A special case of Rh incompatibility (mismatching)
has been observed between the Rhve blood of a pregnant mother with
Rh+ve blood of the foetus. Rh antigens of the foetus do not get exposed to
the Rhve blood of the mother in the first pregnancy as the two bloods are
well separated by the placenta. However, during the delivery of the first
child, there is a possibility of exposure of the maternal blood to small
amounts of the Rh+ve blood from the foetus. In such cases, the mother
starts preparing antibodies against Rh antigen in her blood. In case of
her subsequent pregnancies, the Rh antibodies from the mother (Rhve)
can leak into the blood of the foetus (Rh+ve) and destroy the foetal RBCs.
This could be fatal to the foetus or could cause severe anaemia and
jaundice to the baby. This condition is called erythroblastosis foetalis.
This can be avoided by administering antiRh antibodies to the mother
immediately after the delivery of the first child.