A total of 40 women who demonstrated premature luteinization (serum progesterone greater-than-or-equal-to 3.5 nmol/l (1.1 ng/ml) on or before the day of human chorionic gonadotrophin (HCG) administration) during ovarian stimulation with human menopausal gonadotrophins (HMG) were restimulated in 46 subsequent cycles after pituitary desensitization with the gonadotrophin-releasing hormone agonist (GnRHa, 1 mg), leuprolide acetate. Five women were treated with a double dose of agonist (2 mg) when premature luteinization was determined on the single dose protocol. In HMG-only cycles, a frank luteinizing hormone (LH) surge was detected in 30 cycles; 15 cycles were cancelled because of premature ovulation. In agonist cycles there were no cancellations, although 25 cycles demonstrated premature luteinization and in six cycles a frank LH surge was detected. Doubling the dose of the agonist did not prevent premature luteinization. Agonist cycles with and without premature luteinization did not differ in any in-vitro fertilization (IVF) outcome parameters (ampoules of gonadotrophins, day of HCG administration, peak oestradiol concentration, number of oocytes retrieved, fertilized, transferred or cryopreserved). We conclude that in patients who demonstrate premature luteinization in a gonadotrophin-only cycle, pituitary desensitization may not completely eliminate subtle luteinization or a frank LH surge.
