Status of preimplantation genetic testing and embryo selection

Non Invasive Preimplantation Testing for Aneuploidies in Assisted Reproduction: A SWOT Analysis

The implementation of non-invasive PGT-A offers a new strategy to genetically assess the preimplantation embryo and to enhance IVF results. The extraction of DNA from the embryo culture medium has been sufficiently demonstrated, and the ability to obtain chromosomal information as a result is particularly interesting. As morphological criteria have proven to have a weak correlation with embryo ploidy status, this technique emerges as a promising alternative for embryo selection. It also appears reasonable that avoiding biopsy may enhance further embryo development. However, there are growing concerns regarding several aspects of this technique, such as the origin of this cell free DNA, the degree of representativeness of the whole embryo, the need for extended culture or the absence of standardized protocols. Despite the published data on good prognosis couples are promising, niPGT-A is yet to be considered a substitute for trophectoderm biopsy. The current SWOT analysis aims to summarize both resolved and unresolved issues, as well as limiting aspects of niPGT-A.

On the role of artificial intelligence in analysing oocytes during in vitro fertilisation procedures

Nowadays, the most adopted technique to address infertility problems is in vitro fertilisation (IVF). However, its success rate is limited, and the associated procedures, known as assisted reproduction technology (ART), suffer from a lack of objectivity at the laboratory level and in clinical practice. This paper deals with applications of Artificial Intelligence (AI) techniques to IVF procedures. Artificial intelligence is considered a promising tool for ascertaining the quality of embryos, a critical step in IVF. Since the oocyte quality influences the final embryo quality, we present a systematic review of the literature on AI-based techniques used to assess oocyte quality; we analyse its results and discuss several promising research directions. In particular, we highlight how AI-based techniques can support the IVF process and examine their current applications as presented in the literature. Then, we discuss the challenges research must face in fully deploying AI-based solutions in current medical practice. Among them, the availability of high-quality data sets as well as standardised imaging protocols and data formats, the use of physics-informed simulation and machine learning techniques, the study of informative, descriptive yet observable features, and, above all, studies of the quality of oocytes and embryos, specifically about their live birth potential. An improved understanding of determinants for oocyte quality can improve success rates while reducing costs, risks for long-term embryo cultures, and bioethical concerns.

A study on methods for preimplantation genetic testing (PGT) on in vivo- and in vitro-produced equine embryos, with emphasis on embryonic sex determination

Two methods for preimplantation genetic testing (PGT) have been described for equine embryos: trophoblast cell biopsy (TCB) or blastocoele fluid aspiration (BFA). While TCB is widely applied for both in vivo- and in vitro-produced embryos, BFA has been mostly utilized for in vivo-produced embryos. Alternative methods for PGT, including analysis of cell-free DNA (CFD) in the medium where in vitro-produced embryos are cultured, have been reported in humans but not for equine embryos. In Experiment 1, in vivo- (n = 10) and in vitro-produced (n = 13) equine embryos were subjected to BFA, cultured for 24 h, then subjected to TCB, and cultured for additional 24 h. No detrimental effect on embryonic diameter or re-expansion rates was observed for either embryo group (P > 0.05). In Experiment 2, the concordance (i.e., agreement on detecting the same embryonic sex using two techniques) among BFA, TCB, and the whole embryo (Whole) was studied by detecting the sex-determining region Y (SRY) or testis-specific y-encoded protein 1 (TSPY) (Y-chromosome), and androgen receptor (AR; X-chromosome) genes using PCR. Overall, a higher concordance for detecting embryonic sex was observed among techniques for in vivo-produced embryos (67-100 %; n = 14 embryos) than for in vitro-produced embryos (31-92 %; n = 13 embryos). The concordance between sample types increased when utilizing TSPY (77-100 %) instead of SRY (31-100 %) as target gene. In Experiment 3, CFD analysis was performed on in vitro-produced embryos to determine embryonic sex via PCR (SRY [Y-chromosome] and amelogenin - AMEL [X- and Y-chromosomes]). Overall, CFD was detected in all medium samples, and the concordance between CFD sample and the whole embryo was 60 % when utilizing SRY and AMEL genes. In conclusion, equine embryos can be subjected to two biopsy procedures (24 h apart) without apparent detrimental effects on embryonic size. For in vivo-, but not for in vitro-produced equine embryos, BFA can be considered a potential alternative to TCB for PGT. Finally, CFD can be further explored as a non-invasive method for PGT in in vitro produced equine embryos.

The effect of trophectoderm biopsy for preimplantation genetic testing on fetal birth weight and preterm delivery

BACKGROUND

Preimplantation genetic testing for aneuploidy (PGT-A) is used as part of in-vitro-fertilization (IVF) to assist in selection of euploid embryos, which involves performing trophectoderm biopsy. The effect of possible trauma caused by biopsy and the implication on pregnancy is unknown. Hence, the objective of the study was to determine if embryo biopsy for PGT-A affects birth weight or preterm birth rate.

METHODS

Using National Society for Assisted Reproductive Technology Clinic Outcome Reporting System (SART CORS) data, we identified 6352 cycles which had single embryo transfer (SET) and a singleton live birth following frozen embryo transfer (FET) between 2014 and 2015.

RESULTS

From the initial cohort of 25,121 fresh stimulation cycles, 6352 cycles were included who had a singleton live birth following FET. A total of 3482 (54.8%) had PGT-A confirmed euploid embryos and 2870 (45.2%) had embryos selected based on morphology for transfer. No difference in birthweight (g) was noted when FET was performed using PGT-A confirmed euploid embryos as compared to non-tested morphologically selected embryos (3370.7 vs. 3354.5, adjusted regression coefficient 11.4; 95% CI: -12.6; 35.3). As compared to morphologically selected embryos, performance of PGT-A did not increase the risk of small for gestation age (SGA) (3.9% vs. 4.1%, OR: 1.13; 95% CI: 0.86-1.50), low birth weight (LBW) (<2500 g but ≥1500 g) (5.8% vs. 5.5%, OR: 0.90; 95% CI: 0.66-1.21), or very low birthweight (<1500 g) (1.3% vs. 1.0%, OR: 0.44; 95% CI: 0.44 (0.18-1.10). There was no increased risk of preterm birth (PTB) associated with pregnancy resulting from PGT-A embryos vs. non PGT-A embryos (15.8% vs. 16.4%, OR: 0.94; 95% CI: 0.81-1.09).

CONCLUSIONS

In our study, trophectoderm biopsy for PGT-A did not increase the risk of SGA, LBW or PTB in IVF pregnancies.

Embryo drop-out rates in preimplantation genetic testing for aneuploidy (PGT-A): a retrospective data analysis from the DoLoRes study

PURPOSE

To evaluate the decline in transferable embryos in preimplantation genetic testing for aneuploidy (PGT-A) cycles due to (a) non-biopsable blastocyst quality, (b) failure of genetic analysis, (c) diagnosis of uniform numerical or structural chromosomal aberrations, and/or (d) chromosomal aberrations in mosaic constitution.

METHODS

This retrospective multicenter study comprised outcomes of 1562 blastocysts originating from 363 controlled ovarian stimulation cycles, respectively, 226 IVF couples in the period between January 2016 and December 2018. Inclusion criteria were PGT-A cycles with trophectoderm biopsy (TB) and next generation sequencing (NGS).

RESULTS

Out of 1562 blastocysts, 25.8% were lost due to non-biopsable and/or non-freezable embryo quality. In 10.3% of all biopsied blastocysts, genetic analysis failed. After exclusion of embryos with uniform or chromosomal aberrations in mosaic, only 18.1% of those originally yielded remained as diagnosed euploid embryos suitable for transfer. This translates into 50.4% of patients and 57.6% of stimulated cycles with no euploid embryo left for transfer. The risk that no transfer can take place rose significantly with a lower number of oocytes and with increasing maternal age. The chance for at least one euploid blastocyst/cycle in advanced maternal age (AMA)-patients was 33.3% compared to 52.1% in recurrent miscarriage (RM), 59.8% in recurrent implantation failure (RIF), and 60.0% in severe male factor (SMF).

CONCLUSIONS

The present study demonstrates that PGT-A is accompanied by high embryo drop-out rates. IVF-practitioners should be aware that their patients run a high risk of ending up without any embryo suitable for transfer after (several) stimulation cycles, especially in AMA patients. Patients should be informed in detail about the frequency of inconclusive or mosaic results, with the associated risk of not having an euploid embryo available for transfer after PGT-A, as well as the high cost involved in this type of testing.

