Rh incompatibility occurs when a mother with Rh-negative blood carries a baby with Rh-positive blood, which can lead to hemolysis - a serious condition for the baby if left untreated.

Most of us know that the common blood types include A, B, AB, O. Each blood type has a plus and minus blood group system. Each person is born with genetic inheritance from their father and mother, so they have 1 of the 8 blood group systems listed above and it does not change throughout life.

All pregnant women should be tested for Rh antibodies. This is one of the first and most important tests during pregnancy to determine whether the body carries the Rh protein in the blood.