Prediction of embryo euploidy and pregnancy outcome by blastocyst morphology and development speed for women receiving single embryo transfer

BACKGROUND

Selection of high-quality blastocysts is the most important factor determining the success of assisted reproductive technology. The objective of this study is to assess the values of blastocyst morphological quality and development speed for predicting euploidy and clinical pregnancy outcome.

METHODS

A total of 155 preimplantation genetic testing cycles including 959 blastocysts and 154 euploid blastocyst transfer cycles conducted between January 2018 and December 2019 were retrospectively analysed. The associations of blastocyst morphological quality and development speed (D) with chromosomal status, clinical pregnancy rate, early miscarriage rate, and ongoing pregnancy rate were evaluated by univariate and multivariate regression.

RESULTS

The euploidy rate of development speed D5 blastocysts was significantly greater than that of D6 blastocysts (61.4% vs. 38.1%, P < 0.001), and the euploid rate of morphologically high-grade blastocysts was significantly greater than that of non-high-grade blastocysts. Development speed D5 (OR = 1.6, 95% CI 1.2-2.2, P = 0.02) and high-grade morphology (OR = 2.1, 95% CI 1.5-2.9, P = 0.01) were independent predictors of euploidy. The ongoing pregnancy rate of D5 blastocysts was significantly higher than that of D6 blastocysts (62.3% vs. 43.8%, P = 0.04). Transfer of euploid blastocysts with high-grade morphology resulted in a greater ongoing pregnancy rate than transfer of non-high-grade euploid blastocysts (60.7% vs. 43.2%, P = 0.049). Alternatively, D6 development speed was an independent risk factor for early pregnancy loss after euploid blastocyst transfer. Multivariate regression analysis adjusting for confounding factors identified maternal age, blastocyst development speed, and blastocyst morphological grade as independent predictors of euploidy but not of clinical pregnancy.

CONCLUSION

The recommended sequence of embryo transfer based on the present study is D5 high-grade > D6 high-grade > D5 non-high-grade > D6 non-high-grade.

Total gonadotropin dose did not affect euploid blastocyst rates: an analysis of more than 19,000 oocytes

BACKGROUND

To evaluate whether increasing total gonadotropin (Gn) dose is associated with changes in euploid blastocyst rate in preimplantation genetic testing (PGT) oocytes.

METHODS

This retrospective cohort study was conducted between 2017 and 2022, and 19,246 oocytes were grouped and analyzed based on tri-sectional quantiles of total Gn doses.

SETTING

Single reproductive medical center.

SUBJECTS

All the patients who underwent PGT cycles, including PGT for aneuploidy, monogenic disorders, and structural rearrangements, were included.

EXPOSURE

Next-generation sequencing platforms for chromosomal analysis.

MAIN OUTCOME MEASURES

Blastocyst formation and euploid blastocyst rates.

RESULTS

In total, 19,246 oocytes and 5375 PGT blastocysts were analyzed. There were significant differences in blastocyst formation and euploid blastocyst rates among the groups classified according to tri-sectional quantiles of total Gn doses. Significant differences in age, body mass index (BMI), proportion of primary infertility, anti-Müllerian hormone (AMH) levels, number of oocytes retrieved, controlled ovarian stimulation (COS) regimen, type of Gn, and PGT category were observed among the three groups. After stratifying the analysis by age, BMI, infertility diagnosis, AMH levels, number of oocytes retrieved, PGT category, type of Gn, and COS regimen, significant differences were only seen in a small number of specific subgroups. Furthermore, the results of the multiple logistic regression analysis showed that the blastocyst formation and euploid blastocyst rates did not significantly increase or decrease with the total Gn dose, whether treated as a continuous variable or divided into three Gn groups as categorical variables. Notably, advancing age was a risk factor for blastocyst formation and euploid blastocyst rates. PGT for structural rearrangements was a risk factor for blastocyst formation and euploid blastocyst rates as compared with PGT for aneuploidy.

CONCLUSION

In the total PGT cycles, advancing age, and preimplantation genetic testing for structural rearrangements negatively affected blastocyst formation and euploid blastocyst rates; however, the total Gn dose did not affect blastocyst formation and euploid blastocyst rates.

Confirmation and pathogenicity of small copy number variations incidentally detected via a targeted next-generation sequencing-based preimplantation genetic testing for aneuploidy platform

OBJECTIVE

To evaluate the technical accuracy, inheritance, and pathogenicity of small copy number variants (CNVs) detected by a targeted next-generation sequencing-based preimplantation genetic testing for aneuploidy (PGT-A) platform.

DESIGN

Retrospective observational study performed between 2020 and 2022.

SETTING

Clinic.

PATIENT(S)

A total of 12,157 patients who underwent clinical PGT-A performed by targeted next-generation sequencing for whole chromosome and large segmental aneuploidies.

INTERVENTION(S)

An incidental finding was reported when a CNV gain/loss of at least 3 consecutive amplicons appeared in at least 2 embryos from the same in vitro fertilization cycle.

