Similar endometrial development in oocyte donors treated with either high- or standard-dose GnRH antagonist compared to treatment with a GnRH agonist or in natural cycles

Ovarian stimulation protocols: impact on oocyte and endometrial quality and function

Ovarian stimulation (OS) truly is an art. There exists a myriad of protocols used to achieve the same goal: stimulating the ovaries to produce more than one mature oocyte to improve the chance of a live birth. However, considerable debate remains as to whether OS impacts oocyte and endometrial quality to affect in vitro fertilization outcomes. Although "more is better" has long been considered the best approach for oocyte retrieval, this review challenges that notion by examining the influence of stimulation on oocyte quality. Likewise, improved outcomes after frozen blastocyst transfer suggest that OS perturbs endometrial preparation and/or receptivity, although correlating changes with implantation success remains a challenge. Therefore, the focus of this review is to summarize our current understanding of perturbations in human oocyte quality and endometrial function induced by exogenous hormone administration. We highlight the need for further research to identify more appropriate markers of oocyte developmental competence as well as those that define the roles of the endometrium in the success of assisted reproductive technology.

Does HCG and LH supplementation during ovarian stimulation improve clinical outcome? A evaluation of 30 years of clinical research

This review evaluates the effect of HCG and LH supplementation during ovarian stimulation. Controlled trials were divided into four groups comparing the treatment effect of recombinant FSH (r-FSH) with urinary FSH (u-FSH), with human menopausal gonadotrophin (HMG), with r-FSH + recombinant LH (r-LH) and with rFSH + recombinant HCG (r-HCG). First r-FSH seemed to be more potent than u-FSH in downregulated women, which translated into more follicles and oocytes. In line, numerous trials comparing HMG (containing u-FSH + u-HCG) with r-FSH demonstrated that HMG recruited fewer follicles, thus providing fewer oocytes but resulted in slightly higher pregnancy rates after a first fresh embryo transfer. The latter may be explained by the higher potency of r-FSH resulting in more and higher premature progesterone rises. Prospective trials addressing r-FSH + r-LH compared with r-FSH could not demonstrate any difference in pregnancy rates in normal or poor responders. A placebo-controlled trial of r-HCG added to a fixed daily r-FSH dose revealed that r-HCG inhibited the growth of intermediate follicles, resulting in fewer oocytes, fewer embryos and lower pregnancy rates. In conclusion, the beneficial effect of HCG and LH supplementation on clinical outcome has never been definitely proven for any of the combined gonadotrophin products.

Global research trends in endometrial receptivity from 2000 to 2024: bibliometric analysis

Background

In recent years, extensive research has been conducted on endometrial receptivity (ER), with rapidly evolving research hotspots and trends. Our study aimed to explore the development of ER research from 2000 to the present and provide insights for future endeavors.

Materials and methods

Relevant research publications on ER from 2000 to 2024 were retrieved from the Web of Science Core Collection (WOSCC) database. CiteSpace, VOSviewer and Excel tools were employed to conduct the bibliometric analysis.

Results

A total of 3,354 articles were analyzed, revealing an overall upward trend in annual publication numbers, signifying the increasing attractiveness and research value of this field. Globally, China led with a notable advantage of 1,030 publications, followed by the United States (650) and Spain (251), constituting the first tier of international research. Valencia University topped the list of institutions with 108 publications, closely followed by Shanghai Jiao Tong University with 87. Fertility and Sterility (IF6.6, Q1) is the one with the largest number of publications, accounting for 7.96% of the total publications. The three most co-cited journals were Fertility and Sterility, Biology of Reproduction, and Human Reproduction. A co-citation reference analysis revealed that ER research can be categorized into ten major subfields, including embryo implantation, frozen embryo transfer, integrins, recurrent implantation failure, intrauterine adhesions, etc. Since 2020, the keywords with the strongest citation bursts include repeated implantation failure and frozen.

Conclusion

This study employs bibliometric analysis to offer researchers in the field of ER a comprehensive perspective. Since 2000, there has been a remarkable surge in the number of publications in the ER research field. These studies primarily concentrate on delving into the pathophysiological mechanisms of ER, with the primary objective of enhancing clinical pregnancy rates and live birth rates, benefiting more infertile patients. Currently, addressing the ER issues in patients with recurrent implantation failure represents the forefront of research. The primary treatment approaches currently in use involve optimizing embryo transfer timing and employing innovative strategies such as immunotherapy. These cutting-edge analyses not only provide new insights into the treatment of ER but also offer researchers fresh research directions, and staying abreast of the latest trends and advancements in the field.

Expression profile analysis of LncRNAs and mRNAs in pre-receptive endometrium of women with polycystic ovary syndrome undergoing in vitro fertilization-embryo transfer

BACKGROUND

To compare the expression levels of long non-coding RNA (lncRNA) and messenger RNA (mRNA) in pre-receptive endometrium between patients with Polycystic Ovary Syndrome (PCOS)and normal ovulation undergoing in vitro fertilization-embryo transfer (IVF-ET).

METHODS

Endometrial tissues were collected with endometrial vacuum curette in pre-receptive phase (3 days after oocytes retrieval) from PCOS and control groups. LncRNAs and mRNAs of endometrium were identified via RNA sequencing and alignments. A subset of 9 differentially expressed lncRNAs and 11 mRNAs were validated by quantitative reverse transcription polymerase chain reaction(qRT-PCR)in 22 PCOS patients and 18 ovulation patients. The function of mRNAs with differential expression patterns were explored using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG).

RESULTS

We found out 687 up-regulated and 680 down-regulated mRNAs, as well as 345 up-regulated and 63 down-regulated lncRNAs in the PCOS patients in contrast to normal ovulation patients. qRT-PCR was used to detect the expression of 11 mRNAs, and validated that the expression of these 6 mRNAs CXCR4, RABL6, OPN3, SYBU, IDH1, NOP10 were significantly elevated among PCOS patients, and the expression of ZEB1 was significantly decreased. qRT-PCR was performed to detect the expression of 9 lncRNAs, and validated that the expression of these 7 lncRNAs IDH1-AS1, PCAT14, FTX, DANCR, PRKCQ-AS1, SNHG8, TPT1-AS1 were significantly enhanced among PCOS patients. Bioinformatics analysis showed that differentially expressed genes (DEGs) involved KEGG pathway were tyrosine metabolism, PI3K-Akt pathway, metabolic pathway, Jak-STAT pathway, pyruvate metabolism, protein processing in endoplasmic reticulum, oxidative phosphorylation and proteasome. The up-regulation of GO classification was involved in ATP metabolic process, oxidative phosphorylation, RNA catabolic process, and down-regulation of GO classification was response to corticosteroid, steroid hormone, and T cell activation.

CONCLUSION

Our results determined the characteristics and expression profile of endometrial lncRNAs and mRNAs in PCOS patients in pre-receptive phase, which is the day 3 after oocytes retrival. The possible pathways and related genes of endometrial receptivity disorders were found, and those lncRNAs may be developed as a predictive biomarker of endometrium in pre-receptive phase.

