Daily insemination with cryopreserved donor semen is more effective than alternate-day insemination

A group of 177 consecutive treatment series using daily insemination has been compared with 211 consecutive treatment series using alternate-day insemination. The incidence of female infertility factors, the dropout rate per cycle, and the pregnancy rate per cycle were compared. No significant differences in distribution of female infertility factors or dropout rate were found. In contrast, the pregnancy rate by life-table analysis was significantly different between the two groups, the average monthly fecundability being 1.6 times as high in the daily insemination group. It is argued that after insemination, cryopreserved semen retains its fertilizing capacity no longer than 24 hours.