Rh incompatibility is the incompatibility of the Rh group between the blood of the mother and the blood of her fetus. As a result, the woman can produce antibodies against red blood cells in the fetus. The antibodies cause the destruction of a more or less important number of these globules producing sometimes the denominated haemolytic disease of the new born, a variety of anaemia. In order to fight this anomaly there are different procedures that vary according to the seriousness. Antibodies anti-Rh in the Rh-negative mother can be injected. Sometimes, a transfusion of intrauterine blood is administered to the fetus. Only in some cases blood transfusions will be necessary to the baby when born.