Mild stimulation with clomiphene citrate in combination with recombinant follicle-stimulating hormone and gonadotropin-releasing hormone antagonist and its influence on serum estradiol level and pregnancy rate.

The mild ovarian stimulation protocol for fertilization (IVF) is carried out to minimize adverse side-effects as well as cost. While performing mild ovarian stimulation with a gonadotropin-releasing hormone (GnRH) antagonist, the pregnancy rate was examined in cases that exhibited a serum estradiol (E2) drop down. In this study, 174 patients who requested mild ovarian stimulation for IVF began clomiphene citrate on day 3 and recombinant follicle-stimulating hormone (FSH) on day 5 of their menstrual cycles. A GnRH antagonist was administered when the dominant follicle reached a diameter of 14 mm. Serum luteinizing hormone and estradiol were measured at the time of GnRH antagonist administration and at the time of human chorionic gonadotropin (hCG) injection. Pregnancy rates and implantation rates were compared between 24 cycles in which the E2 level fell at the time of hCG injection and 150 cycles in which it did not fall. The pregnancy rate in the cases in which the E2 level fell (25% decrease) at the time of hCG injection was significantly lower than it was in the cases in which it did not fall (16.7 41.0%). The implantation rate for the cases in which the E2 level fell was also lower than that of the control group (7.0 31.0%). There was no significant difference in the number of good-quality embryos between the two groups. When performing the mild ovarian stimulation protocol, serum E2 should be followed. It is prudent to avoid embryo transfer in the same cycle in cases that exhibit E2 drop down. (Reprod Med Biol 2008; : 85-89).