The effect of a high progesterone concentration before oocyte retrieval on the peri-implantation endometrium

A modified flexible GnRH antagonist protocol using antagonist early cessation and a gonadotropin step-down approach improves live birth rates in fresh cycles: a randomized controlled trial

STUDY QUESTION

Can pregnancy outcomes following fresh elective single embryo transfer (eSET) in gonadotropin-releasing hormone (GnRH) antagonist protocols increase using a gonadotropin (Gn) step-down approach with cessation of GnRH antagonist on the day of hCG administration (hCG day) in patients with normal ovarian response?

SUMMARY ANSWER

The modified GnRH antagonist protocol using the Gn step-down approach and cessation of GnRH antagonist on the hCG day is effective in improving live birth rates (LBRs) per fresh eSET cycle.

WHAT IS KNOWN ALREADY

Currently, there is no consensus on optimal GnRH antagonist regimens. Studies have shown that fresh GnRH antagonist cycles result in poorer pregnancy outcomes than the long GnRH agonist (GnRHa) protocol. Endometrial receptivity is a key factor that contributes to this phenomenon.

STUDY DESIGN, SIZE, DURATION

An open label randomized controlled trial (RCT) was performed between November 2021 and August 2022. There were 546 patients allocated to either the modified GnRH antagonist or the conventional antagonist protocol at a 1:1 ratio.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Both IVF and ICSI cycles were included, and the sperm samples used were either fresh or frozen from the partner, or from frozen donor ejaculates. The primary outcome was the LBRs per fresh SET cycle. Secondary outcomes included rates of implantation, clinical and ongoing pregnancy, miscarriage, and ovarian hyperstimulation syndrome (OHSS), as well as clinical outcomes of ovarian stimulation.

MAIN RESULTS AND THE ROLE OF CHANCE

Baseline demographic features were not significantly different between the two ovarian stimulation groups. However, in the intention-to-treat (ITT) population, the LBRs in the modified antagonist group were significantly higher than in the conventional group (38.1% [104/273] vs. 27.5% [75/273], relative risk 1.39 [95% CI, 1.09-1.77], P = 0.008). Using a per-protocol (PP) analysis which included all the patients who received an embryo transfer, the LBRs in the modified antagonist group were also significantly higher than in the conventional group (48.6% [103/212] vs. 36.8% [74/201], relative risk 1.32 [95% CI, 1.05-1.66], P = 0.016). The modified antagonist group achieved significantly higher implantation rates, and clinical and ongoing pregnancy rates than the conventional group in both the ITT and PP analyses (P < 0.05). The two groups did not show significant differences between the number of oocytes retrieved or mature oocytes, two-pronuclear zygote (2PN) rates, the number of embryos obtained, blastocyst progression and good-quality embryo rates, early miscarriage rates, or OHSS incidence rates (P > 0.05).

LIMITATIONS, REASONS FOR CAUTION

A limitation of our study was that the subjects were not blinded to the treatment allocation in the RCT trial. Only women under 40 years of age who had a good prognosis were included in the analysis. Therefore, use of the modified antagonist protocol in older patients with a low ovarian reserve remains to be investigated. In addition, the sample size for Day 5 elective SET was small, so larger trials will be required to strengthen these findings.

WIDER IMPLICATIONS OF THE FINDINGS

The modified GnRH antagonist protocol using the Gn step-down approach and cessation of GnRH antagonist on hCG day improved the LBRs per fresh eSET cycle in normal responders.

STUDY FUNDING/COMPETING INTEREST(S)

This project was funded by grant 2022YFC2702503 from the National Key Research & Development Program of China and grant 2021140 from the Beijing Health Promotion Association. The authors declare no conflicts of interest.

TRIAL REGISTRATION NUMBER

The RCT was registered in the Chinese Clinical Trial Registry; Study Number: ChiCTR2100053453.

TRIAL REGISTRATION DATE

21 November 2021.

DATE OF FIRST PATIENT’S ENROLLMENT

23 November 2021.

The late-follicular-phase progesterone to retrieved oocytes ratio in normal ovarian responders treated with an antagonist protocol can be used as an index for selecting an embryo transfer strategy and predicting the success rate: a retrospective large-scale study

Objective

To determine whether the late-follicular-phase progesterone to retrieved oocytes (P/O) ratio during in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) impacts pregnancy outcomes.

