Evaluation of the endometrial receptivity assay and the preimplantation genetic test for aneuploidy in overcoming recurrent implantation failure

Clinical outcomes following endometrial receptivity assessment-guided personalized euploid embryo transfer in patients with previous implantation failures

This study aimed to investigate potential improvements when implementing endometrial receptivity analysis (ERA)-guided personalized embryo transfer (pET) using euploid blastocyst in patients with one or more previous failed embryo transfers. A total of 270 patients with one or more previous failed embryo transfers were enrolled between 2017 and 2021 in this multicenter retrospective study. These patients were divided into two groups: study cases (ERA-guided pET) (n = 200) or controls (standard embryo transfer) (n = 70). Clinical outcomes compared were pregnancy rate (PR), implantation rate (IR), ongoing pregnancy rate (OPR), and live birth rate (LBR). Clinical results in terms of PR, OPR, and LBR were significantly higher when performing ERA-guided pET (PR: 65.0%; OPR: 49.0%; LBR: 48.2%) compared to standard embryo transfer (PR: 37.1%; OPR: 27.1%; LBR: 26.1%) (P < 0.01). Logistic regression was applied to examine the correlation between ERA and the primary outcome measured, OPR, including demographic variables as covariates. The effect of ERA was significantly associated with OPR (P = 0.002; aOR 2.8, 95% CI 1.5-5.5); furthermore, OPR decreased significantly when body mass index (BMI) values increased (P = 0.04; aOR 0.9, 95% CI 0.8-0.98). These findings support the potential of ERA-guided pET to improve clinical outcomes and address the challenges encountered by patients with previous implantation failures.

Establishment and application of an RNA-seq-based predictive model for the hourly precision window of implantation (WOI) in patients with recurrent implantation failure

PURPOSE

This study aims to establish a single-time point RNA-sequencing-based endometrial receptivity test (rsERT) to provide hourly precision of endometrial WOI for patients with recurrent implantation failure (RIF).

METHODS

A two-phase study was conducted. In the first phase, a total of 70 patients with successful intrauterine pregnancy after personalized embryo transfer (pET) guided by three-time points rsERT were recruited for modified rsERT. Another 21 patients who underwent the prototype of single-time point rsERT were further included for optimization. In the second phase, another cohort of 574 patients with RIF that was recruited and assigned to the experimental group underwent pET guided by the modified rsERT (n = 261) or the control group underwent conventional ET (n = 313). The positive β-human chorionic gonadotropin (β-hCG), intrauterine pregnancy rate (IPR), implantation rate (IR), ongoing pregnancy rate, and live birth rate of the two groups were analyzed.

RESULT

The modified rsERT provided an hour-based predictive result of endometrial WOI with an average accuracy of 94.51% and sensitivity and specificity of 92.73% and 96.29%, respectively. The positive β-hCG, IPR, IR, ongoing pregnancy rate, and live birth rate of the experimental group were significantly different from those in the control group. After propensity score matching (PSM) control for the confounders, positive β-hCG, IR, and early spontaneous abortion rate showed significant differences.

CONCLUSION

The modified rsERT provided hourly precision WOI prediction using a single-time point endometrial biopsy and pregnancy outcomes were significantly improved, providing an enhanced endometrial receptivity test as an alternative requiring only a single-time point sampling for patients with RIF.

Bibliometric analysis of the links between embryo transfer and endometrial receptivity: Mapping knowledge landscapes and emerging trends (2005-2024)

BACKGROUND

Infertility is a significant global reproductive health challenge with varying prevalence across regions. While assisted reproductive technologies, especially in vitro fertilization, have created new possibilities for treating infertility, embryo transfer success remains limited by multiple factors, particularly endometrial receptivity. Understanding the relationship between embryo transfer and endometrial receptivity is crucial for advancing reproductive medicine and improving infertility treatment outcomes. To address the lack of bibliometric analysis in this field, we conducted a comprehensive bibliometric study of relevant academic literature.

METHODS

We analyzed articles and reviews on endometrial receptivity and embryo transfer from the Web of Science Core Collection using CiteSpace, VOSviewer, and Bibliometrix package. The analysis focused on countries, institutions, journals, authors, keywords, and references.

RESULTS

We identified 1478 documents published over 2 decades, showing an upward trend in annual publications. China led in publication volume, while the USA had the highest citation impact. The University of Valencia and Shanghai Jiao Tong University were the most productive institutions, with fertility and sterility being the leading journal. Simón, C emerged as the most influential author based on publication count and citations. Key research areas included comparing fresh versus frozen embryo transfer, addressing repeated implantation failure, and improving endometrial receptivity. The endometrial receptivity array for personalized embryo transfer represents an emerging research direction in reproductive medicine.

CONCLUSION

This first comprehensive bibliometric analysis of embryo transfer and endometrial receptivity research provides valuable insights into knowledge development, research hotspots, and future directions in the field, serving as a crucial reference for scholars in reproductive medicine.

Novel endometrial receptivity test increases clinical pregnancy and live birth rates in patients with recurrent implantation failure: Secondary analysis of a prospective clinical trial

OBJECTIVES

This study aimed to evaluate the efficiency of endometrial receptivity testing (ERT) in improving pregnancy outcomes for patients with recurrent implantation failure (RIF), and to investigate the incidence of implantation window displacement.

METHODS

Conducted between April 2021 and August 2022, at a university-affiliated reproductive center, the study included 85 RIF patients who had failed to achieve pregnancy after three embryo transfers. As part of a multicenter prospective cohort study (ChiCTR2200059342), 45 patients underwent ERT-guided frozen single blastocyst transfer, while 40 received standard treatment without ERT. Endometrial preparation was performed using a hormone replacement therapy (HRT) protocol in the cycle preceding transfer. Endometrial sampling for ERT, including RNA sequencing, artificial intelligence, and discriminant analysis of endometrial receptivity, was conducted on day 5 after progesterone administration to determine the implantation window. The same HRT protocol was used in the transfer cycle, with embryo transfer timed according to the ERT-calculated window.

RESULTS

Our data showed that 28.07% of patients exhibited a displaced implantation window, all characterized by pre-receptive endometrium. The ERT group had significantly higher clinical pregnancy rates (57.78% vs. 35.00%, p = 0.036) and live birth rates (53.33% vs. 30.00%, p = 0.030) compared with the non-ERT group.

CONCLUSION

Our findings suggest that approximately one-third of RIF occurrences may be due to endometrial factors, and ERT-guided personalized embryo transfer significantly improves pregnancy outcomes, underscoring its value in reproductive medicine.

Effect of Preimplantation Genetic Testing for Aneuploidy on Live Birth Rate in Young Women With Recurrent Implantation Failure: A Secondary Analysis of a Multicentre Randomised Trial

OBJECTIVE

To investigate the benefit of preimplantation genetic testing for aneuploidy (PGT-A) in recurrent implantation failure (RIF).

DESIGN

Secondary analysis of a multicentre, randomised, double-blind, placebo-controlled clinical trial.

SETTING

Eight academic fertility centres in China, 2018-2020.

POPULATION

Overall, 485 infertile women aged < 38 years were evaluated. They had a history of two or more unsuccessful embryo transfer cycles with at least three good-quality embryos that had been transferred cumulatively and underwent a single blastocyst transfer with or without PGT-A. Those with thin endometrium or recurrent pregnancy loss were excluded.

METHODS

Patients were categorised into PGT-A and non-PGT-A groups. All pregnancies were followed to delivery. Pregnancy and neonatal outcomes were obtained from obstetric and neonatal medical records. Propensity score matching (PSM) and multivariate logistic regression models were applied to adjust for potential confounding factors.

MAIN OUTCOME MEASURES

LBR per embryo transfer.

RESULT(S)

There was no significant difference in LBR between the PGT-A and non-PGT-A groups both before (39.1% vs. 41.5%, p = 0.760) and after (39.1% vs. 40.6%, p = 0.862) PSM. Unadjusted and adjusted logistic regression models revealed no beneficial effect of PGT-A on LBR per embryo transfer (crude odds ratio: 0.91, 95% confidence interval: 0.49-1.69; adjusted odds ratio: 1.04, 95% confidence interval: 0.53-2.03). The incidence of maternal and neonatal complications was not significantly different between the groups.

CONCLUSIONS

Patients with RIF aged < 38 years do not benefit from PGT-A. Thus, factors other than genetic abnormalities may contribute to this clinical conundrum.

Optimized gene-enhanced ERA improves in vitro fertilization outcomes in patients with repeated implantation failure: A meta-analysis

BACKGROUND

Assisted reproductive technology still presents a significant challenge when it comes to repeated implantation failure (RIF). To address this issue, personalized embryo transfer (pET) has been suggested as a potential solution. pET involves guiding the embryo transfer process based on an analysis of endometrial receptivity, known as endometrial receptivity analysis (ERA). However, the clinical value of this approach remains uncertain.

METHODS

We conducted a comprehensive analysis of 14 studies pertaining to pET guided by ERA in patients with RIF. The outcomes evaluated in these studies encompassed the clinical pregnancy rate (CPR), implantation rate, and live birth rate (LBR). In addition, we performed subgroup analysis by considering different definitions of RIF and utilizing various ERA techniques, such as traditional and optimized gene-enhanced approaches.

RESULTS

In general, the utilization of ERA-guided pET did not have a substantial impact on CPR (relative risk [RR], 1.25 [95% CI, 0.85-1.84]), implantation rate (RR, 1.59 [95% CI, 0.89-2.82]), or LBR (RR, 1.55 [95% CI, 0.96-2.50]) compared with standard transfer. However, the implementation of optimized gene-enhanced ERA methods demonstrated significant enhancements in CPR (RR, 2.04 [95% CI, 1.53-2.72]) and LBR (RR, 2.61 [95% CI, 1.58-4.31]).

CONCLUSION

While ERA-guided pET shows limited efficacy in improving pregnancy outcomes in patients with RIF, there lies potential in optimizing gene-enhanced ERA techniques to augment both clinical pregnancy rates and LBRs.

Causes of embryo implantation failure: A systematic review and metaanalysis of procedures to increase embryo implantation potential

Introduction

Infertility is characterized by the failure to conceive after 12 months of unprotected sexual intercourse. In assisted reproduction technologies (ARTs), in-vitro fertilization and embryo transfer (IVF-ET) are pivotal, with the quality of embryo quality essential for successful implantation.

Objective

This systematic review with meta-analysis aimed to explore the prevalence of embryonic factors involved in the implantation process, concentrating on the following research inquiries: 1) the implantation rates of euploid versus untested embryo transfers; 2) the efficiency of transferring good embryos in different age groups; 3) the impact of age on good embryo transfers to gestational carriers; and 4) the transfer of donated gametes/embryos. The goal is to identify critical points in implantation to improve therapies.

Methods

A comprehensive literature search identified 1474 relevant papers, 11 of which met the inclusion criteria. The information was gathered using a standardized form, and the risk of bias was evaluated. A meta-analysis of subgroups to determine euploid embryo transfer efficiency was conducted to synthesize and explore the results. Furthermore, data extracted from registries document the persistent secondary role of extraembryonic determinants in successful implantation.

Results

The meta-analysis demonstrated that preimplantation genetic testing for aneuploidy (PGT-A) significantly increased the odds of implantation. Age was found to influence extraembryonic factors, with older women experiencing reduced embryo implantation as gestational carriers. However, the overall incidence of extraembryonic factors was low. This review highlights the need to focus on PGT-A, diagnostic hysteroscopy, and endometrial receptivity for improving implantation rates.

Conclusion

Implantation success in ARTs largely depends on embryo euploidy. While achieving three euploid embryos greatly increases success rates, it is challenging in older women. Extraembryonic factors, although present, have a marginal impact. Subsequent studies ought to concentrate on modulating endometrial responses immunologically and developing algorithms to improve the precision of predicting implantation success; as well as the timing of endometrial receptivity and the occurrence of dormant embryo phenomena also warrants further investigation.

Tailor-made embryo transfer considering embryonic developmental speed to overcome the dilemma of personalized embryo transfer

RESEARCH QUESTION

Does tailor-made embryo transfer (TmET), timed with respect to embryonic developmental speed, affect pregnancy outcomes in patients with recurrent implantation failure?

