Relationship of within-patient semen variability to outcome of intrauterine insemination.

To define the subpopulation of infertility patients who would benefit from intrauterine insemination (IUI) with swim-up homologous sperm, the relationship of within-patient semen variability to outcome of IUI was studied. The 61 women in the study had negative workups. Men had at least one semen sample with greater than or equal to 20 x 10(6) sperm/ml. The 6-month cumulative pregnancy rate for all patients was 31.8%. Patients with original sperm motilities consistently greater than or equal to 30% had a higher cumulative pregnancy rate (62.9%) than patients with one or more motility less than 30% (22.0%, P = 0.0015, log-rank test). Patients with post-swim-up motilities consistently greater than or equal to 70% had a cumulative pregnancy rate (51.2%) significantly greater than patients inconsistent for this parameter (15.6%, P = 0.0116). Consistency of sperm motility is a useful parameter for defining the subpopulation of patients who would benefit from IUI.