In which of the following maternal-fetal blood type pairings should the mother receive Rho-GAM?

Rho-GAM, or Rh immunoglobulin, is administered to Rh-negative mothers to prevent the development of antibodies against Rh-positive blood cells, which can occur if the mother is exposed to Rh-positive fetal blood. This is particularly crucial during pregnancy and delivery and is vital in cases of potential blood type incompatibilities.

In the scenario presented, an AB negative mother experiencing a spontaneous abortion is a key situation where Rho-GAM would be necessary. The reason lies in the risk of the mother’s immune system encountering Rh-positive cells if the fetus had an Rh-positive blood type. If the fetal blood type is Rh-positive, the exposure can lead to sensitization, which can have serious consequences in subsequent pregnancies.

By administering Rho-GAM to the AB negative mother, any Rh-positive fetal cells in her circulation are neutralized before her immune system has a chance to form antibodies against them. This protective measure is vital in safeguarding future pregnancies against hemolytic disease of the newborn due to Rh incompatibility.

The other scenarios do not warrant the administration of Rho-GAM. In the case of the A positive mother with an O negative infant, the mother is Rh-positive and does not need Rho-GAM since there is no risk of sensitization.