Intra-Uterine Selection by the ABO Incompatibility of Mother and Foetus. II

Abstract

With nearly 2, 000 couples who had been pregnant at least more than once, the authors examined spontaneous miscarriages from the view point of the ABO incompatibility of the blood of mother and foetus. Attention was focused on the O×A and O×B matings. It was revealed that the incompatible couples can produce more miscarriages than the compatible, and this increase was considered probably due to the miscarriages of foetus of incompatible groups, which is thought to be an indication of the selective effect caused by the ABO incompatibility. The difference of the mean number of pregnancies between the compatible and the incompatible matings, though not at a significant level, suggests that selection could occur at the earliest period of pregnancy under conditions unknown to the mother.