Question

The erythroblastosis fetalis can be avoided by-
1. Administering anti-Rh antibodies to the mother immediately after conception.
2. Injecting Rh-antigen into the mother's blood immediately after the delivery of the first child.
3. Artificially introducing Rh +ve blood into future mothers.
4. Administering anti-Rh antibodies in mother’s blood immediately after the delivery of the first child.

Answer 1

Hint: Erythroblastosis fetalis is a hemolytic anemia in the foetus (or neonate, as erythroblastosis neonatorum). It is caused by transplacental transmission of maternal antibodies to the foetal red blood cells. The disorder usually results from incompatibility between maternal and foetal blood groups, often Rho(D) antigens.

Complete Answer:
Two blood group systems, Rh and ABO, are primarily associated with erythroblastosis fetalis. The Rh system is responsible when an Rh-negative woman (a woman whose blood cells lack the Rh factor) conceives an Rh-positive foetus. Sensitization of the mother’s immune system (i.e., immunization) occurs when foetal red blood cells that carry the Rh factor (an antigen in this context) across the placental barrier into the mother’s bloodstream. They stimulate the production of antibodies in the mother’s body, some of which will pass across the placenta into the foetal circulation. It sometimes lyse, or break apart, the red blood cells of the foetus which is called haemolysis.
The risk of erythroblastosis can be reduced if the mother receives injections of Rh immunoglobulin. It destroys foetal red blood cells in her bloodstream, during her first pregnancy. The foetus is also protected from Rh haemolytic disease if an ABO blood group incompatibility exists concurrently; protection is conferred by ABO antibodies. These antibodies destroy foetal blood cells in the maternal circulation before the mother develops Rh sensitivity.
Immunoglobulin, also called antibody, is a protective protein produced by the immune system in response to the presence of a foreign substance which is called an antigen. Thus, injecting the mother with anti-Rh antibodies immediately after her first pregnancy will reduce the chances of her second baby being born with erythroblastosis. It is rare for a mother to become sensitized during the course of her first Rh-positive pregnancy because the amount of foetal Rh antigen that enters her circulation is insufficient to cause sensitization. However, Rh sensitivity is likely to develop during labour which is why the risk of the disease developing in subsequent Rh-positive pregnancies increases.

Thus, option (4) is the correct answer.

Note:
The severity of erythroblastosis fetalis varies depending upon the degree of haemolysis. Symptoms include anaemia, with the presence of many immature red blood cells (called erythroblasts) in the circulation; jaundice, resulting from a build-up of bilirubin (a breakdown product of haemoglobin from RBC); and an enlarged liver and spleen. In its mildest form, the disease manifests only as slight anaemia with no other complications whereas in its most extreme form, the foetus dies in the utero.