The second example of Jra incompatible pregnancy in our hospital is reported, with the serological findings of the mother and infant and the clinical course of the infant. In reviewing the literature on Jra incompatible pregnancies the following findings were demonstrated. In 14 out of 18 Jr (a-) pregnant women, anti-Jra antibodies were produced by pregnancy and in 7 out of these 14 cases antibodies appeared during their first pregnancy. The immunoglobulin class of the anti Jra antibodies was IgG in all cases, and the subclass of IgG belonged to IgG1 and/or IgG3 in 6 cases. The direct antiglobulin test on cord red cells was positive in 15 out of 18 infants. No exchange transfusion was reported, and 16.7% of infants received phototherapy. On the basis of the above findings, it is considered that severe jaundice cannot occur in infants born to Jra incompatible pregnancies and that there is no need for amniocentesis during gestation. It is suggested that the mechanism by which no hemolysis was demonstrated despite the positive antiglobulin test in Jra incompatible infants depends on the antigen and not on the antibody.
