The pros and cons of preimplantation genetic testing for aneuploidy: clinical and laboratory perspectives

Association of early cleavage, morula compaction and blastocysts ploidy of IVF embryos cultured in a time-lapse system and biopsied for genetic test for aneuploidy

IVF embryos have historically been evaluated by morphological characteristics. The time-lapse system (TLS) has become a promising tool, providing an uninterrupted evaluation of morphological and dynamic parameters of embryo development. Furthermore, TLS sheds light on unknown phenomena such as direct cleavage and incomplete morula compaction. We retrospectively analyzed the morphology (Gardner Score) and morphokinetics (KIDScore) of 835 blastocysts grown in a TLS incubator (Embryoscope+), which were biopsied for preimplantation genetic testing for aneuploidy (PGT-A). Only the embryos that reached the blastocyst stage were included in this study and time-lapse videos were retrospectively reanalysed. According to the pattern of initial cleavages and morula compaction, the embryos were classified as: normal (NC) or abnormal (AC) cleavage, and fully (FCM) or partially compacted (PCM) morulae. No difference was found in early cleavage types or morula compaction patterns between female age groups (< 38, 38-40 and > 40 yo). Most of NC embryos resulted in FCM (≅ 60%), while no embryos with AC resulted in FCM. Aneuploidy rate of AC-PCM group did not differ from that of NC-FCM group in women < 38 yo, but aneuploidy was significantly higher in AC-PCM compared to NC-FCM of women > 40 yo. However, the quality of embryos was lower in AC-PCM blastocysts in women of all age ranges. Morphological and morphokinetic scores declined with increasing age, in the NC-PCM and AC-PCM groups, compared to the NC-FCM. Similar aneuploidy rates among NC-FCM and AC-PCM groups support the hypothesis that PCM in anomalous-cleaved embryos can represent a potential correction mechanism, even though lower morphological/morphokinetic scores are seen on AC-PCM. Therefore, both morphological and morphokinetic assessment should consider these embryonic development phenomena.

Meiotic and mitotic aneuploidies drive arrest of in vitro fertilized human preimplantation embryos

BACKGROUND

The high incidence of aneuploidy in early human development, arising either from errors in meiosis or postzygotic mitosis, is the primary cause of pregnancy loss, miscarriage, and stillbirth following natural conception as well as in vitro fertilization (IVF). Preimplantation genetic testing for aneuploidy (PGT-A) has confirmed the prevalence of meiotic and mitotic aneuploidies among blastocyst-stage IVF embryos that are candidates for transfer. However, only about half of normally fertilized embryos develop to the blastocyst stage in vitro, while the others arrest at cleavage to late morula or early blastocyst stages.

METHODS

To achieve a more complete view of the impacts of aneuploidy, we applied low-coverage sequencing-based PGT-A to a large series (n = 909) of arrested embryos and trophectoderm biopsies. We then correlated observed aneuploidies with abnormalities of the first two cleavage divisions using time-lapse imaging (n = 843).

RESULTS

The combined incidence of meiotic and mitotic aneuploidies was strongly associated with blastocyst morphological grading, with the proportion ranging from 20 to 90% for the highest to lowest grades, respectively. In contrast, the incidence of aneuploidy among arrested embryos was exceptionally high (94%), dominated by mitotic aneuploidies affecting multiple chromosomes. In turn, these mitotic aneuploidies were strongly associated with abnormal cleavage divisions, such that 51% of abnormally dividing embryos possessed mitotic aneuploidies compared to only 23% of normally dividing embryos.

CONCLUSIONS

We conclude that the combination of meiotic and mitotic aneuploidies drives arrest of human embryos in vitro, as development increasingly relies on embryonic gene expression at the blastocyst stage.

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'.

Making and selecting the best embryo in the laboratory

Over the past 4 decades our ability to maintain a viable human embryo in vitro has improved dramatically, leading to higher implantation rates. This has led to a notable shift to single blastocyst transfer and the ensuing elimination of high order multiple gestations. Future improvements to embryo culture systems will not only come from new improved innovative media formulations (such as the inclusion of antioxidants), but plausibly by moving away from static culture to more dynamic perfusion-based systems now made a reality owing to the breakthroughs in three-dimensional printing technology and micro fabrication. Such an approach has already made it feasible to create high resolution devices for intracytoplasmic sperm injection, culture, and cryopreservation, paving the way not only for improvements in outcomes but also automation of assisted reproductive technology. Although improvements in culture systems can lead to further increases in pregnancy outcomes, the ability to quantitate biomarkers of embryo health and viability will reduce time to pregnancy and decrease pregnancy loss. Currently artificial intelligence is being used to assess embryo development through image analysis, but we predict its power will be realized through the creation of selection algorithms based on the integration of information related to metabolic functions, cell-free DNA, and morphokinetics, thereby using vast amounts of different data types obtained for each embryo to predict outcomes. All of this will not only make assisted reproductive technology more effective, but it will also make it more cost effective, thereby increasing patient access to infertility treatment worldwide.

Automation in ART: Paving the Way for the Future of Infertility Treatment

In vitro fertilisation (IVF) is estimated to account for the birth of more than nine million babies worldwide, perhaps making it one of the most intriguing as well as commoditised and industrialised modern medical interventions. Nevertheless, most IVF procedures are currently limited by accessibility, affordability and most importantly multistep, labour-intensive, technically challenging processes undertaken by skilled professionals. Therefore, in order to sustain the exponential demand for IVF on one hand, and streamline existing processes on the other, innovation is essential. This may not only effectively manage clinical time but also reduce cost, thereby increasing accessibility, affordability and efficiency. Recent years have seen a diverse range of technologies, some integrated with artificial intelligence, throughout the IVF pathway, which promise personalisation and, at least, partial automation in the not-so-distant future. This review aims to summarise the rapidly evolving state of these innovations in automation, with or without the integration of artificial intelligence, encompassing the patient treatment pathway, gamete/embryo selection, endometrial evaluation and cryopreservation of gametes/embryos. Additionally, it shall highlight the resulting prospective change in the role of IVF professionals and challenges of implementation of some of these technologies, thereby aiming to motivate continued research in this field.

Preimplantation genetic testing for aneuploidy: helpful but not a first choice

PURPOSE

This retrospective cohort study aimed to assess and compare the outcomes between cumulative live birth of patients with and without PGT-A and also between prior unsuccessful IVF cycles and PGT-A cycles among patients who experienced IVF but without live birth delivery, and to clarify the effective usage of PGT-A as an in vitro fertilization (IVF) add-on.

METHODS

A total of 2113 females undergoing IVF with at least one blastocyst were reviewed. Patients in the PGT-A and non-PGT-A groups were further categorized into first-time IVF and prior unsuccessful IVF groups (previous IVF experience but without live birth delivery).

RESULTS

In the PGT-A group, there were additional oocyte retrieval cycles, fewer transfer cycles per patient, higher clinical pregnancy rates per embryo transfer, and lower miscarriage rates per clinical pregnancy as compared to the non-PGT-A group, all showing significant differences. However, the first-time IVF group with PGT-A had a significantly longer duration from the first oocyte retrieval to the first live birth delivery (LBD) and a significantly lower LBD rate per patient than the non-PGT-A group. The cumulative probability for a first LBD with PGT-A was inferior in the first-time IVF group for women < 35 years, marginally superior in the prior unsuccessful IVF group of women aged 38-40 years, and similar for other groups.

CONCLUSION

PGT-A should not be recommended to all patients; however, if the first IVF treatment failed, PGT-A may reduce the patient's burden regardless of age.

