Final answer:
During the second or subsequent pregnancies with an Rh-positive child, an Rh-negative mother may develop anti-Rh antibodies causing hemolytic disease of the newborn. This is prevented by administering RhoGAM in the first pregnancy.
Step-by-step explanation:
The Rh factor is a significant antigen found on red blood cells; its presence or absence categorizes blood as Rh-positive or Rh-negative. When an Rh-negative mother carries her first Rh-positive child, there's typically no issue with hemolytic disease of the newborn (HDN), also known as erythroblastosis fetalis, as the immune response and formation of anti-Rh antibodies are generally insufficient to cause harm. It is during the second or subsequent pregnancies with an Rh-positive fetus that risks arise; the previously sensitized immune system of the mother now has anti-Rh antibodies capable of crossing the placenta and attacking the fetus's red blood cells, leading to anemia or more severe consequences.
This issue is mitigated by administering anti-Rh antibodies (RhoGAM) during and after the first pregnancy, a critical measure that destroys any fetal Rh-positive cells that enter the mother's bloodstream, preventing the immune response and subsequent antibody formation.