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Keywords:

  • Sperm immobilizing antibodies;
  • IVF-ET;
  • embryo;
  • abortion;
  • infertility

PROBLEM: Since it was found that anti-sperm antibodies could impair in vitro development of fertilized eggs in the presence of complement in rats, the effects of sperm immobilizing antibodies on human pregnancy were examined in infertile women treated with IVF-ET.

METHOD: The pregnancy outcomes of 143 ET cycles in 58 infertile women with sperm immobilizing antibodies and 363 ET cycles in patients with tubal infertility as control were compared. Diagnosis of chemical pregnancy was done when the urinary hCG level had risen over 50 IU/L but a gestational sac could not be demonstrated later. Antibody titers of sperm immobilizing antibodies (SI50 units) were measured by a quantitative sperm immobilization test.

RESULTS: 33 (23.1%) of 143 cycles in the patients with sperm immobilizing antibodies and 56 (15.4%) of 363 cycles in the control patients were diagnosed as pregnancy. The pregnancy rates were significantly higher in the former than in the latter (P<0.05). In the patients with sperm immobilizing antibodies, 12 (36.4%) were chemical pregnancies, 5 (15.2%) were clinical abortions, and 16 (48.5%) had deliveries. In the control group, 18 (32.1%) were chemical pregnancies, 10 (17.9%) were clinical abortions including ectopic pregnancies and 28 (50.0%) had deliveries. There was no significant differences in each category. When the SI50 titers at the time of conception were considered, chemical pregnancy rates were 22.2% (4/18) in patients with SI50 titers below 10 units, but those in patients with SI50 titers above 10 were 50.0% (5/10) and above 100 were 60.0% (3/5), respectively, (P > 0.05). In four of five patients who had both chemical and clinical pregnancies, the SI50 titers at the time of conception were higher in the chemical pregnancy cycles than in the clinical pregnancy cycles.

CONCLUSIONS: Though the pregnancy rates were significantly higher in the patients with sperm immobilizing antibodies as compared to those with tubal infertility, chemical pregnancy rates were also higher in the patients with higher sperm immobilizing antibody titers. These results suggest that sperm immobilizing antibodies may cause the damage of early development of human embryos in vivo in the small number of patients with a high titer of the antibodies.