DESIGN

Among 741 patients identified as receptive through endometrial receptivity testing, the clinical pregnancy rates and live birth rates were retrospectively compared between those who underwent standard personalized embryo transfer and those who underwent TmET in hormone replacement therapy cycles. Personalized embryo transfer was performed according to endometrial receptivity test results (standard personalized embryo transfer group) or considering embryonic developmental speed (TmET group). For TmET, the expansion grade of warmed blastocysts was estimated based on each patient's previous embryonic developmental pattern. The embryo transfer days were set so that estimated blastocyst grades 3, 4, 5 and 6 were transferred on days P+5, P+5.5, P+6.0 and P+6.5, respectively.

RESULTS

In a propensity score matching analysis, the clinical pregnancy rate was significantly higher in the TmET group than the standard personalized embryo transfer group (P = 0.014), whereas the live birth rates were similar between the two groups (P = 0.65). In a subgroup analysis with euploid embryo transfers, the clinical pregnancy rate was significantly higher in the TmET group than the standard personalized embryo transfer group, although there was no difference in live birth rate between the two groups (P = 0.045 and P = 0.057, respectively).

CONCLUSIONS

For patients experiencing recurrent implantation failure and identified as receptive through endometrial receptivity testing, subsequent TmET strategies may further enhance pregnancy outcomes.

The use of propensity score matching to assess the effectiveness of the endometrial receptivity analysis in patients with recurrent implantation failure

Background

One potential cause of implantation failure is abnormal endometrial receptivity, and how to objectively evaluate endometrial receptivity has been a matter of great concern. Endometrial receptivity analysis (ERA), a next-generation sequencing-based test that assesses endometrial gene expression, may be valuable in predicting endometrial receptivity, but whether ERA improves pregnancy outcomes in patients with recurrent implantation failure (RIF) is currently controversial. The purpose of this study was to investigate the effect of ERA on pregnancy outcomes in patients with RIF.

Methods

We performed a retrospective cohort study analysis for a population of patients with RIF undergoing frozen embryo transfer (FET) cycles in the reproductive center of the Third Affiliated Hospital of Zhengzhou University from January 2019 to December 2022(n=1598). FET cycles with personalized embryo transfer (PET) under ERA guidance were included in the ERA group (n=43); after using propensity score matching (PSM), a total of 120 FET cycles were included as a control group. Pregnancy outcomes were compared between the two groups. Further, the relationship between the number of previous implant failures and the rate of implant window displacement was discussed. The factors affecting the window of implantation (WOI) displacement were also assessed.

Results

There was no statistically significant difference in embryo implantation rate, clinical pregnancy rate, spontaneous abortion rate, and live birth rate between the ERA group and the matched control patients (P > 0.05). There was no significant difference in the rate of WOI displacement between patients in the moderate or severe groups (P > 0.05) and no significant difference in pregnancy outcome ( P>0.05). Finally, analysis of the clinical data of patients in the receptive and non-receptive groups did not uncover any factors influencing WOI displacement.

Conclusion

The results of the study showed no significant difference in pregnancy outcomes in patients who received ERA compared to those who did not.

A review of artificial intelligence applications in in vitro fertilization

The field of reproductive medicine has witnessed rapid advancements in artificial intelligence (AI) methods, which have significantly enhanced the efficiency of diagnosing and treating reproductive disorders. The integration of AI algorithms into the in vitro fertilization (IVF) has the potential to represent the next frontier in advancing personalized reproductive medicine and enhancing fertility outcomes for patients. The potential of AI lies in its ability to bring about a new era characterized by standardization, automation, and an improved success rate in IVF. At present, the utilization of AI in clinical practice is still in its early stages and faces numerous ethical, regulatory, and technical challenges that require attention. In this review, we present an overview of the latest advancements in various applications of AI in IVF, including follicular monitoring, oocyte assessment, embryo selection, and pregnancy outcome prediction. The aim is to reveal the current state of AI applications in the field of IVF, their limitations, and prospects for future development. Further studies, which involve the development of comprehensive models encompassing multiple functions and the conduct of large-scale randomized controlled trials, could potentially indicate the future direction of AI advancements in the field of IVF.

Ectopic pregnancy is associated with increased risk of displaced implantation window: a retrospective study

BACKGROUND

To evaluate the risk factors associated with WOI (window of implantation) displacement based on ERT (endometrial receptivity test), and to confirm the association of ectopic pregnancy with WOI displacement.

METHODS

This is a retrospective study at the Reproductive Medicine Center of Xiangya Hospital from January 2020 to April 2024, consisting of 934 patients who performed ERT. The patients underwent 3771 assisted reproductive technology (ART) cycles and 2629 embryo transfer (ET) cycles, with each patient experiencing at least one implantation failure. The study utilized generalized estimation equation (GEE) models to examine factors associated with WOI displacement, adjusting for confounding factors like age, body mass index (BMI), and infertility type. Non-linear relationships between age or BMI with WOI displacement were explored using generalized additive models (GAM) with thresholds detected by segmented regression.

RESULTS

Among the patients, 60.17% were in the receptive phase, 39.40% in the pre-receptive phase, and 0.43% in the post-receptive phase. Ectopic pregnancy history increased the risk of WOI displacement by 62% (aOR 1.62, 95%CI 1.03-2.53, P = 0.035), patients over 35 years old had a 50% higher risk of WOI displacement compared to patients under 34 (aOR 1.50, 95% CI 1.12-2.00, P = 0.007). Secondary infertility showed a 26% lower risk of WOI displacement than primary infertility without statistical significance (aOR 0.74 95% CI 0.54-1.02, P = 0.062). BMI ≥ 22 kg/m2 was associated with a 25% increased risk of WOI displacement without statistical significance (aOR 1.25, 95% CI 0.94-1.67, P = 0.12).

CONCLUSION

Ectopic pregnancy and advanced age (≥ 35) are significantly associated with increased risk of WOI displacement. Primary infertility and higher BMI (≥ 22 kg/m2) tend to increase the risk of WOI displacement though without statistical significance.

CLINICAL TRIAL NUMBER

Not applicable.

Predictions of live birth in IVF programs of patients with recurrent implantation failure

BACKGROUND

When a high-quality embryo is implanted into the uterus, but the pregnancy is not established as shown by the ultrasound visualization of an intrauterine gestational sac, this is known as "implantation failure." Cases when more than two times implantation failure occurred was defined as recurrent implantation failure (RIF). Additional testing is done at this stage of infertility treatment to avoid a repeat of the same result with a future in vitro fertilization (IVF) effort.

AIM OF THE STUDY

The study aimed to evaluate predictive value of using embryo transfer personalization because of the implantation window study in combination with preimplantation genetic testing in patients with recurrent implantation attempts.

METHODS

Briefly describe the main methods or treatments applied: Ninety-three infertile women make up the sample for this prospective cohort study. In regard to treatment results, the study intends to assess the predictive importance of patient characteristics, screening indicators, and several features of IVF cycles, such as the quantity, quality, and developmental stage of the transferred embryos. Statistical methods employed include the calculation of the median (Me) and interquartile range (IQR) for continuous variables. The Mann-Whitney U test was used to discern differences between unrelated samples, while categorical variables were presented as absolute and percentage values. The Pearson's Chi-squared test assessed differences between groups. Logistic regression, utilizing both enter and backward Wald methods, was applied to establish associations with binary outcomes.

RESULTS

The integration of individualized embryo transfer and preimplantation genetic testing (PGT) significantly enhanced the likelihood of live births by 3.4 times in patients experiencing recurrent implantation failure (RIF), with a statistical significance of p = 0.026. In contrast, employing PGT alone increased the probability of live births by 1.5 times; however, this result was not statistically significant (p = 0.439). The predictive model for live birth in patients with RIF, based on our study findings, is defined as follows: the probability of live birth = 1.936 + [1.014 if PGT-A embryos are utilized for transfer] + [1.742 if endometrial preparation is tailored according to the Wellbeing Index (WI)] - [1.860 in cases of secondary infertility] - [1.891 when a male factor is involved].

CONCLUSIONS

The determination of the implantation window (IW) and PGT of the embryo are efficient methods of live birth achievement for patients with RIF.

Personalized embryo transfer guided by rsERT with hourly precision improves pregnancy outcomes in patients with a receptive window of implantation: a pilot study

PURPOSE

To investigate whether personalized embryo transfer (pET) predicted by a modified RNA-sequencing-based endometrial receptivity test (rsERT) model can improve intrauterine pregnancy rate (IPR) in patients with a receptive window of implantation (WOI).

DESIGN

A retrospective pilot study was conducted in the Center for Reproductive Medicine, Central South University, from January 2018 to December 2023. A total of 524 patients with receptive WOI results from rsERT were assigned into two groups based on whether they underwent conventional embryo transfer (conventional ET) or pET. Patients in the conventional ET were matched with those in the pET group at a 1:1 ratio using propensity score matching (PSM).

RESULTS

Before PSM, the IPR (55.73% vs. 46.19%, P = 0.032) and implantation rate (IR) (47.51% vs. 34.03%, P = 0.000) in the pET group were significantly higher than that in the conventional ET group. However, the number and types of transferred embryos differed significantly between the two groups. After adjusting for confounding factors, IPR (57.38% vs. 44.81, P = 0.016) and IR (46.81% vs. 33.10%, P = 0.001) remained significantly higher in the pET group compared to the conventional ET group. The implantation failure rate was significantly lower in the pET group compared to controls (42.62% vs. 55.19%, P = 0.016). Additionally, the multiple-pregnancy rate was significantly higher in the pET group compared to the conventional ET group (10.29% vs. 1.68%, P = 0.001).

CONCLUSIONS

Women with receptive WOI results could benefit from the receptivity-timed pET predicted by the newly refined rsERT. These findings provide a basis for future research in precision medicine for embryo transfer.

In vitro fertilization and perinatal outcomes of patients with advanced maternal age after single frozen euploid embryo transfer: a propensity score-matched analysis of autologous and donor cycles

OBJECTIVE

To evaluate in vitro fertilization (IVF) and perinatal outcomes of donor egg and autologous cycles in patients with advanced reproductive age after undergoing single frozen euploid embryo transfer.

DESIGN

A multicenter, retrospective, cohort study.

SETTING

University-affiliated and private IVF centers.

PATIENT(S)

Patients aged 39-46 years who underwent IVF with intracytoplasmic sperm injection and preimplantation genetic testing for aneuploidy using whole-chromosome sequencing with donor (n = 278) or autologous (n = 278) oocytes between October 2017 and October 2021.

INTERVENTION(S)

Single frozen euploid embryo transfer with donor or autologous euploid embryo.

MAIN OUTCOME MEASURE(S)

The main outcome measure was the live birth rate (LBR) after the first embryo transfer, calculated per embryo transfer. The secondary outcomes included the implantation rate, ectopic pregnancy rate, miscarriage rate, and gestational age and birth weight at the time of delivery.

RESULT(S)

Patients using donor or autologous oocytes had a similar likelihood of implantation (57.91% [51.87-63.78] vs. 57.19% [51.15-63.09]) and LBR (41.01% [95% confidence interval {CI}, 35.17-47.04] vs. 42.45% [95% CI, 36.56-48.49]). Furthermore, there were no significant differences in the ectopic pregnancy rate (0.72% [0.09-2.57] vs. 0.36% [0.01-1.99]), miscarriage rate (16.19% [12.06-21.05] vs. 14.39% [95% CI, 10.48-19.08]), gestational age (38.50 [38.08-38.92] vs. 39.16 [38.25-40.07] weeks), or birth weight of infants (2,982.25 [2,606.69-3,357.81] vs. 3,128.24 [2,962.30-3,294.17] kg). The univariate analysis showed no association between advanced maternal age and the LBR (relative risk, 1.03 [95% CI, 0.84-1.25]). Multivariate analysis using putative confounders for embryo competency found no associations with LBR (adjusted relative risk, 1.22 [95% CI, 0.75-1.98]).

CONCLUSION(S)

Patients with euploid blastocysts derived from donor or autologous oocytes did not reveal statistically significant differences in the LBR, implantation rate, ectopic pregnancy rate, miscarriage rate, duration of gestation, or infant birth weight. These findings suggest that age-related reproductive decline and/or poor IVF outcomes associated with women with advanced reproductive age undergoing IVF are heavily driven by embryonic aneuploidy.

Predicting risk of endometrial failure: a biomarker signature that identifies a novel disruption independent of endometrial timing in patients undergoing hormonal replacement cycles

OBJECTIVE

To propose a new gene expression signature that identifies endometrial disruptions independent of endometrial luteal phase timing and predicts if patients are at risk of endometrial failure.

