Should embryo rebiopsy be considered a regular strategy to increase the number of embryos available for transfer?

PURPOSE: To investigate whether embryo rebiopsy increases the yield of in vitro fertilization (IVF) cycles. METHODS: Retrospective study including 18,028 blastocysts submitted for trophectoderm biopsy and preimplantation genetic testing for aneuploidy (PGT-A) between January 2016 and December 2021 in a private IVF center. Out of the 517 embryos categorized as inconclusive, 400 survived intact to the warming procedure, re-expanded, and were suitable for rebiopsy. Of them, 71 rebiopsied blastocysts were transferred. Factors affecting the probability of obtaining an undiagnosed blastocyst and clinical outcomes from blastocysts biopsied once and twice were investigated. RESULTS: The overall diagnostic rate was 97.1%, with 517 blastocysts receiving inconclusive reports. Several blastocyst and laboratory features, such as the day of the biopsy, the stage of development, and the biopsy methodology, were related to the risk of obtaining an inconclusive diagnosis after PGT-A. A successful diagnosis was obtained in 384 of the rebiopsied blastocysts, 238 of which were chromosomally transferable. A total of 71 rebiopsied blastocysts were transferred, resulting in 32 clinical pregnancies [(clinical pregnancy rate (CPR)=45.1%], 16 miscarriages [(miscarriage rate (MR)=41%], and, until September 2020, 12 live births [(live birth rate (LBR)=23.1%]. A significantly lower LBR and higher MR were obtained after transferring rebiopsied blastocysts compared to those biopsied once. CONCLUSION: Although an extra round of biopsy and vitrification may cause a detrimental effect on embryo viability, re-analyzing the test-failure blastocysts contributes to increasing the number of euploid blastocysts available for transfer and the LBR.

The higher the score, the better the clinical outcome: retrospective evaluation of automatic embryo grading as a support tool for embryo selection in IVF laboratories.

STUDY QUESTION: Is the automatic embryo grading function of specific time-lapse systems clinically useful as a decision support tool for IVF laboratories? SUMMARY ANSWER: Blastocyst grading according to the automatic scoring system is directly associated with the likelihood of implantation and live birth, at least in treatments without preimplantation genetic testing for aneuploidy (PGT-A). WHAT IS KNOWN ALREADY: Several embryo selection algorithms have been described since the introduction of time-lapse technology in IVF laboratories, but no one algorithm has yet been sufficiently consolidated for universal use. Multicentric models based on automated grading systems offer promise for standardization of embryo selection. STUDY DESIGN, SIZE, DURATION: A retrospective cohort study was performed including 1678 patients who underwent IVF treatments between 2018 and 2020 and whose embryos (n = 12 468) were cultured in time-lapse systems. PARTICIPANTS/MATERIALS, SETTING, METHODS: After obtaining the required parameters (division time to 2, 3, 4 and 5 cells; time of blastocyst formation; inner cell mass quality; and trophectoderm quality), the automatic embryo score was calculated using the software included in the appropriate workstation. First, embryo score was compared with conventional morphological quality and the subsequent clinical outcomes of 1952 single blastocyst transfers. Second, we quantified the contribution of the automatic embryo score and conventional morphological grade to implantation and live birth outcome with multivariate logistic regression analysis in different patient populations. MAIN RESULTS AND THE ROLE OF CHANCE: A higher embryo score was associated with a better clinical outcome of IVF treatment. The mean of the automatic embryo score varied significantly (P < 0.001) among embryos with different morphological categories, between euploid and aneuploid embryos, between embryos resulting in positive versus negative pregnancy, between implanted and non-implanted embryos, and between embryos resulting in positive and negative live birth. Embryo score was related to the odds of implantation and live birth in the oocyte donation program (odds ratio (OR)=1.29; 95% CI [1.19-1.39]; P < 0.001 for implantation and OR = 1.26; 95% CI [1.16-1.36]; P < 0.001 for live birth) and in conventional treatments with autologous oocytes (OR = 1.38; 95% CI [1.24-1.54]; P < 0.001 for implantation and OR = 1.47; 95% CI [1.30-1.65]; P < 0.001 for live birth). There was no significant association of embryo score with implantation or live birth in treatments involving PGT-A. LIMITATIONS, REASONS FOR CAUTION: This study is limited by its retrospective nature. Further prospective randomized trials are required to confirm the clinical impact of these findings. The single-center design should be taken into account when considering the universal application of the model. WIDER IMPLICATIONS OF THE FINDINGS: Evidence of the clinical efficiency of automated embryo scoring for ranking embryos with different morphological grade and potential in order to achieve higher implantation and live birth rates may make it a decision support tool for embryologists when selecting blastocysts for embryo transfer. STUDY FUNDING/COMPETING INTEREST(S): This research has been funded by a grant from the Ministry of Science, Innovation and Universities FIS (PI21/00283) awarded to M.M. There are no competing interests to declare. TRIAL REGISTRATION NUMBER: N/A.

