The effect of halving the standard dose of cryopreserved semen for donor insemination: a controlled study of conception rates.

Employing a common standard technique of intra-cervical insemination from straws of cryopreserved donor semen, a volume of 0.25 ml of 0.5 ml was inseminated in alternate cycles to determine if the lower volume could be used without a decrease in the conception rate. A total of 177 women were recruited and received a median of four cycles of treatment. Of these, 90 women became pregnant, 47 with 0.5 ml and 43 with 0.25 ml inseminations. The conception rates were identical for both volumes in the first nine cycles of treatment and the cumulative rates were 57.7 and 59.3%, respectively. Subsequently more pregnancies were achieved with 0.5 ml than 0.25 ml semen (nine pregnancies in 73 further cycles versus three pregnancies in 68 cycles, respectively), although the difference was not statistically significant. There were no significant differences in the women's ages, luteinizing hormone, follicle stimulating hormone, progesterone, mucus quality, mucus pH, parity or partner's diagnosis between those women who became pregnant and those who failed to conceive with either insemination dose. We conclude that the volume of semen inseminated into the cervical canal without a cervical cap can be decreased to 0.25 ml without an adverse effect on the conception rate at least in the first 9 months of treatment. This will allow more effective use to be made of valuable screened and quarantined cryopreserved semen.