Correlation of semen variables and pregnancy rates for donor insemination: a 15-year retrospective

To determine the validity of the criteria currently used to select fertile sperm donors.

Retrospective study of the outcome of donor insemination treatment cycles over a 15-year period.

The Reproductive Medicine Clinic of Prince Henry's Institute of Medical Research (formerly Medical Research Centre, Prince Henry's Hospital, South Melbourne, Victoria, Australia).

Couples (1,299) presented with severe male factor infertility (azoospermia or severe oligozoospermia) and were treated by donor insemination (10,796 treatment cycles) using cryopreserved semen from 292 normal healthy men aged between 18 and 46 years as sperm donors.

Semen characteristics, including volume, count, motility, motility index, normal morphology, live cells, and post-thaw motility, were analyzed by logistic regression analysis to determine which groups of factors were related independently and significantly to pregnancy rates.

The pregnancy rate for donor insemination was 8.9% per cycle. By logistic regression count, normal morphology, post-thaw motility (%), and post-thaw motility index together explained 28% of the variance of the pregnancy rates. Other factors, including prethaw motility characteristics (percent motility and motility index), donor age, weight, LH, FSH, and T levels, were not significant.

The standard parameters of sperm count, morphology, and post-thaw motility are the most important factors for the selection of highly fertile donors. As most of the variability in the pregnancy rates resulted from other undetermined factors related both to the donor and the recipient, it is suggested that the pragmatic approach of discarding donors after a reasonable number of treatment failures (20 to 50) should continue.