DESIGN

Multicentric, prospective study.

SETTING

Reproductive medicine research department in a public hospital affiliated with private fertility clinics and a reproductive genetics laboratory.

PATIENTS

Caucasian women (n = 281; 39.4 ± 4.8 years old with a body mass index of 22.9 ± 3.5 kg/m2) undergoing hormone replacement therapy between July 2018 and July 2021. Endometrial samples from 217 patients met RNA quality criteria for signature discovery and analysis.

INTERVENTION(S)

Endometrial biopsies collected in the mid-secretory phase.

MAIN OUTCOME MEASURE(S)

Endometrial luteal phase timing-corrected expression of 404 genes and reproductive outcomes of the first single embryo transfer (SET) after biopsy collection to identify prognostic biomarkers of endometrial failure.

RESULTS

Removal of endometrial timing variation from gene expression data allowed patients to be stratified into poor (n = 137) or good (n = 49) endometrial prognosis groups on the basis of their clinical and transcriptomic profiles. Significant differences were found between endometrial prognosis groups in terms of reproductive rates: pregnancy (44.6% vs. 79.6%), live birth (25.6% vs. 77.6%), clinical miscarriage (22.2% vs. 2.6%), and biochemical miscarriage (20.4% vs. 0%). The relative risk of endometrial failure for patients predicted as a poor endometrial prognosis was 3.3 times higher than those with a good prognosis. The differences in gene expression between both profiles were proposed as a biomarker, coined the endometrial failure risk (EFR) signature. Poor prognosis profiles were characterized by 59 upregulated and 63 downregulated genes mainly involved in regulation (17.0%), metabolism (8.4%), immune response, and inflammation (7.8%). This EFR signature had a median accuracy of 0.92 (min = 0.88, max = 0.94), median sensitivity of 0.96 (min = 0.91, max = 0.98), and median specificity of 0.84 (min = 0.77, max = 0.88), positioning itself as a promising biomarker for endometrial evaluation.

CONCLUSION(S)

The EFR signature revealed a novel endometrial disruption, independent of endometrial luteal phase timing, present in 73.7% of patients. This EFR signature stratified patients into 2 significantly distinct and clinically relevant prognosis profiles providing opportunities for personalized therapy. Nevertheless, further validations are needed before implementing this gene signature as an artificial intelligence (AI)-based tool to reduce the risk of patients experiencing endometrial failure.

The synergy of morphokinetic parameters and sHLA-G in cleavage embryo enhancing implantation rates

Objective: This study aimed to assess the relationship between implantation and soluble HLA-G (sHLA-G) expression in cleavage embryo culture medium (ECM) in conjunction with early developmental kinetics determined by time-lapse imaging (TLI). Methods: A retrospective, single-center study was conducted involving 238 embryos from 165 patients who underwent Frozen-thawed embryo transfer (FET) using autologous oocytes, with either single or double embryo transfer. TLI morphokinetic parameters (t2, t3, t4, t5, t6, t7, t8, cc2, s2, cc3, s3) of embryos were analyzed, and sHLA-G levels in D3 ECM were measured using an enzyme-linked immunosorbent assay (ELISA). A hierarchical classification model was developed to categorize embryos into five groups (A, B, C, D, E). The correlation between sHLA-G levels, TLI classification of embryos, and embryo implantation was investigated to establish a non-invasive method for evaluating implantation potential. Multivariate logistic regression analysis was performed to identify potential influencing factors, and receiver operating characteristic (ROC) curves were used to evaluate the predictive value for implantation. Results: Multivariate unconditional logistic regression analysis indicated that TLI parameters t5 and s3 and sHLA-G level in ECM were independent risk factors affecting embryo implantation. The implantation rate decreased from TLI classification A to E. The proposed classification model effectively assessed the implantation potential of embryos. The implantation rate was higher in the sHLA-G positive group compared to the sHLA-G negative group (p < 0.001). The expression of sHLA-G in D3 ECM, combined with the TLI classification model, accurately evaluated the implantation potential of embryos with an AUC of 0.876. Conclusion: The integration of cleavage kinetics and embryonic sHLA-G expression could reliably identify embryos with a high likelihood of successful implantation.

Precise hourly personalized embryo transfer significantly improves clinical outcomes in patients with repeated implantation failure

Purpose

This study investigated whether RNA-Seq-based endometrial receptivity test (rsERT)-which provides precision for the optimal hour of the window of implantation (WOI)-can improve clinical outcomes of frozen embryo transfer (FET) cycles in patients with a history of repeated implantation failure (RIF).

Methods

Patients with a history of RIF who received at least one autologous high-quality blastocyst during the subsequent FET cycle were retrospectively enrolled and divided into two groups: rsERT and FET, comprising patients who underwent rsERT-guided pET (n=115) and standard FET without rsERT (n=272), respectively.

Results

In the rsERT group, 39.1% (45/115) of patients were receptive. rsERT patients showed a higher probability of achieving both positive human chorionic gonadotropin (63.5% vs. 51.5%, P=0.03) and clinical pregnancy (54.8% vs. 38.6%, P=0.003) rates. In subgroup analysis, rsERT patients with non-receptive results had higher clinical pregnancy rates than patients undergoing FET (58.6% vs. 38.6%, P=0.003). rsERT patients with receptive results guided by rsERT with a precise WOI time had higher, although non-significant, clinical pregnancy rates (48.9% vs. 38.6%, P=0.192) than patients who underwent standard-time FET.

Conclusion

Hourly precise rsERT can significantly improve the probability of achieving clinical pregnancy in patients with RIF, especially in those with non-receptive rsERT results.

SARS-CoV-2 infection in pregnant patients on TNFα inhibitor: Real-life data with a review of literature

Tumor necrosis factor alpha (TNFα) is involved in the occurrence of negative pregnancy outcomes. The study aimed to evaluate the safety and efficacy of the immunosuppressive TNFα inhibitors (TNFαi) in the treatment of patients with a history of recurrent reproductive failure in the context of COVID-19 pandemics. We reviewed 85 patients who received TNFαi (certolizumab pegol) during Mainland China's first wave of COVID-19 pandemic, from 21st Nov 2022-11 th Jan 2023. We also collected corresponding data from 130 pregnant patients who never used TNFαi for comparison. There were no significant differences in the history of previous pregnancy loss, miscarriage, embryo implantation failure, comorbidities and doses of COVID-19 vaccination. 82.2% and 87.7% pregnant patients contracted primary COVID-19 with symptoms in TNFαi group and no-TNFαi group. Duration of symptoms was significantly longer in TNFαi group and the incidences of cough and lethargy was significantly higher in TNFαi group. Both groups reported similar severity to same-aged close contacts, similar rates of other symptoms and hospitalization. No deaths were reported. In the in vitro fertilization (IVF) subgroup, we achieved a biochemical pregnancy loss rate of 17.4%, miscarriage rate of 21.7%, ongoing pregnancy rate and live birth rate of 34.2%. COVID-19 did not influence the live birth rate. We concluded that TNFαi administration in pregnancy was not associated with increased susceptivity to and severity of COVID-19. However, TNFαi users showed more prominent symptoms and longer recovery time. The pregnancy outcomes with TNFαi in such high-risk group for pregnancy loss was satisfactory.

Does recurrent implantation failure exist? Prevalence and outcomes of five consecutive euploid blastocyst transfers in 123 987 patients

STUDY QUESTION

What are the clinical pregnancy and live birth rates in women who underwent up to two more euploid blastocyst transfers after three failures in the absence of another known factor that affects implantation?

SUMMARY ANSWER

The fourth and fifth euploid blastocyst transfers resulted in similar live birth rates of 40% and 53.3%, respectively, culminating in a cumulative live birth rate of 98.1% (95% CI = 96.5-99.6%) after five euploid blastocyst transfers.

WHAT IS KNOWN ALREADY

The first three euploid blastocysts have similar implantation and live birth rates and provide a cumulative live birth rate of 92.6%.

STUDY DESIGN, SIZE, DURATION

An international multi-center retrospective study was conducted at 25 individual clinics. The study period spanned between January 2012 and December 2022. A total of 123 987 patients with a total of 64 572 euploid blastocyst transfers were screened for inclusion.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Patients with a history of any embryo transfer at another clinic, history of any unscreened embryo transfer at participating clinics, parental karyotype abnormalities, the use of donor oocytes or a gestational carrier, untreated intracavitary uterine pathology (e.g. polyp, leiomyoma), congenital uterine anomalies, adenomyosis, communicating hydrosalpinx, endometrial thickness <6 mm prior to initiating of progesterone, use of testicular sperm due to non-obstructive azoospermia in the male partner, transfer of an embryo with a reported intermediate chromosome copy number (i.e. mosaic), preimplantation genetic testing cycles for monogenic disorders, or structural chromosome rearrangements were excluded. Ovarian stimulation protocols and embryology laboratory procedures including trophectoderm biopsy followed the usual practice of each center. The ploidy status of blastocysts was determined with comprehensive chromosome screening. Endometrial preparation protocols followed the usual practice of participating centers and included programmed cycles, natural or modified natural cycles.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 105 (0.085% of the total population) patients met the criteria and underwent at least one additional euploid blastocyst transfer after failing to achieve a positive pregnancy test with three consecutive euploid blastocyst transfers. Outcomes of the fourth and fifth euploid blastocyst transfers were similar across participating centers. Overall, the live birth rate was similar with the fourth and fifth euploid blastocysts (40% vs 53.3%, relative risk = 1.33, 95% CI = 0.93-1.9, P value = 0.14). Sensitivity analyses excluding blastocysts biopsied on Day 7 postfertilization, women with a BMI >30 kg/m2, cycles using non-ejaculate or donor sperm, double-embryo transfer cycles, and cycles in which the day of embryo transfer was modified due to endometrial receptivity assay test result yielded similar results. Where data were available, the fourth euploid blastocyst had similar live birth rate with the first one (relative risk = 0.84, 95% CI = 0.58-1.21, P = 0.29). The cumulative live birth rate after five euploid blastocyst transfers was 98.1% (95% CI = 96.5-99.6%).

LIMITATIONS, REASONS FOR CAUTION

Retrospective design has its own inherent limitations. Patients continuing with a further euploid embryo transfer and patients dropping out from treatment after three failed euploid transfers can be systematically different, perhaps with regard to ovarian reserve or economic status.

WIDER IMPLICATION OF THE FINDINGS

Implantation failure seems to be mainly due to embryonic factors. Given the stable and high live birth rates up to five euploid blastocysts, unexplained recurrent implantation failure should have a prevalence of <2%. Proceeding with another embryo transfer can be the best next step once a known etiology for implantation failure is ruled out.

STUDY FUNDING/COMPETING INTEREST(S)

None.

TRIAL REGISTRATION NUMBER

N/A.

Preimplantation genetic testing for aneuploidy optimizes reproductive outcomes in recurrent reproductive failure: a systematic review

Introduction

Recurrent reproductive failure (RRF) is a common pregnancy complication, imposing great physical, emotional and financial burden for the suffered couples. The leading cause of RRF is believed to be aneuploid embryo, which could be solved by preimplantation genetic testing for aneuploidy (PGT-A) in theory. With molecular genetic development, PGT-A based on comprehensive chromosomal screening (CCS) procedures and blastocyst biopsy is widely applied in clinical practice. However, its effects in RRF were not defined yet.

Methods

A systematic bibliographical search was conducted without temporal limits up to June, 2023. Studies about the effects of PGT-A based on CCS procedures and blastocyst biopsy in RRF were included.

Results

Twenty studies about the effects of PGT-A based on CCS procedures and blastocyst biopsy in RRF were included. It revealed that PGT-A could optimise the reproductive outcomes of RRF sufferers, especially in those with advanced age. However, in patients with multiple occurrences of pregnancy losses, the benefits of PGT-A were limited.

Discussion

More randomized controlled trials with large sample size are required to evaluate the benefits of PGT-A in RRF sufferers and identify which population would benefit the most.

Preimplantation Genetic Testing for Aneuploidy Could Not Improve Cumulative Live Birth Rate Among 705 Couples with Unexplained Recurrent Implantation Failure

Objective

We evaluate whether next-generation sequencing (NGS)-based preimplantation genetic testing for aneuploidy (PGT-A) improves the cumulative pregnancy outcomes of patients with unexplained recurrent implantation failure (uRIF) as compared to conventional in vitro fertilization or intracytoplasmic sperm injection (IVF/ICSI).

