Zoology - Body Fluids and Circulation Question with Solution | TestHub

A special case of $\mathrm{Rh}$ incompatibility (mismatching) has been observed between the ${\mathrm{Rh}}^{-\mathrm{ve}}$ blood of a pregnant mother with ${\mathrm{Rh}}^{+\mathrm{ve}}$ blood of the foetus. The ${\mathrm{Rh}}^{-\mathrm{ve}}$ mother is not usually exposed to the $\mathrm{Rh}$ antigen of the foetus during the first pregnancy as the foetal and maternal blood are normally kept well separated by the placental barriers. However, at the time of the birth of the first child, there is a possibility of exposure of the maternal blood to a small amount of ${\mathrm{Rh}}^{+\mathrm{ve}}$ blood from the foetus. Hence, the body of the mother starts preparing antibodies against $\mathrm{Rh}$ antigens in her blood.

These antibodies (a type of $\mathrm{IgG}$ antibody) could cross the placental barriers in subsequent pregnancies and cause haemolysis of the ${\mathrm{Rh}}^{+\mathrm{ve}}$ red blood cells of the foetus. This could be fatal to the foetus or could cause severe anaemia and jaundice to the baby ($\mathrm{HDN}$- a haemolytic disease of newly born). This condition is called erythroblastosis fetalis.