ABO incompatibility as a cause of spontaneous abortion: evidence from abortuses.

Although ABO incompatibility between mother and the conceptus has long been suspected as a cause of spontaneous abortion in man its precise contribution has not been completely resolved (Levene and Rosenfield, 1961). In spite of reports in which the incompatible mating was recognized to be a cause ofhabitual abortion (McNeil et al, 1954) and which eventually results in infertility (Behrman et al, 1960) or a reduction in the mean number of living children compared to the number in compatible matings (Matsunaga and Itoh, 1957/ 1958), such effects were not observed in other studies (Peritz, 1966/1967; Reed, 1968; Solish and Gerschowitz, 1969). Recently, Cohen (1970a) and Peritz (1971) reported a significantly higher fetal mortality in incompatible matings by a statistical analysis of complete reproductive data (ie, including stillbirths) and it has been assumed that the previous negative results might be due, at least in part, to limitation of the analysis to live births (Cohen, 1970a). In all of these reports data were analysed by comparing the fertility between compatible and incompatible matings, which were classified according to maternal and paternal blood types. To the best of our knowledge there has been only one report in which blood types of abortuses as well as the parents were examined, and the data were analysed on the basis of maternal-fetal incompatibility (Krieg and Kasper, 1968). These authors used the haemagglutination-inhibition technique to identify blood types of fresh fetal organs in a relatively small number of specimens, and no statistical analysis was described. According to the study of Coombs and his colleagues the mixed agglutination technique is the most sensitive and it is possible to identify the blood types of old, dried, or even fixed blood, and some other tissues by its application (Holborow et al, 1960; Coombs and Dodd, 1961). Since a large number of abortuses were available to us through an ongoing research project at the Vancouver General Hospital (Poland, 1968) we applied this technique to identify the blood type of spontaneously aborted fetuses with the purpose of estimating the maternalfetal ABO incompatibility as a cause of spontaneous abortion.