MAIN OUTCOME MEASURE(S)

The primary outcome measures were the specificity, incidence, inheritance, and pathogenicity of small CNVs detected by the PGT-A platform. Accuracy of the PGT-A platform CNV calls was assessed via concordance with the CNV calls (size and genomic location) on chromosomal microarray of the gamete provider(s). Parental origin of the CNV and pathogenicity classifications were also reported.

RESULT(S)

An incidental finding that met reporting criteria was identified in 75 (0.62%; 95% confidence interval, 0.5%-0.8%) of 12,157 unique PGT-A patients. Chromosomal microarray follow-up was requested for all cases, and results were received for 1 or both members of 65 reproductive couples. In all cases, 1 of the gamete providers was confirmed to have the CNV identified in the embryos (100.0%, N = 65/65; 95% confidence interval, 94.5-100). The identified CNV was of maternal origin in 34 cases (52.3%) and of paternal origin in 31 cases (47.7%). A significant correlation was identified between PGT-A-predicted CNV sizes and chromosomal microarray detected sizes (r = 0.81) and genomic coordinates on parental deoxyribonucleic acid. Twenty-six (40%) of the CNVs were classified as benign/likely benign, 30 (46.2%) as a variant of uncertain significance, and 9 (13.8%) as pathogenic/likely pathogenic.

CONCLUSION(S)

Certain PGT-A platforms may enable the detection of inherited, small CNVs with extremely high specificity without prior knowledge of parental status. Most CNVs in this data set were confirmed to be benign/likely benign or a variant of uncertain significance. Pathogenic/likely pathogenic CNVs associated with a broad range of phenotypic features may also be detected, although a reliable negative predictive value for small CNVs with current PGT-A technologies is unknown because of the many technical challenges.

Beyond black-box models: explainable AI for embryo ploidy prediction and patient-centric consultation

PURPOSE

To determine if an explainable artificial intelligence (XAI) model enhances the accuracy and transparency of predicting embryo ploidy status based on embryonic characteristics and clinical data.

METHODS

This retrospective study utilized a dataset of 1908 blastocyst embryos. The dataset includes ploidy status, morphokinetic features, morphology grades, and 11 clinical variables. Six machine learning (ML) models including Random Forest (RF), Linear Discriminant Analysis (LDA), Logistic Regression (LR), Support Vector Machine (SVM), AdaBoost (ADA), and Light Gradient-Boosting Machine (LGBM) were trained to predict ploidy status probabilities across three distinct datasets: high-grade embryos (HGE, n = 1107), low-grade embryos (LGE, n = 364), and all-grade embryos (AGE, n = 1471). The model's performance was interpreted using XAI, including SHapley Additive exPlanations (SHAP) and Local Interpretable Model-agnostic Explanations (LIME) techniques.

RESULTS

The mean maternal age was 38.5 ± 3.85 years. The Random Forest (RF) model exhibited superior performance compared to the other five ML models, achieving an accuracy of 0.749 and an AUC of 0.808 for AGE. In the external test set, the RF model achieved an accuracy of 0.714 and an AUC of 0.750 (95% CI, 0.702-0.796). SHAP's feature impact analysis highlighted that maternal age, paternal age, time to blastocyst (tB), and day 5 morphology grade significantly impacted the predictive model. In addition, LIME offered specific case-ploidy prediction probabilities, revealing the model's assigned values for each variable within a finite range.

CONCLUSION

The model highlights the potential of using XAI algorithms to enhance ploidy prediction, optimize embryo selection as patient-centric consultation, and provides reliability and transparent insights into the decision-making process.

Effect of freeze-thawing, cell collection, and laser irradiation cycles on mosaicism occurrence in preimplantation genetic testing for aneuploidy

OBJECTIVE

In preimplantation genetic testing for aneuploidy, opinions regarding the handling of mosaic embryos vary. In this study, we aimed to investigate the effects of freeze-thawing, the number of cells obtained, and the number of laser irradiation cycles on the degree of embryonic mosaicism.

STUDY DESIGN

This study was conducted in three parts. First, we classified specimens into the normal biopsy (control) (119 patients, 304 blastocysts) and thawed-biopsy (TB group) (26 patients, 72 blastocysts)) groups. The control and TB groups were then classified into three categories (euploidy, mosaic and aneuploidy) according to next-generation sequencing (NGS) results, and the number of cells collected and laser irradiation cycles were compared for each category. Subsequently, the effects of differences in the number of cells collected and laser irradiation cycles on NGS results were investigated in the control and TB groups. Finally, data on cell collection and laser irradiation cycles and NGS analysis results for the groups were compared.

RESULTS

The TB group had a significantly higher incidence of chromosomal mosaicism than the control group. Neither the number of cells collected nor the laser irradiation cycles affected the percentage of chromosomal mosaicism. However, the freeze-thaw process increased the occurrence of mosaicism.

CONCLUSIONS

This study showed that repeated freeze-thaw cycles increase the incidence of mosaicism, but the embryos are not aneuploid and are therefore suitable for transfer.

