IMR Press / CEOG / Volume 43 / Issue 2 / DOI: 10.12891/ceog3290.2016

Clinical and Experimental Obstetrics & Gynecology (CEOG) is published by IMR Press from Volume 46 Issue 1 (2019). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on as a courtesy and upon agreement with S.O.G.

Open Access Original Research
The progesterone receptor antagonist mifepristone does not lower serum progesterone induced blocking factor (PIBF) in the presence of progesterone
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1 Cooper Institute for Reproductive and Hormonal Disorders, P.C., Mt. Laurel, NJ
2 Cooper Medical School of Rowan University, Camden, NJ (USA)
Clin. Exp. Obstet. Gynecol. 2016, 43(2), 189–191;
Published: 10 April 2016

Purpose: To determine if mifepristone can lower serum levels of a progesterone (P) induced immunomodulatory protein believed to be needed for the fetus to escape immune surveillance. Materials and Methods: A female volunteer had her serum P induced blocking factor (PIBF) increased by ingestion of oral micronized P. While remaining on P mifepristone, 200 mg/day was given for six days when another serum PIBF level was obtained. Results: The serum PIBF was 273 ng/ml after five days of oral micronized P. It increased further to 737 ng/ml despite taking six days of 200 mg mifepristone. Conclusions: The mechanism for inducing abortion by mifepristone does not seem to be related to decreasing serum levels of PIBF. This does not eliminate the possibility that the mechanism involves reducing the intracytoplasmic PIBF levels.
Selective progesterone receptor antagonists
Serum immunomodulatory protein
Progesterone induced blocking factor
Therapeutic abortion
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