Rh incompatibility refers to a condition whereby RH antibodies are formed in the maternal body that attack fetus. It happens when mother is initially Rh negative and baby is RH positive. First pregnancy is often normal, however, in successive pregnancies, anti-Rh antibodies are developed in mother. These antibodies have serious impact on the Rh positive baby as maternal body perceives Rh positive baby as a foreign body. Reference: https://my.clevelandclinic.org/health/diseases/21053-rh-factor#:~:text=Rh%20incompatibility%20occurs%20when%20a,views%20as%20a%20foreign%20object. Image via: https://www.medicdrive.org/rhesus-incompatibility/