Conventional GnRH antagonist protocols versus long GnRH agonist protocol in IVF/ICSI cycles of polycystic ovary syndrome women: a systematic review and meta-analysis

Gonadotropin-releasing hormone (GnRH) analogues are commonly used in clinical practice to prevent premature luteinizing hormone (LH) surge during In-Vitro Fertilization/ Intra-Cytoplasmic Sperm Injection (IVF/ICSI) cycles. This review aimed to summarize the available evidence comparing the effects of conventional GnRH antagonist protocols, the most commonly used GnRH antagonist protocols, and GnRH agonist protocols on IVF/ICSI outcomes in women with polycystic ovary syndrome (PCOS). A comprehensive electronic search was carried out in Pubmed, Cochrane CENTRAL, Scopus, Web of Science, CINAHL, TRIP, ClinicalTrials.gov and ISRCTN registry from inception until 24 November 2020 without any language or date restrictions. In addition, reference lists of eligible studies and previous meta-analyses were hand-searched to identify relevant studies. Eligible randomized controlled trials were those designed to compare the effects of conventional GnRH antagonist protocols and GnRH agonist protocols on IVF/ICSI outcomes in PCOS subjects. The Cochrane ROB 2.0 tool was used to assess the risk of bias of each study, and the GRADE assessment was used to evaluate the overall quality of evidence. Data synthesis and analyses were done using Review Manager 5.3 with the assistance of Revman Web. A random-effects model was used for all meta-analysis. Dichotomous outcomes were reported as Relative Risk (RR) and continuous outcomes as Weighted Mean Difference (WMD), both with 95% CIs. The primary outcomes were Live birth rate, Ongoing pregnancy rate, and Ovarian hyperstimulation syndrome (OHSS) rate. Other IVF outcomes were considered secondary outcomes. We included ten studies with 1214 randomized PCOS women. Using GnRH antagonist protocols led to a significantly lower OHSS rate (RR = 0.58; 95% CI: [0.44 to 0.77], P = 0.0002), shorter stimulation duration (WMD = - 0.91; 95% CI: [-1.45 to - 0.37] day, P = 0.0009), lower gonadotropin consumption (WMD = - 221.36; 95% CI: [- 332.28 to - 110.45] IU, P < 0.0001), lower E2 levels on hCG day (WMD = - 259.21; 95% CI: [- 485.81 to - 32.60] pg/ml, P = 0.02), thinner endometrial thickness on hCG day (WMD = - 0.73; 95% CI: [- 1.17 to - 0.29] mm, P = 0.001), and lower number of retrieved oocytes (WMD = - 1.82; 95% CI: [- 3.48 to - 0.15] oocytes, P = 0.03). However, no significant differences in live birth rate, ongoing pregnancy rate, clinical pregnancy rate, multiple pregnancy rate, miscarriage rate and cycle cancellation rate were seen between the GnRH antagonist protocols and the long GnRH agonist one. Although more cycles were cancelled due to poor ovarian response in the GnRH antagonist protocol (RR = 4.63; 95% CI: [1.49 to 14.41], P = 0.008), similar rates of cancellation due to risk of OHSS were noticed in both groups. The differences in IVF/ICSI outcomes may arise from the different patterns of gonadotropins suppression that the GnRH analogues exhibit during the early follicular phase of IVF/ICSI cycles and the divergent direct impacts of these analogues on ovaries and endometrial receptivity. The main evidence limitation was Imprecision. Conventional GnRH antagonist protocols represent a safer and more cost-effective treatment choice for PCOS women undergoing IVF/ICSI cycles than the standard long GnRH agonist protocol without compromising the IVF/ICSI clinical outcomes. The study had no sources of financial support and was prospectively registered at PROSPERO (International Prospective Register of Systematic Reviews) under registration number (CRD42021242476).

When Should We Freeze Embryos? Current Data for Fresh and Frozen Embryo Replacement IVF Cycles

Recent years have seen a dramatic rise in the number of frozen-thawed embryo replacement (FER) cycles. Along with the advances in embryo cryopreservation techniques, the optimization of endometrial receptivity has resulted in outcomes for FER that are similar to fresh embryo transfer. However, the question of whether the Freeze all strategy is for all is nowadays a hot topic. This review addresses this issue and describes current evidence based on randomized controlled trials and observational studies. To date, it is reasonable to perform FER in cases with a clear indication for the benefits of such strategy including impending ovarian hyperstimulation syndrome (OHSS) or preimplantation genetic testing for aneuploidy (PGT-A); however, this strategy does not fit for all. This review analyses the pros and cons of the freeze all strategy highlighting the need to follow a personalized plan in embryo transfer, avoiding a freeze all methodology for all patients in an unselected manner.

The proliferative phase endometrium in IVF/ICSI: an in-cycle molecular analysis predictive of the outcome following fresh embryo transfer

STUDY QUESTION

Does an early proliferative phase endometrial biopsy harvested during ovarian stimulation harbour information predictive of the outcome following fresh embryo transfer (ET) in that same cycle?

SUMMARY ANSWER

Transcriptome analysis of the whole-tissue endometrium did not reveal significant differential gene expression (DGE) in relation to the outcome; however, the secretome profile of isolated, cultured and in vitro decidualized endometrial stromal cells (EnSCs) varied significantly between patients who had a live birth compared to those with an implantation failure following fresh ET in the same cycle as the biopsy.

WHAT IS KNOWN ALREADY

In the majority of endometrial receptivity research protocols, biopsies are harvested during the window of implantation (WOI). This, however, precludes ET in that same cycle, which is preferable as the endometrium has been shown to adapt over time. Endometrial biopsies taken during ovarian stimulation have been reported not to harm the chances of implantation, and in such biopsies DGE has been observed between women who achieve pregnancy versus those who do not. The impact of the endometrial proliferative phase on human embryo implantation remains unclear, but deserves further attention, especially since in luteal phase endometrial biopsies, a transcriptional signature predictive for repeated implantation failure has been associated with reduced cell proliferation, possibly indicating proliferative phase involvement. Isolation, culture and in vitro decidualization (IVD) of EnSCs is a frequently applied basic research technique to assess endometrial functioning, and a disordered EnSC secretome has previously been linked with failed implantation.

STUDY DESIGN, SIZE, DURATION

This study was nested in a randomized controlled trial (RCT) investigating the effect of endometrial scratching during the early follicular phase of ovarian stimulation on clinical pregnancy rates after IVF/ICSI. Of the 96 endometrial biopsies available, after eliminating those without fresh ET and after extensive matching in order to minimize the risk of potential confounding, 18 samples were retained to study two clinical groups: nine biopsies of patients with a live birth versus nine biopsies of patients with an implantation failure, both following fresh ET performed in the same cycle as the biopsy. We studied the proliferative endometrium by analysing its transcriptome and by isolating, culturing and decidualizing EnSCs in vitro. We applied this latter technique for the first time on proliferative endometrial biopsies obtained during ovarian stimulation for in-cycle outcome prediction, in an attempt to overcome inter-cycle variability.

PARTICIPANTS/MATERIALS, SETTING, METHODS

RNA-sequencing was performed for 18 individual whole-tissue endometrial biopsies on an Illumina HiSeq1500 machine. DGE was analysed three times using different approaches (DESeq2, EdgeR and the Wilcoxon rank-sum test, all in R). EnSC isolation and IVD was performed (for 2 and 4 days) for a subset of nine samples, after which media from undifferentiated and decidualized cultures were harvested, stored at -80°C and later assayed for 45 cytokines using a multiplex suspension bead immunoassay. The analysis was performed by partial least squares regression modelling.

MAIN RESULTS AND THE ROLE OF CHANCE

After correction for multiple hypothesis testing, DGE analysis revealed no significant differences between endometrial samples from patients who had a live birth and those with an implantation failure following fresh ET. However secretome analysis after EnSC isolation and culture, showed two distinct clusters that clearly corresponded to the two clinical groups. Upon IVD, the secretome profiles shifted from that of undifferentiated cells but the difference between the two clinical groups remained yet were muted, suggesting convergence of cytokine profiles after decidualization.

LIMITATIONS, REASONS FOR CAUTION

Caution is warranted due to the limited sample size of the study and the in vitro nature of the EnSC experiment. Validation on a larger scale is necessary, however, hard to fulfil given the very limited availability of in-cycle proliferative endometrial biopsies outside a RCT setting.

WIDER IMPLICATIONS OF THE FINDINGS

These data support the hypothesis that the endometrium should be assessed not only during the WOI and that certain endometrial dysfunctionalities can probably be detected early in a cycle by making use of the proliferative phase. This insight opens new horizons for the development of endometrial tests, whether diagnostic or predictive of IVF/ICSI treatment outcome.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by Fonds Wetenschappelijk Onderzoek (FWO, Flanders, Belgium, 11M9415N, 1 524 417N), Wetenschappelijk Fonds Willy Gepts (WFWG G160, Universitair Ziekenhuis Brussel, Belgium) and the National Medicine Research Council (NMRC/CG/M003/2017, Singapore). There are no conflicts of interests.

TRIAL REGISTRATION NUMBER

NCT02061228.

