For children with type O blood, the parents’ blood type may be A, B or O. It is unlikely that there will be AB blood. There are 2 antigenic sites on the surface of normal red blood cells, which originate from the father and the mother, respectively. there is neither A nor B antigen on the surface of red blood cells of type O, which can be represented by ii. Parents of blood type A may have blood type AA or Ai, and parents of blood type B may have blood type B or Bi. A child with type O blood only occurs if the parents are Ai in blood type A, Bi in blood type B, or have type O blood. An O child cannot be born if the parents are AA in blood type A, BB in blood type B, or AB. If you need to know the blood type of the parents, we recommend that you complete a blood test at the hospital.