Explanation

A special case of Rh incompatibility has been observed between Rh $- ve$ blood of pregnant mother with Rh $+ ve$ blood of foetus. During the delivery of the first child there is a possibility of exposure of the maternal blood to small amount of Rh $+ ve$ blood from foetus. In such cases, the mother starts preparing antibodies against Rh antigen in her blood. In the case of her subsequent pregnancies, the Rh antibody from the mother can leak to blood of foetus and destroy foetal RBC. This could be fatal to foetus or could cause severe anaemia and jaundice to the foetus. This condition in called erythroblastosis foetalis