Patients and Methods

This was a retrospective cohort study (2015-2022). A total of 705 couples diagnosed with uRIF were included in the study. 229 women transferred blastocysts based on morphological grading (IVF/ICSI) and 476 couples opted for PGT-A to screen blastocysts by NGS. Women were further stratified according to age at retrieval (<38 years and ≥38 years). The primary outcome was the cumulative live-birth rate after all the embryos were transferred in a single oocyte retrieval or until achieving a live birth. Confounders were adjusted using binary logistic regression models.

Results

Cumulative live-birth rate was similar between the IVF/ICSI group and the PGT-A group after stratified by age: IVF/ICSI vs PGT-A in the <38 years subgroup (49.7% vs 57.7%, adjusted OR (95% CI) = 1.25 (0.84-1.84), P = 0.270) and in the ≥38 years subgroup (14.0% vs 19.5%, adjusted OR (95% CI) = 1.09 (0.41-2.92), P = 0.866), respectively. Nonetheless, the PGT group had a lower first-time biochemical pregnancy loss rate (17.0% vs 8.7%, P = 0.034) and a higher cumulative good birth outcome rate (35.2% vs 46.4%, P = 0.014) than the IVF/ICSI group in the <38 years subgroup. Other pregnancy outcomes after the initial embryo transfer and multiple transfers following a single oocyte retrieval were all similar between groups.

Conclusion

Our results showed no evidence of favorable effects of PGT-A treatment on improving the cumulative live birth rate in uRIF couples regardless of maternal age. Use of PGT-A in the <38 years uRIF patients would help to decrease the first-time biochemical pregnancy loss and increase the cumulative good birth outcome.

Assessing the Impact of Genratest on Women With Recurrent Implantation Failure: A Single-Center Study

Objective Recurrent implantation failure (RIF) is a significant challenge in assisted reproduction. Genratest has emerged as a potential tool to identify the displaced window of implantation (WOI). This study aimed to evaluate the impact of this test on the pregnancy outcomes of RIF patients. Methods A retrospective analysis was conducted on 143 RIF patients who were categorized into two groups: the personalized embryo transfer (pET, n=69) group and standard embryo transfer (sET, n=74) group. The main measured outcomes were clinical pregnancy, ongoing pregnancy, miscarriage, and live birth rates. Results Genratest effectively diagnoses the displaced WOI in 90% of RIF patients. The pET group exhibited a higher rate of clinical pregnancy (n=36/69, 52.2%) compared to the sET group (n=35/74, 47.3%), but this difference was not statistically significant (p=0.679). Ongoing pregnancy rates were comparable between the pET (n=28/69, 40.6%) and the sET (n=30/74, 40.5%) groups (p=0.996). Live birth rates showed no statistically significant difference between the two groups (n=26/69, 37.7% versus n=22/74, 29.7%, p=0.407). Miscarriage rates were similar in both groups (n=9/69, 13% versus n=11/74, 14.9%, p=0.942). Conclusions pET based on the results of the Genratest did not show a significant improvement in pregnancy outcomes, including clinical pregnancy, ongoing pregnancy, live birth, or miscarriage rates. Further research is needed to identify the role of Genratest in RIF patients.

Factors affecting the ongoing pregnancy rate in women with repeated implantation failure undergoing an endometrial receptivity array

OBJECTIVE

In this retrospective study, we analyzed factors influencing the ongoing pregnancy rate (PR) in women with repeated implantation failure (RIF) undergoing embryo transfer with endometrial receptivity array (ERA).

METHODS

Eighty-three consecutive personalized embryo transfers (pETs) with ERA, from 54 women with RIF, were selected from June 2020 to April 2022. Vitrified blastocyst transfer was timed based on ERA results.

RESULTS

The ongoing PR per pET was 33.7%. Using ERA, the endometrium was identified as pre-receptive in 26 cycles, early receptive in 25 cycles, receptive in 31 cycles, and late receptive in one cycle. With cycles categorized into three receptivity phases (pre-receptive, early receptive, or receptive), no significant differences were found in the clinical PR (27.3%, 55.6%, and 40%, respectively) or ongoing PR (9.1%, 55.6%, and 40%, respectively) after a single blastocyst transfer. Similarly, no significant differences were observed in the clinical PR or ongoing PR after the transfer of two or more blastocysts. Among women with ongoing pregnancy relative to those without, age at first pET was significantly lower (35 years vs. 39 years, p=0.001), while blastocyst score (23 vs. 18, p=0.012) and the proportion of blastocyst scores >18 (71.4% vs. 38.9%, p=0.005) were significantly higher. In multiple logistic regression analysis, the woman's age (odds ratio [OR], 0.814; 95% confidence interval [CI], 0.706 to 0.940; p=0.005) and blastocyst score >18 (OR, 3.052; 95% CI, 1.075 to 8.665; p=0.036) were identified as significant factors influencing ongoing pregnancy.

CONCLUSION

In pET with ERA, ongoing pregnancy was closely associated with woman's age and blastocyst quality.

ESHRE Add-ons working group, Lundin K, Bentzen JG, Bozdag G, Ebner T, Harper J, Le Clef N, Moffett A, Norcross S, Polyzos NP, Rautakallio-Hokkanen S, Sfontouris I, Sermon K, Vermeulen N, Pinborg A. Good practice recommendations on add-ons in reproductive medicine†

STUDY QUESTION

Which add-ons are safe and effective to be used in ART treatment?

SUMMARY ANSWER

Forty-two recommendations were formulated on the use of add-ons in the diagnosis of fertility problems, the IVF laboratory and clinical management of IVF treatment.

WHAT IS KNOWN ALREADY

The innovative nature of ART combined with the extremely high motivation of the patients has opened the door to the wide application of what has become known as 'add-ons' in reproductive medicine. These supplementary options are available to patients in addition to standard fertility procedures, typically incurring an additional cost. A diverse array of supplementary options is made available, encompassing tests, drugs, equipment, complementary or alternative therapies, laboratory procedures, and surgical interventions. These options share the common aim of stating to enhance pregnancy or live birth rates, mitigate the risk of miscarriage, or expedite the time to achieving pregnancy.

STUDY DESIGN, SIZE, DURATION

ESHRE aimed to develop clinically relevant and evidence-based recommendations focusing on the safety and efficacy of add-ons currently used in fertility procedures in order to improve the quality of care for patients with infertility.

PARTICIPANTS/MATERIALS, SETTING, METHODS

ESHRE appointed a European multidisciplinary working group consisting of practising clinicians, embryologists, and researchers who have demonstrated leadership and expertise in the care and research of infertility. Patient representatives were included in the working group. To ensure that the guidelines are evidence-based, the literature identified from a systematic search was reviewed and critically appraised. In the absence of any clear scientific evidence, recommendations were based on the professional experience and consensus of the working group. The guidelines are thus based on the best available evidence and expert agreement. Prior to publication, the guidelines were reviewed by 46 independent international reviewers. A total of 272 comments were received and incorporated where relevant.

MAIN RESULTS AND THE ROLE OF CHANCE

The multidisciplinary working group formulated 42 recommendations in three sections; diagnosis and diagnostic tests, laboratory tests and interventions, and clinical management.

LIMITATIONS, REASONS FOR CAUTION

Of the 42 recommendations, none could be based on high-quality evidence and only four could be based on moderate-quality evidence, implicating that 95% of the recommendations are supported only by low-quality randomized controlled trials, observational data, professional experience, or consensus of the development group.

WIDER IMPLICATIONS OF THE FINDINGS

These guidelines offer valuable direction for healthcare professionals who are responsible for the care of patients undergoing ART treatment for infertility. Their purpose is to promote safe and effective ART treatment, enabling patients to make informed decisions based on realistic expectations. The guidelines aim to ensure that patients are fully informed about the various treatment options available to them and the likelihood of any additional treatment or test to improve the chance of achieving a live birth.

STUDY FUNDING/COMPETING INTEREST(S)

All costs relating to the development process were covered from ESHRE funds. There was no external funding of the development process or manuscript production. K.L. reports speakers fees from Merck and was part of a research study by Vitrolife (unpaid). T.E. reports consulting fees from Gynemed, speakers fees from Gynemed and is part of the scientific advisory board of Hamilton Thorne. N.P.P. reports grants from Merck Serono, Ferring Pharmaceutical, Theramex, Gedeon Richter, Organon, Roche, IBSA and Besins Healthcare, speakers fees from Merck Serono, Ferring Pharmaceutical, Theramex, Gedeon Richter, Organon, Roche, IBSA and Besins Healthcare. S.R.H. declares being managing director of Fertility Europe, a not-for-profit organization receiving financial support from ESHRE. I.S. is a scientific advisor for and has stock options from Alife Health, is co-founder of IVFvision LTD (unpaid) and received speakers' fee from the 2023 ART Young Leader Prestige workshop in China. A.P. reports grants from Gedeon Richter, Ferring Pharmaceuticals and Merck A/S, consulting fees from Preglem, Novo Nordisk, Ferring Pharmaceuticals, Gedeon Richter, Cryos and Merck A/S, speakers fees from Gedeon Richter, Ferring Pharmaceuticals, Merck A/S, Theramex and Organon, travel fees from Gedeon Richter. The other authors disclosed no conflicts of interest.

DISCLAIMER

This Good Practice Recommendations (GPRs) document represents the views of ESHRE, which are the result of consensus between the relevant ESHRE stakeholders and are based on the scientific evidence available at the time of preparation.ESHRE GPRs should be used for information and educational purposes. They should not be interpreted as setting a standard of care or bedeemedinclusive of all proper methods of care, or be exclusive of other methods of care reasonably directed to obtaining the same results.Theydo not replace the need for application of clinical judgement to each individual presentation, or variations based on locality and facility type.Furthermore, ESHRE GPRs do not constitute or imply the endorsement, or favouring, of any of the included technologies by ESHRE.

Current knowledge on the role of extracellular vesicles in endometrial receptivity

Endometrial receptivity has been widely understood as the capacity of the endometrium to receive implantable embryos. The establishment of endometrial receptivity involves multiple biological processes including decidualization, tissue remodeling, angiogenesis, immune regulation, and oxidative metabolism. Extracellular vesicles (EVs) are lipid-bilayer-membrane nanosized vesicles mediating cell-to-cell communication. Recently, EVs and their cargo have been proven as functional factors in the establishment of endometrial receptivity. In this review, we comprehensively summarized the alteration of endometrium/embryo-derived EVs during the receptive phase and retrospected the current findings which revealed the pivotal role and potential mechanism of EVs to promote successful implantation. Furthermore, we highlight the potentiality and limitations of EVs being translated into clinical applications such as biomarkers of endometrial receptivity or reproductive therapeutic mediators, and point out the direction for further research.

Does endometrial receptivity array improve reproductive outcomes in euploid embryo transfer cycles? a systematic review

Besides chromosomal normality, endometrial receptivity is an important factor in determining successful pregnancies. Endometrial receptivity array (ERA), a promising endometrial receptivity test, was speculated to improve the reproductive outcomes. However, its effectiveness is controversial in clinical practice. Therefore, we conducted this review to investigate its role in in vitro fertilization (IVF) treatment. To eliminate the interference of embryo quality, we only analyzed studies that originally reported the reproductive outcomes of patients who underwent ERA-guided euploid embryo transfer (EET). Unexpectedly, it revealed that ERA could not optimize the reproductive outcomes in EET cycles, no matter in general infertile population or in patients with a history of previous failed embryo transfers.

