“Haemolytic disease of the newborn is mainly divided into ABO haemolysis and Rh haemolysis, with ABO haemolysis being the most common.
ABO haemolysis occurs mainly in cases where the mother has blood type O and the foetus has blood type A or B. It occurs in 40% to 50% of first pregnancies. ABO blood group incompatibility occurs in approximately 15% of all pregnancies, but only 4% of these will result in ABO haemolytic disease.
Rh haemolysis usually occurs when the mother is Rh-negative (i.e. ‘panda blood type’) and the foetus is Rh-positive, which may occur, but not usually in the first pregnancy.”