Maternal selection of human embryos in early gestation: Insights from recurrent miscarriage

Compared to most mammals, human pregnancy is unusual in that it involves chromosomally diverse embryos, cyclical breakdown and regeneration of the uterine mucosa, and intimate integration of fetal and maternal cells at the uteroplacental interface. Not surprisingly, pregnancy often falters in early gestation. Whether these losses result in clinical miscarriages depends on the origins and impacts of chromosomal errors on fetal development and the ability of the decidualizing endometrium to engage in embryo biosensing and selection. Aneuploidy originating in oocytes during meiosis drives the age-related risk of miscarriage. By contrast, the frequency of endometrial cycles with an impaired decidual response may account for the stepwise increase in miscarriage rates with each pregnancy loss independently of maternal age. Additional physiological mechanisms operate in early gestation to ensure that most failing pregnancies are lost before vascular maternal-fetal connections are established by the end of the first trimester. Here, we summarise how investigations into the mechanisms that cause miscarriage led to new insights into the processes that govern maternal selection of human embryos in early gestation.

Does PGT-A improve assisted reproduction treatment success rates: what can the UK Register data tell us?

PURPOSE

To show how naïve analyses of aggregated UK ART Register data held by the Human Fertilisation and Embryology Authority to estimate the effects of PGT-A can be severely misleading and to indicate how it may be possible to do a more credible analysis. Given the limitations of the Register, we consider the extent to which such an analysis has the potential to answer questions about the real-world effectiveness of PGT-A.

METHODS

We utilise the publicly available Register datasets and construct logistic regression models for live birth events (LBE) which adjust for confounding. We compare all PGT-A cycles to control groups of cycles that could have had PGT-A, excluding cycles that did not progress to having embryos for biopsy.

RESULTS

The primary model gives an odds ratio for LBE of 0.82 (95% CI 0.68-1.00) suggesting PGT-A may be detrimental rather than beneficial. However, due to limitations in the availability of important variables in the public dataset, this cannot be considered a definitive estimate. We outline the steps required to enable a credible analysis of the Register data.

CONCLUSION

If we compare like with like groups, we obtain estimates of the effect of PGT-A that suggest an overall modest reduction in treatment success rates. These are in direct contrast to an invalid comparison of crude success rates. A detailed analysis of a fuller dataset is warranted, but it remains to be demonstrated whether the UK Register data can provide useful estimates of the impact of PGT-A when used as a treatment add-on.

Predictive Modelling in Clinical Bioinformatics: Key Concepts for Startups

Clinical bioinformatics is a newly emerging field that applies bioinformatics techniques for facilitating the identification of diseases, discovery of biomarkers, and therapy decision. Mathematical modelling is part of bioinformatics analysis pipelines and a fundamental step to extract clinical insights from genomes, transcriptomes and proteomes of patients. Often, the chosen modelling techniques relies on either statistical, machine learning or deterministic approaches. Research that combines bioinformatics with modelling techniques have been generating innovative biomedical technology, algorithms and models with biotech applications, attracting private investment to develop new business; however, startups that emerge from these technologies have been facing difficulties to implement clinical bioinformatics pipelines, protect their technology and generate profit. In this commentary, we discuss the main concepts that startups should know for enabling a successful application of predictive modelling in clinical bioinformatics. Here we will focus on key modelling concepts, provide some successful examples and briefly discuss the modelling framework choice. We also highlight some aspects to be taken into account for a successful implementation of cost-effective bioinformatics from a business perspective.

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.

An artificial intelligence model (euploid prediction algorithm) can predict embryo ploidy status based on time-lapse data

BACKGROUND

For the association between time-lapse technology (TLT) and embryo ploidy status, there has not yet been fully understood. TLT has the characteristics of large amount of data and non-invasiveness. If we want to accurately predict embryo ploidy status from TLT, artificial intelligence (AI) technology is a good choice. However, the current work of AI in this field needs to be strengthened.

METHODS

A total of 469 preimplantation genetic testing (PGT) cycles and 1803 blastocysts from April 2018 to November 2019 were included in the study. All embryo images are captured during 5 or 6 days after fertilization before biopsy by time-lapse microscope system. All euploid embryos or aneuploid embryos are used as data sets. The data set is divided into training set, validation set and test set. The training set is mainly used for model training, the validation set is mainly used to adjust the hyperparameters of the model and the preliminary evaluation of the model, and the test set is used to evaluate the generalization ability of the model. For better verification, we used data other than the training data for external verification. A total of 155 PGT cycles from December 2019 to December 2020 and 523 blastocysts were included in the verification process.

RESULTS

The euploid prediction algorithm (EPA) was able to predict euploid on the testing dataset with an area under curve (AUC) of 0.80.

CONCLUSIONS

The TLT incubator has gradually become the choice of reproductive centers. Our AI model named EPA that can predict embryo ploidy well based on TLT data. We hope that this system can serve all in vitro fertilization and embryo transfer (IVF-ET) patients in the future, allowing embryologists to have more non-invasive aids when selecting the best embryo to transfer.

A robust metabolomics approach for the evaluation of human embryos from in vitro fertilization

The identification of the most competent embryos for transfer to the uterus constitutes the main challenge of in vitro fertilization (IVF). We established a metabolomic-based approach by applying Fourier transform infrared (FTIR) spectroscopy on 130 samples of 3-day embryo culture supernatants from 26 embryos that implanted and 104 embryos that failed. On examining the internal structure of the data by unsupervised multivariate analysis, we found that the supernatant spectra of nonimplanted embryos constituted a highly heterogeneous group. Whereas ∼40% of these supernatants were spectroscopically indistinguishable from those of successfully implanted embryos, ∼60% exhibited diverse, heterogeneous metabolic fingerprints. This observation proved to be the direct result of pregnancy's multifactorial nature, involving both intrinsic embryonic traits and external characteristics. Our data analysis strategy thus involved one-class modelling techniques employing soft independent modelling of class analogy that identified deviant fingerprints as unsuitable for implantation. From these findings, we could develop a noninvasive Fourier-transform-infrared-spectroscopy-based approach that represents a shift in the fundamental paradigm for data modelling applied in assisted-fertilization technologies.

Polygenic risk scoring of human embryos: a qualitative study of media coverage

BACKGROUND

Current preimplantation genetic testing (PGT) technologies enable embryo genotyping across the whole genome. This has led to the development of polygenic risk scoring of human embryos (PGT-P). Recent implementation of PGT-P, including screening for intelligence, has been extensively covered by media reports, raising major controversy. Considering the increasing demand for assisted reproduction, we evaluated how information about PGT-P is communicated in press media and explored the diversity of ethical themes present in the public debate.

METHODS

LexisNexis Academic database and Google News were searched to identify articles about polygenic embryo screening. This led to 535 news articles. 59 original articles met the inclusion criteria. Inductive content analysis was used to analyse these articles.

RESULTS

8.8% of articles gave embryo polygenic scoring a positive portrayal, while 36.8% expressed a negative attitude. 54.4% were neutral, mostly highlighting limited practical value of the technology in in vitro fertilization settings. We identified five main ethical themes that are also present in academic literature and the broader debate on reproductive technologies: a slippery slope towards designer babies, well-being of the child and parents, impact on society, deliberate choice and societal readiness.

CONCLUSIONS

Implementation of embryo polygenic profiling engenders a need for specific recommendations. Current media analysis discloses important ethical themes to consider when creating future guidelines for PGT-P.

IVF embryo choices and pregnancy outcomes

OBJECTIVE

Investigate the chromosome status and transfer outcomes of embryos selected using routine "best morphology" IVF practices.

METHOD

A prospective multi-center, non-selection cohort study involving patients undertaking IVF treatment. Study entry conditions were blastocyst biopsy, >1 embryo with chromosome analysis and frozen transfer of the best morphology embryo. Primary analyses were βhCG positive, implantation, ongoing pregnancy and birth rates and pregnancy-stage progression failures.

