Final answer:
RhoGAM is a drug given to Rh-negative mothers to prevent hemolytic disease of the newborn (HDN) by providing anti-Rh antibodies that neutralize fetal Rh-positive red blood cells and prevent immune response. This treatment significantly reduces the incidence of HDN.
Step-by-step explanation:
The drug administered to a woman at 28 weeks gestation who is Rh-negative to prevent hemolytic disease of the newborn (HDN) is known as RhoGAM, or Rh immune globulin. When RhoGAM is injected into an Rh-negative mother, it provides anti-Rh antibodies that destroy any fetal Rh-positive erythrocytes that may have entered the maternal circulation, preventing the mother's immune system from producing antibodies that would attack the fetus in current and subsequent pregnancies. This intervention decreases the incidence of HDN from approximately 13-14% to about 0.1% in the United States since its introduction in 1968.
Hemolytic Disease of the Newborn, also called erythroblastosis fetalis, occurs when an Rh-negative mother who has been sensitized in a previous pregnancy develops antibodies against the Rh-positive red blood cells of her fetus. Prior to childbirth and treating with RhoGAM, any potential mixing of blood that would cause the mother to produce anti-D antibodies can be prevented, thereby safeguarding the health of the fetus.