Endometrial Receptivity Analysis (ERA): data versus opinions

This article summarises and contextualises the accumulated basic and clinical data on the ERA test and addresses specific comments and opinions presented by the opponent as part of an invited debate. Progress in medicine depends on new technologies and concepts that translate to practice to solve long-standing problems. In a key example, combining RNA sequencing data (transcriptomics) with artificial intelligence (AI) led to a clinical revolution in personalising disease diagnosis and fostered the concept of precision medicine. The reproductive field is no exception. Translation of endometrial transcriptomics to the clinic yielded an objective definition of the limited time period during which the maternal endometrium is receptive to an embryo, known as the window of implantation (WOI). The WOI is induced by the presence of exogenous and/or endogenous progesterone (P) after proper oestradiol (E2) priming. The window lasts 30-36 hours and, depending on the patient, occurs between LH + 6 and LH + 9 in natural cycles or between P + 4 and P + 7 in hormonal replacement therapy (HRT) cycles. In approximately 30% of IVF cycles in which embryo transfer is performed blindly, the WOI is displaced and embryo-endometrial synchrony is not achieved. Extending this application of endometrial transcriptomics, the endometrial receptivity analysis (ERA) test couples next-generation sequencing (NGS) to a computational predictor to identify transcriptomic signatures for each endometrial stage: proliferative (PRO), pre-receptive (PRE), receptive (R) and post-receptive (POST). In this way, personalised embryo transfer (pET) may be possible by synchronising embryo transfer with each patient's WOI. Data are the only way to confront arguments sustained in opinions and/or misleading concepts; it is up to the reader to make their own conclusions regarding its clinical utility.

Identifying biomarkers for predicting successful embryo implantation: applying single to multi-OMICs to improve reproductive outcomes

BACKGROUND

Successful embryo implantation is a complex process that requires the coordination of a series of events, involving both the embryo and the maternal endometrium. Key to this process is the intricate cascade of molecular mechanisms regulated by endocrine, paracrine and autocrine modulators of embryonic and maternal origin. Despite significant progress in ART, implantation failure still affects numerous infertile couples worldwide and fewer than 10% of embryos successfully implant. Improved selection of both the viable embryos and the optimal endometrial phenotype for transfer remains crucial to enhancing implantation chances. However, both classical morphological embryo selection and new strategies incorporated into clinical practice, such as embryonic genetic analysis, morphokinetics or ultrasound endometrial dating, remain insufficient to predict successful implantation. Additionally, no techniques are widely applied to analyse molecular signals involved in the embryo-uterine interaction. More reliable biological markers to predict embryo and uterine reproductive competence are needed to improve pregnancy outcomes. Recent years have seen a trend towards 'omics' methods, which enable the assessment of complete endometrial and embryonic molecular profiles during implantation. Omics have advanced our knowledge of the implantation process, identifying potential but rarely implemented biomarkers of successful implantation.

OBJECTIVE AND RATIONALE

Differences between the findings of published omics studies, and perhaps because embryonic and endometrial molecular signatures were often not investigated jointly, have prevented firm conclusions being reached. A timely review summarizing omics studies on the molecular determinants of human implantation in both the embryo and the endometrium will help facilitate integrative and reliable omics approaches to enhance ART outcomes.

SEARCH METHODS

In order to provide a comprehensive review of the literature published up to September 2019, Medline databases were searched using keywords pertaining to omics, including 'transcriptome', 'proteome', 'secretome', 'metabolome' and 'expression profiles', combined with terms related to implantation, such as 'endometrial receptivity', 'embryo viability' and 'embryo implantation'. No language restrictions were imposed. References from articles were also used for additional literature.

OUTCOMES

Here we provide a complete summary of the major achievements in human implantation research supplied by omics approaches, highlighting their potential to improve reproductive outcomes while fully elucidating the implantation mechanism. The review highlights the existence of discrepancies among the postulated biomarkers from studies on embryo viability or endometrial receptivity, even using the same omic analysis.

WIDER IMPLICATIONS

Despite the huge amount of biomarker information provided by omics, we still do not have enough evidence to link data from all omics with an implantation outcome. However, in the foreseeable future, application of minimally or non-invasive omics tools, together with a more integrative interpretation of uniformly collected data, will help to overcome the difficulties for clinical implementation of omics tools. Omics assays of the embryo and endometrium are being proposed or already being used as diagnostic tools for personalised single-embryo transfer in the most favourable endometrial environment, avoiding the risk of multiple pregnancies and ensuring better pregnancy rates.

The freeze-all strategy after IVF: which indications?

The freeze-all strategy is gaining popularity worldwide as an alternative to the conventional fresh embryo transfer. It consists of cryopreservation of the entire embryo cohort and the embryo transfer in a subsequent cycle that takes place separately from ovarian stimulation. The freeze-all strategy was initially a 'rescue' strategy for women at high risk of ovarian hyperstimulation syndrome; however, this approach has been extended to other indications as a scheduled strategy to improve implantation rates. This assumes that ovarian stimulation can alter endometrial receptivity in fresh cycles owing to the effect of supraphysiological levels of steroids on endometrial maturation. The procedure, however, has not been associated with increased live birth rates in all infertile couples, and concerns have been raised about the occurrence of several adverse perinatal outcomes. It is, therefore, crucial to identify in which subgroups of patients a freeze-all strategy could be beneficial. The aim of this review is to summarize current scientific research in this field to highlight potential indications for this strategy and to guide clinicians in their daily practice.

A freeze-all strategy does not increase live birth rates in women of advanced reproductive age

RESEARCH QUESTION

Does a freeze-all strategy improve live birth rates in women of different age groups?

DESIGN

Retrospective cohort study of 1882 first embryo transfer cycles, performed between January 2013 and December 2015. Reproductive outcomes between fresh (FRESH) or frozen (FROZEN) embryo transfers were compared in patients stratified by age: < 35, between 35 and 38, or > 38 years. Student's t test for independent samples and χ² analyses were used as needed. A multivariable logistic regression analysis was performed adjusting for age, triggering drug, number of retrieved oocytes, number of transferred embryos, and percentage of top-quality embryos.

MAIN RESULTS AND THE ROLE OF CHANCE

Live birth rates (LBR) were significantly higher for FROZEN in the < 35 years group (43.7% vs 24%; p < 0.001). In both the 35-38 and > 38 years groups, LBR for FROZEN vs FRESH were not statistically different (30.9% in the FROZEN group vs 29.3% in the FRESH group, p = 0.70, and 19.8% in the FROZEN group vs 12.7% in the FRESH group, p = 0.07, respectively). The multivariate analysis found a significantly positive effect of performing FROZEN on LBR in the younger group (OR 2.46, 95% CI 1.31-4.62; p = 0.005) but had no impact in women between 35 and 38 years (OR 1.01, 95% CI 0.55-1.83; p = 0.98) or older (OR 0.96, 95% CI 0.43-2.13; p = 0.92).

CONCLUSIONS

Performing a freeze-all strategy seems to result in better reproductive outcomes when compared with a fresh ET in women under 35 years, with no significant impact on older women.

Frozen IVF Cycles to Circumvent the Hormonal Storm on Endometrium

Controlled ovarian hyperstimulation (COH) determines an anticipation of endometrial maturation and a premature occurrence of the implantation window, as shown by histological, histochemical, and molecular studies and indirectly by clinical trials. There is growing agreement that in patients hyper-responding to COH and in those undergoing transfer at the blastocyst stage, deferring the transfer in a subsequent frozen cycle could increase pregnancy outcomes. For blastocysts, implantation after a fresh transfer may be limited as the implantation window is already closed while, in hyper-responders to COH, the anticipation magnitude could be more marked thus hampering implantation also for cleavage-stage embryos. Research should focus in depth on pregnancy outcomes and on the most suitable modality to prepare the endometrium for frozen transfers.

Transcriptome sequencing of endometrium revealed alterations in mRNAs and lncRNAs after ovarian stimulation

RESEARCH QUESTION

Using RNA-sequencing analysis, we investigated the relationship between ovarian stimulation and endometrial transcriptome profiles during the window of implantation (WOI) to identify candidate predictive factors for the WOI and to optimize timing for embryo transfer.

METHODS

Twelve women with normal basal hormone levels and regular ovulation were randomly assigned into three groups based on sampling time: late-proliferate phase (P group), and receptive phase in natural cycles (LH+7, N group) and stimulated cycles (hCG+7, S group). Transcriptome profiles of mRNAs and long non-coding RNAs (lncRNAs) were then compared among the three groups. Validation was performed using real-time qPCR.