Design

12,874 cycles were retrospectively categorized into four groups according to the P/O ratio percentile, with divisions at the 25th, 50th and 75th percentiles.

Results

The clinical pregnancy and live birth rates of fresh cycle embryos in Group D were significantly lower than those in the other three groups (45.1% and 39.0%, 43.2% and 37.2%, 39.6% and 33.5%, 33.4% and 28.2% in Group A, B, C, D, respectively; both P < 0.008). Multivariate logistic regression analysis revealed a significant negative correlation between the P/O ratio and live birth, particularly when the P/O ratio was ≥0.22 (OR = 0.862, 95% CI [0.774-0.959], P = 0.006).

Conclusions

The P/O ratio has certain predictive value for IVF/ICSI pregnancy outcomes and can be used for decision-making decision regarding fresh embryo transfer.

Effect modification by developmental stage of embryos on the association between late follicular phase progesterone elevation and live birth in fresh transfers

BACKGROUND

Late follicular phase progesterone elevation (LFPE) during ovarian stimulation is associated with reduced live birth rates (LBRs) after cleavage-stage embryo transfer. However, due to better synchronization with a stimulated endometrium, prior studies shown that LFPE had no effect on transferring embryos at blastocyst stage. The study aim to exam whether the developmental stage of embryos and serum progesterone levels on the day of human chorionic gonadotropin (hCG) administration jointly affect the odds of live birth in fresh fresh IVF/intracytoplasmic sperm injection (ICSI) cycles.  METHODS: The single-center retrospective cohort study included a total of 4,471 fresh embryo transfer cycles with 2,342 at cleavage stage versus 2,129 at blastocyst stage. Patients underwent IVF/ICSI with ovarian stimulation in gonadotropin-releasing hormone antagonist protocol. The serum progesterone level was examined both as a continuous variable and as a categorical variable by quartiles. Analysis was performed using the generalized estimating equations framework and multivariate regression models.

RESULTS

LBRs were inversely associated with progesterone as a continuous variable on the day of hCG in both the cleavage-stage (crude OR 0.87, 95%CI 0.73-1.03; adjusted OR 0.80, 95% CI 0.65-0.98) and the blastocyst-stage (crude OR 0.66, 95%CI 0.56-0,78; adjusted OR 0.61, 95%CI 0.50-0.73) groups. The interaction testing was highly significant (P = 0.018) indicating an effect modifying role of stage of embryos transferred on the association of pregesterone values with the LBRs in fresh cycles. A similar pattern for a greater reduction in ORs for live birth in cycles with blastocysts transfer was also observed when progesterone was analyzed by interquartile ranges. The findings remained unchanged in subgroup analysis stratified by types of ovarian response.

CONCLUSIONS

In fresh cycles, detrimental effect of late follicular phase progesterone elevation on live birth was more prominent in blastocyst-stage group compared with that in clevaged-stage group.

The effect of the ratio of serum progesterone level to oocyte count on the day of IVF-ICSI injection on pregnancy outcomes in HCG cycles

BACKGROUND

There has been several discussion and debates regarding the possible setremental influence of elevated serum progesterone (SP) on the day of human chorionic gonadotropin (hCG) administration. Our study aims to assess progestron to oocyte rates for assessing CPR and live birth rate (LBR) in IVF cycles and review previous articles.

METHODS

In this prospective cohort study, women under ovulation induction through IVF-ICSI using the GnRH-antagonist protocol were studied. Five specific indicators were considered to assess pregnancy outcome. The statistical analysis was done using SPSS software.

RESULTS

In the present research, 78 patients underwent IVF. The cut-off points for each of the three parameters were 1.2 (with a sensitivity of 65.4% and a specificity of 54%), 6.5 (with a sensitivity of 73.1% and a specificity of 56%), and 0.16 (with a sensitivity of 65.4% and a specificity of 60%, respectively). Only the number of oocytes (area below the curve of 0.64) was able to predict clinical pregnancy. The cut-off point for this parameter was 6.5 (with a sensitivity of 74.1% and a specificity of 66%). On the other hand, none of the parameters were able to predict live birth.

CONCLUSIONS

The findings of this study should assist in the clinical management of patients with high SP on the day of HCG administration. We recommend, that the ratio of SP to oocyte is a useful parameter for refining the criteria of patients who have had embryo freezing of all embryos (by selective freezing) and subsequent transfer of frozen embryos.

