Factors in prenatal prognosis of hemolytic disease of the newborn due to Rh immunization

Features of the obstetric history, antibody titers, and amniotic fluid spectrophotometry were examined in pregnant women with rhesus isoimmunization to ascertain their relative value in predicting the severity of hemolytic disease in the newborn. Among 17,420 pregnant women, rhesus isoimmunization was found in 158 cases with hemolytic disease of the newborn in 132 cases of varying severity including 24 perinatal deaths. The accuracy of predictions based upon features of the obstetric history and antibody titers was contrasted against predictions made from examination of the amniotic fluid. The use of the obstetric history and antibody titrations in predicting the fetal involvement was not as reliable as amniotic fluid analysis and both under and over assessment of the severity of the hemolytic process in the baby were seen. These features nevertheless remain of value in indicating pregnant women in whom rhesus isoimmunization has occurred and in whom a severely affected baby or perinatal death may occur. The conditions under which this may occur are described and these are also the conditions which become indications for amniocentesis and examination of amniotic fluid for changes in optical density at 450 mμ. It was found that amniotic fluid analysis besides being of increased accuracy, allowed greater confidence in the identification of severely affected babies and gave great assistance in the assessment of the exact timing for interruption of pregnancy. Without its use the indications for more radical therapeutic measures are inadequately defined. The natural outcome of pregnancies regarded as exceptionally high risk cases was examined and showed that the majority of babies survived and a few appeared less affected than in previous pregnancies.