Role of genetic analysis of products of conception and PGT in managing early pregnancy loss

This article considers the addition of comprehensive 24-chromosomal microarray (CMA) analysis of products of conception (POC) to a standard evaluation for recurrent pregnancy loss (RPL) to help direct treatment towards expectant management versus IVF with preimplantation genetic testing for aneuploidies (PGT-A). The review included retrospective data from 65,333 miscarriages, a prospective evaluation of 378 couples with RPL who had CMA testing of POC and the standard workup, and data from an additional 1020 couples who were evaluated for RPL but did not undergo CMA testing of POC. Aneuploidy in POC explained the pregnancy loss in 57.7% (218/378) of cases. In contrast, the full RPL evaluation recommended by the American Society for Reproductive Medicine identified a potential cause in only 42.9% (600/1398). Combining the data from the RPL evaluation and the results of genetic testing of POC provides a probable explanation for the loss in over 90% (347/378) of women. Couples with an unexplained loss after the standard evaluation with POC aneuploidy accounted for 41% of cases; PGT-A may be considered after expectant management. Conversely, PGT-A would have a limited role in those with a euploid loss and a possible explanation after the standard workup. Categorizing a pregnancy loss as an explained versus unexplained loss after the standard evaluation combined with the results of CMA testing of POC may help identify patients who would benefit from expectant management versus PGT-A.

Preimplantation genetic testing for aneuploidy in patients of different age: a systematic review and meta-analysis

This study aimed to summarize the current knowledge on the benefits of in vitro fertilization/intracytoplasmic sperm injection with preimplantation genetic testing for aneuploidy (PGT-A) and to discuss the role of PGT-A in patients of different ages undergoing assisted reproduction. A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 checklist. Registration number: CRD42022354697. Studies were identified by searching the PubMed, Cochrane Library, Google Scholar, Scopus, Embase, and ClinicalTrials databases. Seven meta-analyses were performed with additional stratification of age and prognosis of the women studied. Clinical pregnancy rate per embryo transfer in patients aged >35 years was higher in the PGT-A group (P=0.0002) than in controls. Live birth rate (LBR) per embryo transfer in women 35 years old or younger (P=0.002) was higher in the PGT-A group. The LBR per patient in women aged >35 years was higher in the PGT-A group (P=0.004). The effects of PGT-A on LBR in patients with poor prognosis showed a statistically significant increase (P=0.003). There was no significant difference in the rate between the two groups. PGT-A is effective and can be recommended for patients aged >35 years undergoing assisted reproduction to improve their reproductive outcomes. Moreover, our study showed the possible benefits of PGT-A in patients with a poor prognosis. Overall, our findings suggest that PGT-A is a valuable tool for improving the reproductive outcomes of assisted reproductive procedures in older women and those with a history of pregnancy complications.

Polygenic embryo screening: quo vadis?

Recently, the use of polygenic risk scores in embryo screening (PGT-P) has been introduced on the premise of reducing polygenic disease risk through embryo selection. However, it has been met with extensive critique: considered "technology-driven" rather than "evidence-based", concerns exist about its validity, utility, ethics, and societal effects. Its scientific foundations and criticisms thus need to be carefully considered. However, seeing as PGT-P is already offered in some settings, further questions need to be addressed, in order to give due diligence to various aspects of PGT-P. By examining the complexities of clinical introduction of PGT-P, we discuss whether PGT-P could be responsibly implemented in the first place, what elements need to be addressed if PGT-P is clinically implemented, and subsequently how counselling and decision-making of its users could be envisaged. By dissecting these elements, we provide an overview of important practical questions of PGT-P and emphasize elements of PGT-P that we think have yet to be given sufficient attention. These questions and elements are for example related to the potential target group, scope, and decision-making possibilities of PGT-P. The aspects we raise are crucial to consider by the scientific community and policy makers for the development of guidelines and/or an ethical framework for PGT-P.

Impact of aneuploidy on reproductive success in young infertile women: prospective analysis

RESEARCH QUESTION

What is the clinical outcome of the first attempt at conception between two embryo selection methods, blastocyst morphology and preimplantation genetic testing for aneuploidies (PGT-A), chosen at the initial physician IVF consultation?

DESIGN

In this prospective analysis, a clinical decision regarding embryo selection, blastocyst morphology (group A) or PGT-A (group B) was made during initial physician IVF consultation. Female infertility patients were matched based on maternal age (mean 32.6 ± 3.6 years; range 25-43 years) and a similar time frame of oocyte retrieval. The primary outcome was live birth rate from the initial consultation to the first conception attempt for all female patients and for a subset analysis of patients aged <35 years.

