Briefly explain the significance of RH factor. Why mother with Rh negative blood should receive RhoGAM shot? What type of antibodies would be produced in this case? Why there is no universal donor...

Briefly explain the significance of RH factor. Why mother with Rh negative blood should receive RhoGAM shot? What type of antibodies would be produced in this case?  Why there is no universal donor anymore? What type of blood you can transfuse if patient has type A- blood?