Question

How does the immune process that causes the hemolytic disease of the newborn take place?

Answer 1

In the hemolytic disease of the newborn the mother has Rh- blood. This mother when generating her first Rh+ child makes contact, possibly during delivery, with Rh+ red blood cells of the child and her immune system triggers the primary immune response against the Rh factor. In the next gestation in which the fetus is Rh+ the mother will already have much more anti-Rh antibodies in her circulation; these antibodies cross the placental barrier and gain the fetal circulation causing fetal hemolysis (destruction of the red blood cells of the fetus).

Answer 2

The hemolytic disease of new born (HDN) is resulted due to interference of maternal IgG antibodies with ABO blood group system and passing through the placenta obstructing the fetal circulation resulting in hemolysis of fetal red blood cells. The fetal anemia may be severe and may cause death of fetus if untreated. In case of HDN caused by Rh (rhesus) factor the first pregnancy may be affected because of the anti RH antibodies produced by the mother, thereafter the problem is not caused because of immune memory of these antibodies.

The exposure of surface antigens of A and B groups with IgM antibody normally will not cause a problem. But, in some cases mothers produce IgG anti A and anti B antibodies that cross the placenta and result in HDN.