Effects of progesterone on luteinizing hormone release and estradiol/progesterone ratio in the luteal phase of women superovulated for in vitro fertilization and embryo transfer.

The present study extends the information on the effects of progesterone (P) on the luteinizing hormone (LH) release, and estradiol (E2)/P ratio in the luteal phase in women superovulated for in vitro fertilization and embryo transfer (IVF-ET). Two groups of 34 patients were induced for ovulation with clomiphene citrate and human menopausal gonadotropins. One group was given 25 mg P (Gesterol, Steris Laboratory Inc., Phoenix, AZ) at the time of, or 4 to 6 hours before human chorionic gonadotropin (hCG) administration and another group served as control (no Gesterol). Of the 34 patients in the Gesterol group, 10 had Gesterol 4 to 6 hours before the administration of hCG, 13 at the time of hCG, and 11 after the spontaneous LH surge. Administration of Gesterol 4 to 6 hours before hCG significantly increased the LH values (19.0 +/- 10.3) compared with those who had Gesterol at the time of hCG (6.8 +/- 2.8, P = 0.0006). A single dose of Gesterol (25 mg P) significantly reduced the E2/P ratio during the luteal phase (P = 0.0005). However, the outcome of IVF-ET was the same in the Gesterol and no-Gesterol groups. It is concluded that a significant increase in P triggers an LH surge and a single dose of Gesterol decreases E2/P ratio in the luteal phase of women after ovarian stimulation. The biochemical mechanisms are unclear.