A propensity score-based, comparative study assessing humid and dry time-lapse incubation, with single-step medium, on embryo development and clinical outcomes.

STUDY QUESTION: Does culture in a high relative humidity atmosphere improve clinical outcomes when using a time-lapse integrated incubator and single-step culture medium? SUMMARY ANSWER: Using an integrated time-lapse system and single-step culture medium, culture in a high relative humidity atmosphere increases the likelihood of embryos, especially those subjected to preimplantation genetic testing for aneuploidies, to achieve a pregnancy compared to those cultured in dry conditions. WHAT IS KNOWN ALREADY: The use of a humid atmosphere inside incubators can reduce changes in culture media osmolality, which has been reported to have a significant effect on embryo quality and morphokinetics. Studies assessing the effect of humid culture (HC) in clinical outcomes are, however, scarce and inconclusive, mostly due to a high variability in culture conditions and reduced sample size. STUDY DESIGN, SIZE, DURATION: Retrospective cohort study performed over 1627 ICSI cycles performed during 3 consecutive years in which embryo cohorts were cultured in a time-lapse incubator with three dry and three humidified chambers, and using single-step culture medium. Clinical outcomes were compared between treatments in which embryo cohorts were cultured in either humid (n = 833) or dry (n = 794) conditions. PARTICIPANTS/MATERIALS, SETTING, METHODS: The study includes autologous treatments, with (N = 492) and without (N = 372) preimplantation genetic testing for aneuploidies (PGT-A) and ovum donation treatments (N = 763), performed in three university-affiliated private IVF centres. Stimulation, oocyte pickup and fertilization were performed according to the standard procedures of the clinic. All embryo cohorts were cultured in the same model of time-lapse incubator, distributed to either a dry or humidified chamber, while the rest of the culture variables remained equal. The population was weighted by the inverse probability of treatment to control for all measured confounders. The association between HC and the main outcome was assessed by logistic regression over the weighted population. The E-value was reported as a way of considering for unmeasured confounders. Differences in embryo development and other secondary outcomes between the study groups were assessed by Pearson Chi-squared test, ANOVA test and Kaplan-Meier survival analysis. MAIN RESULTS AND THE ROLE OF CHANCE: An univariable logistic regression analysis, weighted by the inverse probability of treatment, determined that embryos cultured in humid conditions are more likely to achieve a clinical pregnancy than those cultured in dry conditions (odds ratio (OR) = 1.236 (95% CI 1.009-1.515), P = 0.041, E = 1.460). Through stratification, it was determined that said effect is dependent on the type of treatment: no improvement in clinical pregnancy was present in ovum donation or autologous treatments, but a statistically significant positive effect was present in treatments with preimplantation genetic testing (OR = 1.699 (95% CI 1.084-2.663), P = 0.021, E = 1.930). Said increase does not relate with an improvement in later outcomes. Differences were also found in variables related to embryo developmental morphokinetics. LIMITATIONS, REASONS FOR CAUTION: The retrospective nature of the study makes it susceptible to some bias linked to the characteristics of the treatments. To lessen the effect of possible biases, cases were weighted by the inverse probability of treatment prior to the evaluation of the outcome, as means to assess for measured confounders. In addition, the E-value of the weighted OR was calculated as a sensitivity analysis for unmeasured confounders. A randomized prospective study could be performed for further assessing the effect of humid conditions in clinical outcome. WIDER IMPLICATIONS OF THE FINDINGS: These results support that embryo culture under conditions of high relative humidity contributes to optimize clinical results in undisturbed culture in a time-lapse incubator with single-step medium. To our knowledge, this is the largest study on the matter and the first performing a propensity score-based analysis. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by the ''Centro para el Desarrollo Tecnologico Industrial'' from the Spanish Ministry of Science, Innovation, and Universities (CDTI-20170310) and Generalitat Valenciana and European Social Fund (ACIF/2019/264). None of the authors have any competing interest to declare. TRIAL REGISTRATION NUMBER: N/A.

