Rh Types

Hemolytic Disease of the Newborn (Erythroblastosis Fetalis)

• Anti Rh antibodies in the mother attack and destroy baby's RBCs causing baby to suffer from anemia.

  • Baby is the one harmed - there are no ill effects on the mother.

• Mother must be Rh- (in order to have Anti Rh - see above) and  baby must be Rh+(to have Rh antigen and be harmed).  Dad must be Rh+ (the Rh+ must come from somewhere!).

• Mothers are not born with Anti Rh (thus, first pregnancies are not a problem), but develop Anti Rh after exposure to Rh+ blood. 

  • They are exposed to the baby's Rh+ blood when the placenta breaks loose from mother during birth of the first baby.

• The anemia gets worse with each pregnancy because antibody level in the mother increases with each pregnancy.
• Prevention is affected with an injection of RhOGam.

  • RhOGam is Anti Rh (Rh Gammaglobulin) which destroys the Rh+ RBCs that have gotten in to mother, before mother has an opportunity to react to baby's RBCs by making Anti Rh.

• Anti A and Anti B are large molecules that can not cross the placenta and harm baby - thus, A/B conflicts between mother and baby are not an issue (Anti Rh is a small molecule and can cross the placenta).

• Rh- women can also develop Anti Rh as a result of a blood transfusion with Rh+ blood.

  • Thus, in a universal donor situation, women are always given 0- blood.