Characteristics of donor semen and cervical mucus at the time of conception.

With freshly ejaculated semen from 15 donors, 1017 inseminations were performed in 247 women. One hundred conceptions were achieved. The degree of crystallization of the cervical mucus and the characteristics of the donor semen were examined at each insemination. One insemination only from one single ejaculate was performed in each cycle. This procedure made it possible to describe the quality of the cervical mucus and the sperm sample characteristics on each occasion of conception. The conception rate was significantly reduced (P less than 0.001) when the degree of crystallization of the cervical mucus was impaired. The conception rate was low when the sperm density was less than 20 million/ml, the percentage of abnormal sperm was above 50, and the degree of motility was graded 2 or less. The in vitro capillary sperm penetration test gave reliable information on the progressive motility of the sperm, showing a good correlation between penetration ability and conception rate.