RESULTS

Comparison of transcriptome profiles between the natural and stimulated endometrium revealed 173 differentially expressed genes (DEGs), with a > 2-fold change (FC) and p < 0.05, under the influence of supraphysiological estradiol (E2) induced by ovarian stimulation. By clustering and KEGG pathway analysis, molecules and pathways associated with endometrial receptivity were identified. Of the 39 DEGs common to the three groups, eight genes were validated using real-time PCR. ESR1, MMP10, and HPSE were previously reported to be associated with endometrial receptivity. In addition, three novel genes (IL13RA2, ZCCHC12, SRARP) and two lncRNAs (LINC01060, LINC01104) were new potential endometrial receptivity-related markers.

CONCLUSION

Using mRNA and lncRNA sequencing, we found that supraphysiological E2 levels from ovarian stimulation had a marked impact upon endometrial transcriptome profiles and may result in a shift of the WOI. The precise mechanisms underlying the supraphysiological hormone-induced shift of the WOI require further research.

REGISTRATION NUMBER

ChiCTR180001453.

An update on the progress of transcriptomic profiles of human endometrial receptivity

Despite advances in our understanding of fertility, implantation failure remains a significant problem for both spontaneous and assisted pregnancies. Most research efforts concerning the process of implantation are embryo-centric, with a dearth of studies on endometrial factors. Currently, there are no practical and effective diagnostic tools available to precisely predict endometrial receptivity. Transcriptomics, a field based on microarray technology, has a number of procedures for clinical applications, although the functional relevance of most identified genes remains unclear. Importantly, RNA sequencing will further improve the precision and broaden the clinical use of the transcriptome by detecting previously undiscovered genes, which could be used to further our understanding of endometrial receptivity. In this review, potential biomarkers based on endometrium gene expression profiles of human endometrial receptivity were described and compared in natural and stimulated cycles toward discovering future prospects for personalized medical approaches. The intent of this synthesis is to provide researchers, doctors, and clinicians in the field with a better understanding of endometrium receptivity, promote further study in the transcriptome in embryo implantation, and ultimately, improve pregnancy outcome.

Superovulation alters the expression of endometrial genes critical to tissue remodeling and placentation

PURPOSE

Epidemiologic data suggest that in vitro fertilization (IVF) is associated with an increased risk of disorders of placentation including preeclampsia and fetal growth restriction. Specifically, studies have demonstrated that singleton pregnancies conceived following a fresh embryo transfer are at an increased risk of delivering an infant with low birth weight compared to those conceived following a frozen embryo transfer. The mechanism responsible for this association remains unclear. Procedures utilized in IVF have also been linked with epigenetic changes and gene expression changes in both fetal and maternal tissues. Data suggest that modifications in the maternal endometrium can lead to disordered trophoblast invasion and placentation. This study examines the effect of ovarian stimulation on endometrial gene expression and DNA methylation during the window of implantation to examine potential pathways playing a role in the adverse outcomes associated with IVF.

METHODS

Endometrial biopsies were obtained from oocyte donors and age-matched naturally cycling women 11 days following oocyte retrieval in donors or 12 days following luteinizing hormone (LH) surge in naturally cycling women. Global gene expression was analyzed via Affymetrix Human Gene 1.1 ST array and confirmed with RT-qPCR. DNA methylation was assessed with the Infinium DNA methylation 450 K BeadChip.

RESULTS

Analysis of endometrial gene expression from 23 women (11 oocyte donors and 12 controls) demonstrated 165 genes with a greater than twofold change in expression between donors and controls. While there were 785 genes with significant differential methylation in the endometrium of donors when compared with control subjects, none of the genes with altered expression showed significant changes in DNA methylation. Analysis of the differentially expressed genes showed enrichment for genes involved in endometrial remodeling including PLAT, HSPE2, MMP2, and TIMP1. Validation studies using RT-qPCR found a 73% reduction in expression of heparanase 2 (HSPE2) an enzyme associated with both angiogenesis and cell invasion, a greater than twofold increase in tissue-type plasminogen activator (PLAT), a serine protease participating in matrix degradation, and a 70% increase in MMP2, a gelatinase involved in collagen and fibronectin breakdown.

CONCLUSIONS

Superovulation alters expression of genes critical to endometrial remodeling during early implantation. Such changes could lead to altered trophoblast migration and impaired endovascular invasion. These findings offer a potential mechanism for the adverse perinatal outcomes observed following embryo transfer during fresh IVF cycles.

GnRH antagonist for endometrial priming in an oocyte donation programme: a prospective, randomized controlled trial

RESEARCH QUESTION

Can gonadotrophin releasing hormone (GnRH) antagonist be used in egg donation recipients with ovulatory cycles for the purpose of achieving synchronization between the donor´s and recipient´s cycle?

DESIGN

Prospective randomized controlled trial to compare 7-day dosage of GnRH antagonist for endometrial priming in an oocyte donation programme with a single dose of long-acting GnRH agonist. A total of 563 women were randomized in a private single centre, and 473 women underwent embryo transfer. Ongoing pregnancy rate was the primary end point. Analysis was adjusted for embryonic stage at the time of embryo transfer; data collected included days on the waiting list; number of fresh-vitrified oocytes collected; and oocyte donor´s age at the time of retrieval.

RESULTS

No statistically significant differences were found between groups in per intention-to-treat analysis: adjusted OR 1.42 (CI 0.97 to 2.09); per treatment received: adjusted OR 1.43 (CI 0.97 to 2.09); per embryo transfer: adjusted OR for ongoing pregnancy rate 1.47 (CI 1.01 to 2.13), P = 0.047.

CONCLUSIONS

For women with ovulatory cycles undergoing oocyte donation, the outcomes are similar between GnRH antagonist and down-regulated hormone replacement protocols.

GnRH antagonist versus long agonist protocols in IVF: a systematic review and meta-analysis accounting for patient type

BACKGROUND

Most reviews of IVF ovarian stimulation protocols have insufficiently accounted for various patient populations, such as ovulatory women, women with polycystic ovary syndrome (PCOS) or women with poor ovarian response, and have included studies in which the agonist or antagonist was not the only variable between the compared study arms.

OBJECTIVE AND RATIONALE

The aim of the current study was to compare GnRH antagonist protocols versus standard long agonist protocols in couples undergoing IVF or ICSI, while accounting for various patient populations and treatment schedules.

SEARCH METHODS

The Cochrane Menstrual Disorders and Subfertility Review Group specialized register of controlled trials and Pubmed and Embase databases were searched from inception until June 2016. Eligible trials were those that compared GnRH antagonist protocols and standard long GnRH agonist protocols in couples undergoing IVF or ICSI. The primary outcome was ongoing pregnancy rate. Secondary outcomes were: live birth rate, clinical pregnancy rate, number of oocytes retrieved and safety with regard to ovarian hyperstimulation syndrome (OHSS). Separate comparisons were performed for the general IVF population, women with PCOS and women with poor ovarian response. Pre-planned subgroup analyses were performed for various antagonist treatment schedules.

OUTCOMES

We included 50 studies. Of these, 34 studies reported on general IVF patients, 10 studies reported on PCOS patients and 6 studies reported on poor responders. In general IVF patients, ongoing pregnancy rate was significantly lower in the antagonist group compared with the agonist group (RR 0.89, 95% CI 0.82-0.96). In women with PCOS and in women with poor ovarian response, there was no evidence of a difference in ongoing pregnancy between the antagonist and agonist groups (RR 0.97, 95% CI 0.84-1.11 and RR 0.87, 95% CI 0.65-1.17, respectively). Subgroup analyses for various antagonist treatment schedules compared to the long protocol GnRH agonist showed a significantly lower ongoing pregnancy rate when the oral hormonal programming pill (OHP) pretreatment was combined with a flexible protocol (RR 0.74, 95% CI 0.59-0.91) while without OHP, the RR was 0.84, 95% CI 0.71-1.0. Subgroup analysis for the fixed antagonist schedule demonstrated no evidence of a significant difference with or without OHP (RR 0.94, 95% CI 0.79-1.12 and RR 0.94, 95% CI 0.83-1.05, respectively). Antagonists resulted in significantly lower OHSS rates both in the general IVF patients and in women with PCOS (RR 0.63, 95% CI 0.50-0.81 and RR 0.53, 95% CI 0.30-0.95, respectively). No data on OHSS was available from trials in poor responders.

