[Differing response to GnRH antagonists in cycles of ovarian hyperstimulation plus intrauterine insemination]

To compare two flexible protocols of GnRHant in OH plus IUI vs a control group without GnRHant.

Randomized controlled trial 90 infertile patients were analyzed in 116 cycles of IUI. Cycles were randomized in 3 groups; group 1: started GnRHant when the leading follicle reached 14mm, group 2: when it reached 16mm and group 3: without GnRHant hormonal determinations were done during OH. Main outcomes were: premature LH raise incidence, premature luteinization (PL) and pregnancy rate per cycle.

Premature LH rise incidence was 2.6% (3 cycles) and PL 6% (7 cycles). Group 1 didn't present cycles with LH rise or PL, groups 2 and 3 presented LH rise in 3.1% and 1.8% and PL in 12.5% and 5.4% respectively. Pregnancy rate with GnRHant was 16.4% (95% IC 8.1-28.1) vs. 7.2% (95% le 2.0-17.5%) without GnRHant (group 3) (p = 0.16): groups 1 and 2 represented a pregnancy rate of 20.6% (95% IC 7.9-39.7) and 12.5% (95% IC 3.5-28.9%) respectively (p = 0.49). Mature follicles number reached meaning difference between all groups (p = 0.04) specially between groups 1 and 2 (p = 0.02).

A trend to elevate pregnancy rates was observed with GnRHant specially with when it was started when leading follicle reached 14 mm (p > 0.05). Starting GnRHant with 16 mm was not totally usefully to prevent PL.