Effects of NGS-based PGT-a for idiopathic recurrent pregnancy loss and implantation failure: a retrospective cohort study

To clarify the effect of next-generation sequencing (NGS)-based preimplantation genetic testing for aneuploidy (PGT-A) combined with trophectoderm (TE) biopsy on the pregnancy outcomes of idiopathic recurrent pregnancy loss (iRPL) and idiopathic recurrent implantation failure (iRIF), we conducted a retrospective cohort study of 212 iRPL couples and 66 iRIF couples who underwent PGT-A or conventional in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) treatment. The implantation rate (IR) per transfer (64.2%), clinical pregnancy rate (CPR) per transfer (57.5%), and live birth rate (LBR) per transfer (45%) of iRPL couples of the PGT-A treatment group were significantly higher (p < 0.05) than those of the conventional IVF/ICSI group (IR per transfer,38.2%; CPR per transfer,33.3%; LBR per transfer, 28.4%), whereas the pregnancy loss rate (PLR) per transfer was similar between the two groups. These effects were also significant (p < 0.05) in iRPL couples with advanced maternal age (AMA, ≥35 years), whereas no significant differences were found in clinical outcomes between the PGT-A and conventional IVF/ICSI groups in younger iRPL couples (<35 years). The cumulative clinical outcomes of iRPL couples were comparable between the PGT-A and conventional IVF/ICSI groups. No significant differences were found in any clinical outcomes between the PGT-A and conventional IVF/ICSI groups for young or AMA couples with iRIF. In conclusion, NGS-based PGT-A involving TE biopsy may be useful for iRPL women to shorten the time to pregnancy and reduce their physical and psychological burden, especially for iRPL women with AMA; however, couples with iRIF may not benefit from PGT-A treatment. Considering the small sample size of the iRIF group, further investigations with a larger sample size are needed to verify our findings.

Opening the black box: why do euploid blastocysts fail to implant? A systematic review and meta-analysis

BACKGROUND

A normal chromosomal constitution defined through PGT-A assessing all chromosomes on trophectoderm (TE) biopsies represents the strongest predictor of embryo implantation. Yet, its positive predictive value is not higher than 50-60%. This gap of knowledge on the causes of euploid blastocysts' reproductive failure is known as 'the black box of implantation'.

OBJECTIVE AND RATIONALE

Several embryonic, maternal, paternal, clinical, and IVF laboratory features were scrutinized for their putative association with reproductive success or implantation failure of euploid blastocysts.

SEARCH METHODS

A systematic bibliographical search was conducted without temporal limits up to August 2021. The keywords were '(blastocyst OR day5 embryo OR day6 embryo OR day7 embryo) AND (euploid OR chromosomally normal OR preimplantation genetic testing) AND (implantation OR implantation failure OR miscarriage OR abortion OR live birth OR biochemical pregnancy OR recurrent implantation failure)'. Overall, 1608 items were identified and screened. We included all prospective or retrospective clinical studies and randomized-controlled-trials (RCTs) that assessed any feature associated with live-birth rates (LBR) and/or miscarriage rates (MR) among non-mosaic euploid blastocyst transfer after TE biopsy and PGT-A. In total, 41 reviews and 372 papers were selected, clustered according to a common focus, and thoroughly reviewed. The PRISMA guideline was followed, the PICO model was adopted, and ROBINS-I and ROB 2.0 scoring were used to assess putative bias. Bias across studies regarding the LBR was also assessed using visual inspection of funnel plots and the trim and fill method. Categorical data were combined with a pooled-OR. The random-effect model was used to conduct the meta-analysis. Between-study heterogeneity was addressed using I2. Whenever not suitable for the meta-analysis, the included studies were simply described for their results. The study protocol was registered at http://www.crd.york.ac.uk/PROSPERO/ (registration number CRD42021275329).

OUTCOMES

We included 372 original papers (335 retrospective studies, 30 prospective studies and 7 RCTs) and 41 reviews. However, most of the studies were retrospective, or characterized by small sample sizes, thus prone to bias, which reduces the quality of the evidence to low or very low. Reduced inner cell mass (7 studies, OR: 0.37, 95% CI: 0.27-0.52, I2 = 53%), or TE quality (9 studies, OR: 0.53, 95% CI: 0.43-0.67, I2 = 70%), overall blastocyst quality worse than Gardner's BB-grade (8 studies, OR: 0.40, 95% CI: 0.24-0.67, I2 = 83%), developmental delay (18 studies, OR: 0.56, 95% CI: 0.49-0.63, I2 = 47%), and (by qualitative analysis) some morphodynamic abnormalities pinpointed through time-lapse microscopy (abnormal cleavage patterns, spontaneous blastocyst collapse, longer time of morula formation I, time of blastulation (tB), and duration of blastulation) were all associated with poorer reproductive outcomes. Slightly lower LBR, even in the context of PGT-A, was reported among women ≥38 years (7 studies, OR: 0.87, 95% CI: 0.75-1.00, I2 = 31%), while obesity was associated with both lower LBR (2 studies, OR: 0.66, 95% CI: 0.55-0.79, I2 = 0%) and higher MR (2 studies, OR: 1.8, 95% CI: 1.08-2.99, I2 = 52%). The experience of previous repeated implantation failures (RIF) was also associated with lower LBR (3 studies, OR: 0.72, 95% CI: 0.55-0.93, I2 = 0%). By qualitative analysis, among hormonal assessments, only abnormal progesterone levels prior to transfer were associated with LBR and MR after PGT-A. Among the clinical protocols used, vitrified-warmed embryo transfer was more effective than fresh transfer (2 studies, OR: 1.56, 95% CI: 1.05-2.33, I2 = 23%) after PGT-A. Lastly, multiple vitrification-warming cycles (2 studies, OR: 0.41, 95% CI: 0.22-0.77, I2 = 50%) or (by qualitative analysis) a high number of cells biopsied may slightly reduce the LBR, while simultaneous zona-pellucida opening and TE biopsy allowed better results than the Day 3 hatching-based protocol (3 studies, OR: 1.41, 95% CI: 1.18-1.69, I2 = 0%).

WIDER IMPLICATIONS

Embryo selection aims at shortening the time-to-pregnancy, while minimizing the reproductive risks. Knowing which features are associated with the reproductive competence of euploid blastocysts is therefore critical to define, implement, and validate safer and more efficient clinical workflows. Future research should be directed towards: (i) systematic investigations of the mechanisms involved in reproductive aging beyond de novo chromosomal abnormalities, and how lifestyle and nutrition may accelerate or exacerbate their consequences; (ii) improved evaluation of the uterine and blastocyst-endometrial dialogue, both of which represent black boxes themselves; (iii) standardization/automation of embryo assessment and IVF protocols; (iv) additional invasive or preferably non-invasive tools for embryo selection. Only by filling these gaps we may finally crack the riddle behind 'the black box of implantation'.

Transcriptomic patterns in early-secretory and mid-secretory endometrium in a natural menstrual cycle immediately before in vitro fertilization and embryo transfer

OBJECTIVE

This study aimed to evaluate the endometrial transcriptomic patterns in the early secretory phase (ESP) and mid-secretory phase (MSP) of the natural menstrual cycle before in vitro fertilization and embryo transfer (IVF-ET).

METHODS

Thirty patients whose endometrial tissues were obtained from the ESP or MSP of a natural menstrual cycle immediately before IVF-ET were included. Endometrial dating was histologically confirmed as ESP (cycle days 16-18) or MSP (cycle days 19-21), according to the noyes criteria. The patients were divided into two groups depending on the IVF-ET outcome: pregnant (n=14; 7 in ESP and 7 in MSP) or non-pregnant (n=16; 8 in ESP and 8 in MSP). Differentially expressed genes (DEGs) in the MSP, compared to the ESP, were identified using NanoString nCounter (NanoString Technologies, Seattle, WA, USA) data for both the pregnant and non-pregnant groups.

RESULTS

Thirteen DEGs in the pregnant group and 11 DEGs in the non-pregnant group were identified in the MSP compared to those in the ESP. In both groups, adrenoceptor alpha 2A, interleukin 1 receptor-associated kinase 2, a disintegrin and metalloproteinase with thrombospondin repeats 15 (ADAMTS15), serpin family E member 1, integrin subunit beta 3, transmembrane protein 252 (TMEM252), huntingtin associated protein 1, C2 calcium-dependent domain containing 4A, and integrin subunit alpha 2 were upregulated in the MSP, compared to the ESP. TMEM37, galactosidase beta 1 like 2, Rho family GTPase 3, and cytochrome P450 family 24 subfamily A member 1 were upregulated in the MSP only in the pregnant group. ADAMTS8 was downregulated and monoamine oxidase A was upregulated in the MSP only in the non-pregnant group.

CONCLUSION

Transcriptomic patterns in the endometrium immediately before IVF-ET appear to differ according to the IVF-ET outcome. These novel DEGs, which have not been previously studied, may have functional significance during the window of implantation and serve as potential biomarkers of endometrial receptivity.

Preimplantation genetic testing for aneuploidy is not related to adverse obstetric and neonatal outcomes in singleton pregnancies

STUDY QUESTION

What is the potential impact of preimplantation genetic testing for aneuploidy (PGT-A) on obstetric and neonatal outcomes?

SUMMARY ANSWER

PGT-A is not associated with increased rates of adverse maternal and neonatal outcomes in singleton pregnancies following IVF/ICSI cycles.

WHAT IS KNOWN ALREADY

PGT-A pregnancies may be associated with increased risks of lower birthweight, preterm delivery, and hypertensive disorders compared with natural pregnancies. In a recent meta-analysis, the overall obstetric and neonatal outcomes of PGT-A pregnancies were favorable compared with those of IVF/ICSI pregnancies, although PGT-A pregnancies were associated with a higher risk of hypertensive disorders.

STUDY DESIGN, SIZE, DURATION

A multicenter retrospective cohort study was performed in University-affiliated infertility centers. Single live births following IVF/ICSI between October 2016 and January 2021 were included in the study.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 7146 live births after single embryo transfers with (n = 3296) or without (n = 3850) PGT-A were included. The primary outcome was pre-eclampsia and secondary outcomes included gestational diabetes, low birthweight and very low birthweight, cesarean section delivery, emergency cesarean section, as well as preterm birth, birthweight, congenital abnormalities, neonatal sex, Apgar score at 5 min, and neonatal intensive care unit admission. In a subgroup analysis, were included only blastocysts screened with next-generation sequencing (NGS).

MAIN RESULTS AND THE ROLE OF CHANCE

Univariate analysis showed that pre-eclampsia, cesarean section incidence, and low Apgar score were higher in women undergoing PGT-A. However, after performing multivariate logistic and linear regression models accounting for many possible confounders, pregnancies that had been conceived after embryo biopsy showed no increase in adverse obstetric and neonatal outcomes. The subgroup analysis including patients with blastocysts screened by NGS showed a decreased risk of preterm birth in the group undergoing PGT-A.

LIMITATIONS, REASONS FOR CAUTION

Caution should be used when interpreting the data because of its limitations, mainly related to its retrospective design. Although this is a large multicenter study, data acquisition included self-reporting questionnaires, and the deliveries occurred in different institutions with distinct protocols.

WIDER IMPLICATIONS OF THE FINDINGS

The current study does not show any major adverse clinical outcomes after PGT-A. Efforts should be made to promote good quality research on embryo biopsy in terms of neonatal and obstetric outcomes, as well as its long-term consequences.

STUDY FUNDING/COMPETING INTEREST(S)

No specific funding was obtained for this study. The authors declare no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

ESHRE Working Group on Recurrent Implantation Failure, Cimadomo D, de los Santos MJ, Griesinger G, Lainas G, Le Clef N, McLernon DJ, Montjean D, Toth B, Vermeulen N, Macklon N. ESHRE good practice recommendations on recurrent implantation failure

STUDY QUESTION

How should recurrent implantation failure (RIF) in patients undergoing ART be defined and managed?

SUMMARY ANSWER

This is the first ESHRE good practice recommendations paper providing a definition for RIF together with recommendations on how to investigate causes and contributing factors, and how to improve the chances of a pregnancy.

WHAT IS KNOWN ALREADY

RIF is a challenge in the ART clinic, with a multitude of investigations and interventions offered and applied in clinical practice, often without biological rationale or with unequivocal evidence of benefit.

STUDY DESIGN SIZE DURATION

This document was developed according to a predefined methodology for ESHRE good practice recommendations. Recommendations are supported by data from the literature, if available, and the results of a previously published survey on clinical practice in RIF and the expertise of the working group. A literature search was performed in PubMed and Cochrane focussing on 'recurrent reproductive failure', 'recurrent implantation failure', and 'repeated implantation failure'.

PARTICIPANTS/MATERIALS SETTING METHODS

The ESHRE Working Group on Recurrent Implantation Failure included eight members representing the ESHRE Special Interest Groups for Implantation and Early Pregnancy, Reproductive Endocrinology, and Embryology, with an independent chair and an expert in statistics. The recommendations for clinical practice were formulated based on the expert opinion of the working group, while taking into consideration the published data and results of the survey on uptake in clinical practice. The draft document was then open to ESHRE members for online peer review and was revised in light of the comments received.