A review of the 2021/2022 PGDIS Position Statement on the transfer of mosaic embryos

The practice of preimplantation genetic testing for aneuploidy (PGT-A) in association with in vitro fertilization (IVF) since 2016 has been mostly directed by three highly controversial guidance documents issued by the Preimplantation Genetic Diagnosis International Society (PGDIS). Because these documents are so influential on worldwide IVF practice, the most recent one is here the subject of a detailed review, again revealing important misrepresentations and internal contradictions. Most importantly, however, this most recent guidance document still does not prevent the non-use and/or disposal of large numbers of embryos with substantial pregnancy and live-birth potential and, therefore, continues to propagate an IVF practice harmful to many infertile women.

Assisted Reproductive Technology without Embryo Discarding or Freezing in Women ≥40 Years: A 5-Year Retrospective Study at a Single Center in Italy

The protocols commonly used in assisted reproductive technology (ART) consist of long-term embryo culture up to the blastocyst stage after the insemination of all mature oocytes, the freezing of all the embryos produced, and their subsequent transfer one by one. These practices, along with preimplantation genetic testing, although developed to improve the live birth rate (LBR) and reduce the risk of multiple pregnancies, are drawing attention to the possible increase in obstetric and perinatal risks, and adverse epigenetic consequences in offspring. Furthermore, ethical-legal concerns are growing regarding the increase in cryopreservation and storage of frozen embryos. In an attempt to reduce the risk associated with prolonged embryo culture and avoid embryo storage, we have chosen to inseminate a limited number of oocytes not exceeding the number of embryos to be transferred, after two days or less of culture. We retrospectively analyzed 245 ICSI cycles performed in 184 infertile couples with a female partner aged ≥40 from January 2016 to July 2021. The results showed a fertilization rate of 95.7%, a miscarriage rate of 48.9%, and a LBR of 10% with twin pregnancies of 16.7%. The cumulative LBR in our group of couples was 13%. No embryos were frozen. In conclusion, these results suggest that oocyte selection and embryo transfer at the cleaving stage constitute a practice that has a LBR comparable to that of the more commonly used protocols in older women who have reduced ovarian reserve.

Non-invasive evaluation of embryo quality for the selection of transferable embryos in human in vitro fertilization-embryo transfer

The ultimate goal of human assisted reproductive technology is to achieve a healthy pregnancy and birth, ideally from the selection and transfer of a single competent embryo. Recently, techniques for efficiently evaluating the state and quality of preimplantation embryos using time-lapse imaging systems have been applied. Artificial intelligence programs based on deep learning technology and big data analysis of time-lapse monitoring system during in vitro culture of preimplantation embryos have also been rapidly developed. In addition, several molecular markers of the secretome have been successfully analyzed in spent embryo culture media, which could easily be obtained during in vitro embryo culture. It is also possible to analyze small amounts of cell-free nucleic acids, mitochondrial nucleic acids, miRNA, and long non-coding RNA derived from embryos using real-time polymerase chain reaction (PCR) or digital PCR, as well as next-generation sequencing. Various efforts are being made to use non-invasive evaluation of embryo quality (NiEEQ) to select the embryo with the best developmental competence. However, each NiEEQ method has some limitations that should be evaluated case by case. Therefore, an integrated analysis strategy fusing several NiEEQ methods should be urgently developed and confirmed by proper clinical trials.

Comment on the recent PGDIS Position Statement on the Transfer of Mosaic Embryos 2021

The worldwide demand of preimplantation genetic testing for aneuploidy (PGT-A) is still growing. However, chromosomal mosaic results greatly challenge the clinical practice. The recently published PGDIS Position Statement on the Transfer of Mosaic Embryos is the third PGDIS position statement on how to deal with embryos diagnosed as chromosomal mosaics (CM) and, one of many attempts of different societies and working groups to provide a guideline for clinicians, laboratories, clinics, and genetic counselors. But still, as in previous statements, many issues remained unresolved. Moreover, from our point of view, the question how to deal with embryos diagnosed as CM, consisting of two or more karyological cell lines cannot be separated from all the other aspects of PGT-A including its accuracy. The paucity of clearcut indications for PGT-A and evidence of benefit as well as an overall cost-benefit assessment is given below.

Embryologist agreement when assessing blastocyst implantation probability: is data-driven prediction the solution to embryo assessment subjectivity?

STUDY QUESTION

What is the accuracy and agreement of embryologists when assessing the implantation probability of blastocysts using time-lapse imaging (TLI), and can it be improved with a data-driven algorithm?

SUMMARY ANSWER

The overall interobserver agreement of a large panel of embryologists was moderate and prediction accuracy was modest, while the purpose-built artificial intelligence model generally resulted in higher performance metrics.

WHAT IS KNOWN ALREADY

Previous studies have demonstrated significant interobserver variability amongst embryologists when assessing embryo quality. However, data concerning embryologists' ability to predict implantation probability using TLI is still lacking. Emerging technologies based on data-driven tools have shown great promise for improving embryo selection and predicting clinical outcomes.

STUDY DESIGN, SIZE, DURATION

TLI video files of 136 embryos with known implantation data were retrospectively collected from two clinical sites between 2018 and 2019 for the performance assessment of 36 embryologists and comparison with a deep neural network (DNN).

PARTICIPANTS/MATERIALS, SETTING, METHODS

We recruited 39 embryologists from 13 different countries. All participants were blinded to clinical outcomes. A total of 136 TLI videos of embryos that reached the blastocyst stage were used for this experiment. Each embryo's likelihood of successfully implanting was assessed by 36 embryologists, providing implantation probability grades (IPGs) from 1 to 5, where 1 indicates a very low likelihood of implantation and 5 indicates a very high likelihood. Subsequently, three embryologists with over 5 years of experience provided Gardner scores. All 136 blastocysts were categorized into three quality groups based on their Gardner scores. Embryologist predictions were then converted into predictions of implantation (IPG ≥ 3) and no implantation (IPG ≤ 2). Embryologists' performance and agreement were assessed using Fleiss kappa coefficient. A 10-fold cross-validation DNN was developed to provide IPGs for TLI video files. The model's performance was compared to that of the embryologists.

MAIN RESULTS AND THE ROLE OF CHANCE

Logistic regression was employed for the following confounding variables: country of residence, academic level, embryo scoring system, log years of experience and experience using TLI. None were found to have a statistically significant impact on embryologist performance at α = 0.05. The average implantation prediction accuracy for the embryologists was 51.9% for all embryos (N = 136). The average accuracy of the embryologists when assessing top quality and poor quality embryos (according to the Gardner score categorizations) was 57.5% and 57.4%, respectively, and 44.6% for fair quality embryos. Overall interobserver agreement was moderate (κ = 0.56, N = 136). The best agreement was achieved in the poor + top quality group (κ = 0.65, N = 77), while the agreement in the fair quality group was lower (κ = 0.25, N = 59). The DNN showed an overall accuracy rate of 62.5%, with accuracies of 62.2%, 61% and 65.6% for the poor, fair and top quality groups, respectively. The AUC for the DNN was higher than that of the embryologists overall (0.70 DNN vs 0.61 embryologists) as well as in all of the Gardner groups (DNN vs embryologists-Poor: 0.69 vs 0.62; Fair: 0.67 vs 0.53; Top: 0.77 vs 0.54).

LIMITATIONS, REASONS FOR CAUTION

Blastocyst assessment was performed using video files acquired from time-lapse incubators, where each video contained data from a single focal plane. Clinical data regarding the underlying cause of infertility and endometrial thickness before the transfer was not available, yet may explain implantation failure and lower accuracy of IPGs. Implantation was defined as the presence of a gestational sac, whereas the detection of fetal heartbeat is a more robust marker of embryo viability. The raw data were anonymized to the extent that it was not possible to quantify the number of unique patients and cycles included in the study, potentially masking the effect of bias from a limited patient pool. Furthermore, the lack of demographic data makes it difficult to draw conclusions on how representative the dataset was of the wider population. Finally, embryologists were required to assess the implantation potential, not embryo quality. Although this is not the traditional approach to embryo evaluation, morphology/morphokinetics as a means of assessing embryo quality is believed to be strongly correlated with viability and, for some methods, implantation potential.

