The effect of 7 days of letrozole pretreatment combined with misoprostol on the expression of progesterone receptor and apoptotic factors of placental and decidual tissues from first-trimester abortion: a randomized controlled trial

Conference Theme: Past, Present and Future of Obstetrics and GynaecologyObjective: To determine the effect of letrozole on the expression of progesterone receptor and apoptosis in the placentae in first trimester abortion. Hypothesis: Letrozole-induced suppression of estradiol reduces progesterone receptor expression in the first trimester placenta. Methods: This is a double-blinded, randomized, placebo controlled trial. Twenty women requesting first trimester abortion with duration of pregnancy not more than 63 days were randomized to receive either letrozole 10 mg daily or placebo pretreatment for 7 days before administration of 400 micrograms vaginal misoprostol followed by suction abortion. Placental and decidual tissues were collected. Immunohistochemical staining for progesterone receptor and apoptotic markers (active caspase 3, caspase 3, Bcl2, CD95, fas ligand) were performed. TUNEL assay for apoptosis was performed in the samples of 4 women to confirm the findings from apoptotic markers. Results: One woman in the letrozole group was excluded from the analysis because she had spontaneous passage of abortus after taking letrozole, leaving 19 women (9 in the letrozole group, 10 in the placebo group) for analysis. There was no significant difference in the expression of progesterone receptor between the two groups. The H-scores for the progesterone receptor were 8.17 ± 2.67 (mean ± SD) in the letrozole group and 9.01 ± 2.82 in the placebo group (P = 0.36). The scorings of apoptotic markers and proportion of TUNEL assay for apoptosis were not significantly different between the two groups. No significant adverse effects were reported. Conclusion: We were unable to detect a difference in the expression of progesterone receptor and apoptotic markers in placental and decidual tissues after letrozole pretreatment for 7 days in first trimester abortion