How to Figure the Blood Type of Children

Karl Landsteiner discovered the blood groups in 1901, a discovery for which he was awarded the Nobel Prize in 1930. Although the only way to determine with certainty the blood type of a child is to test the child's blood, the possibilities can be narrowed down if the blood type of each of the child's biological parents is known. Since there are four possible blood types -- A, B, AB and O -- there are several possible combinations. Some results can be confusing; for example, it is possible for two type B parents to have a child with type 0 blood.

Things You'll Need

• Pen
• Paper

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Instructions

• 1

  Test the blood of the child's biological mother and father to determine blood type of each. Record the parents' blood typing information on a sheet of paper.

• 2

  Determine if both parents have type O blood. If so, then the child will also have type O blood. This is the only blood type combination where the result for the child is definitive.

• 3

  Determine if either parent has type AB blood. If this is the case, the child will have either A, B or AB blood if the other parent has any of types A, B or AB blood. If the other parent has type O blood, however, the child can only have type A or B blood.

• 4

  Determine if either parent has type B blood. If so, the child will have either type A, B, AB or O blood if the other parent has type A blood. If the other parent has either type B or O blood, the child will have either type B or O blood. For example, it is possible for a child with two type B parents to have either B blood or O blood. If the other parent has type AB blood, the child will have type A, B or AB blood.

• 5

  Determine if one parent has type A blood. If so, the child will have type A or O blood if the other parent has either type A or O blood. For example, it is possible for the child of two type A parents to have type O blood. This child may also have type A blood. The child of a type A parent will have type A, B, AB or O blood if the other parent has type B. The child will have type A, B or AB blood if the other parent is type AB.