question_answer 39)

  What physiological circumstances lead to erythroblast sis foetalis?

Answer:

                  A protein named as rhesus antigen, is present on the surface of red blood corpuscles. The population having this protein are called Rh positive while others who do not have this protein are known as Rh negative (PIT) (dominant). Erythroblastosis Foetalis occurs due to Rh incompatibility between the foetus and mother during pregnancy. Rh antigen of the foetus do not get exposed to the blood of the mother in the first pregnancy. However, during the delivery of the first child, there is a possibility, of exposure of the maternal blood to small amounts of the Rh'^ blood from the foetus. In such cases, the mother starts preparing antibodies against Rh antigen in her blood and during her subsequent pregnancies the Rh antibodies from the mother (Rh - ve) leak into the blood of the foetus (Rh + ve) resulting in the destruction of foetal RBCs. This could be fatal to the foetus or could cause severe anaemia and jaundice , even may lead to the death of the foetus.