WIDER IMPLICATIONS OF THE FINDINGS

Embryo selection is a key element in IVF success and continues to be a challenge. Improving the predictive ability could assist in optimizing implantation success rates and other clinical outcomes and could minimize the financial and emotional burden on the patient. This study demonstrates moderate agreement rates between embryologists, likely due to the subjective nature of embryo assessment. In particular, we found that average embryologist accuracy and agreement were significantly lower for fair quality embryos when compared with that for top and poor quality embryos. Using data-driven algorithms as an assistive tool may help IVF professionals increase success rates and promote much needed standardization in the IVF clinic. Our results indicate a need for further research regarding technological advancement in this field.

STUDY FUNDING/COMPETING INTEREST(S)

Embryonics Ltd is an Israel-based company. Funding for the study was partially provided by the Israeli Innovation Authority, grant #74556.

TRIAL REGISTRATION NUMBER

N/A.

PGT-A: The biology and hidden failures of randomized control trials

OBJECTIVE

PGT-A for embryo selection has undergone significant advancements in the last two decades and yet many studies still fail to demonstrate any clinical benefits over traditional embryo morphology selection. To understand this conundrum, we performed a multi-center clinical study of PGT-A patients, where morphology selection (Mo-S) and euploid selection (Eu-S) outcomes were directly compared.

METHOD

All suitable blastocysts were biopsied and analysed for chromosome copy number. Outcomes (positive beta hCG, implantation, ongoing pregnancy and live birth rates) for euploid selection were compared to morphology selection using single embryo transfers RESULTS: Compared to Eu-S embryos, Mo-S embryos resulted in significant reduction of outcomes for positive beta hCG (P=0.0005), implantation (P=0.0008), ongoing pregnancy (P=0.0046), livebirth (P=0.0112), babies per transfer (P=0.0112) and babies per embryo transferred (P=0.0112). Morphology selection resulted in patients of all age groups having non-euploid embryos chosen for transfer. Post-hoc evaluation of individual clinic performances showed variable transfer outcomes that could potentially confound the true benefits of PGT-A.

CONCLUSION

Embryo chromosome status is central to improved embryo transfer outcomes and sole reliance on current morphology-based selection practices, without euploid selection, will always compromise outcomes. Often overlooked but a major effector of successful PGT-A outcomes are individual clinic performances. This article is protected by copyright. All rights reserved.

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.

Evaluation of Laser Confocal Raman Spectroscopy as a Non-Invasive Method for Detecting Sperm DNA Contents

RESEARCH QUESTION

Is Raman spectroscopy an efficient and accurate method to detect sperm chromosome balance state by DNA content differences?

DESIGN

Semen samples were provided by diploid healthy men, and the analysis parameters met the current World Health Organization standards. The DNA content was assessed by analysis of the corresponding spectra obtained from a laser confocal Raman spectroscope. The sperm sex chromosome information was obtained by fluorescence in situ hybridization (FISH). Comparative analysis was performed between FISH results and Raman spectral analysis results.

RESULTS

Different parts of the sperm head showed different spectral signal intensities, which indicated that there were different chemical components. Standard principal component analysis (PCA) can preliminarily classify sperm with different DNA contents into two groups. Further analysis showed that there were significant differences in the 785 DNA backbone peaks and 714-1,162 cm^-1 DNA skeleton regions among sperm with different DNA contents. The peak and regional peak of the DNA skeleton of X sperm were significantly higher than those of Y sperm (X vs. Y, p < 0.05). The above sperm types were confirmed by FISH. ROC curve analysis shows that there is a correlation between the Raman spectrum data and FISH results.

CONCLUSION

Raman spectroscopy can identify X and Y sperms by analyzing the DNA content difference. However, the accuracy of the detection still needs to be improved. Nevertheless, Raman spectroscopy has a potential application value in the field of sperm aneuploidy detection and may even be used as a non-invasive predictor of sperm aneuploid state in preimplantation genetic testing (PGT-A).

Placental Dysfunction in Assisted Reproductive Pregnancies: Perinatal, Neonatal and Adult Life Outcomes

Obstetric and newborn outcomes of assisted reproductive technology (ART) pregnancies are associated with significative prevalence of maternal and neonatal adverse health conditions, such as cardiovascular and metabolic diseases. These data are interpreted as anomalies in placentation involving a dysregulation of several molecular factors and pathways. It is not clear which extent of the observed placental alterations are the result of ART and which originate from infertility itself. These two aspects probably act synergically for the final obstetric risk. Data show that mechanisms of inappropriate trophoblast invasion and consequent altered vascular remodeling sustain several clinical conditions, leading to obstetric and perinatal risks often found in ART pregnancies, such as preeclampsia, fetal growth restriction and placenta previa or accreta. The roles of factors such as VEGF, GATA3, PIGF, sFLT-1, sEndoglin, EGFL7, melatonin and of ART conditions, such as short or long embryo cultures, trophectoderm biopsy, embryo cryopreservation, and supraphysiologic endometrium preparation, are discussed. Inflammatory local conditions and epigenetic influence on embryos of ART procedures are important research topics since they may have important consequences on obstetric risk. Prevention and treatment of these conditions represent new frontiers for clinicians and biologists involved in ART, and synergic actions with researchers at molecular levels are advocated.

Indian Society for Assisted Reproduction Consensus Guidelines on Preimplantation Genetic Testing in In vitro Fertilization Clinics

Study Question

What are the good practice guidelines for Pre implantation genetic testing applicable in INDIA?

What is Already Known

Pre-Implantation Genetic Testing (PGT) is not new in India. It is used to identify euploid embryos for transfer, thus enabling couples to achieve a healthy pregnancy. There has been a lot of controversy surrounding PGT in the international forums; most of these debates have failed to reach a consensus on whether PGT should be offered or its concerns be validated more.

Study Design Size Duration

This is the report of a 2-day consensus meeting where two moderators were assigned to a group of experts to collate information on Pre implantation genetic testing and embryo biopsy practices in INDIA. This meeting utilised surveys, available scientific evidence and personal laboratory experience into various presentations by experts on pre-decided specific topics.

Participants/Materials Setting Methods

Expert professionals from ISAR representing clinical, embryological and genetic fields.

Main Results and the Role of Chance

The report is divided into various components defining the terminologies, the various requirements, qualifications, recommendations on PGT -A,M,SR, and quality management: the report and recommendations of the expert panel reflect the discussion on each of the topics and try to lay down good practice points for labs to follow.

Limitations Reasons for Caution

The recommendations are solely based on expert opinion. Future availability of data may warrant an update of the same.

Wider Implications of the Findings

These guidelines can help labs across the country to standardise their PGT services and improve clinical outcomes.

Study Funding/Competing InterestS

The consensus meeting and writing of the paper was supported by funds from CooperSurgical India.

Blastocyst Prediction of Day-3 Cleavage-Stage Embryos Using Machine Learning

Background: Embryo selection plays an important role in the success of in vitro fertilization (IVF). However, morphological embryo assessment has a number of limitations, including the time required, lack of accuracy, and inconsistency. This study determined whether a machine learning-based model could predict blastocyst formation using day-3 embryo images.

Methods: Day-3 embryo images from IVF/intracytoplasmic sperm injection (ICSI) cycles performed at My Duc Phu Nhuan Hospital between August 2018 and June 2019 were retrospectively analyzed to inform model development. Day-3 embryo images derived from two-pronuclear (2PN) zygotes with known blastocyst formation data were extracted from the CCM-iBIS time-lapse incubator (Astec, Japan) at 67 hours post ICSI, and labeled as blastocyst/non-blastocyst based on results at 116 hours post ICSI. Images were used as the input dataset to train (85%) and validate (15%) the convolutional neural network (CNN) model, then model accuracy was determined using the training and validation dataset. The performance of 13 experienced embryologists for predicting blastocyst formation based on 100 day-3 embryo images was also evaluated.

Results: A total of 1,135 images were allocated into training ([Formula: see text] 967) and validation ([Formula: see text] 168) sets, with an even distribution for blastocyst formation outcome. The accuracy of the final model for blastocyst formation was 97.72% in the training dataset and 76.19% in the validation dataset. The final model predicted blastocyst formation from day-3 embryo images in the validation dataset with an area under the curve of 0.75 (95% confidence interval [CI] 0.69–0.81). Embryologists predicted blastocyst formation with the accuracy of 70.07% (95% CI 68.12%–72.03%), sensitivity of 87.04% (95% CI 82.56%–91.52%), and specificity of 30.93% (95% CI 29.35%–32.51%).

Conclusions: The CNN-based machine learning model using day-3 embryo images predicted blastocyst formation more accurately than experienced embryologists. The CNN-based model is a potential tool to predict additional IVF outcomes.

