['To elucidate the mode of action of chlormadinone acetate (CMA) in reducing dysmenorrheic pain by studying the effects of CMA and dexamethasone (DEX) on messenger RNA (mRNA) abundance of cyclo-oxygenase-2 (COX-2), annexin-1 (ANXA1), glucocorticoid receptor (GR), progesterone receptor (PR), and concentrations of prostaglandin F(2α) (PGF(2α)) and leukotrienes B(4) (LTB(4)) and C(4) (LTC(4)) in human endometrial explants.', 'Ex vivo study.', 'University hospital.', 'Fifteen premenopausal patients undergoing surgery for benign gynecologic disorders.', 'Endometrial explants were obtained by aspiration curettage and stimulated ex vivo with interleukin-1β before exposure to CMA or DEX; mRNA levels were determined via reverse transcription-quantitative real-time polymerase chain reaction, and concentrations of arachidonic acid metabolites by enzyme immunoassays.', 'Messenger RNA levels of COX-2, ANXA1, PR, and GR; concentrations of PGF(2α), LTB(4), and LTC(4) in endometrial explants treated with CMA or DEX.', 'In IL-1β-treated explants COX-2 mRNA and PGF(2α), concentrations were significantly down-regulated by CMA but not by DEX. Chlormadinone acetate did not affect mRNA abundance of ANXA1, PR, and GR.'] Does chlormadinone acetate suppress prostaglandin biosynthesis in human endometrial explants?