Erythroblastosis foetalis develops in newborn due to incomplatibility between

Explanation

Erythroblastosis foetalis develops in an RH positive foetus, whose father is RH positive and mother is Rh negative. In Rh positive person rhesus antigens are present on the surface of blood cells where as in Rh negative person Rhesus antigens are absent.
During the process of delivery, the foetal blood cells may pass through the ruptured placenta into the Rh negative maternal blood. The mother.s immune system recognises the Rh antigens and gets sensitized and produces Rh antibodies. These antibodies are Ig G type they can pass through placenta . Generally first child is not effected because child is delivered by the time of the mother gets sensitized and produce antibodies.
During second pregnancy, if the second child is Rh positive, these antibodies cross the placenta, enter the foetal blood circulation and destroy the Rh positive blood cell of foetus (haemolysis), leads to heamolytic anaemia and jaundice. To compensate the haemolysis of blood cells there is a rapid production of RBC.s from the bone marrow, and but also from liver and spleen. Now many large and immature blood cells in erythroblast stage are released into circulation,Because of the disease is called erythroblastosis foetalis.