Factors affecting clinical pregnancy in controlled ovarian hyperstimulation with GnRH-a long protocol: a retrospective cross-sectional study

This retrospective cross-sectional study was to investigate factors affecting clinical pregnancy in patients who received gonadotropin-releasing hormone agonist luteal phase long protocol (GnRH-a long protocol) and underwent fresh in-vitro fertilisation (IVF)/intracytoplasmic sperm injection (ICSI) embryo transfer cycle. One thousand five hundred and twenty-five patients who received GnRH-a long protocol and underwent fresh IVF/ICSI embryo transfer cycle were enrolled. The clinical pregnancy rate (63.1 vs. 22.4%, p < .05) and live birth rate (53.8 vs. 14.5%, p < .05) were significantly higher while the miscarriage rate (12.5 vs. 35.3%, p < .05) was significantly lower in the two embryo group than those in the one embryo group. The clinical pregnancy rate (48.5 vs. 64.1%, p < .05) and live birth rate (38.4 vs. 55.0%, p < .05) were significantly lower in patients older than 33.5 years than those in younger patients. The clinical pregnancy rate (52 and 60.6 vs. 79.7%, p < .05) and live birth rate (36 and 51.4 vs. 69.6%, p < .05) of the thin and mediate groups were significantly lower than those in the thick group, whereas the ectopic pregnancy rate (11.5 and 1.9 vs. 0%, p < .05) was significantly higher in the thin group than in the mediate and thick group. Multivariate logistic regression analysis showed that age (OR = 0.956, 95% CI [0.931, 0.982], p < .05), number of embryos transferred (OR = 2.491, 95% CI [1.670, 3.715], p < .05) and endometrial thickness on the transplantation day (OR = 1.124, 95% CI [1.067, 1.185], p < .05) were independent factors significantly associated with clinical pregnancy. In conclusion, endometrial thickness (>14.69 mm) on the day of transfer, two cleavage embryos transferred, and female age (≤33.5 years) are independent factors affecting clinical pregnancy outcomes in controlled ovarian hyperstimulation with GnRH-a long protocol for assisted conception. IMPACT STATEMENTWhat is already known on this subject? Fresh embryo transfer cycle with GnRH-a long protocol will result in a higher pregnancy rate in controlled ovarian hyperstimulation cycles.What do the results of this study add? Endometrial thickness on the day of transfer, number of embryos transferred, and female age were independent factors affecting clinical pregnancy outcomes.What are the implications of these findings for clinical practice and/or further research? When performing a fresh IVF/ICSI embryo transfer cycle with GnRH-a long protocol for ovulation induction, the independent affecting factors should be taken into consideration.

Towards an Improved Understanding of the Effects of Elevated Progesterone Levels on Human Endometrial Receptivity and Oocyte/Embryo Quality during Assisted Reproductive Technologies

Ovarian stimulation is an indispensable part of IVF and is employed to produce multiple ovarian follicles. In women who undergo ovarian stimulation with gonadotropins, supraphysiological levels of estradiol, as well as a premature rise in progesterone levels, can be seen on the day of hCG administration. These alterations in hormone levels are associated with reduced embryo implantation and pregnancy rates in IVF cycles with a fresh embryo transfer. This article aims to improve the reader’s understanding of the effects of elevated progesterone levels on human endometrial receptivity and oocyte/embryo quality. Based on current clinical data, it appears that the premature rise in progesterone levels exerts minimal or no effects on oocyte/embryo quality, while advancing the histological development of the secretory endometrium and displacing the window of implantation. These clinical findings strongly suggest that reduced implantation and pregnancy rates are the result of a negatively affected endometrium rather than poor oocyte/embryo quality. Understanding the potential negative impact of elevated progesterone levels on the endometrium is crucial to improving implantation rates following a fresh embryo transfer. Clinical studies conducted over the past three decades, many of which have been reviewed here, have greatly advanced our knowledge in this important area.

Effect of slightly elevated progesterone on hCG trigger day on clinical pregnancy rate in GnRH-ant IVF/ICSI cycles

Background

It was been agreed that significantly elevated progesterone level on the hCG trigger day have detrimental effect on clinical outcomes in IVF/ICSI cycles. However, few studies explored whether slightly elevated progesterone level also same impact on clinical outcomes.