RESULTS

After transfer, embryo chromosome status was assigned and outcomes divided into two primary groups - euploids (n = 135) and aneuploids (n = 53). Compared to euploid embryo transfers, aneuploid embryos had significantly lower primary outcomes (+βhCG: 67% vs. 30%, p < 0.0001; IR: 56% vs. 19%, p < 0.0001; ongoing week 12: 51% vs. 9%, p < 0.0001; and livebirths: 50% vs. 8%, p < 0.0001, respectively). Transfers were further subdivided into smaller groups according to their main chromosomal feature. Stage analysis showed higher failure rates for aneuploids to initiate a pregnancy (p < 0.0001), higher subclinical miscarriage rate (p = 0.0402) and higher clinical miscarriage rate (p = 0.0038).

CONCLUSION

Routine morphology-based embryo selection resulted in a high euploid selection rate but a significant number of aneuploid embryos were still inadvertently selected for transfer (28%) with the subsequent high failure rates for pregnancy initiation and progression having implications for appropriate patient management.

Time associations between U.S. birth rates and add-Ons to IVF practice between 2005-2016

Until 2010, the National Assisted Reproductive Technology Surveillance System (NASS) report, published annually by the Center for Disease Control and Prevention (CDC), demonstrated almost constantly improving live birth rates following fresh non-donor (fnd) in vitro fertilization (IVF) cycles. Almost unnoticed by profession and public, by 2016 they, however, reached lows not seen since 1996-1997. We here attempted to understand underlying causes for this decline. This study used publicly available IVF outcome data, reported by the CDC annually under Congressional mandate, involving over 90% of U.S. IVF centers and over 95% of U.S. IVF cycles. Years 2005, 2010, 2015 and 2016 served as index years, representing respectively, 27,047, 30,425, 21,771 and 19,137 live births in fnd IVF cycles. Concomitantly, the study associated timelines for introduction of new add-ons to IVF practice with changes in outcomes of fnd IVF cycles. Median female age remained at 36.0 years during the study period and center participation was surprisingly stable, thereby confirming reasonable phenotype stability. Main outcome measures were associations of specific IVF practice changes with declines in live IVF birth rates. Time associations were observed with increased utilization of "all-freeze" cycles (embryo banking), mild ovarian stimulation protocols, preimplantation genetic testing for aneuploidy (PGT-A) and increasing utilization of elective single embryo transfer (eSET). Among all add-ons, PGT-A, likely, affected fndIVF most profoundly. Though associations cannot denote causation, they can be hypothesis-generating. Here presented time-associations are compelling, though some of observed pregnancy and live birth loss may have been compensated by increases in frozen-thawed cycles and consequential pregnancies and live births not shown here. Pregnancies in frozen-thawed cycles, however, represent additional treatment cycles, time delays and additional costs. IVF live birth rates not seen since 1996-1997, and a likely continuous downward trend in U.S. IVF outcomes, therefore, mandate a reversal of current outcome trends, whatever ultimately the causes.

The morphokinetic signature of mosaic embryos: evidence in support of their own genetic identity

OBJECTIVE

To provide full morphokinetic characterization of embryos ranked with different degrees of chromosomal mosaicism.

DESIGN

Retrospective cohort study.

SETTING

University-affiliated private in vitro fertilization clinic.

PATIENT(S)

We analyzed 1,511 embryos from 424 intracytoplasmic sperm injection cycles by culturing embryos in a time-lapse imaging system and performing next-generation sequencing. We assessed 106 mosaic embryos.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Comparison of chromosomal, morphological, and morphokinetic characteristics of blastocysts classified as euploid, aneuploid, low-degree mosaic (30% to <50% aneuploid cells in trophectoderm biopsy), and high-degree mosaic (50% to <70% aneuploid cells in trophectoderm biopsy). Statistical analysis was performed using χ2, Kruskal-Wallis, or analysis of variance tests according to data type and distribution. A two-way random effects model was used to calculate interoperator correlation of annotations, and a logistic mixed effects model was performed to evaluate the effect of confounders on morphokinetic timing.

RESULT(S)

The mosaicism rate was ∼7% regardless of parental age. Mosaicism and uniform aneuploidies were not evenly distributed across chromosomes. The percentage of high-quality blastocysts significantly decreased from euploid (66.9%) to mosaic (52.8%) and aneuploid (47.7%). Aneuploid blastocysts significantly delayed development compared with euploid blastocysts in start of compaction (median, 84.72 hours postmicroinjection [hpm], interquartile range [IQR], 13.2; vs. median, 82.10 hpm, IQR, 11.5), start of blastulation (median, 101 hpm; IQR, 11.7; vs. median, 98.29 hpm, IQR, 10.5), and timing of blastocyst (median, 108.04 hpm, IQR, 11.50; vs. median, 104.71 hpm, IQR, 11.35). However, embryo morphokinetics were not correlated to the degree of mosaicism or to a mosaicism configuration that was apt for embryo transfer.

CONCLUSION(S)

Morphokinetic timing of mosaic embryos overlaps with that of euploid and aneuploid embryos, which may reflect their unique genetic and developmental identity. Although this suggests mosaic embryos are not simply a misdiagnosis by-product, further studies are needed to reveal the true identity of this particular type of embryo.

Comparison of Patients' Ethical Perspectives of Preimplantation Embryo Genetic Testing for Aneuploidy (PGT-A) vs. Monogenic Disorders (PGT-M)

What are the ethical perspectives of preimplantation genetic testing in patients using/considering PGT-A compared to those using/considering PGT-M? A 17-item questionnaire administered online was used to assess ethical perspectives in US patients who recently used/considered PGT-A (n=80) vs. those who used/considered PGT-M (n=72). Kruskal-Wallis, Chi-square, and Fisher exact tests were conducted with STATA. Most PGT-A and PGT-M users/considerers supported using PGT to screen for diseases fatal in childhood (86-89%) and those causing lifelong disabilities (76-79%) and opposed using PGT to screen for non-medical physical (80-87%) or intellectual traits (74-86%). Both groups agreed that PGT aids in parental decision-making, although some expressed concern over its potential to lead to unforeseen consequences for society and the PGT offspring. More PGT-M than PGT-A users/considerers opposed implanting genetically abnormal embryos when requested by parents (29% PGT-A vs. 56% PGT-M, p = 0.007). For embryo disposition, more PGT-A users/considerers favored freezing (95% PGTA vs. 82% PGT-M, p = 0.018) or donating genetically normal embryos to research (73% PGT-A vs. 57% PGT-M, p = 0.044), while more PGT-M users/considerers supported donating embryos with known genetic abnormalities to research (56% PGT-A vs. 81% PGT-M, p = 0.001). Regardless of the reason for using PGT, users generally agreed on the acceptable and unacceptable uses for it, as well as the potential societal impact. PGT-M users/considerers expressed more opposition than PGT-A users/considerers to implanting embryos with a genetic alteration when requested by the parents.

Embryo quality, ploidy, and transfer outcomes in male versus female blastocysts

PURPOSE

The goal is to determine if variations exist between male and female blastocysts in preimplantation measurements of quality and ploidy and in vitro fertilization elective single-embryo transfer (eSET) outcomes.

METHODS

A retrospective chart review was conducted from a private fertility center's database of blastocysts undergoing preimplantation genetic testing for aneuploidy, along with details of eSET from this screened cohort. Main outcomes included preimplantation embryo quality and sex-specific eSET outcomes.