WIDER IMPLICATIONS

In a general IVF population, GnRH antagonists are associated with lower ongoing pregnancy rates when compared to long protocol agonists, but also with lower OHSS rates. Within this population, antagonist treatment prevents one case of OHSS in 40 patients but results in one less ongoing pregnancy out of every 28 women treated. Thus standard use of the long GnRH agonist treatment is perhaps still the approach of choice for prevention of premature luteinization. In couples with PCOS and poor responders, GnRH antagonists do not seem to compromise ongoing pregnancy rates and are associated with less OHSS and therefore could be considered as standard treatment.

Weekend-free scheduled IVF/ICSI procedures and single embryo transfer do not reduce live-birth rates in a general infertile population

INTRODUCTION

Scheduling of ovum pickup only on weekdays may result in cases of apparently suboptimal timing for human chorionic gonadotropin and ovum pickup. This study aimed to assess whether live-birth rates were reduced in women with a potentially suboptimal day for human chorionic gonadotropin and ovum pickup to avoid weekend work, according to ultrasonographic data on the day of human chorionic gonadotropin planning.

MATERIAL AND METHODS

An evaluation of the optimal human chorionic gonadotropin priming date was performed in treatment protocols of 1000 consecutive patients undergoing their first in vitro fertilization/intracytoplasmatic sperm injection with single-embryo transfer. An ideal ovum pickup day was characterized by human chorionic gonadotropin-scheduling when three or more follicles reached 17 mm (day 0) or with one day of delay (day +1) (n = 760). A non-ideal ovum pickup was either early (day -1, -2, -3) (n = 24) or delayed (day +2, +3, +4) (n = 216). Live-birth rates in the ideal and non-ideal ovum pickup groups was set as primary outcome measure.

RESULTS

Early-ovum pickups were excluded as they were infrequent. No differences between ideal and delayed ovum pickup groups were found regarding number of oocytes retrieved (9.87 vs. 9.78, p = 0.990), pregnancy rates (28.3% vs. 29.6%, p = 0.701) or live-birth rates (26.2% vs. 25.9%, p = 0.939). However, sub analyses indicated that treatment with gonadotropin releasing hormone antagonists resulted in significantly lower clinical pregnancy rates in delayed ovum pickups (odds ratio 0.46, p = 0.014), compared with agonist treatments.

CONCLUSIONS

Weekend work may not be needed for in vitro fertilization/intracytoplasmatic sperm injection single-embryo transfer treatments. However, in gonadotropin releasing hormone antagonist cycles, delaying ovum pickup more than one day may result in unfavorable outcomes.

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.

Reduced homeobox protein MSX1 in human endometrial tissue is linked to infertility

STUDY QUESTION

Is protein expression of the muscle segment homeobox gene family member MSX1 altered in the human secretory endometrium by cell type, developmental stage or fertility?

SUMMARY ANSWER

MSX1 protein levels, normally elevated in the secretory phase endometrium, were significantly reduced in endometrial biopsies obtained from women of infertile couples.

WHAT IS KNOWN ALREADY

Molecular changes in the endometrium are important for fertility in both animals and humans. Msx1 is expressed in the preimplantation mouse uterus and regulates uterine receptivity for implantation. The MSX protein persists a short time, after its message has been down-regulated. Microarray analysis of the human endometrium reveals a similar pattern of MSX1 mRNA expression that peaks before the receptive period, with depressed expression at implantation. Targeted deletion of uterine Msx1 and Msx2 in mice prevents the loss of epithelial cell polarity during implantation and causes infertility.

STUDY DESIGN, SIZE DURATION

MSX1 mRNA and cell type-specific levels of MSX1 protein were quantified from two retrospective cohorts during the human endometrial cycle. MSX1 protein expression patterns were compared between fertile and infertile couples. Selected samples were dual-labeled by immunofluorescence microscopy to localize E-cadherin and β-catenin in epithelial cells.

PARTICIPANTS/MATERIALS, SETTING METHODS

MSX1 mRNA was quantified by PCR in endometrium from hysterectomies (n = 14) determined by endometrial dating to be in the late-proliferative (cycle days 10-13), early-secretory (cycle days 14-19) or mid-secretory (cycle days 20-24) phase. MSX1 protein was localized using high-throughput, semi-quantitative immunohistochemistry with sectioned endometrial biopsy tissues from fertile (n = 89) and infertile (n = 89) couples. Image analysis measured stain intensity specifically within the luminal epithelium, glands and stroma during the early-, mid- and late- (cycle days 25-28) secretory phases.

MAIN RESULTS AND THE ROLE OF CHANCE

MSX1 transcript increased 5-fold (P < 0.05) between the late-proliferative and early secretory phase and was then down-regulated (P < 0.05) prior to receptivity for implantation. In fertile patients, MSX1 protein displayed strong nuclear localization in the luminal epithelium and glands, while it was weakly expressed in nuclei of the stroma. MSX1 protein levels accumulated throughout the secretory phase in all endometrial cellular compartments. MSX1 protein decreased (P < 0.05) in the glands between mid- and late-secretory phases. However, infertile patients demonstrated a broad reduction (P < 0.001) of MSX1 accumulation in all cell types throughout the secretory phase that was most pronounced (∼3-fold) in stroma and glands. Infertility was associated with persistent co-localization of E-cadherin and β-catenin in epithelial cell junctions in the mid- and late-secretory phases.

LIMITATIONS, REASONS FOR CAUTION

Details of the infertility diagnoses and other patient demographic data were not available. Therefore, patients with uterine abnormalities (Mullerian) could not be distinguished from other sources of infertility. Antibody against human MSX2 is not available, limiting the study to MSX1. However, both RNAs in the human endometrium are similarly regulated. In mice, Msx1 and Msx2 are imperative for murine embryo implantation, with Msx2 compensating for genetic ablation of Msx1 through its up-regulation in a knockout model.

WIDER IMPLICATIONS OF THE FINDINGS

This investigation establishes that the MSX1 homeobox protein accumulation is associated with the secretory phase in endometrium of fertile couples, and is widely disrupted in infertile patients. It is the first study to examine MSX1 protein localization in the human endometrium, and supported by genetic findings in mice, suggests that genes regulated by MSX1 are linked to the loss of epithelial cell polarity required for uterine receptivity during implantation.

STUDY FUNDING/COMPETING INTERESTS

This research was supported by the NICHD National Cooperative Reproductive Medicine Network grant HD039005 (M.P.D.), NIH grants HD068524 (S.K.D.), HD071408 (D.R.A., M.P.D.), and HL128628 (S.D.), the Intramural Research Program of the NICHD, March of Dimes (S.K.D., S.D.) and JSPS KAKENHI grant 26112506 (Y.H.). There were no conflicts or competing interests.

Diagnosis of Endometrial-Factor Infertility: Current Approaches and New Avenues for Research

Over the last decade, research to improve success rates in reproductive medicine has focused predominantly on the understanding and optimization of embryo quality. However, the emergence of personalized medicine in ovulation induction and embryology has shifted the focus to assessing the individual status of the endometrium. The endometrium is considered receptive during an individually defined period, the window of implantation (WOI), when the mother permits a blastocyst to attach and implant. This individual receptivity status can now be objectively diagnosed using the endometrial receptivity array (ERA) developed in 2011. The ERA, together with a computational algorithm, detects the unique transcriptomic signature of endometrial receptivity by analyzing 238 differentially expressed genes and reliably predicting the WOI. We and others have illustrated the utility of this personalized diagnostic approach to discriminate between individual physiological variation in endometrial receptivity and unknown endometrial pathology, deemed as causal in recurrent implantation failure (RIF). An international randomized controlled trial ("The ERA as a diagnostic guide for personalized embryo transfer." ClinicalTrials.gov Identifier: NCT01954758) is underway to determine the clinical value of this endometrial diagnostic intervention in the work-up for reproductive care. In this review, we analyse the current clinical practice in the diagnosis of the endometrial factor together with new avenues of research.