COVID-19 mRNA vaccines have no effect on endometrial receptivity after euploid embryo transfer.

RESEARCH QUESTION: Does the COVID-19 vaccination affect endometrial receptivity after single euploid embryo transfer, measured by sustained implantation rate? DESIGN: A retrospective cohort study analysing two groups of single euploid embryo transfers using own oocytes: one historical cohort of 3272 transfers 1 year before the pandemic; and one comprising 890 transfers in women previously vaccinated with mRNA vaccines against severe acute respiratory syndrome coronavirus 2. The main outcomes were clinical pregnancy rate (CPR) and sustained implantation rate (SIR) per embryo transfer. These outcomes were compared between non-vaccinated and vaccinated women, and women who had received one and two doses. Lastly, vaccinated women were divided into quartiles according to the time from last dose to embryo transfer. RESULTS: Similar CPR and SIR were found between non-vaccinated and vaccinated women, and the odds ratio for both outcomes was not statistically significant after being controlled for potential confounders (OR 0.937, 95% CI 0.695 to 1.265 and OR 0.910, 95% CI 0.648 to 1.227 respectively). Within the vaccinated group, women who had received one or two doses also had similar outcomes. In addition, no differences were found according to the time interval from vaccination to embryo transfer. CONCLUSION: The administration of mRNA vaccines against COVID-19 had no effect on endometrial receptivity and embryo implantation, regardless of the number of doses and time interval from vaccination to embryo transfer. The potential negative effect of the vaccine on endometrial receptivity and reproductive outcomes is reassuring for patients in the process of undergoing assisted reproductive treatment.

Blastocyst formation is similar in obese and normal weight women: a morphokinetic study.

