ABO incompatibility occurs in 20% of pregnancies, but only 20% of these develop hemolytic disease which is milder than Rh incompatibility and can lead to abortion in the uterus . The blood groups are different, an A mother and an O father will be ABO-compatible, but an O mother and an A father will be defined as an ABO incompatible mate. A further complication is that a father with blood group A may be homozygous (AA) or heterozygous (AO), and thus an ABO-incompatible mating in which the father is A and the mother O may produce a compatible O or an incompatible A fetus. Finally the assessment of couples’ blood group with abortion indicate that the incompatibilities are considerably more … Continue reading Pregnancies: Are you and your partner ABO compatible?