Gonadotrophin-releasing hormone agonist protocol of controlled ovarian hyperstimulation as an efficient treatment in Bologna-defined poor ovarian responders

In this retrospective study the outcomes of two protocols of controlled ovarian hyperstimulation and natural cycle in poor ovarian responders defined according to the Bologna criteria were compared to elucidate which approach is more suitable for the treatment of these patients. We comparatively analyzed 142 cycles of GnRH antagonist (GnRH-ant) protocol, 53 cycles of GnRH agonist (GnRH-a) protocol, and 36 natural cycles. The mean number of oocytes (2.8±1.8) and embryos (1.6±1.2) per aspiration was significantly higher in GnRH-a protocol in comparison to GnRH-ant protocol and natural cycle, but the proportion of immature, fertilized oocytes, and embryos, including the quality of transferred embryos, was very similar in all treatments. The proportion of pregnancies per oocyte aspiration did not differ significantly between treatments (18.9% after GnRH-a, 10.6% after GnRH-ant, 5.6% after natural cycle), but the live birth rate per aspiration was significantly higher after GnRH-a protocol than after GnRH-ant protocol (15.1% vs. 4.2%; p=0.024).

Does the use of gonadotropin-releasing hormone antagonists in natural IVF cycles for poor responder patients cause more harm than benefit?

Poor ovarian response to controlled ovarian stimulation (COS) is one of the most critical factors that substantially limits the success of assisted reproduction techniques (ARTs). Natural and modified natural cycle IVF are two options that could be considered as a last resort. Blocking gonadotropin-releasing hormone (GnRH) actions in the endometrium via GnRH receptor antagonism may have a negative impact on endometrial receptivity. We analysed IVF outcomes in 142 natural (n = 30) or modified natural (n = 112) IVF cycles performed in 82 women retrospectively. A significantly lower proportion of natural cycles reached follicular aspiration compared to modified natural cycles (56.7% vs. 85.7%, p < 0.001). However, the difference between the numbers of IVF cycles ending in embryo transfer (26.7% vs. 44.6%) was not statistically significant between natural cycle and modified natural IVF cycles. Clinical pregnancy (6.7% vs. 7.1%) and live birth rates per initiated cycle (6.7% vs. 5.4%) were similar between the two groups. Notably, the implantation rate was slightly lower in modified natural cycles (16% vs. 25%, p > 0.05). There was a trend towards higher clinical pregnancy (25% vs. 16%) and live birth (25% vs. 12%) rates per embryo transfer in natural cycles compared to modified natural cycles, but the differences did not reach statistical significance.

Genomic, proteomic and lipidomic evaluation of endometrial receptivity

Endometrial receptivity is a complex phenomenon that plays a vital role in infertility. Although quality of embryo can be evaluated for a successful implantation, endometrial receptivity is still an unknown factor. With advances in technology, the microarray approach has provided an 'omic' tool to evaluate endometrial receptivity. In Latin, 'omic' means the whole family. The genomic, proteomic, and lipidomic evaluations of endometrium mean a wholesome evaluation of the genes, lipids and proteins of the endometrium. Evaluation of receptivity with this three-way approach may provide insight to the potential markers of implantation. Genomic analysis has been limited to date because not every gene alteration affects protein expression. Lipidomic analysis has recently gained popularity because lipids are strictly controlled during the implantation period. In summary, with the recent advances in microarray technology, genomic, lipidomic, and proteomic analyses of the endometrium may provide 'optimal' evaluation tools and criteria to assess receptivity in the near future.

Endometrial receptivity array: Clinical application

Human implantation is a complex process requiring synchrony between a healthy embryo and a functionally competent or receptive endometrium. Diagnosis of endometrial receptivity (ER) has posed a challenge and so far most available tests have been subjective and lack accuracy and a predictive value. Microarray technology has allowed identification of the transcriptomic signature of the window of receptivity window of implantation (WOI). This technology has led to the development of a molecular diagnostic tool, the ER array (ERA) for diagnosis of ER. Use of this test in patients with recurrent implantation failure (RIF) has shown that the WOI is displaced in a quarter of these patients and use of a personalized embryo transfer (pET) on the day designated by ERA improves reproductive performance. Our results in the Indian population revealed an endometrial factor in 27.5% RIF patients, which was significantly greater than the non-RIF group 15% (P = 0.04). After pET, the overall ongoing pregnancy rate was 42.4% and implantation rate was 33%, which was at par with our in-vitro fertilization results over 1-year. We also performed ERA in patients with persistently thin endometrium, and it was reassuring to find that the endometrium in 75% of these patients was receptive despite being 6 mm or less. A pregnancy rate of 66.7% was achieved in this group. Though larger studies are required to validate these results ERA has become a useful tool in our diagnostic armamentarium for ER.

Human Endometrial Transcriptomics: Implications for Embryonic Implantation

Human endometrium has been extensively investigated in the search for markers capable of predicting its receptive status. The completion of the Human Genome Project has triggered a rapid development of new fields in molecular biology, the "transcriptomics" being a major turning point in the knowledge acquisition of endometrial receptivity. Based on this, a customized Endometrial Receptivity Array (ERA) has been developed, which is capable of identifying the genomic signature of receptivity. This diagnostic tool showed that the window of implantation (WOI) is displaced in one out of four patients with implantation failure, allowing the identification of their personalized WOI. This strategy allows performing a personalized embryo transfer (pET) on the day in which the endometrium is receptive. The combination of a systems biology approach and next-generation sequencing will overcome the limitations of microarrays, and will, in the future, allow elucidation of the mechanisms involved in embryo implantation.

Comparison of GnRH agonist, GnRH antagonist, and GnRH antagonist mild protocol of controlled ovarian hyperstimulation in good prognosis patients

The reports on how to stimulate the ovaries for oocyte retrieval in good prognosis patients are contradictory and often favor one type of controlled ovarian hyperstimulation (COH). For this reason, we retrospectively analyzed data from IVF/ICSI cycles carried out at our IVF Unit in good prognosis patients (aged <38 years, first and second attempts of IVF/ICSI, more than 3 oocytes retrieved) to elucidate which type of COH is optimal at our condition. The included patients were undergoing COH using GnRH agonist, GnRH antagonist or GnRH antagonist mild protocol in combination with gonadotrophins. We found significant differences in the average number of retrieved oocytes, immature oocytes, fertilized oocytes, embryos, transferred embryos, embryos frozen per cycle, and cycles with embryo freezing between studied COH protocols. Although there were no differences in live birth rate (LBR), miscarriages, and ectopic pregnancies between compared protocols, pregnancy rate was significantly higher in GnRH antagonist mild protocol in comparison with both GnRH antagonist and GnRH agonist protocols and cumulative LBR per cycle was significantly higher in GnRH antagonist mild protocol in comparison to GnRH agonist protocol. Our data show that GnRH antagonist mild protocol of COH could be the best method of choice in good prognosis patients.

MicroRNA and implantation

We provide a review of microRNA (miRNA) related to human implantation which shows the potential diagnostic role of miRNAs in impaired endometrial receptivity, altered embryo development, implantation failure after assisted reproduction technology, and in ectopic pregnancy and pregnancies of unknown location. MicroRNAs may be emerging diagnostic markers and potential therapeutic tools for understanding implantation disorders. However, further research is needed before miRNAs can be used in clinical practice for identifying and treating implantation failure.

Why we should transfer frozen instead of fresh embryos: the translational rationale

Epidemiologic studies have shown an increased rate of adverse perinatal outcomes, including small for gestational age (SGA) births, in fresh in vitro fertilization (IVF) cycles compared with frozen embryo transfer cycles. This increase is not seen in the donor oocyte population, suggesting that it is the peri-implantation environment created after superovulation that is responsible for these changes. During a fresh IVF cycle, multiple corpora lutea secrete high levels of hormones and other factors that can affect the endometrium and the implanting embryo. In this review, we discuss both animal and human data demonstrating that superovulation has significant effects on the endometrium and embryo. Additionally, potential mechanisms for the adverse effects of gonadotropin stimulation on implantation and placental development are proposed. We think that these data, along with the growing body of epidemiologic evidence, support the proposal that frozen embryo transfer should be considered preferentially, particularly in high responders, as a means to potentially decrease at least some of the adverse perinatal outcomes associated with IVF.