RESULTS

A total of 3708 embryos from 578 women were evaluated, with 45.9% male and 54.1% female. The majority were High grade. No difference existed between embryo sex and overall morphological grade, inner cell mass or trophectoderm grade, or blastocyst transformation day. Female blastocysts had a higher aneuploidy rate than male blastocysts (P < 0.001). Five hundred thirty-nine eSETs from 392 women were evaluated, with High grade embryos more likely to have implantation (P < 0.001), clinical pregnancy (P < 0.001), and ongoing pregnancy (P = 0.018) than Mid or Low grade embryos. Day 5 blastocysts were more likely to have implantation (P = 0.018), clinical pregnancy (P = 0.005), and ongoing pregnancy (P = 0.018) than day 6 blastocysts. Male and female embryos had similar transfer outcomes, although female day 5 blastocysts were more likely to result in clinical pregnancy (P = 0.012), but not ongoing pregnancy, than female day 6 blastocysts. Male eSET outcomes did not differ by blastocyst transformation day.

CONCLUSION

Male and female embryos have comparable grade and quality; however, female embryos were more likely to be aneuploid. Ongoing pregnancy rates did not differ by embryo sex. Day 5 embryos had more favorable transfer outcomes than day 6 embryos.

Donor oocyte recipients do not benefit from preimplantation genetic testing for aneuploidy to improve pregnancy outcomes

STUDY QUESTION

Do donor oocyte recipients benefit from preimplantation genetic testing for aneuploidy (PGT-A)?

SUMMARY ANSWER

PGT-A did not improve the likelihood of live birth for recipients of vitrified donor oocytes, but it did avoid embryo transfer in cycles with no euploid embryos.

WHAT IS KNOWN ALREADY

Relative to slow freeze, oocyte vitrification has led to increased live birth from cryopreserved oocytes and has led to widespread use of this technology in donor egg IVF programs. However, oocyte cryopreservation has the potential to disrupt the meiotic spindle leading to abnormal segregation of chromosome during meiosis II and ultimately increased aneuploidy in resultant embryos. Therefore, PGT-A might have benefits in vitrified donor egg cycles. In contrast, embryos derived from young donor oocytes are expected to be predominantly euploid, and trophectoderm biopsy may have a negative effect relative to transfer without biopsy.

STUDY DESIGN, SIZE, DURATION

This is a paired cohort study analyzing donor oocyte-recipient cycles with or without PGT-A performed from 2012 to 2018 at 47 US IVF centers.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Vitrified donor oocyte cycles were analyzed for live birth as the main outcome measure. Outcomes from donors whose oocytes were used by at least two separate recipient couples, one couple using PGT-A (study group) and one using embryos without PGT-A (control group), were compared. Generalized estimating equation models controlled for confounders and nested for individual donors contributing to both PGT-A and non-PGT-A cohorts, enabling a single donor to serve as her own control.

MAIN RESULTS AND THE ROLE OF CHANCE

In total, 1291 initiated recipient cycles from 223 donors were analyzed, including 262 cycles with and 1029 without PGT-A. The median aneuploidy rate per recipient was 25%. Forty-three percent of PGT-A cycles had only euploid embryos, whereas only 12.7% of cycles had no euploid embryos. On average 1.09 embryos were transferred in the PGT-A group compared to 1.38 in the group without PGT-A (P < 0.01). Live birth occurred in 53.8% of cycles with PGT-A versus 55.8% without PGT-A (P = 0.44). Similar findings persisted in cumulative live birth from per recipient cycle.

LIMITATIONS, REASONS FOR CAUTION

Pooled clinical data from 47 IVF clinics introduced PGT-A heterogeneity as genetic testing were performed using different embryology laboratories, PGT-A companies and testing platforms.

WIDER IMPLICATIONS OF THE FINDINGS

PGT-A testing in donor oocyte-recipient cycles does not improve the chance for live birth nor decrease the risk for miscarriage in the first transfer cycle but does increase cost and time for the patient. Further studies are required to test if our findings can be applied to the young infertility patient population using autologous oocytes.

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was used for this study. There are no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

Perceptions, motivations and decision regret surrounding preimplantation genetic testing for aneuploidy

STUDY QUESTION

Is there a difference in level of decision regret following IVF treatment between those who choose to complete or not complete preimplantation genetic testing for aneuploidy [PGT-A]?

SUMMARY ANSWER

Approximately one-third of the participants expressed moderate to severe regret (MSR) following their decision to either complete or not complete PGT-A; notably, decision regret was higher in those who chose not to complete PGT-A, primarily driven by significantly higher regret scores in those that experienced a miscarriage after not testing.

WHAT IS KNOWN ALREADY

Previous research has found that 39% of participants who completed PGT-A expressed some degree of decision regret and that negative clinical outcomes, such as lack of euploid embryos, negative pregnancy test or miscarriage, were associated with a higher level of decision regret. To date, there are no published studies assessing the possible disparity in decision regret surrounding PGT-A in a population of IVF patients that either chose to pursue PGT-A or not.

STUDY DESIGN, SIZE, DURATION

An anonymous online survey was distributed to 1583 patients who underwent IVF with or without PGT-A at a single university institution between January 2016 and December 2017. In total, 335 women accessed the survey, 220 met eligibility criteria and 130 completed the full study survey. Six participants were excluded due to refusal of medical record review, and nine participants were excluded after record review due to not meeting eligibility based on cycle start date or completing only embryo banking without attempting transfer. One hundred and fifteen participants were included in the final analysis.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Of the 115 participants included, 55 (48%) completed PGT-A and 60 (52%) did not complete PGT-A. The online survey included four sections: Demographics; Perceptions about PGT-A risks and benefits [scale from 0 (absolutely not true) to 100 (absolutely true)]; Decision-making factors [scale from 0 (not important) to 100 (very important)]; and Brehaut Decision Regret Scale [DRS] [range 0-100, with >25 indicating MSR]. A retrospective chart review was conducted to confirm study eligibility and collect cumulative clinical outcomes of consenting participants who completed the survey.

MAIN RESULTS AND THE ROLE OF CHANCE

Demographics of the PGT-A and no PGT-A cohorts were similar, with the majority of respondents being Caucasian or Asian, unaffiliated with any religion and with a graduate or professional degree. The two groups differed significantly in mean age, with the PGT-A group being slightly older (mean ± SD: 37 ± 3.7 versus 36 ± 3.4; P = 0.048), and in rate of miscarriages, with fewer participants in the PGT-A cohort experiencing a miscarriage (5% versus 22%; P = 0.012). The majority of participants in both PGT-A and no PGT-A cohorts strongly believed in the purported benefits of PGT-A, including that it decreases the risk of birth defects (median 82 versus 77; P = 0.046), improves the chances of having a healthy baby (median 89 versus 74; P = 0.002) and selects the best embryo for transfer (median 85 versus 80; P = 0.049). When asked to report their motivating factors for decision-making, both groups cited physician counseling as important (median 70 versus 71; P = 0.671); however, the PGT-A cohort was more strongly motivated by a desire to not transfer abnormal embryos (median 84 versus 53; P = 0.0001). Comparison of DRS score between those who did or did not undergo PGT-A showed significantly higher median DRS score after not completing PGT-A (median 15 versus 0; P = 0.013). There was a significantly higher proportion of participants who did not complete PGT-A that expressed mild (36% versus 16%) and MSR (32% versus 24%) compared to those who completed PGT-A (χ2 = 9.03, df = 2; P = 0.011). Sub-group analyses of DRS scores by outcomes of clinical pregnancy, miscarriage and live birth revealed that the higher DRS score in those not completing PGT-A was driven by a large increase in regret noted by those with history of a miscarriage (median 45 versus 0; P = 0.018). Multivariate logistic regression modeling found no evidence that any specific demographic factor, clinical outcome or perception/motivation surrounding PGT-A was independently predictive of increased risk for MSR.

