Effect of two antiprogestins (mifepristone and onapristone) on endometrial factors of potential importance for implantation

Objective: To investigate the effects of postovulatory administration of antiprogestins on endometrial factors that may be of importance for successful implantation. Design: Ten women were given 200 mg mifepristone and an additional 10 women 400 mg of onapristone 48 hours after the LH surge in urine (LH+2). Main Outcome Measure(s): Biopsies were assessed for histologic dating and the immunolocalization of[1] leukemia inhibitory factor, [2] 15-hydroxyprostaglandin dehydrogenase, and [3] the cell proliferation marker Ki 67. Hormonal measurements in blood and urine were used to monitor the effects on the ovarian cycle. Glycodelin (placental protein 14) concentrations were measured in blood taken on LH+12. Result(s): Treatment with antiprogestins retarded the development of secretory changes without affecting the length of the luteal phase. In addition, there was reduced immunostaining for 15-hydroxyprostaglandin dehydrogenase within glands and a significant reduction in serum levels of glycodelin. Reduced immunostaining for leukemia inhibitory factor also was apparent within glands in biopsies taken on LH+6 of the treatment cycle. Increased Ki 67 immunostaining was observed on both cycle days after treatment, consistent with P antagonism. Conclusion(s): Administration of mifepristone and onapristone adversely affects uterine receptivity. This adds further evidence to support their potential as a method of postovulatory fertility control. (C) 1997 by American Society for Reproductive Medicine.