Published online by Cambridge University Press: 01 August 2014
Several studies have appeared in the literature to support the hypothesis of a differential incidence of twin births according to the antigenic structure of maternal erythrocytes (Gedda, 1961).
Osborne and DeGeorge (1957) wrote that twin births exhibit a higher incidence when mothers belong to group O, as compared to other groups within the ABO system; a similarly increased incidence of twin births was indicated for rh-negative mothers within the Rh-Hr system.
The availability of a large number of immunohematological data concerning twin pairs and nontwin individuals examined in our Institute have encouraged us to verify whether this material could reveal some a posteriori effect of the selective tendencies that have been related to the parental level.
Limiting our study in this phase to the ABO system, we have collected data on 1190 twin individuals and 1454 nontwin individuals, for all of whom the ABO blood group had been recorded.
The first step in our analysis was the perequation of the nontwin distribution to the twin distribution, obtaining the figures reported in the column “controls” in Tab. I.