Blood groups and abortions

Abstract

Although fetal loss has an established relationship to ABO incompatibility, the question has been whether the loss is due to infertility or to abortion. The hypothesis has been presented that the outcome of an incompatible pregnancy is determined by the mother's antibody titer. As a first step in testing this hypothesis, blood groups of aborted tissues were tested. A distribution of blood groups of the aborted tissues different from that of the general population would imply that ABO incompatibility is a factor in abortion. A method has been described whereby tissue ABO antigens can be identified in secretors. Tissue antigens agglutinate the corresponding antibodies from serum of known titer: a fall in titer indicates the blood group of the tissue. Testing of the fetal side of the placenta appears to give the blood group of the fetus. Analysis of results for whites and Negroes showed an unusually large proportion of abortuses having B antigen, supporting the hypothesis that ABO incompatibility is a cause of spontaneous abortion. Analysis of 27 mother-abortus pairs showed a relatively large proportion to be ABO incompatible. Particularly outstanding was the large number of incompatibilities due to antigen B, a finding which may contribute to the concept of balanced polymorphism of blood groups.