Methods

We retrospectively studies the effect of slightly elevated progesterone level on outcomes of IVF/ICSI in GnRH-ant cycles. Propensity score matching was used to confounding variables. The women were divided into two groups according to the progesterone level: Group 1: < 1.0 ng/ml; Group 2: 1.0 ng/ml–1.5 ng/ml. Then compare the clinical pregnancy rate (CPR) between the two groups.

Result

A total of 847 IVF/ICSI cycles were included in the present study. The average CPR per transfer cycle was 51.7%. CPR of group 1 was 55.22%, significantly higher than that of group 2 (40.66%, P = 0.013). Progesterone level on the day of hCG injection was further evaluated at threshold increments of 0.1 ng/ml, and the CPR was decreased dramatically once the progesterone level higher than 1.4 ng/ml.

Conclusion

The slight elevation progesterone level on the hCG trigger day may have a negative effect on the clinical pregnancy in GnRH-ant cycles. In the case of progesterone > 1.4 ng/ml on the hCG injection day, freeze-all strategy was recommended.

Summary

The present retrospective study aimed to evaluate the effect of slightly elevated progesterone (1.0 ng/ml ~ 1.5 ng/ml) on outcomes of IVF/ICSI in GnRH-ant cycles. Slightly elevated progesterone level leaded to significant lower clinical pregnancy rate (CPR) that that of group with normal progesterone level (40.66% vs. 55.22%, P = 0.013). The CPR was decreased dramatically once the progesterone level higher than 1.4 ng/ml. So slightly elevated progesterone level on the trigger day may have a negative effect on the clinical pregnancy in GnRH-ant cycles. In the case of progesterone > 1.4 ng/ml on the hCG injection day, freeze-all strategy was recommended.

Comparison of the predictive value of progesterone-related indicators for pregnancy outcomes of women undergoing the short-acting GnRH agonist long protocol: a retrospective study

Background

There are many progesterone (P) elevation-related indicators for predicting pregnancy outcomes, including the serum P, P-to-oestradiol ratio (P/E₂), P-to-follicle index (PFI), and P-to-mature oocyte index (PMOI); however, due to inconsistencies in study populations and controlled ovarian hyperstimulation (COH) protocols among studies, these indicators are controversial. Moreover, no researchers have included these four commonly used indicators in one study to compare their predictive efficacies. The objective of this study was to compare the predictive value of P-related indicators for pregnancy outcomes of women undergoing the short-acting GnRH agonist long protocol.

Methods

A total of 612 infertile women undergoing IVF/ICSI were recruited for this study. Serum samples were obtained on the morning of HCG injection for serum P and E₂ measurements. Transvaginal ultrasound was performed to determine the follicle count (≥ 14 mm in diameter). The number of mature oocytes was observed in the embryo laboratory after oocyte retrieval.

Results

In cases of P < 2.5 ng/ml, there was no significant difference in the serum P level or P/E₂ between the pregnant group and the non-pregnant group. The PFI and PMOI of the pregnant group were significantly lower than those of the non-pregnant group. According to the stratified analysis of the ovarian response, only the PMI and PMOI of the pregnant women in the normal ovarian response group were lower than those of the non-pregnant women. To compare the predictive value of the PFI and PMOI in IVF/ICSI outcomes, the patients were divided into four groups. The good-quality embryo rate and clinical pregnancy rate were highest in Group A (low PFI and low PMOI) and lowest in Group D (high PFI and high PMOI). In the two groups with discordant PFI and PMOI, namely Group B (low PFI and high PMOI) and Group C (high PFI and low PMOI), the good-quality embryo rate and clinical pregnancy rate were not significantly different.

Conclusions

The PFI and PMOI had equal value in predicting clinical pregnancy outcomes in the normal ovarian response group undergoing the short-acting GnRH agonist long protocol. Each clinical centre can choose one of the indicators according to their actual situation in clinical practice and establish individual cut-off values for PFI and PMOI based on their own hormonal measurements.

Evidence from three cohort studies on the expression of MUC16 around the time of implantation suggests it is an inhibitor of implantation

PURPOSE

To examine the expression of MUC16 in the endometrium peri-implantation period in three different cohort studies.