RESULTS

The inclusion of PGT-A (group B) for embryo selection during the initial physician IVF consultation resulted in 23 additional women out of the total 100 achieving a healthy live birth following the first conception attempt in this maternally age-matched infertile population (group B = 72.0% versus group A = 49.0%; P = 0.0014). This same benefit was observed for age-matched, younger infertility patients (<35 years), with live birth rates from the initial consultation being significantly higher when the upfront clinical decision included PGT-A for embryo selection (group B = 76.7% versus group A = 53.4%; P = 0.0052). Interestingly, 17 women from group B would have received an aneuploid embryo transfer if selection had been determined by blastocyst morphology alone, as their best-grade embryo was aneuploid.

CONCLUSIONS

This prospective analysis from the initial physician IVF consultation revealed that euploid embryo selection significantly improved live birth potential with the first conception attempt, even for younger women with infertility.

Analysis of Preimplantation and Clinical Outcomes of Two Cases by Oxford Nanopore Sequencing

It is challenging to distinguish embryos with a balanced translocation karyotype from a normal karyotype by existing conventional genetic testing methods. However, in germ-cell gamete generation, chromosome exchange and separation through cell meiosis form a different proportion of unbalanced gametes. Adverse birth events may occur, such as repeated miscarriages and fetal birth defects. In this study, the exact breakpoints of structural variation (SV) from two balanced translocation carrier families by using Nanopore long reads sequencing technology were obtained, and haplotype analysis and Sanger verified the accuracy of the detection results, confirming the application value of the Nanopore sequencing technology in the detection of balanced translocation before embryo implantation. Nanopore long-read sequencing was performed to find the precise breakpoint of chromosome-balanced translocation carriers. The breakpoints were subsequently verified by designing primers across the breakpoints and Sanger sequencing. Haplotype linkage analysis of SNPs which can be linked by a read block of families around the breakpoint regions was followed. After frozen (-thawed) embryo transfer (FET), prenatal cytogenetic analysis of amniotic fluid cells confirmed the predicted karyotypes from the transferred embryos. The presence of breakpoints was detected in three embryos of patient 1. No breakpoints were detected in either embryo of patient 2. One balanced translocated embryo from patient 1 and one normal euploid embryo from patient 2 were transplanted back into the patients, and amniotic fluid cells were analyzed for the karyotype of fetuses. The results were entirely consistent with the fetal karyotype. And through late follow-up, both patients successfully had a live birth fetus. The breakpoint location of the balanced chromosome translocation can be accurately found by Nanopore sequencing. The haplotype of carriers can be successfully constructed by Nanopore and sanger sequencing confirmed that the results were accurate. This is very advantageous for preimplantation genetic testing for chromosomal structural rearrangements (PGT-SR) detection in the families without proband.

In vitro fertilization as an option for couples with genetic disorders

Errors in human DNA may cause genetic disorders. Technological developments have raised hopes for reducing the risks of genetic inheritance among married couples who have a history of such disorders. Among the developments in reproductive health technology that reduce those risks is the in vitro fertilization (IVF) process. This review aimed to describe the current strategies using IVF and preimplantation genetic testing (PGT), which would be effective for couples with genetic disorders to have healthy offspring. The literature review included full-text, open-access research articles from ScienceDirect, PubMed, and Google Scholar that were published between 2013 and 2023, with 65 articles obtained from various journals. The keywords were "in vitro fertilization," "reproductive genetic disorders," "PGT-A," "PGT-M," "PGT-SR," and "oocyte donor." A total of 46 articles were selected as the most relevant to the review topic, and the results show that the IVF process can be an option for couples with a history of genetic disorders. Several additional procedures can be performed following IVF, such as oocyte donation and PGT, to help couples who want to have offspring without transmitting their genetic disorders. IVF can be an option for couples who have or carry genetic disorders. With IVF, couples can undertake several procedures such as oocyte donation and PGT for aneuploidy, monogenic disorders, or structural rearrangement.

Adverse maternal and neonatal outcomes of preimplantation genetic testing with trophectoderm biopsy: a retrospective cohort study of 3373 intracytoplasmic sperm injection single frozen-thawed blastocyst transfer cycles

PURPOSE

To investigate whether trophectoderm biopsy increases the risk of adverse maternal and neonatal outcomes in intracytoplasmic sperm injection (ICSI) single frozen-thawed blastocyst transfer cycles.

METHODS

This respective cohort study enrolled 3373 ICSI single frozen-thawed blastocyst transfer cycles with and without trophectoderm biopsy. Statistical methods including univariate logistic regression analysis, multivariate logistic regression analysis, and stratified analyses were performed to explore the impact of trophectoderm biopsy on adverse maternal and neonatal outcomes.

RESULTS

The rates of adverse maternal and neonatal outcomes were comparable between the two groups. Univariate analysis showed that the live birth rate (45.15% vs. 40.75%; P = 0.010) in the biopsied group was statistically higher than that in the unbiopsied group, and the rates of miscarriage (15.40% vs. 20.00%; P = 0.011) and birth defects (0.58% vs. 2.16%; P = 0.007) were statistically lower in the biopsied group. After adjusting for confounding factors, the rates of miscarriage (aOR = 0.74; 95% CI = 0.57-0.96; P = 0.022) and birth defects (aOR = 0.24, 95% CI = 0.08-0.70, P = 0.009) in the biopsied group were significantly lower than those in the unbiopsied group. Stratified analyses showed that the birth defects rate after biopsy was significantly reduced in the subgroups of age < 35 years old, BMI ≥ 24 kg/m2, artificial cycle with downregulation, poor-quality blastocysts, and Day 5 poor-quality blastocysts.