MAIN RESULTS AND THE ROLE OF CHANCE

The working group recommends considering RIF as a secondary phenomenon of ART, as it can only be observed in patients undergoing IVF, and that the following description of RIF be adopted: 'RIF describes the scenario in which the transfer of embryos considered to be viable has failed to result in a positive pregnancy test sufficiently often in a specific patient to warrant consideration of further investigations and/or interventions'. It was agreed that the recommended threshold for the cumulative predicted chance of implantation to identify RIF for the purposes of initiating further investigation is 60%. When a couple have not had a successful implantation by a certain number of embryo transfers and the cumulative predicted chance of implantation associated with that number is greater than 60%, then they should be counselled on further investigation and/or treatment options. This term defines clinical RIF for which further actions should be considered. Nineteen recommendations were formulated on investigations when RIF is suspected, and 13 on interventions. Recommendations were colour-coded based on whether the investigations/interventions were recommended (green), to be considered (orange), or not recommended, i.e. not to be offered routinely (red).

LIMITATIONS REASONS FOR CAUTION

While awaiting the results of further studies and trials, the ESHRE Working Group on Recurrent Implantation Failure recommends identifying RIF based on the chance of successful implantation for the individual patient or couple and to restrict investigations and treatments to those supported by a clear rationale and data indicating their likely benefit.

WIDER IMPLICATIONS OF THE FINDINGS

This article provides not only good practice advice but also highlights the investigations and interventions that need further research. This research, when well-conducted, will be key to making progress in the clinical management of RIF.

STUDY FUNDING/COMPETING INTERESTS

The meetings and technical support for this project were funded by ESHRE. N.M. declared consulting fees from ArtPRED (The Netherlands) and Freya Biosciences (Denmark); Honoraria for lectures from Gedeon Richter, Merck, Abbott, and IBSA; being co-founder of Verso Biosense. He is Co-Chief Editor of Reproductive Biomedicine Online (RBMO). D.C. declared being an Associate Editor of Human Reproduction Update, and declared honoraria for lectures from Merck, Organon, IBSA, and Fairtility; support for attending meetings from Cooper Surgical, Fujifilm Irvine Scientific. G.G. declared that he or his institution received financial or non-financial support for research, lectures, workshops, advisory roles, or travelling from Ferring, Merck, Gedeon-Richter, PregLem, Abbott, Vifor, Organon, MSD, Coopersurgical, ObsEVA, and ReprodWissen. He is an Editor of the journals Archives of Obstetrics and Gynecology and Reproductive Biomedicine Online, and Editor in Chief of Journal Gynäkologische Endokrinologie. He is involved in guideline developments and quality control on national and international level. G.L. declared he or his institution received honoraria for lectures from Merck, Ferring, Vianex/Organon, and MSD. He is an Associate Editor of Human Reproduction Update, immediate past Coordinator of Special Interest Group for Reproductive Endocrinology of ESHRE and has been involved in Guideline Development Groups of ESHRE and national fertility authorities. D.J.M. declared being an Associate Editor for Human Reproduction Open and statistical Advisor for Reproductive Biomedicine Online. B.T. declared being shareholder of Reprognostics and she or her institution received financial or non-financial support for research, clinical trials, lectures, workshops, advisory roles or travelling from support for attending meetings from Ferring, MSD, Exeltis, Merck Serono, Bayer, Teva, Theramex and Novartis, Astropharm, Ferring. The other authors had nothing to disclose.

DISCLAIMER

This Good Practice Recommendations (GPR) document represents the views of ESHRE, which are the result of consensus between the relevant ESHRE stakeholders and are based on the scientific evidence available at the time of preparation. ESHRE GPRs should be used for information and educational purposes. They should not be interpreted as setting a standard of care or be deemed inclusive of all proper methods of care, or be exclusive of other methods of care reasonably directed to obtaining the same results. They do not replace the need for application of clinical judgement to each individual presentation, or variations based on locality and facility type. Furthermore, ESHRE GPRs do not constitute or imply the endorsement, or favouring, of any of the included technologies by ESHRE.

One center experience with a personalized frozen-thawed embryo transfer in patients with recurrent implantation failure

PURPOSE

Displaced endometrial receptivity has been discussed as a possible cause of recurrent implantation failure in patients undergoing assisted reproductive technology. The aim of this study was to document our experience with the endometrial receptivity analysis in patients with recurrent implantation failure.

METHODS

This retrospective cohort study, conducted at the Fertility Centre of the University Hospital, Duesseldorf Germany, presents the results of the endometrial receptivity analysis in 67 patients with recurrent implantation failure and compares the clinical outcome between these 67 patients who underwent a personalized frozen-thawed embryo transfer guided by the results of the endometrial receptivity analysis and 32 patients with recurrent implantation failure who performed a standardized frozen-thawed embryo transfer.

RESULTS

The data analysis revealed a displaced endometrial receptivity in 73% (49/67) of all tested patients. Out of these patients, 24% (12/49) were early receptive, 74% (36/49) were pre-receptive, and 2% (1/49) were post-receptive. Comparison of pregnancy rate, clinical pregnancy rate, and live-birth rate between personalized (49%, 39%, 27%, respectively) and standardized embryo transfer (44%, 31%, 19%, respectively) reveals no statistically significant difference. In both groups, patients had an average of four unsuccessful embryo transfers.

CONCLUSION

In this cohort of patients with recurrent implantation failure, the endometrial receptivity analysis showed a high incidence of displaced endometrial receptivity. However, a personalized embryo transfer did not increase reproductive outcome. Displaced endometrial receptivity might not be the main cause for recurrent implantation failure in this cohort.

Impact of Endometrial Receptivity Analysis on Pregnancy Outcomes In Patients Undergoing Embryo Transfer: A Systematic Review and Meta-Analysis

To analyze the influence of endometrial receptivity analysis (ERA) on embryo transfer (ET) results in patients undergoing in vitro fertilization (IVF) treatment. PubMed, Embase, Cochrane Central Register of Controlled Trials, and BioMed Central databases were searched from inception up to December 2022 for studies comparing pregnancy outcomes in patients undergoing personalized embryo transfer (pET) by ERA versus standard ET. Data were pooled by meta-analysis using a random effects model. We identified twelve studies, including 14,224 patients. No differences were observed between patients undergoing ERA test and those not undergoing ERA test prior to ET in terms of live birth (OR 1.00, 95% CI 0.63-1.58, I2 = 92.7%), clinical pregnancy (OR 1.20, 95% CI 0.90-1.61, I2 = 86.5%), biochemical pregnancy (OR 0.83, 95% CI 0.46-1.49, I2 = 87%), positive pregnancy test (OR 0.99, 95% CI 0.80-1.22, I2 = 0%), miscarriage (OR 0.91, 95% CI 0.62-1.34, I2 = 67.1%), and implantation rate (OR 1.18, 95% CI 0.44-3.14, I2 = 93.2%). pET with ERA is not associated with any significant differences in pregnancy outcomes as compared to standard ET protocols. Therefore, the utility of ERA in patients undergoing IVF should be revisited.

Review of Endometrial Receptivity Array: A Personalized Approach to Embryo Transfer and Its Clinical Applications

Successful outcomes of in vitro fertilization (IVF) rely on both the formation of a chromosomally normal embryo and its implantation in a receptive endometrium. Pre-implantation genetic testing for aneuploidy (PGT-A) has been widely accepted as a tool to assess the viability of an embryo. In 2011, the endometrial receptivity array (ERA) was first published as a tool to determine when the endometrium is most receptive to an embryo, commonly referred to as the "window of implantation" (WOI). The ERA uses molecular arrays to assess proliferation and differentiation in the endometrium and screens for inflammatory markers. Unlike PGT-A, there has been dissent within the field concerning the efficacy of the ERA. Many studies that contest the success of the ERA found that it did not improve pregnancy outcomes in patients with an already-good prognosis. Alternatively, studies that utilized the ERA in patients with repeated implantation failure (RIF) and transfer of known euploid embryos demonstrated improved outcomes. This review aims to describe the ERA as a novel technique, review the various settings that the ERA may be used in, such as natural frozen embryo transfer (nFET) and hormone replacement therapy frozen embryo transfer (HRT-FET), and provide a summary of the recent clinical data for embryo transfers in patients with RIF utilizing the ERA.

Personalized versus standard frozen-thawed embryo transfer in IVF/ICSI cycles: a systematic review and meta-analysis

PURPOSE

To investigate whether personalized embryo transfer (pET) protocol guided by an endometrial receptivity array (ERA) can improve clinical outcomes of assisted reproduction.

METHODS

We searched PubMed, Embase, Web of Science, and the Cochrane library for studies in which analytical comparisons of outcomes of pET and standard embryo transfer (sET) groups were undertaken. The references to the included studies were also manually searched. The primary outcome was clinical pregnancy rate (CPR), and the secondary outcomes were live birth rate (LBR), human chorionic gonadotropin (HCG) positivity, biochemical pregnancy rate (BPR), miscarriage rate (MR), implantation rate (IR), and ongoing pregnancy rate (OPR).

RESULTS

Ten studies were included in the meta-analysis, including one randomized controlled trial (RCT) and nine cohort studies. We observed no significant difference in the primary outcome of CPR between the pET and sET groups in unselected patients (RR = 1.07; 95% confidence interval [CI], 0.87-1.30; P = 0.53; I2 = 89%). In terms of secondary outcomes, we likewise noted no significant differences between the groups. Further subgroup analyses indicated that the pET protocol not only significantly reduced the MR for poor-prognosis patients, but it also reduced the CPR in donor cycles, elevated the BPR for good-prognosis patients, non-preimplantation genetic testing (PGT), and programmed cycles, and decreased the proportion of women showing HCG positivity in non-PGT cycles.

CONCLUSIONS

This meta-analysis revealed that ERA appears to possess limited guidance in embryo transfer. More high-quality RCTs are therefore needed to investigate the clinical validity and feasibility of ERA in the future.

Adjustment of progesterone administration after endometrial transcriptomic analysis does not improve reproductive outcomes in women with adenomyosis

RESEARCH QUESTION

Do patients with adenomyosis present a dysregulated endometrial receptivity that can be reversed with personalized embryo transfer (PET) by transcriptomic-based progesterone adjustment, improving IVF outcomes?

DESIGN

A multicentre, retrospective, cohort study that transcriptomically analysed the endometrial receptivity of the endometrium in patients with adenomyosis (n = 81) and healthy women (n = 231). Subsequently, implantation, biochemical and clinical miscarriage, and live birth rates between adenomyosis patients with one previous implantation failure using donor oocytes who received (n = 59) or did not receive (n = 66) PET based on endometrial receptivity, were observed to evaluate if adjusted progesterone improves reproductive outcomes of adenomyosis patients.

RESULTS

Patients with adenomyosis significantly presented an altered endometrial receptivity (non-receptive) compared with healthy patients (53.1% versus 37.2%, P = 0.0179), elevating the risk of adenomyosis patients having a non-receptive endometrium 42.59% higher (95% CI 41.50 to 44.45). No significant differences were found in implantation (62.7% versus 78.8%, P = 0.0514), biochemical (13.5% versus 3.9%, P = 0.1223) and clinical (10.8% versus 15.4%, P = 0.7543) miscarriage, or live birth rates (75.7% versus 80.8%, P = 0.6066), in patients with PET compared with those without PET.

CONCLUSIONS

Women with adenomyosis presented an altered expression of genes involved in decidualization, and a higher rate of non-receptive endometrial statuses than controls. Although progesterone is indispensable for implantation, adjusting progesterone before PET, using endometrial transcriptomic signatures, does not improve IVF outcomes in patients with adenomyosis. Other molecular mechanisms beyond progesterone regulation may be involved in implantation failure.

Is it necessary for young patients with recurrent implantation failure to undergo preimplantation genetic testing for aneuploidy?

OBJECTIVE

To determine whether preimplantation genetic testing for aneuploidy (PGT-A) can improve the pregnancy outcomes of patients aged under 38 years who have a history of recurrent implantation failure(RIF).

DESIGN

Retrospective cohort study.

METHODS

We retrospectively studied the pregnancy outcomes of RIF patients aged under 38 years from January 2017 to December 2021.178 patients were divided into two groups according to whether they underwent PGT-A: the PGT-A group(n=59)and the control group(n=119).In the PGT-A group, we compared the euploidy rate of the different quality and developmental rate blastocysts. In both groups,the patients were the first frozen-thaw single blastocysts transfer after the diagnosis of RIF. Among the pregnancy outcomes, the clinical pregnancy rate was assessed as the primary outcome. The spontaneous abortion rate and ongoing pregnancy rate were the secondry outcomes. The generalized estimation equation was used to adjust for the blastocysts derived from the same patients. Multivariate logistic analysis models were used to compare the pregnancy outcomes between the two groups.

