Pregnancies: Are you and your partner ABO compatible?

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 common than in normal couples.

The Incidence of Spontaneous Abortion in Mothers with Blood Group O Compared with other Blood Types