Impact of current and previous sperm findings on outcomes of intrauterine insemination.

Purpose: To examine the association between semen characteristics and outcomes of intrauterine insemination (IUI).

Methods: This retrospective analysis examined 1380 IUI procedures involving 421 couples. The association of clinical pregnancy with pre- and post-wash sperm characteristics was assessed.

Results: Pre- and post-wash sperm characteristics did not differ between IUI cycles that resulted in pregnancy and those that did not. When the motility of pre-wash sperm was below the normal range (<42%) established by the World Health Organization (WHO), the pregnancy rate was significantly lower. In the IUI cycles when post-wash sperm motility was below the WHO standard, pregnancy was not achieved. The frequency of improvement in post-wash sperm motility in repeated IUI cycles appeared to correlate with the success of future IUI cycles. At the fourth IUI cycle, pregnancy was not achieved unless the post-wash sperm motility was normal in at least two of three attempts. When post-wash sperm concentration was below the normal range, the woman's age did not affect the IUI outcomes.

Conclusions: Sperm motility above the lower limit of the WHO criteria in post-wash semen samples is an important factor in IUI outcomes.