RESULTS

In the PGT-A group, 293 blastocysts obtained from59 patients underwent PGT-A. The proportions of euploidy, aneuploidy and mosaic blastocysts were 56.31%, 25.60% and 18.09%, respectively. A comparison of the euploidy rates of different quality blastocysts showed that the rate of good-quality blastocysts was significantly higher than that of poor-quality blastocysts (67.66% vs 46.88%; odds ratio [OR], 2.203; 95%confidence interval[CI], 0.943-3.612; P=0.002). However, no significant difference was observed in the different developmental rates blastocysts. Compared with Day 5 blastocysts, the euploidy rates of Day 6 and Day 7 blastocysts were not significantly different(61.54%vs51.91%; OR,0.945; 95%CI, 0.445-2.010; P=0.884; and 61.54%vs47.37%; OR, 1.106; 95%CI, 0.774-1.578; P=0.581, respectively).As for the pregnancy outcomes, the clinical pregnancy rate was significantly increase after the use of PGT-A compared with the control group(71.19%vs56.30%; OR, 0.538; 95%CI, 0.262-1.104; P=0.039). However, the spontaneous abortion rates and ongoing pregnancy rates were not significantly different between the control and PGT-A groups (21.43% vs 19.40%; aOR,0.727; 95%CI,0.271-1.945; P=0.525; and55.93% vs 45.38%; aOR, 0.649; 95%CI, 0.329-1.283; P = 0.214,respectively).

CONCLUSION

PGT-A improved the clinical pregnancy rate after blastocyst transfer in RIF patients aged under 38 years.

Commercially Available Molecular Approaches to Evaluate Endometrial Receptivity: A Systematic Review and Critical Analysis of the Literature

Despite the advances in the field of reproductive medicine, implantation failure represents a challenging condition affecting 10-30% of patients subjected to in vitro fertilization (IVF). Research has focused on the identification of molecules playing crucial roles in endometrial receptivity, with the aim of designing predictive tools for efficient detection of the implantation window. To that end, novel molecular genomic and transcriptomic approaches have been introduced as promising tools to enable personalized approaches with the aim of optimizing embryo transfer dating. However, the clinical value of these approaches remains unclear. The aim of this study is to provide a systematic review and critical analysis of the existing evidence regarding the employment of commercially available novel approaches to evaluate endometrial receptivity. An Embase and PubMed/Medline search was performed on 1 February 2022. From the 475 articles yielded, only 27 were included and analyzed. The considerable heterogeneity of the included articles indicates the uniqueness of the implantation window, showcasing that the optimal time for embryo transfer varies significantly between women. Moreover, this study provides information regarding the technical aspects of these advanced molecular tools, as well as an analysis of novel possible biomarkers for endometrial receptivity, providing a basis for future research in the field.

Use of the endometrial receptivity array to guide personalized embryo transfer after a failed transfer attempt was associated with a lower cumulative and per transfer live birth rate during donor and autologous cycles

OBJECTIVE

To determine whether personalized embryo transfer (pET) guided by endometrial receptivity array (ERA) test improves reproductive outcomes for fresh embryo transfers (fsETs) or frozen embryo transfers (FETs) during autologous and donor cycles.

DESIGN

A retrospective, observational, multicenter cohort study.

SETTING

University-affiliated in vitro fertilization center.

PATIENT(S)

The study included patients with a single previous failed transfer and yielded 3,239 autologous transfers and 2,133 donor transfers. Among autologous transfers, 255 were pET guided by ERA; among unguided autologous transfers, 1,122 and 1,862 transfers involved fresh or previously frozen embryos, respectively. Among donor transfers, 319 were ERA-guided; among unguided donor transfers, 1,175 and 639 involved fsETs or FETs, respectively.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Primary outcomes were live birth rate per embryo transfer and cumulative live birth rate on consecutive transfers until live birth or cessation of pregnancy. Secondary outcomes were implantation, pregnancy rate, clinical pregnancy rates per embryo transfer, and miscarriage rate per pregnancy.

RESULT(S)

During both autologous or donor transfers, live birth rate and cumulative live birth rate were higher in FET and fsET than in pET groups, even with euploid transfers. Logistic regression analysis, considering possible confounders, indicated patients receiving pET had poorer outcomes than those undergoing FET and fsET in autologous and donor cycles. Implantation, pregnancy, and clinical pregnancy rates were lower in patients undergoing pET.

CONCLUSION(S)

Using ERA to guide pET during either autologous or donor cycles after a failed transfer attempt did not improve reproductive outcomes. Conversely, worse outcomes were detected when ERA was used.

microRNA-based signatures obtained from endometrial fluid identify implantative endometrium

STUDY QUESTION

Is it possible to use free and extracellular vesicle-associated microRNAs (miRNAs) from human endometrial fluid (EF) samples as non-invasive biomarkers for implantative endometrium?

SUMMARY ANSWER

The free and extracellular vesicle-associated miRNAs can be used to detect implantative endometrium in a non-invasive manner.

WHAT IS KNOWN ALREADY

miRNAs and extracellular vesicles (EVs) from EF have been described as mediators of the embryo–endometrium crosstalk. Therefore, the analysis of miRNA from this fluid could become a non-invasive technique for recognizing implantative endometrium. This analysis could potentially help improve the implantation rates in ART.

STUDY DESIGN, SIZE, DURATION

In this prospective study, we first optimized different protocols for EVs and miRNA analyses using the EF of a setup cohort (n = 72). Then, we examined differentially expressed miRNAs in the EF of women with successful embryo implantation (discovery cohort n = 15/validation cohort n = 30) in comparison with those for whom the implantation had failed (discovery cohort n = 15/validation cohort n = 30). Successful embryo implantation was considered when pregnancy was confirmed by vaginal ultrasound showing a gestational sac 4 weeks after embryo transfer (ET).

PARTICIPANTS/MATERIALS, SETTING, METHODS

The EF of the setup cohort was obtained before starting fertility treatment during the natural cycle, 16–21 days after the beginning of menstruation. For the discovery and validation cohorts, the EF was collected from women undergoing frozen ET on Day 5, and the samples were collected immediately before ET. In this study, we compared five different methods; two of them based on direct extraction of RNA and the other three with an EV enrichment step before the RNA extraction. Small RNA sequencing was performed to determine the most efficient method and find a predictive model differentiating between implantative and non-implantative endometrium. The models were confirmed using quantitative PCR in two sets of samples (discovery and validation cohorts) with different implantation outcomes.

MAIN RESULTS AND THE ROLE OF CHANCE

The protocols using EV enrichment detected more miRNAs than the methods based on direct RNA extraction. The two most efficient protocols (using polymer-based precipitation (PBP): PBP-M and PBP-N) were used to obtain two predictive models (based on three miRNAs) allowing us to distinguish between an implantative and non-implantative endometrium. The first Model 1 (PBP-M) (discovery: AUC = 0.93; P-value = 0.003; validation: AUC = 0.69; P-value = 0.019) used hsa-miR-200b-3p, hsa-miR-24-3p and hsa-miR-148b-3p. Model 2 (PBP-N) (discovery: AUC = 0.92; P-value = 0.0002; validation: AUC = 0.78; P-value = 0.0002) used hsa-miR-200b-3p, hsa-miR-24-3p and hsa-miR-99b-5p. Functional analysis of these miRNAs showed strong association with key implantation processes such as in utero embryonic development or transforming growth factor-beta signaling.

LARGE SCALE DATA

The FASTQ data are available in the GEO database (access number GSE178917).

LIMITATIONS, REASONS FOR CAUTION

One important factor to consider is the inherent variability among the women involved in the trial and among the transferred embryos. The embryos were pre-selected based on morphology, but neither genetic nor molecular studies were conducted, which would have improved the accuracy of our tests. In addition, a limitation in miRNA library construction is the low amount of input RNA.

WIDER IMPLICATIONS OF THE FINDINGS

We describe new non-invasive protocols to analyze miRNAs from small volumes of EF. These protocols could be implemented in clinical practice to assess the status of the endometrium before attempting ET. Such evaluation could help to avoid the loss of embryos transferred to a non-implantative endometrium.

STUDY FUNDING/COMPETING INTEREST(S)

J.I.-P. was supported by a predoctoral grant from the Basque Government (PRE_2017_0204). This study was partially funded by the Grant for Fertility Innovation (GFI, 2011) from Merck (Darmstadt, Germany). It was also supported by the Spanish Ministry of Economy and Competitiveness MINECO within the National Plan RTI2018-094969-B-I00, the European Union's Horizon 2020 research and innovation program (860303), the Severo Ochoa Centre of Excellence Innovative Research Grant (SEV-2016-0644) and the Instituto de Salud Carlos III (PI20/01131). The funding entities did not play any role in the study design, collection, analysis and interpretation of data, writing of the report or the decision to submit the article for publication. The authors declare no competing interests.

Noninvasive Chromosome Screening for Evaluating the Clinical Outcomes of Patients With Recurrent Pregnancy Loss or Repeated Implantation Failure

This retrospective cohort study explores whether noninvasive chromosome screening (NICS) for aneuploidy can improve the clinical outcomes of patients with recurrent pregnancy loss (RPL) or repeated implantation failure (RIF) in assisted reproductive technology. A total of 273 women with a history of RPL or RIF between 2018 and 2021 were included in this study. We collected data of all oocyte retrieval cycles and single blastocyst resuscitation transfer cycles. For the patients experiencing RPL, NICS reduced the miscarriages rate per frozen embryo transfer (FET), improved the ongoing pregnancies rate and live birth rate: 17.9% vs 42.6%, adjusted OR 0.39, 95% CI 0.16-0.95; 40.7% vs 25.0%, adjusted OR 2.00, 95% CI 1.04-3.82; 38.9% vs 20.6%, adjusted OR 2.53, 95% CI 1.28-5.02, respectively. For the patients experiencing RIF, the pregnancy rates per FET in the NICS group were significantly higher than those in the non-NICS group (46.9% vs. 28.7%, adjusted OR 2.82, 95% CI 1.20-6.66). This study demonstrated that the selection of euploid embryos through NICS can reduce the miscarriage rate of patients experiencing RPL and improve the clinical pregnancy rate of patients experiencing RIF. Our data suggested NICS could be considered as a possibly useful screening test in clinical practice.

Evaluation of endometrial receptivity and implantation failure

PURPOSE OF REVIEW

To succinctly review the basic mechanisms of implantation and luteal phase endometrial differentiation, the etiologies of impaired endometrial function and receptivity, and the current methods that exist to evaluate and treat impaired endometrial receptivity.

RECENT FINDINGS

Human embryo implantation requires bidirectional communication between blastocyst and a receptive endometrium. Etiologies of impaired endometrial receptivity are varied. Some of these include delayed endometrial maturation, structural abnormalities, inflammation, and progesterone resistance. Current methods to evaluate endometrial receptivity include ultrasonography, hysteroscopy, and endometrial biopsy. Treatments are limited, but include operative hysteroscopy, treatment of endometriosis, and personalized timing of embryo transfer.

SUMMARY

Although some mechanisms of impaired endometrial receptivity are well understood, treatment options remain limited. Future efforts should be directed towards developing interventions targeted towards the known mediators of impaired endometrial receptivity.

The role of extracellular vesicles in endometrial receptivity and their potential in reproductive therapeutics and diagnosis

Extracellular vesicles (EVs) are small, nanometre sized, membrane-enclosed structures released by cells and are thought to be crucial in cellular communication. The cargo of these vesicles includes lipids, proteins, RNAs and DNA, and control various biological processes in their target tissues depending on the parental and receiver cell's origin and phenotype. Recently data has accumulated in the role of EVs in embryo implantation and pregnancy, with EVs identified in the uterine cavity of women, sheep, cows, horses, and mice, in which they aid blastocyst and endometrial preparation for implantation. Herein is a critical review to decipher the role of extracellular vesicles in endometrial receptivity and their potential in reproductive therapies and diagnosis. The current knowledge of the function of embryo and endometrial derived EVs and their cargoes, with regards to their effect on implantation and receptivity are summarized and evaluated. The findings of the below review highlight that the combined knowledge on EVs deriving from the endometrium and embryo have the potential to be translated to various clinical applications including treatment, a diagnostic biomarker for diseases and a drug delivery tool to ultimately improve pregnancy rates.