STUDY QUESTION: Does the embryo cleavage pattern and rate of blastocyst formation differ between normal weight and obese women undergoing IVF? SUMMARY ANSWER: Embryo morphokinetic development, final blastocyst formation rate and blastocyst morphology do not differ between obese and normal weight women. WHAT IS KNOWN ALREADY: Female obesity has been related to impaired IVF outcomes. Although the mechanisms responsible for this detrimental effect are thought to include impaired oocyte and embryo quality and reduced endometrial receptivity, they are yet to be confirmed. Embryo quality has been commonly assessed using static morphological criteria. Only three studies have analysed the progress of embryos up to the blastocyst stage in women with elevated BMI, but they have used small samples of patients or have obtained contradictory results. STUDY DESIGN, SIZE, DURATION: This retrospective, cohort study, was performed from January 2016 to May 2020. A total of 3316 ICSI cycles from 2822 women were included, of which 1251 cycles were part of a preimplantation genetic testing programme. In total, 17 848 embryos were analysed. PARTICIPANTS/MATERIALS, SETTING, METHODS: This study reports on the IVF cycles of infertile women, with a known BMI, who underwent ICSI and whose embryos were grown until the fifth/sixth day of development in a time-lapse system. Patients were grouped as follows. Underweight was defined as a BMI <18.5 kg/m2; normal weight was a BMI of 18.5-24.9 kg/m2; overweight was a BMI of 25-29.9 kg/m2; and obesity was a BMI of ≥30 kg/m2. Embryo development was assessed on an external computer with analysis software. MAIN RESULTS AND THE ROLE OF CHANCE: Despite an initial slower pattern of embryo development, the blastocyst formation rate on day 5 or on day 5 plus day 6 did not differ in obese women with respect to the other three BMI groups. Moreover, based on the evaluation of inner cell mass and the trophectoderm on both days of blastocyst development, embryo quality was similar across the BMI groups, as were the pattern of development and arrest up to blastocyst formation and the distribution of the categories of full, expanded and hatching blastocysts. LIMITATIONS, REASONS FOR CAUTION: Limitations include the retrospective analysis of data, the use of BMI as the only parameter to define normal/abnormal female body weight, and the lack of complete information about clinical outcomes. WIDER IMPLICATIONS OF THE FINDINGS: Blastocyst formation and embryo morphokinetics are not affected by female obesity, and the poorer IVF outcomes described for such women are probably due to deficient endometrial receptivity. The role of endometrial progesterone exposure on the day of embryo transfer should be analysed in future studies as a possible determining factor. STUDY FUNDING/COMPETING INTEREST(S): No external funding was used and there are no competing interests. TRIAL REGISTRATION NUMBER: N/A.

Will the introduction of automated ART laboratory systems render the majority of embryologists redundant?

IVF techniques have changed over time with the aim of improving clinical results. Today, embryology is facing a change common to most areas of medicine, the introduction of automation. The use of automated systems in the IVF laboratory is already happening, for example, with electronic witnessing and the ranking of embryos according to their implantation potential. It is expected that in the near future, various systems in the IVF laboratory will be automated. In this way, gamete manipulation would cease to be manual and embryo culture and selection would be performed by means of microfluidics and artificial intelligence. Therefore, the tasks of the embryologist will inevitably be reduced. However, new functions related to data capture, management and analysis will emerge, along with other research skills and increased communication with other professionals and patients.

Focus on time-lapse analysis: blastocyst collapse and morphometric assessment as new features of embryo viability.

The main goal of assisted reproductive technology (ART) is to achieve a healthy singleton live birth after the transfer of one embryo. A major objective of IVF scientists has always been to use adequate criteria for selecting the embryo for transfer according to its implantation potential. Indeed, embryo quality is usually assessed by evaluating visual morphology, which relies on the removal of the embryo from the incubator and might include inter- and intra-evaluator variation among embryologists. Recently, an advancement in embryo culture has taken place with the introduction of a new type of incubator with an integrated time-lapse monitoring system, which enables embryologists to analyse the dynamic events of embryo development from fertilization to blastocyst formation. This novel practice is rapidly growing and has been used in many IVF centres worldwide. Therefore, the main aim of this review is to present the benefits of time-lapse monitoring in a modern embryology laboratory; in particular, we discuss blastocyst collapse and morphometric blastocyst assessment, and analyse their association with embryo viability and implantation potential. In addition, we highlight preliminary studies involving artificial intelligence and machine learning models as non-invasive markers of clinical pregnancy.

Prediction of embryo survival and live birth rates after cryotransfers of vitrified blastocysts.

