Interrelationships Between Pituitary Gonadotrophins and Ovarian Steroids in Baboons During Continuous Intrauterine Progesterone Treatment

This study was designed to investigate possible menstrual cycle alterations brought about by an intrauterine device or by contraceptive levels of localized intrauterine progesterone in baboons. In one group of baboons having either an Intrauterine Progesterone Contraceptive System (IPCS) releasing 65 µg progesterone/day or a Lippes Loop in place, plasma luteinizing hormone (LH), follicle stimulating hormone (FSH). progesterone (P), and estradiol 17β (E2) were measured by radioimmunoassay during the menstrual cycle. In another group, only progesterone and estradiol were assayed to detect any quantitative difference in plasma progesterone with the two contraceptives. Results indicated no significant differences in hormone levels between control, Lippes Loop, or IPCS treated cycles. An apparent increase in plasma progesterone while the Lippes Loop was in place was not statistically significant.