CONCLUSION

Preimplantation genetic testing (PGT) with trophectoderm biopsy does not increase the risk of adverse maternal and neonatal outcomes in ICSI single frozen-thawed blastocyst transfer cycles, and PGT can effectively reduce the rates of miscarriage and birth defects.

The utility of human two plus one small pronucleated zygotes (2.1PN) based on clinical outcomes and the focused ploidy analysis

PURPOSE

Are human embryos arising from two plus one small pronucleated zygotes, called 2.1 pronuclei (PN), clinically useful?

METHODS

In a retrospective embryo cohort study and prospective experimental study, a total of 287 cycles in which at least one 2.1PN was identified in the fertilization check were included. Embryonic development and clinical outcome were compared for the 1395 2PN zygotes and 304 2.1PN zygotes that were siblings. All embryos were individually cultured in time-lapse systems. Twenty-five 2.1PN-derived blastocysts, donated for research, were used in focused single-nucleotide variant ploidy analysis to identify the distribution pattern of heterozygosity.

RESULTS

The average diameter of PN was 24.9 ± 2.4 µm for large PN and 10.2 ± 2.4 µm for small PN; 79.9% of small PN was derived from female pronuclei. Blastocyst formation rate and good-quality blastocyst rate were significantly lower with 2.1PN embryos than with 2PN embryos (40.0% vs. 57.7%, 21.4% vs. 33.5%, respectively). A total of 13 embryos derived from 2.1PN were transferred, and three healthy babies were born. In ploidy constitutions of trophectoderm (TE), 2.1PN-derived blastocyst TE was shown to be mostly diploid (95.8%, 23/24), and only one blastocyst showed triploid.

CONCLUSIONS

It was suggested that 2.1PN embryos have lower embryonic developmental potential than 2PN embryos, but most of the 2.1PN were diploid, indicating that they are likely to be clinically usable. It is recommended to perform embryo transfer following a combination of PGT-A and ploidy analysis.

Perspectives of preimplantation genetic testing patients in Belgium on the ethics of polygenic embryo screening

RESEARCH QUESTION

What are the perspectives of preimplantation genetic testing (PGT) patients in Belgium on the ethics of PGT for polygenic risk scoring (PGT-P)?

DESIGN

In-depth interviews (18 in total, 10 couples, 8 women, n = 28) were performed with patients who had undergone treatment with PGT for monogenic/single-gene defects (PGT-M) or chromosomal structural rearrangements (PGT-SR) between 2017 and 2019 in Belgium. Participants were asked about their own experiences with PGT-M/SR and about their viewpoints on PGT-P, including their own interest and their ideas on its desirability, scope and consequences. Inductive content analysis was used to analyse the interviews.

RESULTS

Participants stated that their experiences with PGT-M/SR had been physically, psychologically and practically difficult. Most participants stated that, partly because of these difficulties, they did not see the added value of knowing the risk scores of embryos via PGT-P. Many participants worried that PGT-P could lead to additional anxieties, responsibilities and complex choices in reproduction and parenthood. They argued that not everything should be controlled and felt that PGT-P, especially non-medical and broad screening, was going too far. With regards to the clinical implementation of PGT-P, participants in general preferred PGT-P to be limited to people with a serious polygenic family history and wanted embryo selection decisions to be made by healthcare professionals.

CONCLUSIONS

This study shows that individuals with experience of PGT-M/SR saw PGT-P as different from PGT-M/SR. They had various ethical concerns with regards to PGT-P, especially regarding broadly offering PGT-P. These stakeholder viewpoints need to be considered regarding potential PGT-P implementation and guidelines.

Embryos derived from single pronucleus are suitable for preimplantation genetic testing

OBJECTIVE

To study and compare the preimplantation genetic testing for monogenic disorders (PGT-M) results, and to evaluate the treatment cycle outcomes of embryos derived from a single pronucleus (1PN) vs. two pronuclei (2PN).

DESIGN

A retrospective cohort study from January 2018 to December 2022 involving in vitro fertilization (IVF)-PGT-M treatment cycles.

SETTING

Single, academically affiliated fertility center.

PATIENTS

A total of 244 patients underwent 351 IVF-PGT-M treatment cycles.

INTERVENTION

Embryo biopsy with molecular testing for a monogenic disorder.

MAIN OUTCOME MEASURES

The molecular diagnosis results and clinical outcomes after the transfer of embryos derived from 1PN and 2PN in IVF-PGT-M treatment cycles.