Legal challenges in reproductive genetics

Recent advancements in reproductive genetics have resulted in the availability of an extraordinary amount of new and detailed information for patients and providers. Whereas this information can inform many who are facing difficult clinical decisions, it can also introduce complex and uncertain choices. Expanded carrier screening and preimplantation genetic diagnosis for aneuploidy are important examples of new genetic techniques that are now widely used in reproductive medicine. This paper will explore these techniques through a medical-legal prism to better understand the opportunities and obligations incumbent on both patients and providers in this new age of genetic diagnosis.

Preimplantation Genetic Testing for Aneuploidy: A Review of the Evidence

Preimplantation genetic testing for aneuploidy was developed as an invasive embryo-selection technique and is extensively used in in vitro fertilization (IVF) cycles. Around 95,000 preimplantation genetic testing cycles were carried out in the United States between 2014 and 2016, the majority of which were performed for aneuploidy. The objective of preimplantation genetic testing for aneuploidy is to select for transfer a euploid embryo, after embryo biopsy and cytogenetic analysis. The current technique consists of applying comprehensive chromosome screening on trophectoderm cells after blastocyst-stage embryo biopsy. This article reviews all the published randomized controlled trials on preimplantation genetic testing for aneuploidy with comprehensive chromosome screening and comments on the subject of embryo mosaicism detected by this technique. Most of these trials have been criticized because they only included good prognosis patients having normal ovarian reserve producing a high number of embryos available for biopsy. Preimplantation genetic testing for aneuploidy does not improve ongoing pregnancy rates per cycle started when routinely applied on the general IVF population but seems to be a good tool of embryo selection for a selected category of patients with normal ovarian reserve, yet should be only practiced by experienced IVF clinics. If no euploid embryo is available after preimplantation genetic testing for aneuploidy, a low-level mosaic embryo can be considered and prioritized for transfer after appropriate genetic counseling.

A mathematical model for predicting the number of transferable blastocysts in next-generation sequencing-based preimplantation genetic testing

PURPOSE

To investigate the clinical factors that could be used predict the number of transferable blastocysts in preimplantation genetic testing (PGT) cycles based on next-generation sequencing (NGS) and formed form a mathematical model to predict the chance likelihood of obtaining one transferable blastocyst, which is helpful for genetic counseling.

METHODS

This retrospective study enrolled couples undergoing PGT cycles for chromosomal structural rearrangement (PGT-SR, n = 363, 202 with reciprocal translocation carriers, 131 with Robertsonian translocation carriers, 30 with inversion carriers), monogenic diseases (PGT-M, n = 47), and for Aneuploidies (PGT-A, n = 132) from January 2015 to October 2018. Stepwise multiple linear regression analysis was used to identify the factors relevant for obtaining at least one transferable blastocyst. The factors that predict the number of biopsied blastocysts were further analyzed.

RESULTS

The transferable blastocyst rates were 29.94, 41.99, 49.09, 41.42, and 44.37% in the reciprocal translocation carrier, Robertsonian translocation carrier, inversion carrier, PGT-M, and PGT-A cycles, respectively. The number of transferable blastocysts in these cycles were 0.3004 × the number of biopsied blastocysts (NBB) - 0.0031, 0.4063 × NBB + 0.0460, 0.5762 × NBB - 0.3128, 0.3611 × NBB + 0.1910, and 0.4831 × NBB - 0.0970, respectively. Furthermore, the number of MII oocytes and female age were clinical predictors of NBB in reciprocal translocation and PGT-A couples, while the number of MII oocytes was the only clinical predictor in Robertsonian translocation carriers, inversion carriers, and PGT-M couples.

CONCLUSIONS

The number of biopsied blastocysts was the only clinical predictor of the ability to obtain a transferable blastocyst in PGT cycles; therefore, for clinical practice, theoretically the minimum numbers of biopsied blastocysts is 4 in reciprocal translocation carrier and 3 in couples undergoing PGT for other reasons. The number of MII oocytes and female age were clinical predictors of the number of biopsied blastocysts. With the mathematical models in our study as a reference, in clinical practice, clinicians will be able to conduct a more targeted genetic consultation for different kinds of PGT patients.

Chromosomal analyses of human giant diploid oocytes by next-generation sequencing

PURPOSE

Although giant oocytes (GOs) having about twice cytoplasmic volume compared with general oocytes in mammals including the human are rarely recovered, it is thought that GOs have potentially chromosomal abnormalities. The aim of the present study was to assess chromosome numbers in chromosome-spindle complexes (CSCs) and polar bodies of human GOs by using micromanipulation for sampling and next-generation sequencing (NGS) for analyses of the chromosome numbers.

METHODS

When recovered oocytes whose cytoplasm has lager than 140 µm or above, the oocytes were defined as GOs, and recovered GOs were vitrified. After warming, the CSCs, polar bodies, and enucleated cytoplasm were collected by micromanipulation from 3 GOs. The collected samples were analyzed by NGS.

RESULTS

Chromosomal aneuploidy in the GOs was confirmed in all the three GOs. Comparing the CSCs with the chromosomes from polar bodies, the deletion and overlapping chromosome numbers were complementary in each GO.

CONCLUSIONS

The authors could collect the CSCs and the polar bodies from human GOs by micromanipulation, and then could analyze the chromosome numbers of the GOs by NGS method. As our data suggest that human GOs have chromosomal abnormalities, GOs should be excluded from clinical purpose as gamete sources for embryo transfer in the human.

The precise determination of the window of implantation significantly improves ART outcomes

The human endometrium is receptive to the embryo for a specific period of time known as the window of implantation (WOI). During this period, the endometrium shows a specific gene expression profile suitable for endometrial function evaluation. ER Map is a molecular tool able to accurately predict endometrial receptivity status by transcriptomic analysis. In this retrospective study, including 2256 subfertile patients undergoing ART treatment, the clinical value of precise WOI determination is studied in detail. Results obtained when single embryo transfers (sET) were scheduled either within the WOI timeframe as established by ER Map, or deviating from this WOI, are assessed and compared. Data obtained showed that 34.18% (771/2256) of patients had a displaced WOI. Analysis of ART outcomes showed significantly higher pregnancy rates in transfers scheduled within the WOI predicted compared to transfers that deviated more than 12h from this WOI (44.35% vs 23.08%, p < 0.001). The deviation from the WOI had also an impact on the progression of pregnancy, with a significant increase in pregnancy loss (~ twofold) observed in transfers that deviated more than 12h from the WOI predicted. These results indicate that the precise determination of the WOI and personalised embryo transfer can significantly improve clinical outcomes.

Impact of trophectoderm biopsy on obstetric and perinatal outcomes following frozen-thawed embryo transfer cycles

STUDY QUESTION

Does trophectoderm biopsy for preimplantation genetic testing (PGT) increase the risk of obstetric or perinatal complications in frozen-thawed embryo transfer (FET) cycles?

SUMMARY ANSWER

Trophectoderm biopsy may increase the risk of hypertensive disorders of pregnancy (HDP) in pregnancies following FET cycles.

WHAT IS KNOWN ALREADY

Trophectoderm biopsy has replaced blastomere biopsy as the standard of care to procure cells for PGT analysis. Recently, there has been concern that trophectoderm biopsy may adversely impact obstetric and perinatal outcomes. Previous studies examining this question are limited by use of inappropriate control groups, small sample size or reporting on data that no longer reflects current IVF practice.

STUDY DESIGN, SIZE, DURATION

This was a retrospective cohort study conducted at a single university-affiliated fertility center. A total of 756 patients who underwent FET with transfer of previously vitrified blastocysts that had either trophectoderm biopsy or were unbiopsied and resulted in a singleton live birth between 2013 and 2019 were included.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Obstetric and perinatal outcomes for patients aged 20-44 years who underwent FET with transfer of previously vitrified blastocysts that were either biopsied (n = 241) or unbiopsied (n = 515) were analyzed. Primary outcome was odds of placentation disorders including HDP and rate of fetal growth restriction (FGR). Binary logistic regression was performed to control for potential covariates.

