Significance of Rh-sensitization during pregnancy: its relation to a preventive programme.

A study of the incidence of Rh-sensitization showed a 6.5% incidence of anti-D appearing for the first time during the last trimester of pregnancy. In 24 of the 29 subjects these antibodies were weak, and were found only when a sensitive technique using enzyme-treated Rh-deletion test cells was employed. The remaining five, however, had high-titre antibodies, which were associated with a positive Coombs test on cord blood.Rh-immune globulin administered at delivery resulted in disappearance of the anti-D in all but one of the subjects with weak antibody to whom it was given, suggesting that this treatment can reverse early sensitization. There was no effect when Rh-immune globulin was given to one subject with a high anti-D titre.Since sensitization has been found to occur frequently during the last trimester of pregnancy, an antenatal schedule of prophylaxis is advocated.