Question

In erythroblastosis foetalis, which factors of the mother pass through the placenta into the foetus?
A. Rh antigens
B. Rh antibodies
C. ABO antibodies
D. Agglutinins

Answer 1

Erythroblastosis fetalis is haemolytic anemia of a foetus that is usually caused by the placental transmission of maternal antibodies to the red blood cells of the neonate. It is usually caused by Rh incompatibility between the parents.

Complete answer: The doctor suggested not having more than one child to a couple where the male was $Rh^+$ and the female was $Rh^-$. As it may lead to erythroblastosis fetalis. It is a potentially dangerous condition that occurs during the development of an infant. The condition occurs when the Rh factor is incompatible between the pregnant woman and the foetus. This can lead to the death of the child inside the womb. In the case of subsequent pregnancies, the Rh antibodies from the mother (Rh-) can leak into the blood of the fetus ($Rh^+$) and destroy the foetal RBCs. This could be fatal to the foetus.
Hence, the correct option is B-Rh antibodies.

Note: Erythroblastosis fetalis is also known as erythroblastosis neonatorum. It is caused by the incompatibility between maternal and fetal blood groups, often Rh antigens. It is usually characterized by erythroblasts circulating in the blood. Initially, Rh antigen activates maternal B cells to produce anti- Rh antibodies. It leads to damage of red blood cells (RBCs) and can also lead to yellow fever in the infant. It can be fatal to the neonate.