Comparing Different Durations Of Progestrone Adminstration Before Embryo Transfer In Prog-rammed Thawed Cycles

INTRODUCTION Progesterone is a steroid hormone, which performs an essential function in the implantation process and maintenance of pregnancy. Optimal progesterone exposure is essential for a successful conception in HRT cycles. However, the current data is insufficient to determine the most ideal route, dose and duration of progesterone in HRT- FET cycle.Regarding the ideal duration of progesterone exposure before FET in HRT cycles, progesterone seems to have a critical role in determining the window of implantation which is confined to be a limited duration of endometrial receptivity. Receptivity of the endometrium is significantly decreased when the embryo is transferred before or after this limited period.Therefore determination of the duration of progesterone exposure before frozen embryo transfer is essential for increasing the success rate of ART.Monitoring serum progesterone has a significant role in embryo implantation and pregnancy maintenance. The aim of monitoring progesterone before FET is to perform rescue progesterone protocol if the serum progesterone level is low.