Serum progesterone level and ongoing pregnancy rate following frozen-thawed embryo transfer after artificial endometrial preparation: a monocentric retrospective study.

INTRODUCTION: In some studies, early pregnancy loss (EPL) rate is higher with artificial cycle (AC) endometrial preparation for frozen-thawed embryo (FET) transfer than with other protocols, even though pregnancy rates are similar. An inadequate luteal phase support could explain these findings. The aim of this study was to compare, among the patients who had a pregnancy after FET with AC endometrial preparation, serum progesterone (PG) levels between those who experienced an EPL or an ongoing pregnancy. MATERIAL AND METHODS: A monocentric retrospective cohort study, conducted at a University affiliated fertility center, studied 130 FET cycles with AC endometrial preparation between June 2016 and July 2017. Serum PG rates were compared according to reproductive outcomes and to endometrial preparation protocol on day 10 or 12 after FET (PG0) according to the embryo stage, and every 48h in case of pregnancy (i.e. PG1; PG2). RESULTS: Among patients who had a pregnancy after FET with AC (n=33), serum PG levels were higher in case of an ongoing pregnancy than EPL, only significantly at PG1 (PG0 12.4ng/mL [7.5-14.6] vs 8.2ng/mL [6.0-13.0], p= 0.320; PG1 15.0 ng/mL [14.0-15.9] vs 8.5ng/mL [5.9-13.8], p= 0.048). DISCUSSION: We found that serum PG level was lower in women experiencing early pregnancy loss after FET with AC endometrial preparation, potentially reflecting a lack of appropriate luteal phase support with PG. A cycle AC test, monitoring serum PG levels after its steady state, could detect this lack of PG, allowing physicians to adapt PG supplementation.

[Progesterone and frozen-thawed embryo transfer after hormonal replacement therapy for endometrial preparation: An update on medical practices]. / Progestérone et transfert d'embryon congelé préparé par traitement hormonal substitutif : état des lieux des pratiques.

Frozen-thawed embryo transfer (FET) has recently become the most frequently performed ART procedure. Many protocols for endometrial preparation are used, without any evidence-based superiority of one protocol above the others. Most French fertility centers mainly use hormonal replacement treatment (HRT) for endometrial preparation for organizational reasons. According to some studies, early pregnancy losses rate is higher with HRT endometrial preparation for FET than with other protocols, leading to new insights in improving outcomes into ART centers. There is a lack of consensual guidelines regarding the use of HRT for FET: there are various protocols, with different dosages, duration and routes for progesterone (PG) prescription. To date, the vaginal route is the most popular around the world as it gives higher intra-uterine concentration of PG because of the first uterine pass. However, recent scientific publications have pointed the importance of PG measurement in order to detect a lack of PG supplementation. Whatever the route of administration, it seems that a significant proportion of patients do not reach adequate PG concentrations for successful implantation and ongoing pregnancy. Timing of the measurement and ideal serum PG rate to reach are yet to be defined. What treatment strategy to adopt according to the results is still under investigation. Individualization of PG doses and routes of administration could lead to a decrease in miscarriages and better outcome.