LIMITATIONS, REASONS FOR CAUTION

The retrospective nature of data collection incurs the possibility of sampling and recall bias. As only 59% of eligible respondents completed the full survey, it is possible that mainly those with very positive or negative sentiments following treatment felt compelled to complete their response. This bias, however, would apply to the whole of the population, and not simply to those who did or did not complete PGT-A.

WIDER IMPLICATIONS OF THE FINDINGS

The proportion of participants expressing any degree of decision regret in this PGT-A cohort was 40%, which is comparable to that shown in prior research. This study adds to prior data by also assessing decision regret experienced by those who went through IVF without PGT-A, and showed that 68% expressed some level of regret with their decision-making. These results should not be interpreted to mean that all patients should opt for PGT-A to pre-emptively mitigate their risk of regret. Instead, it suggests that drivers of decision regret are likely multifactorial and unique to the experience of one's personal expectations regarding PGT-A, motivations for pursuing or not pursuing it and resultant clinical outcome. Highlighting the complex nature of regret, these data should encourage physicians to more carefully consider individual patient values toward risk-taking or risk-averse behavior, as well as their own positions regarding PGT-A. Until there are clear recommendations regarding utilization of PGT-A, a strong collaboration between physicians and genetic counselors is recommended to educate patients on the risks and potential benefits of PGT-A in a balanced and individualized manner.

STUDY FUNDING/COMPETING INTEREST(S)

No funding was utilized for study completion and the authors have no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

Preimplantation genetic testing for aneuploidy in uterus transplant patients

Uterus transplantation is an emerging treatment for uterine factor infertility. In vitro fertilization with cryopreservation of embryos prior is required before a patient can be listed for transplant. Whether or not to perform universal preimplantation genetic testing for aneuploidy should be addressed by centers considering a uterus transplant program. The advantages and disadvantages of preimplantation genetic testing for aneuploidy in this unique population are presented. The available literature is reviewed to determine the utility of preimplantation genetic testing for aneuploidy in uterus transplantation protocols. Theoretical benefits of preimplantation genetic testing for aneuploidy include decreased time to pregnancy in a population that benefits from minimization of exposure to immunosuppressive agents and decreased chance of spontaneous abortion requiring a dilation and curettage. Drawbacks include increased cost per in vitro fertilization cycle, increased number of required in vitro fertilization cycles to achieve a suitable number of embryos prior to listing for transplant, and a questionable benefit to live birth rate in younger patients. Thoughtful consideration of whether or not to use preimplantation genetic testing for aneuploidy is necessary in uterus transplant trials. Age is likely a primary factor that can be useful in determining which uterus transplant recipients benefit from preimplantation genetic testing for aneuploidy.

Genetic Counseling and Assisted Reproductive Technologies

Despite the ever-increasing number of patients undergoing fertility treatments and the expanded use of genetic testing in this context, there has been limited focus in the literature on the involvement of genetics professionals in the assisted reproductive technology (ART) setting. Here we discuss the importance of genetic counseling within reproductive medicine. We review how genetic testing of embryos is performed, the process of gamete donation, the challenges associated with genetic testing, and the complexities of genetic test result interpretation.

Opinion de comité no 406 : Dépistage prénatal après FIV avec test génétique préimplantatoire des aneuploïdies

OBJECTIFS

Examiner l'approche du dépistage génétique prénatal et du diagnostic des anomalies chromosomiques dans les grossesses conçues par fécondation in vitro à la suite d'un test génétique préimplantatoire des aneuploïdies. PROFESSIONNELS CONCERNéS: Omnipraticiens, médecins de famille, obstétriciens, sages-femmes, infirmières, spécialistes en médecine fœto-maternelle, spécialistes en fertilité, conseillers en génétique, généticiens et autres professionnels de la santé qui participent au dépistage prénatal.

POPULATION CIBLE

Toute personne ou tout couple dont la grossesse est issue d'une fécondation in vitro et dont l'embryon a préalablement été soumis à un dépistage génétique préimplantatoire des aneuploïdies. DONNéES PROBANTES: Des recherches ont été effectuées dans les bases de données Medline, PubMed et Cochrane Library pour extraire la littérature publiée au plus tard en septembre 2018. DÉCLARATIONS SOMMAIRES.

Noninvasive Preimplantation Genetic Testing for Aneuploidy (niPGT-A): The first Brazilian baby

Recently, a new technology known as the Noninvasive Preimplantation Genetic Testing for Aneuploidy (niPGT-A) emerged, using cell-free DNA present in the spent culture media of human blastocysts. Unlike PGT-A, in which only trophectoderm cells are used, niPGT-A reflects the ploidy state of these cells and internal cell mass, suggesting that this new technology may be less prone to error, being more reliable than the invasive test. The aim of the present study was to report the first occurrence of childbirth following niPGT-A in Brazil.

Why are multiple pregnancy rates and single embryo transfer rates so different globally, and what do we do about it?

In the early years of in vitro fertilization, overall pregnancy rates were low, and it was considered necessary to transfer more than one embryo to increase the chances of pregnancy. It was not until advances in assisted reproductive technologies resulting in increased pregnancy rates that the concept of transferring just one embryo was considered possible. A consequence of improvements in implantation rates was also an increase in multiple pregnancies when more than one embryo was transferred. Although some countries have reduced the number of embryos transferred, international data show that in many parts of the world high twin and higher order multiple pregnancy rates still exist. Even in developed countries these problems persist depending on clinical practice, funding of health services, and patient demands. Perinatal and other outcomes are significantly worse with twins compared with singleton pregnancies and there is an urgent need to reduce multiple pregnancy rates to at least 10%. This has been achieved in several countries and clinics by introducing single embryo transfer but there are many barriers to the introduction of this technique in most clinics worldwide. We discuss the background to the high multiple rate in assisted reproduction and the factors that contribute to its persistence even in excellent clinics and in high-quality health services. Practices that may promote single embryo transfer are discussed.

Copy number analysis of meiotic and postzygotic mitotic aneuploidies in trophectoderm cells biopsied at the blastocyst stage and arrested embryos

Preimplantation genetic testing for aneuploidy (PGT-A) by copy number analysis is now widely used to select euploid embryos for transfer. Whole or partial chromosome aneuploidy can arise in meiosis, predominantly female meiosis, or in the postzygotic, mitotic divisions during cleavage and blastocyst formation, resulting in chromosome mosaicism. Meiotic aneuploidies are almost always lethal, however, the clinical significance of mitotic aneuploidies detected by PGT-A is not fully understood and healthy live births have been reported following transfer of mosaic embryos. Here, we used single nucleotide polymorphism genotyping of both polar bodies and embryo samples to identify meiotic aneuploidies and compared copy number changes for meiotic and presumed mitotic aneuploidies in trophectoderm cells biopsied at the blastocyst stage and arrested embryos. PGT-A detected corresponding full copy number changes (≥70%) for 36/37 (97%) maternal meiotic aneuploidies. The number of presumed mitotic copy number changes detected exceeded those of meiotic origin. Although mainly in the mosaic range, some of these mitotic aneuploidies had copy number changes ≥70% and would have been identified as full aneuploidies. Interestingly, many arrested embryos had multiple mitotic aneuploidies across a broad range of copy number changes, which may have arisen through tripolar spindle and other mitotic abnormalities.

