess the OBs need to cover themselves.

So all they care about is if the mother is Negative. If so, she will need the injections.