How fetus with ab+ blood group can survive while the time of pregnancy?

AB+ foetus: No reason an ab+ foetus cannot survive, especially if the mother is also rh positive. If the mother is rh negative the problem would only arise if she had a previous rh positive baby and was not treated with a medicine called Rhogam during pregnancy and immediately after delivery. Treating a pregnant rh negative woman with Rhogam prevents her body from reacting against the growing baby.