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OBJECTIVE: To evaluate in vitro fertilization (IVF) and perinatal outcomes of donor egg and autologous cycles in patients with advanced reproductive age after undergoing single frozen euploid embryo transfer. DESIGN: A multicenter, retrospective, cohort study. SETTING: University-affiliated and private IVF centers. PATIENT(S): Patients aged 39-46 years who underwent IVF with intracytoplasmic sperm injection and preimplantation genetic testing for aneuploidy using whole-chromosome sequencing with donor (n = 278) or autologous (n = 278) oocytes between October 2017 and October 2021. INTERVENTION(S): Single frozen euploid embryo transfer with donor or autologous euploid embryo. MAIN OUTCOME MEASURE(S): The main outcome measure was the live birth rate (LBR) after the first embryo transfer, calculated per embryo transfer. The secondary outcomes included the implantation rate, ectopic pregnancy rate, miscarriage rate, and gestational age and birth weight at the time of delivery. RESULT(S): Patients using donor or autologous oocytes had a similar likelihood of implantation (57.91% [51.87-63.78] vs. 57.19% [51.15-63.09]) and LBR (41.01% [95% confidence interval {CI}, 35.17-47.04] vs. 42.45% [95% CI, 36.56-48.49]). Furthermore, there were no significant differences in the ectopic pregnancy rate (0.72% [0.09-2.57] vs. 0.36% [0.01-1.99]), miscarriage rate (16.19% [12.06-21.05] vs. 14.39% [95% CI, 10.48-19.08]), gestational age (38.50 [38.08-38.92] vs. 39.16 [38.25-40.07] weeks), or birth weight of infants (2,982.25 [2,606.69-3,357.81] vs. 3,128.24 [2,962.30-3,294.17] kg). The univariate analysis showed no association between advanced maternal age and the LBR (relative risk, 1.03 [95% CI, 0.84-1.25]). Multivariate analysis using putative confounders for embryo competency found no associations with LBR (adjusted relative risk, 1.22 [95% CI, 0.75-1.98]). CONCLUSION(S): Patients with euploid blastocysts derived from donor or autologous oocytes did not reveal statistically significant differences in the LBR, implantation rate, ectopic pregnancy rate, miscarriage rate, duration of gestation, or infant birth weight. These findings suggest that age-related reproductive decline and/or poor IVF outcomes associated with women with advanced reproductive age undergoing IVF are heavily driven by embryonic aneuploidy.
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The role of cumulus cells (CCs) in the acquisition of oocyte developmental competence is not yet fully understood. In a previous study, we matured cumulus-denuded fully-grown mouse oocytes to metaphase II (MII) on a feeder layer of CCs (FL-CCs) isolated from developmentally competent (FL-SN-CCs) or incompetent (FL-NSN-CCs) SN (surrounded nucleolus) or NSN (not surrounding nucleolus) oocytes, respectively. We observed that oocytes cultured on the former could develop into blastocysts, while those matured on the latter arrested at the 2-cell stage. To investigate the CC factors contributing to oocyte developmental competence, here we focused on the CCs' release into the medium of extracellular vesicles (EVs) and on their miRNA content. We found that, during the 15-h transition to MII, both FL-SN-CCs and FL-NSN-CCs release EVs that can be detected, by confocal microscopy, inside the zona pellucida (ZP) or the ooplasm. The majority of EVs are <200 nm in size, which is compatible with their ability to cross the ZP. Next-generation sequencing of the miRNome of FL-SN-CC versus FL-NSN-CC EVs highlighted 74 differentially expressed miRNAs, with 43 up- and 31 down-regulated. Although most of these miRNAs do not have known roles in the ovary, in silico functional analysis showed that seven of these miRNAs regulate 71 target genes with specific roles in meiosis resumption (N = 24), follicle growth (N = 23), fertilization (N = 1), and the acquisition of oocyte developmental competence (N = 23). Overall, our results indicate CC EVs as emerging candidates of the CC-to-oocyte communication axis and uncover a group of miRNAs as potential regulatory factors.
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Células do Cúmulo , Vesículas Extracelulares , MicroRNAs , Oócitos , Animais , Células do Cúmulo/metabolismo , Vesículas Extracelulares/metabolismo , Vesículas Extracelulares/genética , Oócitos/metabolismo , MicroRNAs/metabolismo , MicroRNAs/genética , Camundongos , Feminino , Técnicas de Maturação in Vitro de Oócitos , Oogênese/genética , Zona Pelúcida/metabolismoRESUMO
In recent years a troubling trend has emerged in the medical research field, notably in reproductive medicine, manifesting an increased emphasis on quantity over quality in articles published. The pressure to collect copious publication records risks compromising meticulous expertise and impactful contributions. This tendency is exemplified by the rise of 'hyper-prolific researchers' publishing at an extraordinary rate (i.e. every 5 days), prompting a deeper analysis of the reasons underlying this behaviour. Prioritizing rapid publication over Galileo Galilei's systematic scientific principles may lead to a superficial approach driven by quantitative targets. Thus, the overreliance on metrics to facilitate academic careers has shifted the focus to numerical quantification rather than the real scientific contribution, raising concerns about the effectiveness of the evaluation systems. The Hamletian question is: are we scientist or journalist? Addressing these issues could necessitate a crucial re-evaluation of the assessment criteria, emphasizing a balance between quantity and quality to foster an academic environment that values meaningful contributions and innovation.
