Evaluation of the ideal vaginal Progesterone effectiveness doses for luteal support in embryo thawing cycles after endometrial preparation without using the GnRh analogue

OBJECTIVE: Frozen-thawed embryo transfer (FET) cycles require the use of luteal phase support (LPS) for supporting implantation, endometrial and embryo maturity. Individualized LPS should be chosen according to the used endometrial preparation protocol. The aim of the study was to analyze the effectiveness of two different vaginal Progesterone doses for women who underwent FET cycle and the same endometrial preparation without using the GnRh analogue. PATIENTS AND METHODS: 607 women who underwent FET cycle were included in the study. 305 patients received luteal support with 600 mg/day vaginal Progesterone and 302 patients were treated with 800 mg/day of vaginal Progesterone. RESULTS: In the 800 mg/day group, the mean serum Progesterone concentration on the day of embryo transfer was higher than in the 600 mg group (14.00±6.18 ng/mL and 12.22±5.39, respectively, p < 0.001). Moreover, human chorionic gonadotrophin (hCG) positive and ongoing pregnancy rates were higher in the group of patients who received LPS with 800 mg/day of Progesterone than in the group of patients treated with 600 mg/day of Progesterone.  CONCLUSIONS: In patients undergoing FET cycles following endometrial preparation made without previously using the GnRh analogue, 800 mg doses of vaginal Progesterone as LPS improve reproductive outcomes.