Effect of sperm dose on pregnancy rate from intrauterine insemination: a retrospective analysis.

Both the number of motile spermatozoa inseminated and the site of insemination have been correlated with the probability of pregnancy in patients inseminated with donor sperm cells from fertile men. Nevertheless, more data on the minimum sperm dose required to achieve a pregnancy are needed to understand this apparent relationship. We analyzed retrospectively 2280 cycles of intrauterine insemination to test the hypothesis that intrauterine insemination requires a minimum number of motile sperm cells to maximize the pregnancy rate. Our analysis of 1761 cycles of intrauterine insemination using from 200,000 to more than 200 million motile sperm cells showed no significant relationship between sperm dose and pregnancy rate.