There is no problem in your baby having AB-ve group .Itwill not cause any problem in any aspect in your baby .
Only thing is availability of the blood in case of emergency . There may be some difficulty in getting it . . It will be good practice to contact with voluntary blood donor groups and get contact number of the donors so that in emergency it may be helpful .
There is no surprise in having -ve blood group
of baby even both parents are +ve . iT IS GENETICALLY DETERMINED AND MAY BE THERE IS SOME BODY IN FAMILY TREE OF PARENTS WITH _VE GROUP .SOME TIMES MUTATION
Do not worry .