The HLA antigens in women with recurrent abnormal pregnancies of unknown etiology.

Women with recurrent abnormal pregnancies of unknown etiology--as compared with those with recurrent abnormal pregnancies of known etiology and with normal controls--had a significantly increased frequency of antigen HLA--A9 (corr. P less than 0.01). Analysis of the frequencies in matings performed at different levels of HLA incompatibility between parents in 35 couples with recurrent abnormal pregnancies of unknown etiology revealed a high degree of wife husband compatibility of the antigens of the HLA--A locus, but not of the antigens of the HLA--B locus. These results indicate that the HLA chromosomal region may influence the reproductive efficiency and the fate of the fetus.