So this is what I understood about the disease by researching about it
When a Rh-ve mother has a Rh+ve baby in her womb,
- The placenta prevents mixing of fetal and maternal blood preventing antigen detection by her immune system.
- There are no pre-made antibodies that can attack the fetal RBCs to kill them
- At the time of birth, the placenta breaks thereby exposing the fetal RBCs to her immune system
- The WBCs get sensitised and begin antibody formation which takes atleast 6 months
- The first baby is born safely
- In the event a second Rh+ve baby is conceived, the antibodies aleady present in the blood cross the placenta and destroy the fetal RBCs killing it.(secondary immune response)
- To prevent this an injection of Rh antibodies is given to the mother after first birth which destroys all fetal RBCs before they sensitise the immune system preventing secondary immune response.
My Question is
Why does this happen only with the Rh antigen?
I know many people whose mothers have B+ve/A+ve blood but their children are born normally even when they have A+ve/B+ve blood(opposite of the mother). There even are people whose mothers have O+ve blood while they have B+ve/A+ve blood groups.
The body has pre-made a and b antibodies which should kill the fetus unlike in case of Rh where 1st birth is safe. Also much lesser time is needed to produce these antibodies which is why there cannot be any blood transfusion between incompatible ABO system blood types while one transfusion is possible between incompatible Rh blood types
My take on this will be that antibodies against ABO blood groups can never cross placenta but most antibodies do so this seems less like a solution
A lot of research failed me a solution.
I found a somewhat similar question here but it does not address my query completely