RESULTS

Embryos derived from 1PN have a significantly low developmental potential with a lower rate of embryos that underwent biopsy compared with 2PN-derived embryos; 1PN-derived embryos demonstrated a significantly lower number of blastocysts (24% vs. 37.9%) and top-quality blastocysts (22.3% vs. 48.1%) compared with 2PN-derived embryos. Lower successfully completed and unaffected PGT-M results were achieved in 1PN compared with 2PN-derived embryos (47.1% vs. 65.5% and 18.7% vs. 31.6%, respectively), with significantly higher abnormal molecular results (39.6% vs. 22.7%). The embryo transfer of 24 1PN-derived embryos with no affected genetic disorder resulted in 5 (20.8%) clinical pregnancies and 4 (16.7%) live births (LBs).

CONCLUSIONS

Within the limits of fewer embryos derived from 1PN that yielded unaffected embryos suitable for transfer, the clinical pregnancy and LB rate of 1PN embryos undergoing PGT-M are reassuring. We, therefore, suggest applying PGT-M to embryos derived from 1PN embryos to improve the cumulative clinical pregnancy and LB rates.

[Reproductive Health-Oriented Development in Assisted Reproductive Technologies]

Assisted reproductive technologies (ARTs) are core components of the field of reproductive medicine, encompassing multiple pivotal stages of early development from gamete maturation and fertilization to embryo development. Against the backdrop of a deteriorating trend of global decline in fertility rates, patients with infertility problems increasingly turn to ARTs to realize their dreams of parenthood. However, concomitant with this trend is a growing apprehension regarding the potential adverse effects of ARTs. Herein, we endeavor to discuss several common ARTs procedures utilized in clinical settings and the relevant cutting-edge advancements. The ARTs discussed in the article include in vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI), biphasic in vitro maturation (biphasic IVM), frozen embryo transfer (FET), preimplantation genetic testing (PGT), non-invasive PGT (niPGT), etc. In addition, we reevaluated their roles within the broader context of assisted reproduction aimed at promoting reproductive health. Additionally, we will delve into the impact of ARTs on the reproductive health of the offspring. By prioritizing the reproductive well-being of both patients and their offspring, the ongoing development and improvement of ARTs to enhance their efficacy and safety will contribute significantly to the advancement of human reproductive health.

Preimplantation genetic testing in the current era, a review

BACKGROUND

Preimplantation genetic testing (PGT), also referred to as preimplantation genetic diagnosis (PGD), is an advanced reproductive technology used during in vitro fertilization (IVF) cycles to identify genetic abnormalities in embryos prior to their implantation. PGT is used to screen embryos for chromosomal abnormalities, monogenic disorders, and structural rearrangements.

DEVELOPMENT OF PGT

Over the past few decades, PGT has undergone tremendous development, resulting in three primary forms: PGT-A, PGT-M, and PGT-SR. PGT-A is utilized for screening embryos for aneuploidies, PGT-M is used to detect disorders caused by a single gene, and PGT-SR is used to detect chromosomal abnormalities caused by structural rearrangements in the genome.

PURPOSE OF REVIEW

In this review, we thoroughly summarized and reviewed PGT and discussed its pros and cons down to the minutest aspects. Additionally, recent studies that highlight the advancements of PGT in the current era, including their future perspectives, were reviewed.

CONCLUSIONS

This comprehensive review aims to provide new insights into the understanding of techniques used in PGT, thereby contributing to the field of reproductive genetics.

Patient interest in and clinician reservations on polygenic embryo screening: a qualitative study of stakeholder perspectives

PURPOSE

We explored and compared perspectives of reproductive endocrinology and infertility specialists (REIs) and in vitro fertilization (IVF) patients regarding polygenic embryo screening (PES), a new type of preimplantation screening that estimates the genetic chances of developing polygenic conditions and traits in the future.

METHODS

Qualitative thematic analysis of semi-structured interviews with US-based REIs and IVF patients.

RESULTS

Clinicians and patients often held favorable views of screening embryos for physical or psychiatric conditions, though clinicians tended to temper their positive attitudes with specific caveats. Clinicians also expressed negative views about screening embryos for traits more frequently than patients, who generally held more positive views. Most clinicians were either unwilling to discuss or offer PES to patients or were willing to do so only under certain circumstances, while many patients expressed interest in PES. Both stakeholder groups envisioned multiple potential benefits or uses of PES and raised multiple potential, interrelated concerns about PES.

CONCLUSION

A gap exists between clinician and patient attitudes toward PES; clinicians generally maintained reservations about such screening and patients indicated interest in it. Clinicians and patients sometimes imagined using PES to prepare for the birth of a predisposed or "affected" individual-a rationale that is often associated with prenatal testing. Many clinicians and patients held different attitudes depending on what is specifically screened, despite the sometimes blurry distinction between conditions and traits. Considerations raised by clinicians and patients may help guide professional societies in developing guidelines to navigate the uncertain terrain of PES.

Assessing the necessity of screening ≤5 Mb segmental aneuploidy in routine PGT for aneuploidies

RESEARCH QUESTION

Does routine clinical practice require an increase in the resolution of preimplantation genetic testing for aneuploidies (PGT-A) to detect segmental aneuploidies ≤5 Mb?

