How does the immune system affect a patients ability to not reject baby during pregnancy?

Hemolytic D. newborn: It is extermely important in women of childbearing age who are rh neg. To be sure they get no rh pos. Blood so there is no chance that they develop antibodies in case they have an rh pos. Child and so have hemolytic disease of the newborn. If an rh. Neg. Woman gets exposed to rh. Pos. Blood and develops antibodies, they can attack and kill the rbcs of the next child she has if it is rh pos..