Longer time interval between semen processing and intrauterine insemination does not affect pregnancy outcome.

OBJECTIVE: To study whether the pregnancy outcome of intrauterine insemination (IUI) is affected by a longer time interval between semen processing and insemination.

DESIGN: Retrospective cohort.

SETTING: Teaching hospital.

PATIENT(S): Couples with subfertility and an indication for IUI over a 10-year period.

INTERVENTION (S): Insemination performed the day after but within 24 hours of semen collection and processing (delayed insemination) compared with insemination performed immediately after sperm collection and processing (immediate insemination).

MAIN OUTCOME MEASURE(S): Ongoing pregnancy rate, defined as a pregnancy confirmed by ultrasound at 10 to 12 weeks of gestation.

RESULT(S): In total, 1,136 cycles were analyzed. In 77 of 547 couples (14%) an ongoing pregnancy occurred after delayed insemination, and in 77 of 589 couples (13%) an ongoing pregnancy occurred after immediate insemination. Both groups had similar baseline characteristics. After adjustment for confounders, there was no difference in the ongoing pregnancy rate between delayed as compared with immediate insemination (odds ratio 0.89; 95% confidence interval, 0.63-1.25).

CONCLUSION(S): There is no negative effect on pregnancy rate when IUI of processed sperm is delayed until the next day. This approach allows additional flexibility for couples when the male partner is not available on the day of ovulation, and it allows for a spread of workload in the laboratory.