RESEARCH QUESTION: Which pre-vitrification parameters are the most predictive of survival and live birth in vitrified-warmed blastocyst transfer cycles? DESIGN: A retrospective study including 11,936 warmed blastocysts. Pre-vitrification morphological parameters analysed for blastocysts included day of vitrification; blastocyst expansion degree; trophoectoderm grade (A, B and C); and inner cell mass grade (A, B and C). Univariate and multivariate generalized estimating equations models were used to analyse survival, clinical pregnancy and live birth rate. A stepwise regression analysis was conducted to select and classify by order which outcomes were the most predictive. RESULTS: The odds of survival increased almost twice for blastocysts with lower expansion degree (OR 1.92; 95% CI 1.37 to 2.69; P < 0.001) and by about 50% for blastocysts vitrified on day 5 (OR 1.56; 95% CI 1.27 to 1.89; P < 0.001). Multivariate generalized estimating equations model showed that trophectoderm grade followed by the day of vitrification were the most significant predictors of live birth. The odds of live birth increased nearly three times for blastocysts with trophectoderm graded as A compared with those with trophectoderm graded as C (OR 2.85; 95% CI 2.48 to 3.27; P < 0.001), and double for blastocysts vitrified on day 5 compared with those vitrified on day 6 (OR 2.22; 95% CI 1.97 to 2.49; P < 0.001). The odds of live birth also increased in higher expansion degree blastocysts. CONCLUSIONS: Blastocysts vitrified on day 5 and those with higher trophoectoderm grade should be given priority when warming.

Assessment of embryo implantation potential with a cloud-based automatic software.

RESEARCH QUESTION: Is embryo selection by Dana (automatic software for embryo evaluation) associated with a higher implantation rate in IVF treatments? DESIGN: A three-phase study for Dana system's validation: creation of a data-cloud of known implantation data (KID) embryos from 1676 transferred embryos; embryo evaluation by Dana considering manual annotations and embryo development videos (389 transferred embryos); and validation of Dana automatic selection, without embryologist's intervention (147 transferred embryos); RESULTS: The implantation rate of the 1021 KID embryos from phase 1 served to set four grades of embryos referring to implantation rate: A = 34%, B = 25%, C = 24%, and D = 19%. Phase 2: a classification ranking according to the unit average distance (UAD) and implantation potential was established: top (UAD ≤0.50), high (UAD = 0.51-0.66), medium (UAD = 0.67-1.03) and low (UAD >1.03). Pregnancy rates were 59%, 46%, 36% and 28%, respectively (P < 0.001). Phase 3: embryos were automatically categorized according to Dana's classification ranking. Most implanted embryos were found in groups top, high and medium (UAD ≤1.03), whereas the implantation rate in group low (UAD >1.03) was significantly lower: 46% versus 25%, respectively (P = 0.037). The twin gestation rate was higher when number of top embryos (UAD ≤0.5) transferred were two (52%) versus one (25%) (P < 0.001). CONCLUSIONS: Embryo selection based on Dana ranking increases the success of IVF treatments at least in oocyte donation programmes. The multicentre nature of the study supports its applicability at different clinics, standardizing the embryo development's interpretation. Dana's innovation is that the system increases its accuracy as the database grows.

An artificial intelligence model based on the proteomic profile of euploid embryos and blastocyst morphology: a preliminary study.

RESEARCH QUESTION: The study aimed to develop an artificial intelligence model based on artificial neural networks (ANNs) to predict the likelihood of achieving a live birth using the proteomic profile of spent culture media and blastocyst morphology. DESIGN: This retrospective cohort study included 212 patients who underwent single blastocyst transfer at IVI Valencia. A single image of each of 186 embryos was studied, and the protein profile was analysed in 81 samples of spent embryo culture medium from patients included in the preimplantation genetic testing programme. The information extracted from the analyses was used as input data for the ANN. The multilayer perceptron and the back-propagation learning method were used to train the ANN. Finally, predictive power was measured using the area under the curve (AUC) of the receiver operating characteristic curve. RESULTS: Three ANN architectures classified most of the embryos correctly as leading (LB+) or not leading (LB-) to a live birth: 100.0% for ANN1 (morphological variables and two proteins), 85.7% for ANN2 (morphological variables and seven proteins), and 83.3% for ANN3 (morphological variables and 25 proteins). The artificial intelligence model using information extracted from blastocyst image analysis and concentrations of interleukin-6 and matrix metalloproteinase-1 was able to predict live birth with an AUC of 1.0. CONCLUSIONS: The model proposed in this preliminary report may provide a promising tool to select the embryo most likely to lead to a live birth in a euploid cohort. The accuracy of prediction demonstrated by this software may improve the efficacy of an assisted reproduction treatment by reducing the number of transfers per patient. Prospective studies are, however, needed.

