Vaginal progesterone administration before ovulation induction with exogenous gonadotropins in polycystic ovarian syndrome.

We studied the value of vaginal progesterone (P4) in suppressing serum LH concentrations and restoring normal luteal phase serum LH concentrations before administration of exogenous gonadotropins in anovulatory women with the polycystic ovarian syndrome (PCOS). P4 (50 mg every 12 h) was administered by vaginal suppository to 9 women (18 cycles) for 14 days before ovulation induction with human menopausal gonadotropin (hMG) and hCG. Serum LH, FSH, estradiol, P4, and PRL levels were measured daily. A biphasic effect on LH secretion occurred during P4 administration. Peak serum LH levels occurred on day 5 (125% of basal levels; P less than 0.05) of vaginal P4 suppository use, followed by a progressive fall (P less than 0.05) to 79% of basal levels, but serum LH levels were still higher than those in normal women despite achieving physiological luteal phase P4 concentrations. Ovulation occurred in 56% of cycles after P4 and hMG/hCG treatment and in 65% of control cycles after hMG/hCG alone. In 7 women, serum LH was measured at 10-min intervals for 6 h before and after vaginal P4 administration for 10 days. LH pulse frequency decreased from 7.4 +/- 1.1 to 4.4 +/- 1.2 pulses/6 h (P less than 0.01), and LH pulse amplitude increased from 3.8 +/- 1.8 to 6.1 +/- 2.9 IU/L (P less than 0.01) after P4 administration. We conclude that vaginal P4 (50 mg every 12 h) 1) produces serum P4 concentrations within the normal range for the luteal phase of the menstrual cycle; 2) elevates serum LH, but not FSH, within 5 days; 3) decreases LH pulse frequency and increases LH pulse amplitude after 10 days, but does not normalize serum LH values; and 5) fails to improve the results of subsequent ovulation induction with exogenous gonadotropins in patients with PCOS.