Influence of semen and donor factors on the success rate of artificial insemination with frozen semen.

Influence of some semen and donor factors on the success rate of artificial insemination by frozen donor semen (AID) was examined. The percentage of insemination cycles resulting in pregnancy was significantly higher for women who became pregnant within six cycles (33%) when compared with all the women in the AID programme (14%). Therefore the influence of semen and donor characteristics on the fertilizing capacity of frozen semen was studied in women who became pregnant within the first six cycles of insemination in order to minimize any influence of non-semen effects such as recipient and insemination factors. Donors less than 20 years of age appear to have a better chance of obtaining a pregnancy. Semen stored for less than six months in liquid nitrogen had a similar proportion of insemination cycles resulting in pregnancy compared with semen stored for longer than six months. Conventional semen values were not correlated with fertility, and none of these values could be used accurately to predict the fertilizing capacity of frozen semen.