DESIGN

This retrospective study analysed 963 trophectoderm biopsies from 346 couples undergoing PGT between 2019 and 2023. Segmental aneuploidies ≥1 Mb were reported. The characteristics, clinical interpretation and concordance of segmental aneuploidies ≤5 Mb were analysed.

RESULTS

The incidence of segmental aneuploidies was 15.1% (145/963) in blastocysts, with segmental aneuploidies of ≤5 Mb accounting for 2.3% (22/963). The size of the segmental aneuploidies showed a skewed distribution. Segmental aneuploidies ≤5 Mb were found to occur more frequently on the q arm of the chromosome, compared with the p arm. Losses of ≤5 Mb segmental aneuploidies were more prevalent than gains, with 17 deletions compared with 5 duplications. Of the segmental aneuploidies, 63.6% (14/22) ≤5 Mb were de novo, and 50.0% (7/14) of de-novo segmental aneuploidies were pathogenic/likely pathogenic (P/LP) copy number variations, accounting for 0.7% of 963 blastocysts. For blastocysts carrying ≤5 Mb segmental aneuploidies, a re-analysis of back-up biopsy samples showed that 35.7% of de-novo segmental aneuploidies (5/14) were not detected in the back-up samples. Cases were reported in which prenatal diagnosis (amniocentesis) revealed the absence of embryonic ≤5 Mb segmental aneuploidies detected at the blastocyst stage.

CONCLUSIONS

The incidence of P/LP de-novo ≤5 Mb segmental aneuploidies in human blastocysts is extremely low. There is no compelling need to increase the resolution of PGT-A to 5 Mb in routine clinical practice.

Increasing Endometrial Thickness Beyond 8 mm Does Not Alter Clinical Pregnancy Rate After Single Euploid Embryo Transfer

The aim of this study was to investigate if variation in endometrial thickness affects clinical pregnancy and live birth rates among patients undergoing single euploid embryo transfer (SET). A retrospective review of IVF cycles performed at a single private fertility institution between 2015 and 2020 was performed. Patients with normal uterine anatomy undergoing their first SET of a euploid embryo undergoing their first cycle at the center were included, for a total of 796 cycles. Endometrial thickness was measured by transvaginal ultrasound following 10-14 days of estradiol exposure. Specific infertility diagnoses did not significantly impact endometrial lining thickness with means across diagnoses ranging from 9.3 to 11.0 mm. Endometrial thickness was grouped into five categories: < 8 mm, 8-10 mm, 10-13 mm, 13-15 mm, and ≥ 15 mm. Using 8-10 mm as the reference group, the odds ratio of live birth was 0.5, 1.22, 1.05, and 1.05 for < 8 mm, 10-13 mm, 13-15 mm, and ≥ 15 mm groups, respectively. Risk of first trimester miscarriage was equivalent across groups. There was a trend toward an increased rate of biochemical pregnancies in patients with a < 8 mm and ≥ 15 mm endometrium; however, this was not statistically significant. The clinical pregnancy and live birth rate were lowest in patients with < 8-mm endometrial thickness. For single euploid embryo transfers, an endometrial lining greater than or equal to 8 mm confers optimal live birth rates following a medicated FET cycle. These data confirm the findings of prior studies in fresh embryo transfers without the confounders of supraphysiologic ovarian hormone concentrations and genetically untested embryos.

The impact of first-trimester subchorionic hematomas on pregnancy outcomes after euploid embryo transfer: a retrospective cohort study

BACKGROUND

The aim of the retrospective cohort study was to investigate the prognostic effect of subchorionic hematomas (SCH) in the first trimester on pregnancy outcomes after euploid embryo transfer.

METHODS

We retrospectively analyzed women achieving singleton pregnancy by PGT-A or PGT-SR from January 2017 to January 2022. Patients were enrolled in the study if they had a viable intrauterine pregnancy at ultrasound between 6 0/7 and 8 0/7 weeks of gestation. Pregnancy outcomes as well as the incidence of maternal complications were compared between patients with and without SCH. Logistic regression was used for adjusting for potential confounding factors.

RESULTS

A total of 1539 women were included, of which 298 with SCH and 1241 with non-SCH. The early miscarriage rate in SCH group was significantly higher than that in the non-SCH group (10.1% vs. 5.6%, adjusted odds ratio [aOR] 1.99, 95% confidence interval [CI] 1.25-3.16, P = 0.003). The live birth rate in SCH group was significantly lower than that in the non-SCH group. (85.6% vs. 91.2%, aOR 0.57, 95% CI 0.39-0.84, P = 0.005). In addition, SCH group had an increased risk of hypertensive disorder of pregnancy (HDP) (8.9% vs. 5.2%, P = 0.022), especially in hematoma with bleeding (19.3% vs. 6.0%, P = 0.002). The incidence of gestational diabetes mellitus (GDM), major congenital abnormalities rate, normal birth weight rate and low birth weight rate were similar between the two groups.