Endometrial receptivity profile in patients with premature progesterone elevation on the day of HCG administration

The impact of a premature elevation of serum progesterone level, the day of hCG administration in patients under controlled ovarian stimulation during IVF procedure, on human endometrial receptivity is still debated. In the present study, we investigated the endometrial gene expression profile shifts during the prereceptive and receptive secretory stage in patients with normal and elevated serum progesterone level on the day of hCG administration in fifteen patients under stimulated cycles. Then, specific biomarkers of endometrial receptivity in these two groups of patients were tested. Endometrial biopsies were performed on oocyte retrieval day and on day 3 of embryo transfer, respectively, for each patient. Samples were analysed using DNA microarrays and qRT-PCR. The endometrial gene expression shift from the prereceptive to the receptive stage was altered in patients with high serum progesterone level (>1.5 ng/mL) on hCG day, suggesting accelerated endometrial maturation during the periovulation period. This was confirmed by the functional annotation of the differentially expressed genes as it showed downregulation of cell cycle-related genes. Conversely, the profile of endometrial receptivity was comparable in both groups. Premature progesterone rise alters the endometrial gene expression shift between the prereceptive and the receptive stage but does not affect endometrial receptivity.

Effect of ovarian stimulation with recombinant follicle-stimulating hormone, gonadotropin-releasing hormone agonist and antagonists, on follicular fluid stem cell factor and serum urocortin 1 levels on the day of oocyte retrieval

PURPOSE

To compare the serum and follicular fluid (FF) concentrations of stem cell factor (SCF) as well as the serum urocortin 1 (UCN1) concentration in gonadotropin-releasing hormone antagonist (GnRH-ant) and gonadotropin-releasing hormone agonist (GnRH-a) protocols for controlled ovarian hyperstimulation (COH) in IVF patients.

METHODS

Follicular fluids and blood samples of 42 infertile women undergoing COH for IVF-embryo transfer with either GnRH agonist (n = 22) or GnRH antagonist (n = 20) protocols from 2010 to 2011 were collected during oocyte retrieval. SCF concentrations of serum and FF were assessed by sandwich enzyme immunoassay using ELISA Kit for SCF kid. Serum UCN1 concentration were measured using commercially available enzyme-linked immunosorbent assay.

RESULTS

Concentrations of serum UCN1, serum and FF SCF were similar in the two groups. The serum SCF levels correlated strongly with the follicular SCF levels (r = 0.770, p < 0.001). The mean implantation rate, biochemical and clinical pregnancy rate and live birth rate per cycle were also similar in the groups.

CONCLUSIONS

These observations suggest that there is no significant difference in follicular microenvironment in terms of SCF and UCN1 between agonist and antagonist protocols.

The extrapituitary effects of GnRH antagonists and their potential clinical implications: a narrated review

Potential roles of gonadotropin-releasing hormone (GnRH) antagonists on GnRH/GnRH receptor systems and their effects on the extrapituitary tissues are largely elusive. In this narrated review, we summarized the systemic effects of GnRH antagonists on ovary, endometrium, embryo implantation, placental development, fetal teratogenicity, reproductive tissue cancer cells, and heart while briefly reviewing the GnRH and GnRH receptor system. GnRH antagonists may have direct effects on ovarian granulosa cells. Data are conflicting regarding their effects on endometrial receptivity. The GnRH antagonists may potentially have detrimental effect on early placentation by decreasing the invasive ability of cytotrophoblasts if the exposure to them occurs during early pregnancy. The GnRH antagonists were not found to increase the rates of congenital malformations. Comparative clinical data are required to explore their systemic effects on various extrapituitary tissues such as on cardiac function in the long term as well as their potential use in other human cancers that express GnRH receptors.

Endometrial expression of selected genes in patients achieving pregnancy spontaneously or after ICSI and patients failing at least two ICSI cycles

The objective of this study was to identify the endometrial gene expression profile in receptive phase, which could represent a useful prognostic tool for selecting IVF patients. Endometrial expression of 47 selected genes biopsied during the window of implantation in natural cycles was compared between patients who achieved a successful pregnancy spontaneously or after subsequent intracytoplasmic sperm injection (ICSI) cycles and patients who did not achieve a pregnancy after at least two failed ICSI cycles. The comparative analysis showed significantly different levels of expression in 19 genes, five implicated in apoptosis (CASP8, FADD, CASP10, APAF1, ANXA4), three in immunity (LIF, SPP1, C4BPA), five in transcriptional activity (MSX1, HOXA10, MSX2, HOXA11, GATA2), two in lipid metabolism (LEPR, APOD) and four in oxidative metabolism (AOX1, ALDH1A3, GPX3, NNMT). The evidence for these genes being differently expressed could represent the starting point of identifying the ideal receptive endometrial gene expression profile, which could be used in the future as a prognostic tool for IVF patients. Gene expression analysis technology has opened new important perspectives on the study of the physiological processes of different tissues and organs. Specifically for the endometrium, it would be really interesting to find out an endometrial gene expression profile of receptive phase, which could be used in future as a useful prognostic tool for selecting IVF patients. To achieve this aim, the objective of the present paper was the comparison of endometrial expression in natural cycles of 47 selected genes between the biopsies of patients who achieved a successful pregnancy, either spontaneously or after subsequent ICSI cycles, and those of patients who did not achieve a pregnancy after at least two failed ICSI cycles. The comparative analysis showed a significant different expression in 19 genes: five implicated in programmed cell death, known as apoptosis (CASP8, FADD, CASP10, APAF1, ANXA4), three in immunity (LIF, SPP1, C4BPA), five in transcriptional activity (MSX1, HOXA10, MSX2, HOXA11, GATA2), two in lipid metabolism (LEPR, APOD) and four in oxidative metabolism (AOX1, ALDH1A3, GPX3, NNMT). The evidence of these genes being differently expressed could represent the starting point of identifying the ideal receptive endometrial gene expression profile which could be used in the future as a prognostic tool for IVF patients.

The genomics of the human endometrium

The endometrium is a complex tissue that lines the inside of the endometrial cavity. The gene expression of the different endometrial cell types is regulated by ovarian steroids and paracrine-secreted molecules from neighbouring cells. Due to this regulation, the endometrium goes through cyclic modifications which can be divided simply into the proliferative phase, the secretory phase and the menstrual phase. Successful embryo implantation depends on three factors: embryo quality, the endometrium's state of receptivity, and a synchronised dialogue between the maternal tissue and the blastocyst. There is a need to characterise the endometrium's state of receptivity in order to prevent reproductive failure. No single molecular or histological marker for this status has yet been found. Here, we review the global transcriptomic analyses performed in the last decade on a normal human endometrium. These studies provide us with a clue about what global gene expression can be expected for a non-pathological endometrium. These studies have shown endometrial phase-specific transcriptomic profiles and common temporal gene expression patterns. We summarise the biological processes and genes regulated in the different phases of natural cycles and present other works on different conditions as well as a receptivity diagnostic tool based on a specific gene set profile. This article is part of a Special Issue entitled: Molecular Genetics of Human Reproductive Failure.

GnRH agonist versus GnRH antagonist in assisted reproduction cycles: oocyte morphology

BACKGROUND

The selection of developmentally competent human gametes may increase the efficiency of assisted reproduction. Spermatozoa and oocytes are usually assessed according to morphological criteria. Oocyte morphology can be affected by the age, genetic characteristics, and factors related to controlled ovarian stimulation. However, there is a lack of evidence in the literature concerning the effect of gonadotropin-releasing hormone (GnRH) analogues, either agonists or antagonists, on oocyte morphology. The aim of this randomized study was to investigate whether the prevalence of oocyte dysmorphism is influenced by the type of pituitary suppression used in ovarian stimulation.

METHODS

A total of 64 patients in the first intracytoplasmic sperm injection (ICSI) cycle were prospectively randomized to receive treatment with either a GnRH agonist with a long-term protocol (n: 32) or a GnRH antagonist with a multi-dose protocol (n: 32). Before being subjected to ICSI, the oocytes at metaphase II from both groups were morphologically analyzed under an inverted light microscope at 400x magnification. The oocytes were classified as follows: normal or with cytoplasmic dysmorphism, extracytoplasmic dysmorphism, or both. The number of dysmorphic oocytes per total number of oocytes was analyzed.