Preimplantation genetic testing for aneuploidies (abnormal number of chromosomes) in in vitro fertilisation

BACKGROUND

In in vitro fertilisation (IVF) with or without intracytoplasmic sperm injection (ICSI), selection of the most competent embryo(s) for transfer is based on morphological criteria. However, many women do not achieve a pregnancy even after 'good quality' embryo transfer. One of the presumed causes is that such morphologically normal embryos have an abnormal number of chromosomes (aneuploidies). Preimplantation genetic testing for aneuploidies (PGT-A), formerly known as preimplantation genetic screening (PGS), was therefore developed as an alternative method to select embryos for transfer in IVF. In PGT-A, the polar body or one or a few cells of the embryo are obtained by biopsy and tested. Only polar bodies and embryos that show a normal number of chromosomes are transferred. The first generation of PGT-A, using cleavage-stage biopsy and fluorescence in situ hybridisation (FISH) for the genetic analysis, was demonstrated to be ineffective in improving live birth rates. Since then, new PGT-A methodologies have been developed that perform the biopsy procedure at other stages of development and use different methods for genetic analysis. Whether or not PGT-A improves IVF outcomes and is beneficial to patients has remained controversial.

OBJECTIVES

To evaluate the effectiveness and safety of PGT-A in women undergoing an IVF treatment.

SEARCH METHODS

We searched the Cochrane Gynaecology and Fertility (CGF) Group Trials Register, CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL, and two trials registers in September 2019 and checked the references of appropriate papers.

SELECTION CRITERIA

All randomised controlled trials (RCTs) reporting data on clinical outcomes in participants undergoing IVF with PGT-A versus IVF without PGT-A were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies for inclusion, assessed risk of bias, and extracted study data. The primary outcome was the cumulative live birth rate (cLBR). Secondary outcomes were live birth rate (LBR) after the first embryo transfer, miscarriage rate, ongoing pregnancy rate, clinical pregnancy rate, multiple pregnancy rate, proportion of women reaching an embryo transfer, and mean number of embryos per transfer.

MAIN RESULTS

We included 13 trials involving 2794 women. The quality of the evidence ranged from low to moderate. The main limitations were imprecision, inconsistency, and risk of publication bias. IVF with PGT-A versus IVF without PGT-A with the use of genome-wide analyses Polar body biopsy One trial used polar body biopsy with array comparative genomic hybridisation (aCGH). It is uncertain whether the addition of PGT-A by polar body biopsy increases the cLBR compared to IVF without PGT-A (odds ratio (OR) 1.05, 95% confidence interval (CI) 0.66 to 1.66, 1 RCT, N = 396, low-quality evidence). The evidence suggests that for the observed cLBR of 24% in the control group, the chance of live birth following the results of one IVF cycle with PGT-A is between 17% and 34%. It is uncertain whether the LBR after the first embryo transfer improves with PGT-A by polar body biopsy (OR 1.10, 95% CI 0.68 to 1.79, 1 RCT, N = 396, low-quality evidence). PGT-A with polar body biopsy may reduce miscarriage rate (OR 0.45, 95% CI 0.23 to 0.88, 1 RCT, N = 396, low-quality evidence). No data on ongoing pregnancy rate were available. The effect of PGT-A by polar body biopsy on improving clinical pregnancy rate is uncertain (OR 0.77, 95% CI 0.50 to 1.16, 1 RCT, N = 396, low-quality evidence). Blastocyst stage biopsy One trial used blastocyst stage biopsy with next-generation sequencing. It is uncertain whether IVF with the addition of PGT-A by blastocyst stage biopsy increases cLBR compared to IVF without PGT-A, since no data were available. It is uncertain if LBR after the first embryo transfer improves with PGT-A with blastocyst stage biopsy (OR 0.93, 95% CI 0.69 to 1.27, 1 RCT, N = 661, low-quality evidence). It is uncertain whether PGT-A with blastocyst stage biopsy reduces miscarriage rate (OR 0.89, 95% CI 0.52 to 1.54, 1 RCT, N = 661, low-quality evidence). No data on ongoing pregnancy rate or clinical pregnancy rate were available. IVF with PGT-A versus IVF without PGT-A with the use of FISH for the genetic analysis Eleven trials were included in this comparison. It is uncertain whether IVF with addition of PGT-A increases cLBR (OR 0.59, 95% CI 0.35 to 1.01, 1 RCT, N = 408, low-quality evidence). The evidence suggests that for the observed average cLBR of 29% in the control group, the chance of live birth following the results of one IVF cycle with PGT-A is between 12% and 29%. PGT-A performed with FISH probably reduces live births after the first transfer compared to the control group (OR 0.62, 95% CI 0.43 to 0.91, 10 RCTs, N = 1680, I² = 54%, moderate-quality evidence). The evidence suggests that for the observed average LBR per first transfer of 31% in the control group, the chance of live birth after the first embryo transfer with PGT-A is between 16% and 29%. There is probably little or no difference in miscarriage rate between PGT-A and the control group (OR 1.03, 95%, CI 0.75 to 1.41; 10 RCTs, N = 1680, I² = 16%; moderate-quality evidence). The addition of PGT-A may reduce ongoing pregnancy rate (OR 0.68, 95% CI 0.51 to 0.90, 5 RCTs, N = 1121, I² = 60%, low-quality evidence) and probably reduces clinical pregnancies (OR 0.60, 95% CI 0.45 to 0.81, 5 RCTs, N = 1131; I² = 0%, moderate-quality evidence).

AUTHORS' CONCLUSIONS

There is insufficient good-quality evidence of a difference in cumulative live birth rate, live birth rate after the first embryo transfer, or miscarriage rate between IVF with and IVF without PGT-A as currently performed. No data were available on ongoing pregnancy rates. The effect of PGT-A on clinical pregnancy rate is uncertain. Women need to be aware that it is uncertain whether PGT-A with the use of genome-wide analyses is an effective addition to IVF, especially in view of the invasiveness and costs involved in PGT-A. PGT-A using FISH for the genetic analysis is probably harmful. The currently available evidence is insufficient to support PGT-A in routine clinical practice.

Committee Opinion No. 406: Prenatal Testing After IVF With Preimplantation Genetic Testing for Aneuploidy

OBJECTIVE

To review the approach to prenatal genetic screening and diagnosis for chromosomal abnormalities in pregnancies conceived through in vitro fertilization and following preimplantation genetic testing for aneuploidy.

INTENDED USERS

General practitioners, family physicians, obstetricians, midwives, nurses, maternal-fetal medicine specialists, fertility specialists, genetic counsellors, geneticists, and other health care providers involved in prenatal screening.

TARGET POPULATION

All individuals or couples who conceivd through in vitro fertilization and underwent preimplantation genetic testing for aneuploidy.

EVIDENCE

Literature published in or before September 2018 was retrieved through searches of Medline, PubMed, and the Cochrane Library. SUMMARY STATEMENTS.

Bioinformatic identification of euploid and aneuploid embryo secretome signatures in IVF culture media based on MALDI-ToF mass spectrometry

PURPOSE

Embryo genotyping in IVF clinics aims to identify aneuploid embryos, and current methodologies rely on costly, invasive and time-consuming approaches such as PGT-A screening. MALDI-ToF-based mass spectral analysis of embryo culture has been demonstrated to be a non-invasive, affordable and accurate technique that is able to capture secretome profiles from embryo culture media extremely quick. Thus, aneuploid embryo genotypes can be distinguished from euploids from these profiles towards the development of novel embryo selection tools.

METHODS

A retrospective cohort study, including 292 spent media samples from embryo cultures collected from a single IVF clinic in USA. There were 149 euploid and 165 aneuploid embryos previously analysed by PGT-A next-generation sequencing techniques. Secretome mass spectra of embryos were generated using MALDI-ToF mass spectrometry in the UK. Data was systematically analysed using a fully automated and ultra-fast bioinformatic pipeline developed for the identification of mass spectral signatures.

RESULTS

Distinct spectral patterns were found for euploid and aneuploid genotypes in embryo culture media. We identified 12 characteristic peak signatures for euploid and 17 for aneuploid embryos. Data analysis also revealed a high degree of complementarity among regions showing that 22 regions are required to differentiate between genotypes with a sensitivity of 84% and a false positive rate of 18%.

