Male a+ and female o-, are these compatible?

Yes,with proper care. In this situation, the possibility of both ABO and Rh incompatibility exists. ABO incompatibility is generally less severe that Rh and is somewhat protective against Rh sensitization. Sensitization to ABO or Rh can occur during a first pregnancy, spontaneous or induced abortion, subsequent preganancies may produce disease in the infant. Proper prenatal care can usually prevent/treat problems.