Hormonal evaluation of the intrauterine progesterone contraceptive system.

Nine women were studied for one menstrual cycle prior to the insertion of an intrauterine progesterone contraceptive system (IPCS) delivering 65 microng progesterone/day into the uterus and again at 1 month after its insertion. Eight of these women were again studied between 6-8 months after the insertion of the IPCS. Luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol-17beta, progesterone, prolactin and relaxin were measured in each plasma sample. The data from each study were combined according to the day of the LH peak. Ovulation occurred in all the cycles studied in spite of an elevation in plasma estradiol-17beta and a depression of prolactin and relaxin immunoactivities at the 6-8 month follow up. Menstruations noted at the 6-8 month of use occurred while levels of estradiol-17beta and progesterone were elevated.