The genes that determine the blood type are A and B as dominant genes and O as recessive genes, so the father has AB blood type, the genetic phenotype is both A and B chromosomes, and the mother has O blood type, the mother’s genotype can only be OO, these two genotypes paired to give birth to a child with 50% possibility of A blood type, 50% possibility of B blood type, no other blood type is possible. If the mother is type O and the father is type AB, there is a risk of neonatal ABO hemolysis. If jaundice occurs after birth, the possibility of ABO hemolysis should be considered, and the child should be treated at the neonatal unit as soon as possible, and if the condition is serious, some of them need blood exchange treatment.