MAIN RESULTS AND THE ROLE OF CHANCE

The biopsy group was significantly older, had fewer anovulatory patients, was more often nulliparous and had fewer embryos transferred compared to the unbiopsied group. After controlling for potential covariates, the probability of developing HDP was significantly higher in the biopsy group compared with unbiopsied group (adjusted odds ratio (aOR) 1.943, 95% CI 1.072-3.521; P = 0.029).There was no significant difference between groups in the probability of placenta previa or placenta accreta. There was also no significant difference in the rate of FGR (aOR 1.397; 95% CI, 0.815-2.395; P = 0.224) or the proportion of low (aOR 0.603; 95% CI, 0.336-1.084; P = 0.091) or very low (aOR 2.948; 95% CI, 0.613-14.177; P = 0.177) birthweight infants comparing biopsied to unbiopsied groups.

LIMITATIONS, REASON FOR CAUTION

This was a retrospective study performed at a single fertility center, which may limit the generalizability of our findings.

WIDER IMPLICATIONS OF THE FINDINGS

Trophectoderm biopsy may increase the risk of HDP in FET cycles, however, a prospective multicenter randomized trial should be performed to confirm these findings.

STUDY FUNDING/COMPETING INTEREST(S)

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

TRIAL REGISTRATION NUMBER

NA.

Embryo biopsy and perinatal outcomes of singleton pregnancies: an analysis of 16,246 frozen embryo transfer cycles reported in the Society for Assisted Reproductive Technology Clinical Outcomes Reporting System

BACKGROUND

Preimplantation genetic testing is commonly performed by removing cells from the trophectoderm, the outer layer of the blastocyst, which subsequently forms the placenta. Because preimplantation genetic testing removes the cells that are destined to form the placenta, it is possible that preimplantation genetic testing could be associated with an increased risk for adverse outcomes associated with abnormal placentation. Despite the increasing utilization of preimplantation genetic testing, few studies have investigated the perinatal outcomes, with published studies yielding contradictory findings and using small sample sizes.

OBJECTIVE

This study aimed to compare the perinatal outcomes of singleton pregnancies conceived following frozen embryo transfer of a single, autologous blastocyst either with or without preimplantation genetic testing.

STUDY DESIGN

This was a retrospective analysis of autologous frozen embryo transfer cycles that led to singleton live births per the Society for Assisted Reproductive Technology Clinical Outcomes Reporting System, including cycles initiated between 2014 and 2015. The perinatal outcomes, including birthweight, Z-score, small for gestational age, large for gestational age, macrosomia, and preterm birth, were compared between pregnancies with or without preimplantation genetic testing. We conducted multivariable linear regression analyses for the birthweight and Z-score and logistic regression for the binary outcomes. A false discovery rate was adjusted to decrease the type I error from multiple hypothesis testing.

RESULTS

Of the 16,246 frozen embryo transfers resulting in singleton births included in this analysis, 6244 involved the transfer of a single blastocyst that had undergone preimplantation genetic testing, and the remainder (n=10,002) involved the transfer of a single blastocyst that had not undergone a biopsy. When compared with the women from the nonpreimplantation genetic testing group, the average maternal age (35.8±4.1 vs 33.7±3.9; P<.001) and prevalence of prior spontaneous abortion (37.3% vs 27.7%; P<.001) were higher among women from the preimplantation genetic testing group. Bivariate analysis revealed a higher prevalence of small-for-gestational-age newborns (4.8% vs 4.0%; P=.008) and premature delivery (14.1% vs 12.5%; P=.005) and a lower prevalence of large-for-gestational-age newborns (16.3% vs 18.2%; P=.003) and macrosomia (11.1% vs 12.4%; P=.013) among the preimplantation genetic testing pregnancies. Multivariate regression analyses, adjusting for the year of transfer, maternal age, maternal body mass index, smoking status (3 months before the treatment cycle), obstetrical histories (full-term birth, preterm birth, and spontaneous abortion), infertility diagnosis, and infant sex suggested a significantly increased odds of preterm birth (adjusted odds ratio, 1.20; 95% confidence interval, 1.09-1.33; P<.001) from preimplantation genetic testing blastocysts. Birthweight (-14.63; 95% confidence interval, -29.65 to 0.38; P=.056), birthweight Z-score (-0.03; 95% confidence interval, -0.06 to 0.00; P=.081), and odds of small-for-gestational-age newborns (adjusted odds ratio, 1.17; 95% confidence interval, 0.99-1.38; P=.066), large-for-gestational-age newborns (adjusted odds ratio, 0.96; 95% confidence interval, 0.88-1.06; P=.418), and macrosomia (adjusted odds ratio, 0.96; 95% confidence interval, 0.85-1.07; P=.427) did not differ between the frozen transfer cycles with or without preimplantation genetic testing in the analysis adjusted for the confounders. Subgroup analysis of the cycles with a stated infertility diagnosis (n=14,285) yielded consistent results.

CONCLUSION

Compared with frozen embryo transfer cycles without preimplantation genetic testing, the frozen embryo transfer cycles with preimplantation genetic testing was associated with a small increase in the likelihood of preterm birth. Although the increase in the risk for prematurity was modest in magnitude, further investigation is warranted.

Aneuploid embryo transfer: clinical policies and provider opinions at United States fertility clinics

OBJECTIVE

To describe institutional clinical policies and individual provider opinions regarding aneuploid embryo transfer (aET).

DESIGN

A survey about clinical policies was electronically sent to Society for Assisted Reproductive Technology (SART) member laboratory directors, and a separate survey about personal opinions was electronically sent to all SART members.

SETTING

Not applicable.

PATIENTS

Patients pursuing preimplantation genetic testing for aneuploidy (PGT-A).

INTERVENTION

Not applicable.

MAIN OUTCOME MEASURES

Current clinical policies about aET were described. Individual provider opinions about aET in the context of specific aneuploidies and mosaicism were also described.

RESULTS

A total of 48 laboratory directors and 212 individual providers responded to their respective surveys. Twelve (25%) clinics report that they do not have a policy regarding aET, but clinics performing PGT-A in >100 cycles per year were more likely to have a policy. Half of the individual providers agree that an embryo with trisomy 21 should be available for aET, but most disagreed with aET of embryos with other aneuploidies and most were either unsure about or unwilling to transfer embryos with mosaicism. Those who worked in primarily patient-facing roles held more agreeable opinions regarding aET.

CONCLUSION

There is no consensus regarding ideal clinical policies for aET. The wide range of current clinical practices and individual provider opinions regarding under what circumstances, if any, aET should be available to patients indicates that this is a divisive issue among ART providers, and there is a clear need for specific professional guidelines to address this issue.

An overview of the current and emerging platforms for preimplantation genetic testing for aneuploidies (PGT-A) in in vitro fertilization programs

Preimplantation genetic testing for aneuploidies (PGT-A) and PGT for monogenic disorders (PGT-M) have currently been used widely, aiming to improve IVF outcomes. Although with many years of unsatisfactory results, PGT-A has been revived because new technologies have been adopted, such as platforms to examine all 24 types of chromosomes in blastocysts. This report compiles current knowledge regarding the available PGT platforms, including quantitative PCR, array CGH, and next-generation sequencing. The diagnostic capabilities of are compared and respective advantages/disadvantages outlined. We also address the limitations of current technologies, such as assignment of embryos with balanced translocation. We also discuss the emerging novel PGT technologies that likely will change our future practice, such as non-invasive PGT examining spent culture medium. Current literature suggest that most platforms can effectively reach concordant results regarding whole-chromosome ploidy status of all 24 types of chromosomes. However, different platforms have different resolutions and experimental complexities; leading to different turnaround time, throughput and differential capabilities of detecting mosaicism, segmental mutations, unbalanced translocations, concurrent PGT-A and PGT-M etc. Based on these information, IVF staff can more appropriately interpret PGT data and counsel patients, and select suitable platforms to meet personalized needs. The present report also concisely discusses some crucial clinical outcomes by PGT, which can clarify the role of applying PGT in daily IVF programs. Finally the up-to-date information about the novel use of current technologies and the newly emerging technologies will also help identify the focus areas for the design of new platforms for PGT in the future.

Commentary on two recently published formal guidelines on management of "mosaic" embryos after preimplantation genetic testing for aneuploidy (PGT-A)

Two professional societies recently published opinions on the clinical management of "mosaic" results from preimplantation genetic testing for aneuploidy (PGT-A) in human blastocyst-stage embryos in associations with in vitro fertilization (IVF). We here point out three principal shortcomings: (i) Though a most recent societal opinion states that it should not be understood as an endorsement of the use of PGT-A, any discussion of how PGT-A should be clinically interpreted for all practical purposes does offer such an endorsement. (ii) The same guideline derived much of its opinion from a preceding guidance in favor of utilization of PGT-A that did not follow even minimal professional requirements for establishment of practice guidelines. (iii) Published guidelines on so-called "mosaic" embryos from both societies contradict basic biological characteristics of human preimplantation-stage embryos. They, furthermore, are clinically unvalidated and interpret results of a test, increasingly seen as harmful to IVF outcomes for many infertile women. Qualified professional organizations, therefore, should finally offer transparent guidelines about the utilization of PGT-A in association with IVF in general.

