Question

What is erythroblastosis?

Answer 1

A life-threatening disease of a fetus or infant in which the Mother’s immune system produces antibodies against the erythrocytes of the infant is called Erythroblastosis fetal.
It leads to the destruction of the RBC of the fetus.

Complete answer: If an Rh-positive baby is growing in the womb of an Rh-negative Mother, there are chances that the fetus is affected due to the interaction between the antibodies of the mother. The fetus possesses the Rh antigens.
These antigens would be considered as foreign pathogens in the mother's body.
Hence, a protective mechanism may be initiated by her immune system that can end up harming the child, especially during the second pregnancy.
This is referred to as erythroblastosis fetal.

Note: The antibodies remain in lower concentration during the conception of the first child. So the fetus is not harmed much but the mother’s body would produce antibodies against the Rh factor during the first child’s delivery.
So, the concentration of antibodies against remains in higher concentrations during the second pregnancy with Rh+ baby.
Hence, the blood cells of the fetus are attacked by the antibodies and it is fatal for the fetus.