Minimal stimulation using gonadotropin combined with clomiphene citrate or letrozole for intrauterine insemination

To evaluate the efficacy of minimal stimulation using discretely administered gonadotropin combined with clomiphene citrate (CC) or letrozole (LTZ) for intrauterine insemination (IUI) cycles.

Total 257 IUI cycles from 158 infertile couples were assessed. A CC dose of 100 mg/day (n=126 cycles) or a LTZ dose of 5 mg/day (n=131 cycles) was administered on days 3-5 of the menstrual cycle for 5 days. Each group received human menopausal gonadotropin at a dose of 150 IU by two or three alternative day: CC combined with alternate-day regimen for 2 or 3 days (CC+300, n=37; CC+450, n=89) and LTZ combined with alternate-day regimen for 2 or 3 days (LTZ+300, n=36; LTZ+450, n=95).

The clinical pregnancy rate was comparable between the CC and LTZ groups (18.3% vs. 13.0%, p=0.243). The clinical pregnancy rate also showed no significant difference among the 4 groups (21.6% vs. 16.9% vs. 11.1% vs. 12.6%, p=0.507). The multiple pregnancy rate was significantly higher in LTZ compared to CC group (37.5% vs. 8.7%, p=0.028) and in the LTZ+450 compared to CC+450 group (50% vs. 13.3%, p=0.038). Overall, there were 15 cases of ovarian hyperstimulation syndrome (OHSS), with the prevalence being significantly lower in the LTZ compared to CC group (1.5% vs. 10.3%, p=0.003). OHSS was more prevalent in the CC+450 compared to the LTZ+450 group (12.4% vs. 1.1%, p=0.002).

Our findings suggest that minimal stimulation using two alternate-day gonadotropin with LTZ decreases the development of OHSS and multiple pregnancies, while maintaining comparable pregnancy rates in IUI cycles.