Endometrial compaction before frozen euploid embryo transfer improves ongoing pregnancy rates

OBJECTIVE

To assess whether the calculated difference in endometrial thickness from the end of the estrogen phase to the day of ET (after 6 days of P in hormonally prepared cycles) is associated with ongoing pregnancy rates in euploid frozen ETs (FETs).

DESIGN

An observational cohort study.

SETTING

Single tertiary care medical center.

PATIENT(S)

Ultrasound images from 234 hormonally prepared FET cycles were assessed. All the transfers were elective single ETs of a euploid embryo, post-preimplantation genetic testing for aneuploidy (PGT-A).

INTERVENTION(S)

Ultrasound measurements of peak endometrial thickness at the end of the estrogen phase and again after 6 days of P at the time of ET.

MAIN OUTCOME MEASURE(S)

Ongoing pregnancy rate in relation to the delta between endometrial thickness at the end of estrogen phase and at the time of ET.

RESULT(S)

We calculated the ongoing pregnancy rate in cycles where the endometrial lining decreased (compacted) after addition of P by 5%, 10%, 15%, and 20% and demonstrated a significantly higher pregnancy rate after all rates of compaction of the endometrial lining in comparison with cycles where the endometrial lining did not compact. The ongoing pregnancy rate in this cohort, after compaction of 15% or more, was 51.5%, compared with 30.2% in cycles where the endometrial lining did not compact.

CONCLUSION(S)

There is a significant correlation between endometrial lining compaction and ongoing pregnancy rate in FET cycles of euploid embryos. These findings help to explain why some euploid embryos may fail to implant.

Cell-free DNA in spent culture medium effectively reflects the chromosomal status of embryos following culturing beyond implantation compared to trophectoderm biopsy

This prospective study evaluated the accuracy of non-invasive preimplantation genetic testing for aneuploidy (niPGT-A) using cell-free DNA in spent culture medium, as well as that of preimplantation genetic testing for aneuploidy (PGT-A) using trophectoderm (TE) biopsy after culturing beyond implantation. Twenty frozen blastocysts donated by 12 patients who underwent IVF at our institution were investigated. Of these, 10 were frozen on day 5 and 10 on day 6. Spent culture medium and TE cells were collected from each blastocyst after thawing, and the embryos were cultured in vitro for up to 10 days. The outgrowths after culturing beyond implantation were sampled and subjected to chromosome analysis using next-generation sequencing. Chromosomal concordance rate, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), false-positive rate (FPR), and false-negative rate (FNR) of niPGT-A and PGT-A against each outgrowth were analyzed. The concordance rate between the niPGT-A and outgrowth samples was 9/16 (56.3%), and the concordance rate between the PGT-A and outgrowth samples was 7/16 (43.8%). NiPGT-A exhibited 100% sensitivity, 87.5% specificity, 88.9% PPV, 100% NPV, 12.5% FPR, and 0% FNR. PGT-A exhibited 87.5% sensitivity, 77.8% specificity, 87.5% PPV, 75% NPV, 14.3% FPR, and 22.2% FNR. NiPGT-A may be more accurate than PGT-A in terms of ploidy diagnostic accuracy in outgrowths.

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

PURPOSE

To evaluate the clinical usefulness of the endometrial receptivity array (ERA) and the preimplantation genetic test for aneuploidy (PGT-A) in patients with severe and moderate recurrent implantation failure (RIF).

DESIGN

A retrospective multicenter cohort study was conducted in patients who failed to achieve implantation following transfer of 3 or more or 5 or more embryos in at least three single embryo transfers; patients were classified as moderate or severe RIF, respectively. Patients with previous RIF were compared based on the testing they received: PGT-A, ERA, or PGT-A+ERA versus a control group with no testing. Mean implantation rate and ongoing pregnancy rates per embryo transfer were considered primary outcomes. Multiple logistic regression analysis was performed and adjusted ORs were calculated to control possible bias.

RESULTS

Of the 2110 patients belonging to the moderate RIF group, those who underwent transfer of euploid embryos after PGT-A had a higher implantation rate than those who did not. Additionally, the PGT-A group had a significantly higher rate of ongoing pregnancy. The same outcomes measured for the 488 patients in the severe RIF group did not reveal any statistically significant improvements. The use of the ERA test did not appear to significantly improve outcomes in either group.

CONCLUSIONS

PGT-A may be beneficial for patients with moderate recurrent implantation failure but not for severe cases. At its current level of development, ERA does not appear to be clinically useful for patients with RIF.

The Relationship between Sperm Oxidative Stress Alterations and IVF/ICSI Outcomes: A Systematic Review from Nonhuman Mammals

Achieving high embryo quality following IVF and ICSI procedures is a key factor in increasing fertility outcomes in human infertile couples. While the male factor is known to underlie infertility in about 50% of cases, studies performed in human infertile couples have not been able to define the precise effect of sperm affectations upon embryo development. This lack of consistency is, in most cases, due to the heterogeneity of the results caused by the multiple male and female factors that mask the concrete effect of a given sperm parameter. These biases can be reduced with the use of animal gametes, being a good approach for basic researchers to design more homogeneous studies analyzing the specific consequences of a certain affectation. Herein, we conducted a systematic review (March 2020) that assessed the relationship between sperm oxidative stress alterations and IVF/ICSI outcomes in nonhumans mammals. The review was conducted according to PRISMA guidelines and using the MEDLINE-PubMed and EMBASE databases. Thirty articles were included: 11 performed IVF, 17 conducted ICSI, and two carried out both fertilization methods. Most articles were conducted in mouse (43%), cattle (30%) and pig models (10%). After IVF treatments, 80% of studies observed a negative effect of sperm oxidative stress on fertilization rates, and 100% of studies observed a negative effect on blastocyst rates. After ICSI treatments, a positive relationship of sperm oxidative stress with fertilization rates (75% of studies) and with blastocyst rates (83% of studies) was found. In conclusion, the present systematic review shows that sperm oxidative stress is associated with a significant reduction in fertilization rates and in vitro embryo development.

Generation of viable blastocysts from discarded human cleavage embryos

Background

While a relationship between embryo morphology, developmental ability, and genetic integrity exists, the selection of embryos with higher implantation potential remains a major challenge in assisted reproductive technology (ART). This study investigated blastocyst developmental competence and euploidy status in human embryos that had been classed as too poor quality to transfer (ET) or cryopreserve at the cleavage stage.

Embryos were divided into three groups. Group 1 (n = 41) included good quality embryos from candidates of preimplantation genetic testing for aneuploidy (PGT-A). Groups II and III were the “rejected” supernumerary embryos, defined as suboptimal for ET or vitrification after morphological examination, with embryos randomly divided between the groups. Group II embryos (n = 31) were cultured up to the day 3 cleavage stage, when they were biopsied and fixed. Group III embryos (n = 27) were cultured up to the day 5 blastocyst stage, when they were evaluated for morphology and chromosomal status. Chromosomal status in all groups was assessed by multi-color fluorescence in situ hybridization (FISH) for chromosomes 13, 18, 21, X, and Y.

Results

Euploidy rates in groups I, II, and III were 56.1%, 38.7%, and 55.5 %, respectively. Among the blastocysts that developed from “rejected” embryos, 59.3% were classed as good quality. The most frequent chromosomal aneuploidy was related to the sex chromosome (22.2%). The mosaicism rate was not significantly different between the group II and III embryos (25.8% vs. 37.0%, p = 0.28).

Conclusion

In conclusion, surplus poor-quality embryos rejected from clinical utilization at the cleavage stage may develop into viable blastocysts with normal chromosomal status for at least 5 chromosomes. Recovery of euploidy during poor-quality embryo transition from cleavage stage to blastocyst could provide an alternative choice for ET.

