The effects of timing of intrauterine insemination in relation to ovulation and the number of inseminations on cycle pregnancy rate in common infertility etiologies.

Background: Controlled ovarian hyperstimulation with intrauterine insemination (COH/IUI) is an established tool in medically assisted conception for many infertility factors. However, the proper timing of IUI after hCG trigger and the frequency of IUI are still debated. We aimed to examine the association between the cycle pregnancy rate (CPR) and: (i) single IUI timed at 36 ± 2 h post-hCG (pre- or post-ovulation) (ii) the number of IUI (single or double) for pre-ovulatory cases both aims in male, anovulatory and unexplained infertility.

Methods: The study included a total 1146 first-stimulated cycles in infertile couples due to male factor, anovulation or unexplained infertility. Cycles were stimulated by clomiphine citrate (CC) or sequential CC-hMG or hMG and monitored by transvaginal ultrasound. When the leading follicle reached ≥ 18 mm mean diameter, 10000 IU hCG was given to trigger ovulation and IUI was timed for 36 ± 2 h later. Semen was processed and ovulation was checked at the time of IUI. Post-ovulatory cases received single IUI, while pre-ovulatory cases were sequentially randomized to receive either single or double IUI. The end-point of the cycle was CPR.

Results: Overall CPR in the whole cohort was 10.1%. When ovulation was present before IUI, CPR was 11.7% compared with 6.7% when ovulation was absent [OR (95% CI): 1.85 (1.12-3.06), P = 0.015]. When this OR was computed according to infertility etiology, it was 1.26 (0.52-2.95) (P = 0.82) for male factor infertility and 2.24 (1.23-4.08) (P = 0.007) for non-male factor infertility. Comparing the CPR for double versus single IUI in pre-ovulatory cases, the OR for all cycles was 1.9 (0.76-4.7) (P = 0.22), but according to etiology, it was 4.667 (0.9-24.13) (P = 0.06) in male factor and 1.2 (0.43-3.33) (P = 0.779) for non-male factors.

Conclusions: Single IUI timed post-ovulation gives a better CPR when compared with single pre-ovulation IUI for non-male infertility, whereas for male factors, pre-ovulation, double IUI gives a better CPR when compared with single IUI.