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Editoração , Humanos , Pesquisa Biomédica , Bibliometria , Medicina Reprodutiva , Fator de Impacto de RevistasRESUMO
STUDY QUESTION: What are the clinical pregnancy and live birth rates in women who underwent up to two more euploid blastocyst transfers after three failures in the absence of another known factor that affects implantation? SUMMARY ANSWER: The fourth and fifth euploid blastocyst transfers resulted in similar live birth rates of 40% and 53.3%, respectively, culminating in a cumulative live birth rate of 98.1% (95% CI = 96.5-99.6%) after five euploid blastocyst transfers. WHAT IS KNOWN ALREADY: The first three euploid blastocysts have similar implantation and live birth rates and provide a cumulative live birth rate of 92.6%. STUDY DESIGN, SIZE, DURATION: An international multi-center retrospective study was conducted at 25 individual clinics. The study period spanned between January 2012 and December 2022. A total of 123 987 patients with a total of 64 572 euploid blastocyst transfers were screened for inclusion. PARTICIPANTS/MATERIALS, SETTING, METHODS: Patients with a history of any embryo transfer at another clinic, history of any unscreened embryo transfer at participating clinics, parental karyotype abnormalities, the use of donor oocytes or a gestational carrier, untreated intracavitary uterine pathology (e.g. polyp, leiomyoma), congenital uterine anomalies, adenomyosis, communicating hydrosalpinx, endometrial thickness <6 mm prior to initiating of progesterone, use of testicular sperm due to non-obstructive azoospermia in the male partner, transfer of an embryo with a reported intermediate chromosome copy number (i.e. mosaic), preimplantation genetic testing cycles for monogenic disorders, or structural chromosome rearrangements were excluded. Ovarian stimulation protocols and embryology laboratory procedures including trophectoderm biopsy followed the usual practice of each center. The ploidy status of blastocysts was determined with comprehensive chromosome screening. Endometrial preparation protocols followed the usual practice of participating centers and included programmed cycles, natural or modified natural cycles. MAIN RESULTS AND THE ROLE OF CHANCE: A total of 105 (0.085% of the total population) patients met the criteria and underwent at least one additional euploid blastocyst transfer after failing to achieve a positive pregnancy test with three consecutive euploid blastocyst transfers. Outcomes of the fourth and fifth euploid blastocyst transfers were similar across participating centers. Overall, the live birth rate was similar with the fourth and fifth euploid blastocysts (40% vs 53.3%, relative risk = 1.33, 95% CI = 0.93-1.9, P value = 0.14). Sensitivity analyses excluding blastocysts biopsied on Day 7 postfertilization, women with a BMI >30 kg/m2, cycles using non-ejaculate or donor sperm, double-embryo transfer cycles, and cycles in which the day of embryo transfer was modified due to endometrial receptivity assay test result yielded similar results. Where data were available, the fourth euploid blastocyst had similar live birth rate with the first one (relative risk = 0.84, 95% CI = 0.58-1.21, P = 0.29). The cumulative live birth rate after five euploid blastocyst transfers was 98.1% (95% CI = 96.5-99.6%). LIMITATIONS, REASONS FOR CAUTION: Retrospective design has its own inherent limitations. Patients continuing with a further euploid embryo transfer and patients dropping out from treatment after three failed euploid transfers can be systematically different, perhaps with regard to ovarian reserve or economic status. WIDER IMPLICATION OF THE FINDINGS: Implantation failure seems to be mainly due to embryonic factors. Given the stable and high live birth rates up to five euploid blastocysts, unexplained recurrent implantation failure should have a prevalence of <2%. Proceeding with another embryo transfer can be the best next step once a known etiology for implantation failure is ruled out. STUDY FUNDING/COMPETING INTEREST(S): None. TRIAL REGISTRATION NUMBER: N/A.
