EFFECTS OF LONG-TERM LOW-DOSE MIFEPRISTONE ON REPRODUCTIVE FUNCTION IN WOMEN

Low-dose antiprogestin administration has been proposed as a new contr aceptive modality to interference with endometrial receptivity without disturbing ovarian function. The effects of 1 mg/day mifepristone for 150 days on the menstrual cycle were assessed in 21 surgically steril ized women. The aim was to study each woman for one control cycle and during months 1, 3 and 5 of treatment. Ovulation, endometrial thicknes s, serum oestradiol and progesterone, urinary luteinizing hormone, end ometrial morphology and cervical mucus were assessed. Luteal phase pro gesterone concentrations were observed in 36 of the 60 treated months assessed and less frequently as treatment progressed. The bleeding pat tern was regular in most biphasic cycles, while prolonged interbleedin g intervals or no bleeding were associated with monophasic cycles. Alt ered endometrial morphology was found in all cases irrespective of the occurrence of luteal activity. Increased endometrial thickness and di lated glands were; observed in 25 and 34% respectively of the monophas ic cycles, Mifepristone, 1 mg/day, interferes with endometrial develop ment while allowing the occurrence of biphasic ovarian cycles and regu lar bleeding, However, it also prevents ovarian cyclicity in a high pr oportion of treated months, and this is associated with increased endo metrial growth in some women, which may be of concern.