If the mother has Rh negative blood and becomes pregnant with a baby who has Rh positive blood, the mother's body will see those Rh antigens as foreign particles and will try to fight it off.
Typically the first pregnancy is okay.
But the mother's body will have built up an immunity against the Rh antigen by the second pregnancy.
Dramatic-Move8793 t1_j1stzyf wrote
Reply to What happens if a mother‘a child has a non-compatible blood type? What will happen when she is pregnant? by thebookklepto
If the mother has Rh negative blood and becomes pregnant with a baby who has Rh positive blood, the mother's body will see those Rh antigens as foreign particles and will try to fight it off. Typically the first pregnancy is okay. But the mother's body will have built up an immunity against the Rh antigen by the second pregnancy.