Differential sperm proteomic profiles according to pregnancy achievement in intracytoplasmic sperm injection cycles: a pilot study.

PURPOSE: To describe the proteomic profiles in semen samples and define the differences in sperm proteomic profiles among samples that ultimately achieved pregnancy (P) via intracytoplasmic sperm injection (ICSI) in an oocyte donation program and those that were unsuccessful (NP). METHODS: Prospective, analytical, observational nested case and control study evaluating the proteomic profile of spermatozoa from patients' ejaculates where pregnancies were (group pregnant (P), n= 4) or were not (group non-pregnant (NP), n=4) achieved after ICSI in an oocyte donation program aiming to standardize female factor. Proteins were separated and analyzed by means of SWATH-MS) and compared between P/NP groups to identify sperm biomarkers of fertility/infertility. Proteins are available via ProteomeXchange. RESULTS: We identified and quantified 2228 proteins, with 37 significantly higher in the P group and 16 higher in NP. Enrichment analysis revealed that the increased proteins in P group sperm were related to motility, anaerobic metabolism, and protein biosynthesis functions, while the increased proteins in the NP group were involved in protein biosynthesis, protein folding, aerobic metabolism, and signal transduction, all of which are functions not previously described as influencing sperm success. Some proteins identified (e.g., SLC2A3, or CD81) are located in the cell membrane and thus may be employed to select spermatozoa by magnetic-activated cell sorting (MACS). CONCLUSION(S): This work revealed differences in the proteomic profiles of sperm samples successful in achieving pregnancy and those that were not, expanding our understanding of sperm function and infertility-related molecular markers, and enabling the future development of male fertility diagnostic tools and therapies.

Fertility technologies and how to optimize laboratory performance to support the shortening of time to birth of a healthy singleton: a Delphi consensus.

PURPOSE: To explore how the assisted reproductive technology (ART) laboratories can be optimized and standardized to enhance embryo culture and selection, to bridge the gap between standard practice and the new concept of shortening time to healthy singleton birth. METHODS: A Delphi consensus was conducted (January to July 2018) to assess how the ART laboratory could be optimized, in conjunction with existing guidelines, to reduce the time to a healthy singleton birth. Eight experts plus the coordinator discussed and refined statements proposed by the coordinator. The statements were distributed via an online survey to 29 participants (including the eight experts from step 1), who voted on their agreement/disagreement with each statement. Consensus was reached if ≥ 66% of participants agreed/disagreed with a statement. If consensus was not achieved for any statement, that statement was revised and the process repeated until consensus was achieved. Details of statements achieving consensus were communicated to the participants. RESULTS: Consensus was achieved for all 13 statements, which underlined the need for professional guidelines and standardization of lab processes to increase laboratory competency and quality. The most important points identified were the improvement of embryo culture and embryo assessment to shorten time to live birth through the availability of more high-quality embryos, priority selection of the most viable embryos and improved cryosurvival. CONCLUSION: The efficiency of the ART laboratory can be improved through professional guidelines on standardized practices and optimized embryo culture environment, assessment, selection and cryopreservation methodologies, thereby reducing the time to a healthy singleton delivery.

Managing the IVF laboratory during a pandemic: international perspectives from laboratory managers.

