TRIGGERING OF OVULATION IN HUMAN MENOPAUSAL GONADOTROPIN-STIMULATED CYCLES - COMPARISON BETWEEN INTRAVENOUSLY ADMINISTERED GONADOTROPIN-RELEASING-HORMONE (100-MU-G AND 500-MU-G), GNRH AGONIST (BUSERELIN, 500-MU-G) AND HUMAN CHORIONIC-GONADOTROPIN (10000-IU)

We studied the peri-ovulatory and luteal phases in 38 human menopausal gonadotrophin (HMG)-stimulated cycles, in which ovulation was trigger ed with four different i.v. bolus ovulation triggers: 100 mu g gonadot rophin-releasing hormone (GnRH; group A, n = 9), 500 mu g GnRH agonist (GnRHa; group B, n = 10), 10 000 IU human chorionic gonadotrophin (HC G; group C, n = 10) and 500 mu g GnRH (group D, n 9), Endogenous lutei nizing hormone (LH) surges occurred in all cycles of groups A, B and D . The rise was slowest but highest in group B (P < 0.0001) and lowest in group A, Although the to serum oestradiol values were similar in al l groups, day +8 oestradiol and day +4 and +8 progesterone concentrati ons were higher in group C (P < 0.05), At day +4 and +8, serum LH conc entrations were lowest (P < 0.01) but follicle stimulating hormone (FS H) concentrations were higher. Clinically, day +8 luteal scores showed a more conspicuous degree of ovarian hyperstimulation id the HCG grou p (P = 0.0292). Luteal insufficiency, defined as cycles with progester one concentrations of <8 ng/ml, occurred much more frequently in group s A, B and D than in group C (day +4: P < 0.0003; day +8: P < 0.0001), despite progesterone supplementation. Three pregnancies (one in group C and two in group D) and one moderate case of ovarian hyperstimulati on syndrome (OHSS) (in a nonconceptional group D cycle) occurred. Thes e findings show that (i) ovulation occurs and pregnancy can be achieve d following an endogenous LH surge induced by GnRH and its agonists, ( ii) a high frequency of luteal insufficiency occurs in such cycles eve n with luteal supplementation and (iii) OHSS cannot be totally prevent ed by this approach, although cycles with an endogenous LH surge in ge neral result in fewer subclinical signs of ovarian hyperstimulation.