Minimally Invasive Cell-Free Human Embryo Aneuploidy Testing (miPGT-A) Utilizing Combined Spent Embryo Culture Medium and Blastocoel Fluid -Towards Development of a Clinical Assay

Preimplantation genetic testing for aneuploidies (PGT-A) using trophectoderm (TE) biopsy samples is labour intensive, invasive, and subject to sampling bias. In this study, we report on the efficacy and factors affecting accuracy of a technique we pioneered for minimally invasive preimplantation genetic testing for aneuploidy (miPGT-A). Our technique uses cell-free embryonic DNA (cfeDNA) in spent embryo culture medium (SEM) combined with blastocoel fluid (BF) to increase the amount of assayable cfeDNA. We compared miPGT-A results (n = 145 embryos) with standard PGT-A analysis of the corresponding trophectoderm biopsy. We found that accuracy of miPGT was not related to blastocyst morphological grade. The overall concordance rate per sample for euploidy/aneuploidy status between miPGT-A and TE biopsy samples was 88/90 (97.8%), and was not different between good 47/48 (97.9%) and moderate/low quality blastocysts 41/42 (97.9%) (p > 0.05). Importantly, we also discovered that for cfeDNA analysis, the SurePlex whole genome amplification (WGA) kit can be utilized without an additional cell lysis/extraction DNA step; this efficiency likely reduces the risk of maternal contamination. Regarding origin of embryonic cfeDNA, the average amount of miPGT-A WGA-DNA we obtained from blastocysts with different morphological grades, as well as the size miPGT-A WGA-DNA fragments, suggest that it is unlikely that apoptosis and necrosis are only mechanisms of DNA release from the inner cell mass (ICM) and TE into BF and SEM.

Genome sequencing of human in vitro fertilisation embryos for pathogenic variation screening

Whole-genome sequencing of preimplantation human embryos to detect and screen for genetic diseases is a technically challenging extension to preconception screening. Combining preconception genetic screening with preimplantation testing of human embryos facilitates the detection of de novo mutations and self-validates transmitted variant detection in both the reproductive couple and the embryo’s samples. Here we describe a trio testing workflow that involves whole-genome sequencing of amplified DNA from biopsied embryo trophectoderm cells and genomic DNA from both parents. Variant prediction software and annotation databases were used to assess variants of unknown significance and previously not described de novo variants in five single-gene preimplantation genetic testing couples and eleven of their embryos. Pathogenic variation, tandem repeat, copy number and structural variations were examined against variant calls for compound heterozygosity and predicted disease status was ascertained. Multiple trio testing showed complete concordance with known variants ascertained by single-nucleotide polymorphism array and uncovered de novo and transmitted pathogenic variants. This pilot study describes a method of whole-genome sequencing and analysis for embryo selection in high-risk couples to prevent early life fatal genetic conditions that adversely affect the quality of life of the individual and families.

Comprehensive analysis of the associations between previous pregnancy failures and blastocyst aneuploidy as well as pregnancy outcomes after PGT-A

PURPOSE

To investigate the associations of previous pregnancy failures, including implantation failures (IFs), biochemical pregnancy losses (BPLs), and early (EMs) and late miscarriages (LMs), with blastocyst aneuploidy and pregnancy outcomes after PGT-A.

METHODS

This study included 792 couples who underwent PGT-A after multiple pregnancy failures. Subgroup analyses were used to compare the blastocyst aneuploidy rate (BAR), implantation rate (IR), early miscarriage rate (EMR), and live birth rate (LBR). Multiple linear and logistic regression models were used to evaluate the associations. The control group comprised couples with ≤ 2 IFs, ≤ 1 BPL, ≤ 1 EM, and no LM.

RESULTS

Notably, a history of ≥ 4 IFs was significantly associated with an increase in aneuploid blastocysts (42.86% vs. 33.05%, P = 0.044, B = 10.23 for 4 IFs; 48.80% vs. 33.05%, P = 0.002, B = 14.43 for ≥ 5 IFs). Women with ≥ 4 prior EMs also harbored more aneuploid blastocysts (41.00% vs. 33.05%, P = 0.048; B = 9.23). Compared with the control group, women with ≥ 4 prior EMs had a significantly higher EMR (6.58% vs. 31.11%, P < 0.001, OR = 6.49) and a lower LBR (53.49% vs. 34.18%, P = 0.007, OR = 0.56) after euploid transfer. Moreover, a history of LM(s) was associated with adverse pregnancy outcomes after PGT-A (OR for EM = 3.16; OR for live birth = 0.48). However, previous BPLs and 2 EMs were not associated significantly with blastocyst aneuploidy and pregnancy outcomes after PGT-A.

CONCLUSION

A history of high-order IFs or EMs and existence of LM(s) were significantly associated with blastocyst aneuploidy and adverse pregnancy outcomes after PGT-A, whereas no such associations were observed with BPLs or 2 EMs.

Is cell-free DNA in spent embryo culture medium an alternative to embryo biopsy for preimplantation genetic testing? A systematic review

Preimplantation genetic testing (PGT) is increasingly used worldwide. It currently entails the use of invasive techniques, i.e. polar body, blastomere, trophectoderm biopsy or blastocentesis, to obtain embryonic DNA, with major technical limitations and ethical issues. Evidence suggests that invasive PGT can lead to genetic misdiagnosis in the case of embryo mosaicism, and, consequently, to the selection of affected embryos for implantation or to the destruction of healthy embryos. Recently, spent culture medium (SCM) has been proposed as an alternative source of embryonic DNA. An increasing number of studies have reported the detection of cell-free DNA in SCM and highlighted the diagnostic potential of non-invasive SCM-based PGT for assessing the genetic status of preimplantation human embryos obtained by IVF. The reliability of this approach for clinical applications, however, needs to be determined. In this systematic review, published evidence on non-invasive SCM-based PGT is presented, and its current benefits and limitations compared with invasive PGT. Then, ways of optimizing and standardizing procedures for non-invasive SCM-based PGT to prevent technical biases and to improve performance in future studies are discussed. Finally, clinical perspectives of non-invasive PGT are presented and its future applications in reproductive medicine highlighted.

Levels of caspase-3 and histidine-rich glycoprotein in the embryo secretome as biomarkers of good-quality day-2 embryos and high-quality blastocysts

Morphological assessment at defined developmental stages is the most important method to select viable embryos for transfer and cryopreservation. Timing of different developmental stages in embryo development has been shown to correlate with its potential to develop into a blastocyst. However, improvements in pregnancy rates by using time-lapse techniques have been difficult to validate scientifically. Therefore, there is a need for new methods, preferably non-invasive methods based on metabolomics, genomics and proteomics, to improve the evaluation of embryo quality even further. The aim of this study was to investigate if different levels of caspase-3 and histidine-rich glycoprotein (HRG), secreted by the embryo into the culture media, can be used as biomarkers of embryo quality. In this study, a total of 334 samples of culture media were collected from in vitro fertilization (IVF) treatments at three different clinics. Protein analysis of the culture media was performed using multiplex proximity extension protein analysis to detect levels of caspase-3 and HRG in the embryo secretome. Protein levels were compared in secretome samples from high- and low-quality blastocysts and embryos that became arrested during development. Correlation between protein levels and time to morula formation was also analyzed. Furthermore, protein levels in secretomes from day-2 cultured embryos were compared on the basis of whether or not pregnancy was achieved. The results showed that caspase-3 levels were lower in secretomes from high-quality vs. low-quality blastocysts and those that became arrested (p ≤ 0.05 for both). In addition, higher HRG levels correlated with a shorter time to morula formation (p ≤ 0.001). Caspase-3 levels were also lower in secretomes from day-2 cultured embryos resulting in a pregnancy vs. those that did not (p ≤ 0.05). Furthermore, it was shown that caspase-3 might be used as a marker for predicting potential success rate after transfer of day-2 cultured embryos, where a caspase-3 cutoff level of 0.02 gave a prediction probability of 68% (p = 0.038). In conclusion, in future prediction models, levels of caspase-3 and HRG might be used as potential markers of embryo quality, and secreted caspase-3 levels could to some extent predict the outcome after transfer of day-2 cultured embryos.

The mechanisms and clinical application of mosaicism in preimplantation embryos

Embryos containing distinct cell lines are referred to as mosaic embryos, which are considered to be caused by mitotic errors in chromosome segregation during preimplantation development. As the accuracy and resolution of detection techniques improve, more and more mosaic embryos were identified recently. The impacts of mosaic embryos on survival and potential pregnancy outcome have been reported to be diverse in different studies. Because of the universality and clinical significance of mosaicism, it is essential to unravel the mechanisms and consequences with regard to this phenomenon in human pre- and post-implantation embryos. The purpose of this review is to explore the mechanisms, causes of mosaicism, and the development of pre- and post-implantation mosaic embryos in the light of recent emerging data, with the aim of providing new references for clinical applications.

