Association between recurrent spontaneous abortions and circulating IgG antibodies to sperm tails in women.

The isotype and regional specificity of antisperm antibodies in the circulation of women with recurrent spontaneous abortions was examined. There was a statistically significant association (P less than 0.005) between the presence of IgG tail-directed antisperm antibodies and a history of unexplained recurrent spontaneous abortion. These antibodies were detected in 36.4% of 44 women with recurrent abortions and 14.6% of 616 female partners of infertile marriages. In contrast, no differences in IgG sperm head-directed antibodies or in IgA and IgM antisperm antibodies were observed between the two groups. Husbands of women in the miscarriage or infertile groups had similar semen evaluations. Antisperm antibodies may be a marker for defective immunosuppression in women with recurrent miscarriages. Alternatively, exposure of sperm-sensitized pregnant women to sperm may activate the maternal immune system to respond to paternal antigens present on the embryo.