Fertility societies worldwide responded to the COVID-19 pandemic by recommending that fertility clinics close, or sharply reduce, the clinical operation, leading to a shift in the management of IVF laboratories in three phases: shutdown preparation; maintenance during shutdown; and restart. Each of these phases carries distinct risks that need identification and mitigation, forcing laboratory managers to rethink and adapt their procedures in response to the pandemic. The sudden and unprecedented nature of the pandemic forced laboratory managers from around the world to base decisions on opinion and experience when evidence-based response options were unavailable. These perspectives on pandemic response were presented during a virtual international symposium on COVID-19, held on 3 April 2020, and organized by the London Laboratory Managers' Group. Laboratory managers from seven different countries at different stages of the pandemic (China, Italy, Spain, France, UK, Brazil and Australia) presented their personal experiences to a select audience of experienced laboratory managers from 19 different countries. The intention of this paper is to collect the learnings and considerations from this group of laboratory managers who collaborated to share personal experiences to contribute to the debate surrounding what constitutes good IVF laboratory practice in extraordinary circumstances, such as the COVID-19 pandemic.

Blastocyst collapse as an embryo marker of low implantation potential: a time-lapse multicentre study.

Spontaneous blastocyst collapse during in vitro embryo development has been suggested as a novel marker of embryo quality. Therefore, the aim of this multicentre study was to carry out a retrospective multicentre analysis to investigate the correlation between blastocyst collapse and pregnancy outcome. Here, 1297 intracytoplasmic sperm injection (ICSI)/in vitro fertilization (IVF) fresh cycles, with an elective single blastocyst transfer (eSET) were included in this study. Embryos were cultured individually in 6.0% CO2, 5.0% O2, 89.0% N2, using single step medium (GTLTM VitroLife, Sweden) or sequential medium (CookTM, Cook Medical, Australia) and selected for transfer using standard morphological criteria. With the use of time-lapse monitoring (TLM), blastocysts were analyzed by measuring the maximum volume reduction and defined as having collapsed, if there was ≥ 50% volume reduction from the expanded blastocyst and the collapse event. Following embryo replacement, each blastocyst was retrospectively allocated to one of two groups (collapsed or not collapsed). Here, 259 blastocysts collapsed once or more during development (19.9%) and the remaining 1038 either contracted minimally or not collapsed (80.1%). A significantly higher ongoing pregnancy rate (OPR) of 51.9% (95% CI 48.9-59.9%) was observed when blastocysts that had not collapsed were replaced compared with cycles in which collapsed blastocysts were transferred 37.5% (95% CI 31.6-43.4%). This study suggests that human blastocysts that collapse spontaneously during development are less likely to implant and generate a pregnancy compared with embryos that do not. Although this is a retrospective study, the results demonstrated the utility of collapse episodes as new marker of embryo selection following eSET at blastocyst stage.

AI in the treatment of fertility: key considerations.

Artificial intelligence (AI) has been proposed as a potential tool to help address many of the existing problems related with empirical or subjective assessments of clinical and embryological decision points during the treatment of infertility. AI technologies are reviewed and potential areas of implementation of algorithms are discussed, highlighting the importance of following a proper path for the development and validation of algorithms, including regulatory requirements, and the need for ecosystems containing enough quality data to generate it. As evidenced by the consensus of a group of experts in fertility if properly developed, it is believed that AI algorithms may help practitioners from around the globe to standardize, automate, and improve IVF outcomes for the benefit of patients. Collaboration is required between AI developers and healthcare professionals to make this happen.

Time-lapse imaging: the state of the art†.

The introduction of time-lapse imaging to clinical in vitro fertilization practice enabled the undisturbed monitoring of embryos throughout the entire culture period. Initially, the main objective was to achieve a better embryo development. However, this technology also provided an insight into the novel concept of morphokinetics, parameters regarding embryo cell dynamics. The vast amount of data obtained defined the optimal ranges in the cell-cycle lengths at different stages of embryo development. This added valuable information to embryo assessment prior to transfer. Kinetic markers became part of embryo evaluation strategies with the potential to increase the chances of clinical success. However, none of them has been established as an international standard. The present work aims at describing new approaches into time-lapse: progress to date, challenges, and possible future directions.

Sperm chromosomal abnormalities and their contribution to human embryo aneuploidy.