CONCLUSIONS

The presence of SCH in the first trimester was associated with worse pregnancy outcomes after euploid embryo transfer, including an increased risk of early miscarriage and hypertensive disorder of pregnancy, along with a reduced live birth rate.

A clinical predictive model for live birth in women of advanced age undergoing PGT cycles

PURPOSE

The trend of delaying childbirth has resulted in a growing number of advanced-aged women who are opting for preimplantation genetic testing (PGT) to screen for monogenic diseases or structural chromosomal rearrangements (PGT-M and PGT-SR). This increase in demand necessitates the development of a clinical predictive model for live birth outcomes in these women. Therefore, the objective of this study is to construct a comprehensive predictive model that assesses the likelihood of achieving a successful live birth in advanced-aged women undergoing PGT-M and PGT-SR treatments.

METHODS

A retrospective cohort study of 37-45-year-old women undergoing preimplantation genetic testing for monogenic disease or structural chromosomal rearrangement cycles from 2010 to 2021 was conducted at a university hospital reproductive centre. The purpose was to develop a clinical predictive model for live birth in these women. The main outcome studied was the cumulative live birth rate in the first or subsequent cycles. Developing a decision tree enabled a comprehensive study of clinical parameters and expected outcomes.

RESULTS

The analysis included 158 women undergoing 753 preimplantation genetic testing cycles. The cumulative live birth rate was 37.342% (59/158). Decision tree analysis revealed that women aged ≤ 40.1 or women > 40.1 with one or more top-quality transferable embryos in their first cycle had the best chance for a live baby (56% and 41%, respectively). Those older than 40.1 without top-quality embryos and seven or fewer dominant follicles had no live births. A Kaplan-Meier curve showed that for autosomal dominant diseases, there was a negligible increase in live birth rate after three cycles, compared to six cycles in autosomal recessive inheritance.

CONCLUSION

In older women, the chance of delivering after repeated cycles is higher in those with at least one top-quality unaffected embryo in their first preimplantation genetic testing cycle. Additional preimplantation genetic testing cycles after three in carriers of an autosomal dominant disorder and six in those with an autosomal recessive disorder should be considered prudently.

Does embryo biopsy, independent of vitrification, impact perinatal outcomes? An analysis of perinatal outcomes following preimplantation genetic testing biopsy in fresh and frozen embryo transfer cycles

Objective

To compare neonatal outcomes in pregnancies resulting from embryos that have undergone preimplantation genetic testing (PGT) biopsy compared with no biopsy in both fresh and frozen embryo transfers (ETs) and determine whether findings are mediated by multiple births.

Design

Retrospective cohort study.

Setting

Society of Assisted Reproductive Technologies-Clinical Outcomes Reporting System data, 2014-2015.

Patients

Autologous in vitro fertilization treatment cycles using fresh or frozen blastocyst ET, with or without PGT biopsy.

Interventions

Not applicable.

Main Outcome Measures

Large for gestational age (LGA), small for gestational age, and preterm delivery. Secondary outcomes included high birthweight, low birthweight, and clinical pregnancy measures. Outcomes were evaluated using log-binomial regression models with repeated measures. Models were used to estimate the controlled direct effects of biopsy on birth outcomes that were not mediated by multiple gestations.

Results

In fresh ET, biopsy was associated with an increase in LGA (relative risk [RR] 1.45, confidence interval [CI] 1.04-2.02) that persisted in the model mediated for multiple gestation (RR 1.36, 95% CI 1.01-1.83) but was not present in an analysis restricted to elective single ET (RR 0.99, 95% CI 0.91-1.09). In frozen ET, there were no differences in any of the primary outcomes after accounting for multiple gestations.

Conclusions

In a large multicenter database, there were no differences in neonatal outcomes after PGT biopsy in frozen ET cycles, and an increase in LGA was noted in fresh transfers that persisted even after accounting for multiple gestations but was not present in analysis restricted to elective single ET.

To transfer or not to transfer: the dilemma of mosaic embryos - a narrative review

A frequent finding after preimplantation genetic diagnostic testing for aneuploidies using next-generation sequencing is an embryo that is putatively mosaic. The prevalence of this outcome remains unclear and varies with technical and external factors. Mosaic embryos can be classified by the percentage of cells affected, type of chromosome involvement (whole or segmental), number of affected chromosomes or affected cell type (inner mass cell, trophectoderm or both). The origin of mosaicism seems to be intrinsic as a post-zygotic mitotic error, but some external factors can play a role. As experience has increased with the transfer of mosaic embryos, clinical practice has gradually become more flexible in recent years. Nevertheless, clinical results show lower implantation, pregnancy and clinical pregnancy rates and higher miscarriage rates with mosaic embryo transfer when compared with the transfer of euploid embryos. Prenatal diagnosis is highly recommended after the transfer of mosaic embryos. This narrative review is intended to serve as reference material for practitioners in reproductive medicine who must manage a mosaic embryo result after preimplantation genetic testing for aneuploidies.