By Dr Joel Enejeta
Fathers who are doubtful of the paternity of their children can use the ABO grouping system to know if they are really the father of their children when your blood group and that of your wife is known. Blood type can be used to disprove paternity in many ways.
| MOTHER’S BLOOD TYPE | FATHER’S BLOOD TYPE | POSSIBLE BLOOD TYPE OF THE CHILD |
| A | A | A or O |
| B | B | B or O |
| O | O | O |
| A | B | A, B, AB or O |
| A | AB | A, B or AB |
| A | O | A or O |
| B | O | B or O |
Note that the above type can be assigned to either parent
RHESUS GROUPING
| MOTHER’S RHESUS | FATHER’S RHESUS | POSSIBLE RHESUS OF THE CHILD |
| Rh- | Rh+ | Rh+ |
| Rh+ | Rh+ | Rh+ |
| Rh- | Rh- | Rh- |
From the table above, if both parents have group A blood type, the possible type of the baby is A or O.
If both parents have the B type, the possible type of the child is B or O.
If both parents have type O, the possible blood type of their baby is O only.
If one parent is A and the other is B, the possible blood type of their baby is A, B, AB or O.
If one parent has A and the other AB, the possible type of their baby is A, B or AB.
If one parent has A and the other has O, the possible type of their baby will be A or O.
If one parent has B and the other has O, the possible blood type of their baby is group B or O.
For the rhesus system, if mother is negative and father is positive, the baby will be positive.
If both parents are positive, the baby will be positive and also if both parents are negative, the baby will be negative.