In this work we reviewed 18 years of experience using fluorescence in situ hybridization (FISH) for sperm aneuploidy testing. We evaluated parameters associated with increased numerical sperm chromosome abnormalities and determined the male contribution to embryo aneploidies in terms of reproductive outcome by increased sperm aneuploidy. This retrospective study analyzed data from 2008 sperm samples of infertile males undergoing FISH analysis because of clinical history of repetitive implantation failure, recurrent miscarriage, impaired sperm parameters, or mixed causes. Sperm concentration was the only sperm parameter associated with FISH results-we observed a gradual increase of abnormal sperm FISH results in males with decreasing sperm concentration. However, a great proportion of normozoospermic males also showed increased sperm aneuploidies, suggesting that sperm parameters alone do not enable identification of a substantial proportion of infertile males at risk of sperm aneuploidies. Regarding reproductive outcomes, couples with normal sperm FISH results for the male had similar outcomes regardless of conventional in vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI), or preimplantation genetic testing for aneuploidies (PGT-A). However, couples with abnormal sperm FISH results for the male showed better clinical outcomes after PGT-A, suggesting a potential contribution of sperm to embryo aneuploidy. Moreover, PGT-A cycles showed better clinical outcomes when 24 chromosomes were analyzed by array comparative genome hybridization (aCGH) or next-generation sequencing (NGS) instead of only nine chromosomes analyzed by FISH. In conclusion, sperm FISH analysis offers clinical prognostic value to evaluate reproductive possibilities in infertile couples. Therefore, couples with abnormal sperm FISH results should be offered genetic counseling and presented with clinical options such as PGT-A.

Effect of oocyte morphology on post-warming survival and embryo development in vitrified autologous oocytes.

RESEARCH QUESTION: Does the presence of dysmorphisms affect post-warming survival and embryo development in vitrified autologous oocytes? DESIGN: A retrospective study comparing post-warming survival, fertilization and embryo development between morphologically normal (n = 269) and dysmorphic oocytes (n = 147). RESULTS: The survival rate was 81.4% in the morphologically normal oocytes and 87.1% in the dysmorphic oocyte group (OR 1.53; 95% CI 0.86 to 2.72). The fertilization rate was 69.9 versus 66.4% (OR 0.85; 95% CI 0.53 to 1.36), the proportion of good-quality embryos on day 3 was 30.3% versus 32.0% (OR 1.08; 95% CI 0.59 to 1.97) and the blastocyst formation rate was 54.5% versus 60.5% (OR 1.27; 95% CI 0.60 to 2.72) for the morphologically normal and the dysmorphic oocytes group, respectively. No statistical differences were found when the number and type of dysmorphism were analysed. CONCLUSION: Oocyte dysmorphisms did not seem to affect survival, fertilization and embryo development in vitrified autologous oocytes, and yielded comparable results to the morphologically normal oocytes.

A Strength, Weaknesses, Opportunities and Threats analysis on time lapse.

PURPOSE OF REVIEW: The study of embryonic development through conventional microscopy has contributed significantly to the success of IVF. However, clinical pregnancy rates per transfer remain as low as 30% according to the latest records of European society if human reproduction and society if assisted reproduction. Considering the increased need to reduce the number of multiple pregnancies, the embryologist is required to improve embryo selection methods to reduce the number of embryos transferred and identify those with the highest implantation potential. This represents a big challenge considering that applying this strategy could jeopardize the overall success rates. New strategies have been proposed including the use of time-lapse systems among others. Although this technology has been used for a decade in IVF labs controversies still exist regarding its potential to substitute conventional morphology for embryo evaluation. RECENT FINDINGS: Lately, different algorithms have been developed correlating embryo kinetics to blastocyst formation, implantation potential, chromosomal content and live birth rate. Moreover, automation and the use of artificial intelligence have recently been introduced to improve this technology. SUMMARY: The present review describes the time-lapse technology and the models available, using a Strength, Weaknesses, Opportunities and Threats analysis based on the clinical experience and published data since 2010.