The Clinical Efficacy of Personalized Embryo Transfer Guided by the Endometrial Receptivity Array/Analysis on IVF/ICSI Outcomes: A Systematic Review and Meta-Analysis

Objective: To assess the prevalence of displaced window of implantation (WOI) in infertile women, and the clinical utility of personalized embryo transfer (pET) guided by the endometrial receptivity array/analysis (ERA) on IVF/ICSI outcomes.

Methods: The protocol was registered at Prospero: CRD42020204237. We systematically searched all published English literature related to the prevalence of WOI displacement and ongoing pregnancy rate/live birth rate in the overall good-prognosis infertile patients (GPP) and/or repeated implantation failure (RIF) patients undergoing IVF/ICSI-ET cycles after ERA test until August 2021.

Result(s): 11 published studies were enrolled in the final analysis. The estimate of the incidence of WOI displacement based on ERA was 38% (95%CI 19–57%) in GPP and 34% (95%CI 24–43%) in RIF, respectively. There was no difference in OPR/LBR between patients undergoing routine ET without ERA test and those who following pET with ERA (39.5 vs. 53.7%, OR 1.28, p = 0.49, 95%CI 0.92–1.77, I² = 0%) in relative GPP. Notably, the meta-analysis revealed that OPR/LBR of patients with RIF undergoing pET who had non-receptive ERA increased to the level of to those undergoing sET with receptive ERA (40.7 vs.49.6%, OR 0.94, p = 0.85, 95%CI 0.70–1.26, I² = 0%).

Conclusion: Considering the approximately one third of infertile women could suffered from displaced WOI, the ERA test emerged as a promising tool. Although the present meta-analysis demonstrates that patients with general good-prognosis may not benefit from ERA, pET guided by ERA significantly increases the chances of pregnancy for non-receptive patients with RIF of endometrial origin.

Non-Invasive and Mechanism-Based Molecular Assessment of Endometrial Receptivity During the Window of Implantation: Current Concepts and Future Prospective Testing Directions

Suboptimal endometrial receptivity and altered embryo-endometrial crosstalk account for approximately two-thirds of human implantation failures. Current tests of the window of implantation, such as endometrial thickness measurements and the endometrial receptivity assay, do not consistently improve clinical outcomes as measured by live birth rates. Understanding the mechanisms regulating the endometrial receptivity during the window of implantation is a critical step toward developing clinically meaningful tests. In this narrative review, the available literature is evaluated regarding mechanisms that regulate the endometrial receptivity during the window of implantation and the current tests developed. Overall, both animal and human studies point to five possible and interrelated mechanisms regulating the endometrial window of implantation: suitable synchrony between endometrial cells, adequate synchrony between the endometrium and the embryo, standard progesterone signaling and endometrial responses to progesterone, silent genetic variations, and typical morphological characteristics of the endometrial glands. The biological basis of current clinical markers or tests of window of implantation is poor. Future studies to elucidate the mechanisms shaping the window of implantation and to investigate the potential markers based on these mechanisms are required. In addition, molecular testing of the endometrium at single-cell resolution should be an initial step toward developing clinically meaningful tests for the optimal window of implantation. As understanding of the optimal window of implantation continues to evolve, one can envision the future development of non-invasive, mechanism-based testing of the window of implantation.

The clinical efficiency of transcriptome-based endometrial receptivity assessment (Tb-ERA) in Chinese patients with recurrent implantation failure (RIF): A study protocol for a prospective randomized controlled trial

Background

Today, approximately 10% of participants in assisted reproductive technology (ART) are defined as having recurrent implantation failure (RIF). Recent studies show that endometrial receptivity array can improve pregnancy and implantation rates by nearly 20% in women with RIF. However, these studies are limited, with little published data in the Chinese population. Recently, we have established a transcriptome-based endometrial receptivity assessment (Tb-ERA) method of predicting the endometrial window of implantation (WOI) using transcriptome-profiling data of different phases of the menstrual cycle from healthy fertile Chinese women by RNA-Seq. It is meaningful to conduct a randomized controlled trial (RCT) to assess the clinical efficiency of Tb-ERA in Chinese patients with RIF.

Methods

In this RCT, a total of 200 RIF patients will be recruited and randomized into 2 groups. Patients in the Tb-ERA group will undergo a Tb-ERA test, after which embryo transfer time will be adjusted according to Tb-ERA results and embryo transfer will be performed again in the next cycle. Patients in the control group will not receive any interventions until the next transfer cycle. We will perform statistical analysis on both groups at the primary endpoint (clinical-pregnancy rate) and at secondary endpoints (rate of WOI displacement, embryo implantation, biochemical pregnancy, early abortion, and ectopic pregnancy). Implications: This study aims to evaluate the effectiveness of our Tb-ERA test in Chinese RIF patients and to determine that whether Tb-ERA could improve the clinical-pregnancy rate in these RIF patients.

Trial registration

NCT04497558, registered August 4, 2020.

Emerging trends and frontier research on recurrent implantation failure: a bibliometric analysis

Background

Recurrent implantation failure (RIF) has been recognized to be a major obstacle to the successful application of artificial reproduction technologies. In this study, the trends in RIF research were examined through a bibliometric analysis evaluating relevant literature quantitatively and qualitatively.

Methods

A total of 1,764 publications from 2000 to 2020 were downloaded from the Web of Science Core Collection (WoSCC). Relevant articles were searched using the term "recurrent implantation failure" and other synonyms of this term. Using Excel 2013, CiteSpace V, and VOSviewer 1.6.10 software, data extracted from the literature, including countries/regions, institutions, journals, keywords, and trends, were analyzed. Next, a clustered network was constructed based on 46,718 references cited by the 1,764 publications to determine the top 10 cocited articles.

Results

The annual number of publications on RIF progressively increased over time. The highest number of publications were from the United States. Analysis of the cocited reference cluster showed that "endometrial injury", "platelet-rich plasma", "chronic endometritis" and "extracellular vesicles" were the hotspots in RIF research. Burst detection analysis of the top keywords showed that "hysteroscopy" and "improvement" are emerging research foci.

Conclusions

This study clarifies the current research status and evolution of research in the field of RIF. New therapeutic interventions designed to improve pregnancy outcomes are the focus of current research and are expected to dominate future research in the field of RIF.

Identifying and optimizing human endometrial gene expression signatures for endometrial dating

STUDY QUESTION

What are the key considerations for developing an enhanced transcriptomic method for secretory endometrial tissue dating?

SUMMARY ANSWER

Multiple gene expression signature combinations can serve as biomarkers for endometrial dating, but their predictive performance is variable and depends on the number and identity of the genes included in the prediction model, the dataset characteristics and the technology employed for measuring gene expression.

WHAT IS KNOWN ALREADY

Among the new generation of transcriptomic endometrial dating (TED) tools developed in the last decade, there exists variation in the technology used for measuring gene expression, the gene makeup and the prediction model design. A detailed study, comparing prediction performance across signatures for understanding signature behaviour and discrepancies in gene content between them, is lacking.

STUDY DESIGN, SIZE, DURATION

A multicentre prospective study was performed between July 2018 and October 2020 at five different centres from the same group of clinics (Spain). This study recruited 281 patients and finally included in the gene expression analysis 225 Caucasian patients who underwent IVF treatment. After preprocessing and batch effect filtering, gene expression measurements from 217 patients were combined with artificial intelligence algorithms (support vector machine, random forest and k-nearest neighbours) allowing evaluation of different prediction models. In addition, secretory-phase endometrial transcriptomes from gene expression omnibus (GEO) datasets were analysed for 137 women, to study the endometrial dating capacity of genes independently and grouped by signatures. This provided data on the consistency of prediction across different gene expression technologies and datasets.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Endometrial biopsies were analysed using a targeted TruSeq (Illumina) custom RNA expression panel called the endometrial dating panel (ED panel). This panel included 301 genes previously considered relevant for endometrial dating as well as new genes selected for their anticipated value in detecting the secretory phase. Final samples (n = 217) were divided into a training set for signature discovery and an independent testing set for evaluation of predictive performance of the new signature. In addition, secretory-phase endometrial transcriptomes from GEO were analysed for 137 women to study endometrial dating capacity of genes independently and grouped by signatures. Predictive performance among these signatures was compared according to signature gene set size.

MAIN RESULTS AND THE ROLE OF CHANCE

Testing of the ED panel allowed development of a model based on a new signature of 73 genes, which we termed 'TED' and delivers an enhanced tool for the consistent dating of the secretory phase progression, especially during the mid-secretory endometrium (3-8 days after progesterone (P) administration (P + 3-P + 8) in a hormone replacement therapy cycle). This new model showed the best predictive capacity in an independent test set for staging the endometrial tissue in the secretory phase, especially in the expected window of implantation (average of 114.5 ± 7.2 h of progesterone administered; range in our patient population of 82-172 h). Published sets of genes, in current use for endometrial dating and the new TED genes, were evaluated in parallel in whole-transcriptome datasets and in the ED panel dataset. TED signature performance was consistently excellent for all datasets assessed, frequently outperforming previously published sets of genes with a smaller number of genes for dating the endometrium in the secretory phase. Thus, this optimized set exhibited prediction consistency across datasets.

LARGE SCALE DATA

The data used in this study is partially available at GEO database. GEO identifiers GSE4888, GSE29981, GSE58144, GSE98386.

LIMITATIONS, REASONS FOR CAUTION

Although dating the endometrial biopsy is crucial for investigating endometrial progression and the receptivity process, further studies are needed to confirm whether or not endometrial dating methods in general are clinically useful and to guide the specific use of TED in the clinical setting.

WIDER IMPLICATIONS OF THE FINDINGS

Multiple gene signature combinations provide adequate endometrial dating, but their predictive performance depends on the identity of the genes included, the gene expression platform, the algorithms used and dataset characteristics. TED is a next-generation endometrial assessment tool based on gene expression for accurate endometrial progression dating especially during the mid-secretory.

STUDY FUNDING/COMPETING INTEREST(S)

Research funded by IVI Foundation (1810-FIVI-066-PD). P.D.-G. visiting scientist fellowship at Oxford University (BEFPI/2010/032) and Josefa Maria Sanchez-Reyes' predoctoral fellowship (ACIF/2018/072) were supported by a program from the Generalitat Valenciana funded by the Spanish government. A.D.-P. is supported by the FPU/15/01398 predoctoral fellowship from the Ministry of Science, Innovation and Universities (Spanish Government). D.W. received support from the NIHR Oxford Biomedical Research Centre. The authors do not have any competing interests to declare.

Endometrial Expression of Insulin Signaling Pathway Genes in Pregnancy Leading to Abortion under 20 Weeks in Infertile Women: A Case-Control Study

BACKGROUND

Impaired expression of genes which act on hormone signaling pathways is one of the factors affecting miscarriage. In this study, the expression levels of insulin receptor (INSR) and insulin receptor substrates-1 (IRS-1) genes in endometrial tissue of infertile women and fertile women with miscarriage in less than twenty weeks gestation for unknown reasons were evaluated.

MATERIALS AND METHODS

In this case-control study, forty-two fertile women with children and 42 infertile women, who underwent in vitro fertilization (IVF), were selected. Both groups had abortions under twenty weeks gestation for unknown reasons. The endometrial tissue of all patients was prepared to evaluate the expression of INSR and IRS-1 genes by quantitative real-time polymerase chain reaction (PCR) method after RNA extraction.

RESULTS

There was a statistically significant relationship between the expressions of INSR and IRS-1 genes in the endometrial tissue of the infertile women compared with the fertile women (P=0.002 and P=0.008, respectively). The expression level of genes was decreased in both groups by age and increasing body mass index (BMI). Comparison of genes expression levels in healthy and diabetic participants in each group showed a significant difference (P<0.0001), but no meaningful difference was indicated between diabetic infertile and fertile groups in terms of gene expression. INSR gene expression levels showed an increase in the fertile group in the second 10 weeks and a decrease in IRS-1 gene expression. But in the infertile group, both genes showed a slight increase in expression.

CONCLUSION

It seems a decreased expression of insulin signaling pathway genes in the endometrial tissue of infertile women can be one of reasons for unspecified abortion. These genes may be strong molecular markers for infertility.