METHODS

This was a retrospective observational cohort study. A total of 245 participants were recruited in three separate cohort studies: (1) women with recurrent miscarriage (n = 50) and fertile controls (n = 29); (2) women who had high (n = 20) or normal (n = 20) progesterone on the day of hCG trigger in ovarian stimulation cycle for IVF; and (3) women who did (n = 95) or did not (n = 31) conceive following frozen embryo transfer in HRT cycles. All subjects had archived endometrial samples precisely taken on LH+7 in natural cycles, or hCG+6 in ovarian stimulation cycles, or P+5 in HRT cycles. The H-score (median, range) of MUC16 in the luminal epithelium and glandular epithelium was determined by using immunohistochemistry.

RESULTS

The median (range) of H-score of MUC16 in the luminal epithelium (1) in women with recurrent pregnancy loss was 23.7 (0-300), which was significantly (P < 0.05) lower than that of 118.4 (7.7-300) in fertile controls; (2) in women with elevated progesterone on the day of hCG administration (147.8, 18.0-230.1), significantly (P < 0.05) higher than that of women with normal progesterone (61.0, 2.3-205.3); (3) in women who conceived (23.1, 0-250.3), significantly (P < 0.001) lower than that in women who did not conceive (58.4, 0-300).

CONCLUSION

The expression of MUC16 in all three cohort studies is consistent with it being an inhibitor of implantation.

Lipid Profiling of Peri-implantation Endometrium in Patients With Premature Progesterone Rise in the Late Follicular Phase

CONTEXT

Late follicular phase elevation in serum progesterone (P) during controlled ovarian hyperstimulation negatively affects the outcome of assisted reproductive technology by contributing to endometrial-embryo asynchrony. There are still no data on lipid metabolite alterations during this process.

OBJECTIVES

To investigate alterations in the lipid profile during the window of implantation in patients with premature P rise.

DESIGN

Lipidomic variations in the endometrium were evaluated by ultrahigh-performance liquid chromatography coupled with electrospray ionization high-resolution mass spectrometry.

SETTING

University assisted reproductive medicine unit.

PATIENTS OR OTHER PARTICIPANTS

Forty-three patients undergoing in vitro fertilization/intracytoplasmic sperm injection because of a tubal factor or male factor infertility were included in this study. The patients were divided into a high P group (P ≥ 1.5 ng/mL, 15 patients) and a normal P group (P < 1.5 ng/mL, 28 patients) on the day of human chorionic gonadotropin administration.

INTERVENTIONS

The endometrial tissues were obtained by Pipelle biopsy 7 days after human chorionic gonadotropin administration.

MAIN OUTCOME MEASURES

Alterations in lipid metabolites.

RESULTS

A total of 1026 ions were identified, and 25 lipids were significantly upregulated. The endometrial lipid profile was characterized by substantial increases in the concentrations of phosphatidylcholine, phosphatidylethanolamine, lysophosphatidylcholine, diacylglycerol, ceramide, phosphatidylinositol, and phosphatidylserine in patients with a premature P rise at the end of the follicular phase. The correlation analysis between P levels and lipids showed a stronger negative correlation between phosphatidylethanolamine or phosphatidylserine and P levels.

CONCLUSIONS

Premature P elevation disrupts the lipid homeostasis of the endometrium during the peri-implantation period. The altered lipid levels may impair endometrial receptivity and early embryo implantation.

A comparison of uterine natural killer cell density in the peri-implantation period between natural cycles and hormone replacement therapy cycles

PROBLEM

A reference range for uterine natural killer (uNK) cell density in the peri-implantation period has recently been established in natural cycles. However, it is uncertain whether the results can be applied to hormonal replacement therapy (HRT) cycles, used increasingly in frozen-thaw embryo replacement cycles and which is known to be capable of supporting implantation.

METHOD OF STUDY

A total of 183 women from two IVF centers participated in this study, including 75 women in natural cycles and 108 women in HRT cycles. All endometrial biopsies were collected precisely on the putative day of embryo implantation, namely 7 days after LH surge (LH+7) of the natural cycles or 5 days after initiation of progesterone (P+5) of the HRT cycles. Endometrial sections were immunostained for CD56 for uNK cells. Cell counting was performed by a standardized protocol, and results were expressed as percentage of positive uNK cells/total stromal cells.

RESULTS

There was no significant difference (P > 0.05) in uNK cell density between natural cycles (median 2.28%, range 0.99%-4.78%) and HRT cycles (median 2.55%, range 0.69%-5.02%) in women undergoing IVF-ET treatment on the putative day of blastocyst transfer. Using reference range from 1.2% to 4.5% for uNK cell density, there was no significant difference (P > 0.05) in high uNK cell density proportion between natural cycles (8%, 6/75) and HRT cycles (10.2%, 11/108).

