Comparison of live birth rates of different endometrial preparation protocols in frozen-thawed single euploid blastocyst transfer Cycles

OBJECTIVE: There has been increasing trend in the use of frozen embryo replacement (FER) cycles in recent years. Although various protocols have been used to prepare the endometrium during FER cycles, there is paucity of data for the best protocol particularly when tested blastocysts were transferred after trophectoderm biopsy. In the current study, we aimed to determine the best protocol after pre-implantation genetic testing for aneuploidy (PGT-A) in frozen-thawed cycles. METHOD: All patients undergoing FER cycle after PGT-A were scrutinized in Reproductive Endocrinology and Infertility Unit, Department of Obstetrics and Gynecology, Hacettepe University and Anatolia Women's Health and In-Vitro Fertilization Center between May-2015 and June-2017. Only patients tested via trophectoderm biopsy due to advanced maternal age (≥ 35 years) either on Day 5 or 6 were included. Nevertheless, cases for PGT due to monogenetic diseases and translocation were excluded. Of them, a total of 155 initial FER cycles were retrospectively identified and finally analyzed. Next generation sequencing (NGS) and array comparative genomic hybridization (aCGH) had been preferred for the detection of aneuploidy. The patients were stratified according to the protocol of FER as follows; artificial endometrial preparation (AC) with gonadotropin releasing hormone agonist (GnRHa) suppression (n = 113), natural cycle (NC) (n = 19), AC without GnRHa supression (n = 15) and oral contraceptive pill plus AC with GnRHa suppression (n = 8). Single euploid embryo transfer was performed in all cycles. Primary outcome was ongoing pregnancy/live birth rate per embryo transfer (ET). Secondary outcomes were implantation rate, clinical pregnancy rate per ET and miscarriage rate. RESULTS: In the context of demographic features, mean female/male age, female body mass index, number of previous cycles, duration of infertility and number of antral follicles were comparable. The total FSH dose used during ovarian stimulation, number of oocytes collected and number of 2-pronucleus embryos were also similar among all groups. Implantation, clinical pregnancy, biochemical pregnancy rates did not differ significantly between groups at all. The ongoing pregnancy/live birth rates were 46.9%, 52.6%, 49% and 62.5% in AC with GnRHa suppression, NC, AC without GnRHa suppression and OC plus AC with GnRHa suppression arms, respectively (p= 0.821). CONCLUSION: In patients undergoing FER cycle particularly after PGT-A, any of endometrial preparation protocol was superior in terms of ongoing pregnancy/live birth rate. However, those results should be confirmed with a randomized controlled trial with a larger sample size. KEYWORDS: IVF, FROZEN EMBRYO TRANSFER, ENDOMETRIAL PREPARATION, PREIMPLANTATION GENETIC TESTING FOR ANEUPLOIDY