Immunogenetic studies of recurrent spontaneous abortions in humans

31 clinically defined couples suffering between 3 and 17 consecutive idiopathic spontaneous abortions have been studied. The female partners demonstrated a lower frequency than expected of serum lymphocytotoxic antibodies. Sharing of HLA-A, B or DR antigens was not significantly increased overall within these couples compared with controls, although two couples did show marked HLA sharing (greater than or equal to 4 antigens shared at HLA-A, B and DR loci). There was increased apparent HLA-A and HLA-B locus homozygosity in these women compared with controls (p less than 0.02 and p less than 0.005, respectively), with no significant apparent homozygosity either at HLA-DR or in the males. An increased prevalence of HLA-A, B and DR antigen phenotypes characteristic of various extended haplotypes was also observed in these couples.