Relationships between the ABO blood group system and some obstetric factors

Abstract

SummaryAnalysis was made of relations between the ABO blood group system and mother–child pairs in an ethnically homogeneous sample of Australian births. There was an increase in the proportion ofB-positive (AB or B) children with increasing number of pregnancies and maternal age. A discriminant analysis indicated that pregnancy number was the basic determinant of the effect. A decreasing proportion of parturients of group O was noted as the number of previous fetal deaths, due to natural abortion or stillbirth, increased. This was independent of maternal Rh type. A dominant effect whereby the gestation period lengthened according to the proportion ofO-containing genes in the phenotypes was also observed.