CONCLUSION

The results indicated that the reference range for uNK cell density derived from natural cycles may apply to HRT cycles.

Does oral contraceptives pretreatment affect the pregnancy outcome in polycystic ovary syndrome women undergoing ART with GnRH agonist protocol?

This study aims to investigate whether oral contraceptive pills (OCP) pretreatment impairs pregnancy outcomes in polycystic ovary syndrome (PCOS) women undergoing GnRH agonist protocol. A total of 1025 couples underwent their first cycle of in vitro fertilization. Patients were divided into GnRH agonist protocol group (LP group) and OCP dual suppression GnRH agonist protocol group (OC-LP group). Logistic regressions were performed to estimate the risk factors affecting live birth following fresh embryo transfer between groups. Frozen-thawed embryos from the first oocyte retrieval cycle were replaced into uterus for women did not get live birth. Cumulative live birth rates between groups were compared by Kaplan-Meier survival analysis. Serum luteinizing hormone level, endometrial thickness, and live birth rate were significantly reduced in the OC-LP group in fresh cycle. Thinner endometrium, higher progesterone, and poorer embryo quality were independent risk factors for failure in getting live birth following fresh embryo transfer. However, cumulative live birth rate, medium embryo transfer attempts required to achieve live birth were comparable between groups. OCP pretreatment in GnRH agonist protocol does not seem to impair the pregnancy outcome when calculated by cumulative live birth rate in PCOS women.

Association between progesterone to number of mature oocytes index and live birth in GnRH antagonist protocols

RESEARCH QUESTION

What is the association between blood progesterone level alone, progesterone to mature oocytes index (PMOI) and IVF outcomes?

DESIGN

Clinical data from 960 couples undergoing their first fresh embryo transfer after an intracytoplasmic sperm injection attempt carried out between September 2012 and July 2017 were analysed. All patients underwent ovarian stimulation combining recombinant FSH and gonadotrophin releasing hormone antagonist. Progesterone was measured on the day on which ovulation was triggered. The PMOI was divided into four groups based on 25th, 50th and 75th percentiles, and live birth and implantation rates were compared between the groups.

RESULTS

A negative association was found between PMOI levels, live birth and implantation rates. When adjusting for age, ovarian stimulation index (OSI) and number of embryos transferred, the PMOI remained negatively correlated to live birth rate (LBR) (OR = 0.147 [0.031 to 0.701]; P = 0.0161), whereas total blood progesterone was no longer evident. Moreover, the LBR (18.5% versus 28.4%; P < 0.01) and implantation rate (12.4% versus 21.0%; P < 0.01) were significantly decreased only when PMOI was 0.167 ng/ml or greater, irrespective of progesterone concentration (< or ≥1.08 ng/ml). The opposite was not true, however. Similar PMOIs were recorded in the same patient from one attempt to the next, and were partially linked to basal FSH, anti-Müllerian hormone, antral follicle count and OSI.

CONCLUSIONS

PMOI seems to be more predictive than total progesterone level of IVF outcome and reflects the ability of embryos to develop as it is linked to the implantation rate.

The curious case of premature luteinization

PURPOSE

Premature luteinization (PL) affects 12.3-46.7% of fresh in vitro fertilization cycles, and there is accumulating evidence confirming its negative effect on success rates. However, despite its clinical significance, PL is poorly understood and defined. This narrative review aims to provide a fresh look at the phenomenon of PL by summarizing the existing evidence and re-evaluating fundamental issues.

METHODS

A thorough electronic search was conducted covering the period from 1978 until January 2018 in PubMed, Embase, and Medline databases, and references of relevant studies were cross-checked. Meeting proceedings of the European Society of Human Reproduction and Embryology and the American Society for Reproductive Medicine were also hand searched.

RESULTS

In the curious case of PL, one should go back to the beginning and re-consider every step of the way. The pathogenesis, definition, measurement methods, clinical implications, and management strategies are discussed in detail, highlighting controversies and offering "food for thought" for future directions.

CONCLUSIONS

Authors need to speak the same language when studying PL in order to facilitate comparisons. The terminology, progesterone cut-off, measurement methods and days of measurement should be standardized and globally accepted; otherwise, there can be no scientific dialog. Future research should focus on specific patient profiles that may require a tailored approach. Progesterone measurements throughout the follicular phase possibly depict the progesterone exposure better than an isolated measurement on the day of hCG. Adequately powered randomized controlled trials should confirm which the best prevention and management plan of PL is, before introducing any strategy into clinical practice.

