The purpose of antenatal antibody tests is to determine before delivery which Rh-negative expectant mothers have become sensitized, so that Rh-negative blood of a compatible A-B-O group can be made available to treat the baby promptly after birth, when necessary. In this way, lives of erythroblastotic babies can be saved and among affected babies who survive neurological sequelae can be prevented. Every Rh-negative multipara who has had a previous Rh-positive baby is a possible candidate for Rh sensitization, which may develop at any time during a pregnancy. If Rh sensitization does develop, it is probable that the baby will be erythroblastotic and may require treatment by exchange transfusion.
The first Rh antibody test should be done as soon as the patient becomes pregnant, to determine whether the patient is already sensitized at the beginning of the pregnancy and, if she is, what the level of the antibody titer is. Since