Does Serum Estradiol Prior to Progesterone Administration in Programmed Frozen Embryo Transfer Cycle Impacts Live Birth Rate: A Prospective Cohort Study.

Abstract

There is a paucity of data on the optimal threshold of oestradiol (E2) levels required for successful implantation as this is a valid question to be answered, considering that significant number of in vitro fertilisation cycles are deferred for FET cycles. The aim of this study is to investigate the serum E2 levels before starting exogenous progesterone in artificial autologous frozen thawed embryo transfers on pregnancy outcomes. This was a cohort study wherein clinical data of 213 artificial autologous programmed hormone-regulated frozen embryo transfer (HR-FET) cycles were collected. The HR-FET cycles were divided into three groups based on the E2 levels before starting progesterone: Group A: E2 ≤300 pg/mL, Group B: E2 301-500 pg/mL and Group C: E2 >500 pg/mL. After adequate endometrial stripe was appreciated by transvaginal ultrasonography, single blastocyst transfer was performed in all the cycles. The clinical pregnancy rate (CPR) in Groups A, B and C were 41.8%, 73.5% and 0.95%, respectively (P = 0.0001). The live birth rate (LBR) in Groups A, B and C was 18.1%, 62.2% and 0%, respectively (P = 0.0001). The miscarriage rate (MR) was significantly lower (15.3%) when E2 was between 301 and 500 pg/mL (P = 0.001). At both the extremes of serum E2 values, the rate of miscarriage increased. If serum E2 levels were ≤300 pg/mL or >500 pg/mL, the rate of miscarriage was 56.5% and 100%, respectively. Serum E2 levels in the range of 301-500 pg/mL before starting progesterone in programmed FET cycle are associated with an improved CPR and LBR and also decreased MR as compared to the extreme values of E2 ≤300 pg/mL or >500 pg/mL.