RESULTS

Out of a total of 681 oocytes, 189 (27.8%) were morphologically normal, 220 (32.3%) showed cytoplasmic dysmorphism, 124 (18.2%) showed extracytoplasmic alterations, and 148 (21.7%) exhibited both types of dysmorphism. No significant difference in oocyte dysmorphism was observed between the agonist- and antagonist-treated groups (P>0.05). Analysis for each dysmorphism revealed that the most common conditions were alterations in polar body shape (31.3%) and the presence of diffuse cytoplasmic granulations (22.8%), refractile bodies (18.5%) and central cytoplasmic granulations (13.6%). There was no significant difference among individual oocyte dysmorphisms in the agonist- and antagonist-treated groups (P>0.05).

CONCLUSIONS

Our randomized data indicate that in terms of the quality of oocyte morphology, there is no difference between the antagonist multi-dose protocol and the long-term agonist protocol. If a GnRH analogue used for pituitary suppression in IVF cycles influences the prevalence of oocyte dysmorphisms, there does not appear to be a difference between the use of an agonist as opposed to an antagonist.

Peak serum estradiol level during controlled ovarian hyperstimulation is associated with increased risk of small for gestational age and preeclampsia in singleton pregnancies after in vitro fertilization

OBJECTIVE

To assess the impact of elevated peak serum E(2) levels (EPE(2); defined as levels >90th percentile) on the day of hCG administration during controlled ovarian hyperstimulation (COH) for IVF on the likelihood for small for gestational age (SGA), preeclampsia (PreE), and preterm delivery (PTD) in singleton pregnancies.

DESIGN

Retrospective cohort study.

SETTING

Tertiary-care academic medical center.

PATIENT(S)

Singleton live-birth pregnancies conceived after fresh IVF-ET.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The delivery rate of SGA infants and the development of PreE and PTD in patients with and without EPE(2).

RESULT(S)

Patients with EPE(2) during COH were more likely to deliver SGA infants (7 [26.9%] vs. 10 [3.8%]; odds ratio [OR], 95% confidence interval [CI] {9.40, 3.22-27.46}) and develop PreE (5 [18.5%] vs. 12 [4.5%]; adjusted OR, 95% CI {4.79, 1.55-14.84}). No association was found between EPE(2) and the likelihood for delivery before 37 weeks, 35 weeks, or 32 weeks of gestation. Receiver operating characteristic analysis revealed that EPE(2) level predicted adverse obstetrical outcome (SGA + PreE) with 38.5% and 91.7% sensitivity and specificity, respectively. Using a serum peak E(2) cutoff value of 3,450 pg/mL (>90th percentile level), the positive predictive value was 37%, while the negative predictive value was 92%.

CONCLUSION(S)

EPE(2) level (>3,450 pg/mL) on the day of hCG administration during COH is associated with greater odds of developing PreE and delivery of an SGA infant in singleton pregnancies resulting from IVF cycles.

High throughput, cell type-specific analysis of key proteins in human endometrial biopsies of women from fertile and infertile couples

BACKGROUND

Although histological dating of endometrial biopsies provides little help for prediction or diagnosis of infertility, analysis of individual endometrial proteins, proteomic profiling and transcriptome analysis have suggested several biomarkers with altered expression arising from intrinsic abnormalities, inadequate stimulation by or in response to gonadal steroids or altered function due to systemic disorders. The objective of this study was to delineate the developmental dynamics of potentially important proteins in the secretory phase of the menstrual cycle, utilizing a collection of endometrial biopsies from women of fertile (n = 89) and infertile (n = 89) couples.

METHODS AND RESULTS

Progesterone receptor-B (PGR-B), leukemia inhibitory factor, glycodelin/progestagen-associated endometrial protein (PAEP), homeobox A10, heparin-binding EGF-like growth factor, calcitonin and chemokine ligand 14 (CXCL14) were measured using a high-throughput, quantitative immunohistochemical method. Significant cyclic and tissue-specific regulation was documented for each protein, as well as their dysregulation in women of infertile couples. Infertile patients demonstrated a delay early in the secretory phase in the decline of PGR-B (P < 0.05) and premature mid-secretory increases in PAEP (P < 0.05) and CXCL14 (P < 0.05), suggesting that the implantation interval could be closing early. Correlation analysis identified potential interactions among certain proteins that were disrupted by infertility.

CONCLUSIONS

This approach overcomes the limitations of a small sample number. Protein expression and localization provided important insights into the potential roles of these proteins in normal and pathological development of the endometrium that is not attainable from transcriptome analysis, establishing a basis for biomarker, diagnostic and targeted drug development for women with infertility.

Ovarian stimulation and low birth weight in newborns conceived through in vitro fertilization

OBJECTIVE

Singleton neonates born after in vitro fertilization (IVF) are at increased risk for low birth weight, preterm delivery, or both. We sought to assess whether the alteration of the peri-implantation maternal environment resulting from ovarian stimulation may contribute to increased risk of low birth weight in IVF births.

METHODS

The Society for Assisted Reproductive Technologies database was used to identify IVF-conceived neonates born in the United States between 2004 and 2006. Associations were assessed in neonates born after fresh compared with frozen and thawed embryo transfer in women of similar ovarian responsiveness, in paired analysis of neonates born to the same woman after both types of embryo transfer, and in neonates born after oocyte donation.

RESULTS

Of 56,792 neonates identified, 38,626 and 18,166 were conceived after transfer of fresh and frozen embryos, respectively. In singletons, there was no difference in preterm delivery. However, the odds of overall low birth weight (10% compared with 7.2%; adjusted odds ratio [OR] 1.35; 95% confidence interval [CI] 1.20-1.51), low birth weight at term (2.5% compared with 1.2%, adjusted OR 1.73, 95% CI 1.31-2.29), and preterm low birth weight (34.1% compared with 23.8%, adjusted OR 1.49, 95% CI 1.24-1.78) were all significantly higher after fresh embryo transfer. In singletons, after either fresh or frozen embryo transfer in the same patient, this association was even stronger (low birth weight: 11.5% compared with 5.6%, adjusted OR 4.66, 95% CI 1.18-18.38). In oocyte donor recipients who do not undergo any ovarian hormonal stimulation for either a fresh or a frozen embryo transfer, no difference in low birth weight was demonstrated (11.5% compared with 11.3% adjusted OR 0.99, 95% CI 0.82-1.18).

CONCLUSION

The ovarian stimulation-induced maternal environment appears to represent an independent mediator contributing to the risk of low birth weight, but not preterm delivery, in neonates conceived after IVF.

LEVEL OF EVIDENCE

II.

Research resource: interactome of human embryo implantation: identification of gene expression pathways, regulation, and integrated regulatory networks

A prerequisite for successful embryo implantation is adequate preparation of receptive endometrium and the establishment and maintenance of a viable embryo. The success of implantation further relies upon a two-way dialogue between the embryo and uterus. However, molecular bases of these preimplantation and implantation processes in humans are not well known. We performed genome expression analyses of human embryos (n = 128) and human endometria (n = 8). We integrated these data with protein-protein interactions in order to identify molecular networks within the endometrium and the embryo, and potential embryo-endometrium interactions at the time of implantation. For that, we applied a novel network profiling algorithm HyperModules, which combines topological module identification and functional enrichment analysis. We found a major wave of transcriptional down-regulation in preimplantation embryos. In receptive-stage endometrium, several genes and signaling pathways were identified, including JAK-STAT signaling and inflammatory pathways. The main curated embryo-endometrium interaction network highlighted the importance of cell adhesion molecules in the implantation process. We also identified cytokine-cytokine receptor interactions involved in implantation, where osteopontin (SPP1), leukemia inhibitory factor (LIF) and leptin (LEP) pathways were intertwining. Further, we identified a number of novel players in human embryo-endometrium interactions, such as apolipoprotein D (APOD), endothelin 1 (END1), fibroblast growth factor 7 (FGF7), gastrin (GAST), kringle containing trnasmembrane protein 1 (KREMEN1), neuropilin 1 (NRP1), serpin peptidase inhibitor clade A member 3 (SERPINA3), versican (VCAN), and others. Our findings provide a fundamental resource for better understanding of the genetic network that leads to successful embryo implantation. We demonstrate the first systems biology approach into the complex molecular network of the implantation process in humans.