During pregnancy, Rh incompatibility is seen when the father’s blood is Rh+ while the mother’s blood is Rh-.
Therefore, if a father’s blood is Rh+ and the mother’s blood is Rh-, the blood of their baby will be Rh+ ( Rh+ is dominant over Rh- ).
In such interaction, generally, the first child does not suffer, however, the subsequent foetuses do
In the subsequent foetuses, anti-Rh factors of mothers blood attack and destroy the RBCs of the foetus. This leads to haemolytic disease of the newborn or HDN
This condition is called erythroblastosis fetalis.
The newborns that survive are anaemic
Therefore, Marriage between Rh- woman and Rh+ man is not recommended.