Prerequisites for successful human sperm cryobanking: sperm quality and prefreezing holding time.

Frozen-thawed donor semen was used in artificial inseminations and in vitro fertilization programs. Semen accepted for donation was characterized (mean +/- SE) by sperm concentration of 150 +/- 18.6 x 10(6)/mL, normal morphology of 57% +/- 1.4%, good progressive motility at 1 hour of 57% +/- 1.0%, and post-thaw motility of 45% +/- 1.0%. Delay of the freezing process for greater than 1 hour after semen delivery caused a deleterious effect to the freezability of sperm. The average monthly fecundability for the 1st 6 months after inseminations was 13.6%. This value decreased dramatically to 2.6% from the 7th month onward. In 74 IVF/embryo transfer (ET) cycles, the fertilization rate was 55.3% +/- 3.8%, pregnancy rate (PR) per ET was 39.6%, and the PR per woman was 42.8%.