New perspectives with the use of noninvasive chromosome screening (NICS) in ART

After more than 20 years of use of preimplantation genetic tests for aneuploidies (PGS/PGT-A) there are still many problems related to the efficiency of this technique, most of them still without an adequate solution (Gleicher et al., 2018; Homer, 2019). From the clinical point of view, the benefits attributed to invasive PGT-A in the selection of euploid embryos remain controversial, especially due to the lack of scientific proof of its effectiveness in increasing live birth rates in various clinical situations, such as patients with advanced age, repeated implantation failures or recurrent miscarriages. In addition, evidence-based medicine also severely criticizes the rare randomized trials analyzing the clinical use of invasive PGT-A (Orvieto, 2016). If these criticisms were not enough, and undoubtedly one of the most important, it would be difficult to accurately assess the presence of embryonic mosaicism creating significant levels of false positive results, and worse, causing a real possibility of discarding healthy embryos. This makes the clinical application of PGT-A as a risky approach (Munné et al., 2017; Spinella et al., 2018). Another problem, not less important, would be the obligation to perform PGT-A by experienced embryologists, since otherwise the embryonic loss due to biopsy would be a frequent fact, something usually estimated below 10% but in some laboratories it may reach up to 30% of biopsied embryos (Munné, 2018). On the other hand, there are doubts about the future risks of invasive action of the usually 5-10 cell removed during biopsy for genetic diagnosis. Would there be repercussions for the health of these children? In animals, there are data suggesting that embryonic biopsies could be linked to changes in fetal neural tube or adrenal development (Wu et al., 2014; Zeng et al., 2013). Recently, Xu et al. (2016) described noninvasive chromosomal screening (NICS) by obtaining and sequencing free DNA dripped by embryos in the culture medium (without the need of embryo biopsy) creating a new non-aggressive and elegant perspective to preimplantation genetic diagnosis.

The evolving role of genetic tests in reproductive medicine

Infertility is considered a major public health issue, and approximately 1 out of 6 people worldwide suffer from infertility during their reproductive lifespans. Thanks to technological advances, genetic tests are becoming increasingly relevant in reproductive medicine. More genetic tests are required to identify the cause of male and/or female infertility, identify carriers of inherited diseases and plan antenatal testing. Furthermore, genetic tests provide direction toward the most appropriate assisted reproductive techniques. Nevertheless, the use of molecular analysis in this field is still fragmented and cumbersome. The aim of this review is to highlight the conditions in which a genetic evaluation (counselling and testing) plays a role in improving the reproductive outcomes of infertile couples. We conducted a review of the literature, and starting from the observation of specific signs and symptoms, we describe the available molecular tests. To conceive a child, both partners' reproductive systems need to function in a precisely choreographed manner. Hence to treat infertility, it is key to assess both partners. Our results highlight the increasing importance of molecular testing in reproductive medicine.

Do serum androgens influence blastocysts ploidy in karyotypically normal women?

The aim of the study was to determine if serum testosterone (T) and dehydroepiandrosterone (DHEAS) levels are a factor in determining increased risk for embryonic aneuploidy in karyotypically normal women undergoing in vitro fertilization (IVF) and preimplantation genetic testing screening for aneuploidy (PGT-A). This is a retrospective cohort study of IVF cycles with PGT-A performed during 2015-2016. A total of 256 cycles with 725 embryos were initially considered for inclusion. A total of 208 cycles and 595 embryos determined to be either euploid or aneuploid were included in the analysis. The mean age of women was 37.4 ± 4.4 years. There were 193 (32.44%) euploid, and 338 (56.81%) aneuploid blastocysts. Sixty-four (10.76%) had 'no diagnosis' after PGT-A. The 32 embryos with 'no diagnosis' after first PGT-A were biopsied again and after the second analysis, 7 were found to be euploid and 3 aneuploid. The remaining 32 embryos were not reanalyzed due to the lack of patients' consent for the second biopsy. The relationship between embryo ploidy and levels of serum testosterone and dehydroepiandrosterone sulfate was assessed using ordinal multivariable regression analysis. The model, adjusted for both anti-Mullerian hormone (AMH) and age, showed no association between ploidy status and serum levels of the two hormones. We concluded that the serum levels of testosterone and DHEAS do not influence embryo ploidy in karyotypically normal women undergoing IVF. Abbreviations: T: testosterone; DHEAS: dehydroepiandrosterone; IVF: in vitro fertilization; PGT-A: preimplantation genetic testing screening for aneuploidy; AMH: anti-Mullerian hormone; FSH: follicle-stimulating hormone; LH: luteinizing hormone; E2: oestradiol; P: progesterone.

Preimplantation genetic testing for aneuploidy (PGT-A): The biology, the technology and the clinical outcomes

Preimplantation genetic testing for aneuploidy (PGT-A) seeks to identify preimplantation embryos with a normal chromosome complement (euploid) during in vitro fertilisation (IVF). By sifting out embryos with abnormal chromosome numbers (aneuploid), PGT-A should theoretically improve pregnancy success. However, earlier versions of PGT-A were ineffective, and in some cases, detrimental, due to biopsy-induced trauma and because the technology at the time could analyse only a fraction of all chromosomes. More recently, the emergence of technologies enabling all chromosomes to be analysed and a switch to less traumatic blastocyst-stage biopsy have seen widespread uptake of PGT-A. Assessing the full impact of blastocyst biopsy PGT-A requires consideration of multiple factors, including embryonic mosaicism, sensitivity of the technological platform used, embryo loss during long-term in vitro culture, embryo cryopreservation and inter-clinic variability in expertise. Significantly, there hasnt yet been an appropriately designed randomised controlled trial (RCT) of blastocyst biopsy PGT-A analysed by intention-to-treat that accounts for all these parameters on a per-cycle basis. The three RCTs reporting benefits studied outcomes on a per-embryo transfer basis were small and underpowered and demonstrated benefits for a very select sub-group of good prognosis patients. The liberal use of this very expensive IVF add-on for other patient populations has not yet been shown to be effective, or indeed, without harm.

Cumulative Live Birth Rates of Good and Low Prognosis Patients According to POSEIDON Criteria: A Single Center Analysis of 18,455 Treatment Cycles

Objective: To investigate the characteristics and outcomes of low prognosis patients defined by POSEIDON criteria undergoing IVF treatment. Design: Retrospective cohort analysis. Setting: An IVF clinic in a public hospital. Patients: 18,455 fresh aspirated IVF cycles with subsequently frozen embryo transfer from Jan 2014 to Jan 2017 in a single IVF clinic were included in the analysis. The low prognosis patients were categorized into 4 groups based on POSEIDON criteria: group 1: age < 35, antral follicle count (AFC) ≥ 5, number of oocytes retrieved ≤ 9 in the previous cycle; group 2: age ≥ 35, AFC≥5, number of oocytes retrieved ≤ 9 in the previous cycle; group 3: age < 35, AFC < 5; group 4: age ≥ 35, AFC < 5. The non-low prognosis patients: group 5: AFC ≥ 5, previous number of oocytes retrieved > 9 oocytes; group 6: AFC ≥ 5, no previous ovarian stimulation. Intervention(s): None. Main Outcome Measure: The primary outcome was cumulative live birth rate (CLBR). Result(s): Taking group 1 as reference, the CLBR from young women in group 3 (35.5%, OR 0.9, 95% CI 0.7-1.2) was slightly lower than that in group 1 (44.6%, p = 0.615). The CLBR in group 2 (24.5%, OR 0.6, 95% CI 0.4-0.8, p = 0.004) and group 4 (12.7%, OR 0.4, 95% CI 0.3-0.6, p < 0.001) was significant lower than that in group 1. In non-poor prognosis patients, the CLBR from young women in group 5 (53.5% OR 1.3 95% CI 0.9, 1.7, p = 0.111) was a slight higher than the reference group 1 while the highest CLBR was originated from the first IVF patients with good ovarian reserve in group 6 (66.9%, OR 2.0, 95% CI 1.6, 2.4). Conclusion(s): The CLBRs and implantation rates in the young women (group 3) with diminished ovarian reserve was similar in those young women (group 1), and was significantly higher than in advanced age women with a fair ovarian reserve (group 2). Though patients in group 2 had better ovarian reserve, more oocytes and more embryos, the pregnancy outcome was inferior to that of group 3 patients with poorer ovarian reserve, fewer oocytes and fewer embryos.