i have A- and df has O+ blood, ive was always told that you only need to have the anti d at 28 weeks and arround 32 and after birth, i know for a fact one of my children have positive, but not 100% on the other 2, even if your patner had negaive blood, you would still need to have the anti d. definitly ask if your worried about anything. it dosent hurt to be well-informed!