Effect of postovulatory treatment with a luteinizing hormone-releasing hormone analog on the plasma level of progesterone in women.

(des-Gly-NH2(10),Pro-ethylamide9) luteinizing hormone-releasing hormone (LH-RH) (100 microgram) was administered subcutaneously once daily for 5 days during the postovulatory period in six women with regular menstrual cycles. Plasma levels of luteinizing hormone, follicle-stimulating hormone, estradiol, and progesterone were measured daily by radioimmunoassay from the ovulatory stage to menses. Suppression of plasma progesterone occurred during the treated luteal phase as compared with that of the control luteal phase. This finding suggests that repetitive, massive, endogenous luteinizing hormone or massive, exogenous, LH-RH itself during the early luteal phase of the cycle may induce functional luteolysis.