CONCLUSION

Ultra-fast and fully automated screening of an embryo genotype is possible based on multiple combinations of specific mass spectral peak signatures. This constitutes a breakthrough towards the implementation of non-invasive and ultra-fast tools for embryo selection immediately prior to transfer.

Key metrics and processes for validating embryo diagnostics

Embryo diagnostics are somewhat controversial in clinical assisted reproduction technology (ART) practice and remain an active area of investigation. Application of embryo diagnostics holds great potential to raise the standard of clinical care by eliminating futile transfers, allowing highly effective single-embryo transfer, and reducing the probability of clinical loss and ongoing abnormal gestations. These advantages are accompanied by risks, principally the chance that a reproductively competent embryo will be mislabeled and discarded. This would lower the ultimate probability that one or more of the embryos might implant and lead to delivery of a healthy infant. Rigorous validation should be required for embryo diagnostics. Metrics for validation can be divided into three simple areas: analytical validation, determination of clinical predictive values for normal and abnormal test results, and a randomized clinical trial to demonstrate that the selection advantage gained through the diagnostic improves clinical outcomes.

Single-cell analysis of human embryos reveals diverse patterns of aneuploidy and mosaicism

Less than half of human zygotes survive to birth, primarily due to aneuploidies of meiotic or mitotic origin. Mitotic errors generate chromosomal mosaicism, defined by multiple cell lineages with distinct chromosome complements. The incidence and impacts of mosaicism in human embryos remain controversial, with most previous studies based on bulk DNA assays or comparisons of multiple biopsies of few embryonic cells. Single-cell genomic data provide an opportunity to quantify mosaicism on an embryo-wide scale. To this end, we extended an approach to infer aneuploidies based on dosage-associated changes in gene expression by integrating signatures of allelic imbalance. We applied this method to published single-cell RNA sequencing data from 74 human embryos, spanning the morula to blastocyst stages. Our analysis revealed widespread mosaic aneuploidies, with 59 of 74 (80%) embryos harboring at least one putative aneuploid cell (1% FDR). By clustering copy number calls, we reconstructed histories of chromosome segregation, inferring that 55 (74%) embryos possessed mitotic aneuploidies and 23 (31%) embryos possessed meiotic aneuploidies. We found no significant enrichment of aneuploid cells in the trophectoderm compared to the inner cell mass, although we do detect such enrichment in data from later postimplantation stages. Finally, we observed that aneuploid cells up-regulate immune response genes and down-regulate genes involved in proliferation, metabolism, and protein processing, consistent with stress responses documented in other stages and systems. Together, our work provides a high-resolution view of aneuploidy in preimplantation embryos, and supports the conclusion that low-level mosaicism is a common feature of early human development.

The PGS/PGT-A controversy in IVF addressed as a formal conflict resolution analysis

PURPOSE

To use conflict resolution analysis on the conflict between proponents and opponents of preimplantation genetic testing for aneuploidy (PGT-A), previously called preimplantation genetic screening (PGS).

METHODS

Considered in conflict analysis a case study, we reviewed the English literature based on key-word searches at www.pubmed.com and www.google.com, and interviewed professional opinion leaders and other actor-representatives. This analysis was the product of a mandated externship by L.M. at the Foundation for Reproductive Medicine (FRM), as part of the Master of Science Program in Negotiations and Conflict Resolution at Columbia University, New York, NY.

RESULTS

Initially a typical difference of opinion, conflict evolved after proponents rejected studies that failed to confirm expected benefits, and authors felt demeaned by their criticism. Becoming "destructive," the conflict evolved according to Glasl's escalation model stages. Proponents became continuous attractors. Unable to produce validations for PGT-A, proponents moved goal posts through 3 stages (PGS 1.0-PGS 3.0). Ultimately concurring that pregnancy and live birth rates are unaffected, they started claiming new benefits.

CONCLUSIONS

The FRM underwrote this study as a starting tool for a conflict resolution process. A consensus building conference of stakeholders appears as of this point to represent the most promising potential intervention. The goal of such a conference should be sustainable consensus about clinical utilization of PGS/PGT-A in IVF, based on transparent and validated criteria. A potential date for such a conference is set for 2020.

Preimplantation genetic testing for aneuploidy: a comparison of live birth rates in patients with recurrent pregnancy loss due to embryonic aneuploidy or recurrent implantation failure

STUDY QUESTION

Can preimplantation genetic testing for aneuploidy (PGT-A) improve the live birth rate and reduce the miscarriage rate in patients with recurrent pregnancy loss (RPL) caused by an abnormal embryonic karyotype and recurrent implantation failure (RIF)?

SUMMARY ANSWER

PGT-A could not improve the live births per patient nor reduce the rate of miscarriage, in both groups.

WHAT IS KNOWN ALREADY

PGT-A use has steadily increased worldwide. However, only a few limited studies have shown that it improves the live birth rate in selected populations in that the prognosis has been good. Such studies have excluded patients with RPL and RIF. In addition, several studies have failed to demonstrate any benefit at all. PGT-A was reported to be without advantage in patients with unexplained RPL whose embryonic karyotype had not been analysed. The efficacy of PGT-A should be examined by focusing on patients whose previous products of conception (POC) have been aneuploid, because the frequencies of abnormal and normal embryonic karyotypes have been reported as 40–50% and 5–25% in patients with RPL, respectively.

STUDY DESIGN, SIZE, DURATION

A multi-centre, prospective pilot study was conducted from January 2017 to June 2018. A total of 171 patients were recruited for the study: an RPL group, including 41 and 38 patients treated respectively with and without PGT-A, and an RIF group, including 42 and 50 patients treated respectively with and without PGT-A. At least 10 women in each age group (35–36, 37–38, 39–40 or 41–42 years) were selected for PGT-A groups.

PARTICIPANTS/MATERIALS, SETTING, METHODS

All patients and controls had received IVF-ET for infertility. Patients in the RPL group had had two or more miscarriages, and at least one case of aneuploidy had been ascertained through prior POC testing. No pregnancies had occurred in the RIF group, even after at least three embryo transfers. Trophectoderm biopsy and array comparative genomic hybridisation (aCGH) were used for PGT-A. The live birth rate of PGT-A and non-PGT-A patients was compared after the development of blastocysts from up to two oocyte retrievals and a single blastocyst transfer. The miscarriage rate and the frequency of euploidy, trisomy and monosomy in the blastocysts were noted.

MAIN RESULT AND THE ROLE OF CHANCE

There were no significant differences in the live birth rates per patient given or not given PGT-A: 26.8 versus 21.1% in the RPL group and 35.7 versus 26.0% in the RIF group, respectively. There were also no differences in the miscarriage rates per clinical pregnancies given or not given PGT-A: 14.3 versus 20.0% in the RPL group and 11.8 versus 0% in the RIF group, respectively. However, PGT-A improved the live birth rate per embryo transfer procedure in both the RPL (52.4 vs 21.6%, adjusted OR 3.89; 95% CI 1.16–13.1) and RIF groups (62.5 vs 31.7%, adjusted OR 3.75; 95% CI 1.28–10.95). Additionally, PGT-A was shown to reduce biochemical pregnancy loss per biochemical pregnancy: 12.5 and 45.0%, adjusted OR 0.14; 95% CI 0.02–0.85 in the RPL group and 10.5 and 40.9%, adjusted OR 0.17; 95% CI 0.03–0.92 in the RIF group. There was no difference in the distribution of genetic abnormalities between RPL and RIF patients, although double trisomy tended to be more frequent in RPL patients.