The high concentration of progesterone is harmful for endometrial receptivity and decidualization

Progesterone is required for the establishment and maintenance of mammalian pregnancy and widely used for conservative treatment of luteal phase deficiency in clinics. However, there are limited solid evidences available for the optimal timing and dose of progesterone therapy, especially for the possible adverse effects on implantation and decidualization when progesterone is administrated empirically. In our study, mouse models were used to examine effects of excess progesterone on embryo implantation and decidualization. Our data indicate that excess progesterone is not only harmful for mouse implantation, but also impairs mouse decidualization. In excess progesterone-treated mice, the impaired LIF/STAT3 pathway and dysregulated endoplasmic reticulum stress may lead to the inhibition of embryo implantation and decidualization. It is possible that the decrease in birth weight of excess progesterone-treated mice is due to a compromised embryo implantation and decidualization. Furthermore, excess progesterone compromises in vitro decidualization of human endometrial stromal cells.

Effects of high progesterone level on the day of human chorionic gonadotrophin administration in in vitro fertilization cycles on epigenetic modification of endometrium in the peri-implantation period

OBJECTIVE

To investigate the effects of high P level on the day of hCG administration in IVF cycles on epigenetic modifications of endometrium in the peri-implantation period.

DESIGN

Retrospective study.

SETTING

University assisted reproductive unit.

PATIENT(S)

Forty patients were recruited: 20 women with high P levels were compared with 20 women with normal P levels.

INTERVENTION(S)

Endometrial tissues were collected 7 days after hCG administration in women with normal or high P levels on the day of hCG administration. Immunohistochemical staining of DNA methylation (5-methylcytosine, 5-mC), histone methylation (H3K4me2/3, H3K9me2, H3K27me3), and histone acetylation (H3K4ac, H3K9ac) was performed.

MAIN OUTCOME MEASURE(S)

A semiquantitative analysis was performed in the luminal epithelium, glandular epithelium, and stroma, separately. Correlations between P, estrogen levels, and epigenetic markers were compared.

RESULT(S)

In luminal epithelium, the expression of H3K9me2 in the high P group was significantly higher than that in the normal P group. In glandular epithelium, the expression of 5-mC, H3K9me2, and H3K9ac in the high P group was significantly higher than that in the normal P group. In stroma, the expression of H3K27me3 in the high P group was significantly higher than that in the normal P group. Expression of 5-mC in glandular epithelium, H3k9me2 in glandular and luminal epithelium, and H3K27me3 in stroma was significantly correlated with P levels. H3k9me2 in glandular epithelium was significantly correlated with estrogen levels.

CONCLUSION(S)

High P level on the day of hCG administration in IVF cycles affects epigenetic modifications in three compartments of endometrium in the peri-implantation period. The epigenetic markers' expression was mainly correlated with P level. The altered epigenetic modification status in the endometrium may disrupt the endometrial receptivity in women with high P on the day of hCG administration.

Deferred Frozen Embryo Transfer: What Benefits can be Expected from this Strategy in Patients with and without Endometriosis?

Progress with cryopreservation techniques have enabled development of the deferred frozen-thawed embryo transfer (DET) strategy as an alternative to relying on fresh embryo transfers.

With DET, the entire embryo cohort is cryopreserved, and embryo transfer is then performed in a subsequent cycle that takes place separately from the controlled ovarian stimulation (COS).

Initially developed to limit the risk of ovarian hyperstimulation syndrome that occurs with high responders, this strategy has been applied extensively with other populations in an effort to improve implantation rates. The assumption is that COS, which is essential for in vitro fertilization/intra cytoplasmic sperm injection (IVF/ICSI) procedures to obtain a multi-follicular development, could have a detrimental impact on the endometrium as a result of greatly elevated levels of steroids. It is currently not clear whether the DET strategy can be generally applied to all women requiring an IVF/ICSI procedure.

The objectives of this literature review regarding DET, were hence: (i) to present the scientific background that contributed to extensive adoption of this technique, (ii) to detail the pregnancy outcomes and potential obstetric and neonatal consequences, (iii) to report on its ability to prevent risks induced by COS, and (iv) to propose indications for the DET strategy in clinical practice.