Which blood group incompatibility is the most common?

ABO incompatibility is the most common type of blood group incompatibility seen in neonates. This occurs when a mother with type O blood has a baby with blood type A or B. In this situation, the mother's immune system can produce antibodies against the A or B antigens present in her baby's red blood cells. While this condition can lead to hemolytic disease of the newborn (HDN), it is generally less severe than Rh incompatibility.

ABO incompatibility's prevalence is attributed to the high occurrence of blood type O in the population, which often leads to multiple pregnancies where the child may inherit a non-O blood type from the father. In contrast, Rh incompatibility, while potentially more severe, is not as common due to the introduction of Rh immunoglobulin (RhoGAM) therapy that has significantly reduced its incidence.

Understanding the differences and roles of these incompatibilities is crucial for neonatal care, as early recognition and management can greatly improve outcomes for affected infants.