LIMITATIONS, REASONS FOR CAUTION

The sample size was too small to find any significant advantage for improving the live birth rate and reducing the clinical miscarriage rate per patient. Further study is necessary.

WIDER IMPLICATION OF THE FINDINGS

A large portion of pregnancy losses in the RPL group might be due to aneuploidy, since PGT-A reduced the overall incidence of pregnancy loss in these patients. Although PGT-A did not improve the live birth rate per patient, it did have the advantage of reducing the number of embryo transfers required to achieve a similar number live births compared with those not undergoing PGT-A.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the Japan Society of Obstetrics and Gynecology and grants from the Japanese Ministry of Education, Science, and Technology. There are no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A

Noninvasive embryo selection: kinetic analysis of female and male pronuclear development to predict embryo quality and potential to produce live birth

OBJECTIVE

To evaluate a noninvasive method of examining euploid embryos, focusing on kinetic analyses, from second polar body extrusion to pronuclear membrane breakdown (PNMBD).

DESIGN

Retrospective embryo cohort study.

SETTING

Private IVF clinic.

PATIENT(S)

213 frozen-thawed single blastocyst transfers.

INTERVENTION(S)

Fertilized oocytes were recorded by means of time-lapse photography, followed by kinetic analysis of female and male pronuclei (PNs).

MAIN OUTCOME MEASURE(S)

The differences in size between the 2PNs in embryos resulting in live births compared with those of embryos from failed pregnancies were analyzed according to sequential size from early PN stages to PNMBD.

RESULT(S)

It was found that the difference in areas between male and female PNs immediately before PNMBD is a better predictor of embryo quality if this difference is below a known cutoff value. The size of male PNs 8 hours before the onset of PNMBD should be larger than female PNs (B). The difference in size between male and female PNs 8 hours before PNMBD should be larger than the difference in their size immediately before PNMBD. When normal embryos were defined using the equation (A∪C)∩B, the birth rates for in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) were 68.1% and 50.0%, respectively. For the remaining embryos, defined as abnormal according to the above criteria, birth rates were 9.4% for IVF and 4.2% for ICSI.

CONCLUSION(S)

We have developed a method for noninvasive embryo evaluation by means of the kinetic analysis of female and male PN growths. This method should enable us to select embryos that have a higher potential for healthy births.

Detection of a balanced translocation carrier through trophectoderm biopsy analysis: a case report

BACKGROUND

Balanced translocation carriers are burdened with fertility issues due to improper chromosome segregation in gametes, resulting in either implantation failure, miscarriage or birth of a child with chromosomal disorders. At the same time, these individuals are typically healthy with no signs of developmental problems, hence they often are unaware of their condition. Yet, because of difficulties in conceiving, balanced translocation carriers often turn to assisted reproduction, some of whom may also undergo preimplantation genetic testing for aneuploidy (PGT-A) to improve the likelihood of achieving a successful pregnancy.

CASE REPORT

We describe a female patient, who pursued in vitro fertilization (IVF) treatment coupled with PGT-A following two consecutive miscarriages, unaware of her genetic condition. PGT-A was performed on blastocyst-stage embryos and the results of comprehensive chromosome screening from a first IVF cycle demonstrated reciprocal segmental aberrations on chromosome 7 and chromosome 10 in two out of four embryos. Due to distinct embryo profiles, the couple was then referred for genetic counselling and subsequent parental karyotyping revealed the presence of a previously undetected balanced translocation in the mother.

CONCLUSIONS

These results confirm previous reports that genome-wide PGT-A can facilitate the identification of balanced translocation carriers in IVF patients, providing explanation for poor reproductive outcome and allowing adjustments in treatment strategies.

Secretome profile selection of optimal IVF embryos by matrix-assisted laser desorption ionization time-of-flight mass spectrometry

Purpose

Selecting an embryo at the transfer stage with the best chance of a successful pregnancy is still largely dependent on preceding subjective evaluation of morphokinetics. Expensive prenatal genomic profiling has been so far proved ineffective. Proteomics and metabolomics are promising new approaches to assess embryo viability, but methodologies are often complex and do not lend themselves to rapid analysis in the critical time between blastocyst formation and embryo transfer. Here, we used matrix-assisted laser desorption ionization time-of-flight (MALDI ToF) mass spectrometry to assess the secretome of blastocysts in the minutes prior to embryo transfer and correlated spectral features with pregnancy outcome.

Methods

Four hundred one samples of spent blastocyst culture media were collected from embryo cultures at the time of embryo transfer, of which 136 were used to construct the predictive model. The media samples were frozen at − 20 °C and stored for analysis. Sample analysis was conducted in batches using 1 μl of spent embryo in direct MALDI ToF mass spectral analysis. Quantitative characteristics within this mass range (2000–17,000 m/z) were used to generate a score for selected mass regions (bins) in order to predict pregnancy outcome for each sample.

Results

With a simple algorithm based on nine mass bins within the 2000–10,000 m/z region, it was possible to identify samples with the best chance of becoming an ongoing pregnancy (positive predictive value of 82.9%, p = 0.0018).

Conclusion

A simple, direct and rapid analysis of spent culture fluid from blastocysts at the point of embryo transfer can quickly identify optimal embryos with the best chance of achieving ongoing pregnancy. Methods like this, which take less than 20 min to perform, could dramatically improve the approach to embryo selection and live births.

The demise of preimplantation genetic testing for aneuploidy (PGT-A) in Hungary and its effect on patient care

Preimplantation genetic testing for aneuploidy (PGT-A) is a suitable technique to identify euploid embryos, which have the highest potential to implant, thus increase the chance of a healthy live birth. The main indications of PGT-A are advanced maternal age, repeated implantation failure, repeated miscarriages and severe male infertility. Several studies have already proven that testing embryos for genetic abnormalities in the above cases results in higher implantation rate and reduced number of pregnancy loss. In spite of these - due to a legislative change in Hungary in 2015 - PGT-A was reclassified as an experimental procedure and its use became banned throughout the country. For this reason, after 4 years of successful practice, Hungarian patients were not able to participate in IVF procedure combined with PGT-A anymore. In this retrospective analysis, efficacy of PGT-A-based embryo selection was evaluated and was compared to the conventional morphology-based selection (MBS) in patients with advanced maternal age, between 2013 and 2017 at our private fertility clinic. PGT-A was performed with array comparative genomic hybridization. We found that implantation rate was significantly higher (43.62% vs. 27.88%; p = 0.0208) and miscarriage rate was significantly lower (17.07% vs. 37.93%; p = 0.0492) in the PGT-A group compared to the MBS group from 2013 to 2015. These outcomes were achieved with a significantly lower number of transferred embryos in the PGT-A group (1.25 vs. 1.58; p = 0.0003). In 2016-2017, the number of transferred embryos were significantly reduced in the MBS group as well (1.14 vs. 1.58; p < 0.0001). However, outcomes of the IVF treatments did not change significantly compared to the previous two years (2013-2015). Our results imply that PGT-A-based embryo selection is more efficient than morphology-based selection in patients with advanced maternal age. Therefore, prohibition of the use of PGT-A had significant consequences on the efficiency and safety of IVF treatment in the country.

Abnormal cleavage and developmental arrest of human preimplantation embryos in vitro

Despite improvements in culture conditions and laboratory techniques still only about 50% of human embryos reach the blastocyst stage of development in vitro. While many factors influence embryo development, aberrant cleavage divisions have only recently been shown to directly affect the genome in individual cells of human embryos resulting in chromosome loss, mosaicism and cell arrest. In this article we review the current literature in the area of aberrant cleavage in human embryos and its effect on blastocyst development. Further to this, we propose a series of common abnormal cleavage events, with particular attention to timing and frequency, and illustrate how these might influence a number of different embryo fates.