P-550 Comparison of progesterone levels according to the type of vaginal micronized progesterone used for luteal phase support in artificial-cycles for endometrial preparation in embryo transfer.

Abstract Study question Are there differences in the ongoing pregnancy rate (OPR) using Cyclogest® versus Progeffik® at a dose of 800 mg daily as luteal phase support? Summary answer The administration of Cyclogest® as luteal phase support shows higher ongoing pregnancy rates (OPR) in a cycle of hormone replacement therapy (HRT) with own oocytes What is known already The importance of serum progesterone levels around the time of embryo transfer in patients undergoing FET under artificial endometrial preparation has been well established; some studies have shown that optimizing serum progesterone levels on the day before, leads to an improvement in live birth rates (LBR). However, to date, no study has examined which vaginal preparation reports better serum progesterone levels and its impact on OPR. Study design, size, duration This prospective randomized clinical trial was performed between September 2019 and June 2022 and enrolled 490 patients scheduled for cryopreserved ET after an artificial endometrial preparation cycle with estradiol valerate and micronized vaginal progesterone. They were divided into two groups, those who used Progeffik® and others with Cyclogest® total dose of 800mg. SPLs were measured the day before (P + 4), the day of the transfer (P + 5) and the day of BHCG (P + 19) and compared the OPR. Participants/materials, setting, methods Patients between 18-40 years of age with BMI <30 and triple-layer endometrium > 7,5mm underwent transfer of one blastocysts with own oocytes. The study was carried out in the assisted human reproduction unit of the Virgen de Valme University Hospital (Seville). Ethical approval was granted and formed consent was obtained. The primary endpoint is to assess which vaginal progesterone preparation gives better ongoing pregnancy rates. Main results and the role of chance The 484 patients were randomized (1:1) into two groups. Progeffik was administered to 149 patient and Cuyclogest to 335 patient. The characteristics of the patients were comparable between groups with similar causes of fertility and type of IVF. Regarding the results of serum progesterone levels measured according to the type of micronized vaginal progesterone used to support the luteal phase, we obtained for day P + 4 (13,69 for Progeffik® vs 15.89 for Cyclogest®), while for day P + 5 (11.95 vs 17.69) and on day P + 19 (13.69 vs 15.41), the results obtained after the administration of Cyclogest® being significantly higher with a p-value of 0,01. When assessing the ongoing pregnancy rate, they were also significantly higher with the administration of Cyclogest® versus Progeffik® (59.7% vs 48.3%) with a p value of 0,024. Limitations, reasons for caution The newborm rate needs to be validated as it has not exceeded 9 months since the study. Wider implications of the findings This study demonstrates the statistically significant superiority of Cyclogest-type vaginal micronized progesterone administration over its competitor Progeffik used for luteal phase support, being a more convenient way of administration for women since it's simplicity. Trial registration number 0388-N-22