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Implantação do Embrião , Transferência Embrionária , Taxa de Gravidez , Humanos , Feminino , Gravidez , Estudos Retrospectivos , Transferência Embrionária/métodos , Transferência Embrionária/estatística & dados numéricos , Adulto , Prevalência , Coeficiente de Natalidade , Nascido Vivo , Falha de Tratamento , Blastocisto , Fertilização in vitro/métodos , Fertilização in vitro/estatística & dados numéricos , Resultado da Gravidez/epidemiologiaRESUMO
RESEARCH QUESTION: Can a novel classification system of the infertile male - 'APHRODITE' (Addressing male Patients with Hypogonadism and/or infeRtility Owing to altereD, Idiopathic TEsticular function) - stratify different subgroups of male infertility to help scientists to design clinical trials on the hormonal treatment of male infertility, and clinicians to counsel and treat the endocrinological imbalances in men and, ultimately, increase the chances of natural and assisted conception? DESIGN: A collaboration between andrologists, reproductive urologists and gynaecologists, with specialization in reproductive medicine and expertise in male infertility, led to the development of the APHRODITE criteria through an iterative consensus process based on clinical patient descriptions and the results of routine laboratory tests, including semen analysis and hormonal testing. RESULTS: Five patient groups were delineated according to the APHRODITE criteria; (1) Hypogonadotrophic hypogonadism (acquired and congenital); (2) Idiopathic male infertility with lowered semen analysis parameters, normal serum FSH and normal serum total testosterone concentrations; (3) A hypogonadal state with lowered semen analysis parameters, normal FSH and reduced total testosterone concentrations; (4) Lowered semen analysis parameters, elevated FSH concentrations and reduced or normal total testosterone concentrations; and (5) Unexplained male infertility in the context of unexplained couple infertility. CONCLUSION: The APHRODITE criteria offer a novel and standardized patient stratification system for male infertility independent of aetiology and/or altered spermatogenesis, facilitating communication among clinicians, researchers and patients to improve reproductive outcomes following hormonal therapy. APHRODITE is proposed as a basis for future trials of the hormonal treatment of male infertility.
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Hipogonadismo , Infertilidade Masculina , Humanos , Masculino , Infertilidade Masculina/terapia , Hipogonadismo/complicações , Hipogonadismo/tratamento farmacológico , Análise do Sêmen/métodos , Testosterona/uso terapêutico , Hormônio FoliculoestimulanteRESUMO
OBJECTIVE: To outline oocyte competence after progestin primed ovarian stimulation with Norethisterone acetate (NETA-PPOS) compared to conventional GnRH-antagonist protocol. STUDY DESIGN: Retrospective matched case-control study involving advanced-maternal-age women undergoing ICSI with PGT-A. 89 NETA-PPOS were matched with 178 control patients based on maternal age and ovarian reserve biomarkers. Both groups underwent recombinant-FSH OS with GnRH-agonist ovulation trigger and collected ≥1 MII. In the study group, NETA (10 mg/day) was administered orally starting from day2 of the menstrual cycle. Euploid blastocyst rate per cohort of metaphase-II oocytes (EBR per MII) was the primary outcome. All other embryological and clinical outcomes were reported. Gestational age, birthweight and length were also assessed. RESULTS: The EBR per MII was comparable among PPOS and control (13.9 % ± 19.3 % versus 13.3 % ± 17.9 %; the sample size allowed to exclude up to a 10 % difference). Blastocysts morphology and developmental rate were similar. No difference was reported for all clinical outcomes among the 61 and 107 vitrified-warmed euploid single blastocyst transfers respectively conducted. The cumulative live birth delivery rate per concluded cycles was also comparable (24.7 % versus 21.9 %). Neonatal outcomes were analogous. CONCLUSIONS: Oocyte competence after NETA-PPOS and standard OS is comparable. This evidence is reassuring and, because of its lower cost and possibly higher patients' compliance, supports PPOS administration whenever the patients are indicated to freeze-all (e.g., fertility preservation, PGT-A, oocyte donation). More data are required about follicle recruitment, oocyte yield, gestational and perinatal outcomes. Randomized-controlled-trials are advisable to confirm our evidence.
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Indução da Ovulação , Progestinas , Gravidez , Recém-Nascido , Humanos , Feminino , Acetato de Noretindrona , Estudos de Casos e Controles , Estudos Retrospectivos , Indução da Ovulação/métodos , Oócitos/fisiologia , Esteroides , Antagonistas de Hormônios , Hormônio Liberador de Gonadotropina , Fertilização in vitro/métodosRESUMO
In-vitro fertilization (IVF) aims at overcoming the causes of infertility and lead to a healthy live birth. To maximize IVF efficiency, it is critical to identify and transfer the most competent embryo within a cohort produced by a couple during a cycle. Conventional static embryo morphological assessment involves sequential observations under a light microscope at specific timepoints. The introduction of time-lapse technology enhanced morphological evaluation via the continuous monitoring of embryo preimplantation in vitro development, thereby unveiling features otherwise undetectable via multiple static assessments. Although an association exists, blastocyst morphology poorly predicts chromosomal competence. In fact, the only reliable approach currently available to diagnose the embryonic karyotype is trophectoderm biopsy and comprehensive chromosome testing to assess non-mosaic aneuploidies, namely preimplantation genetic testing for aneuploidies (PGT-A). Lately, the focus is shifting towards the fine-tuning of non-invasive technologies, such as "omic" analyses of waste products of IVF (e.g., spent culture media) and/or artificial intelligence-powered morphologic/morphodynamic evaluations. This review summarizes the main tools currently available to assess (or predict) embryo developmental, chromosomal, and reproductive competence, their strengths, the limitations, and the most probable future challenges.
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Inteligência Artificial , Blastocisto , Humanos , Blastocisto/patologia , Testes Genéticos , Fertilização in vitro , AneuploidiaRESUMO
Recent advances in anticancer treatment have significantly improved the survival rate of young females; unfortunately, in about one third of cancer survivors the risk of ovarian insufficiency and infertility is still quite relevant. As the possibility of becoming a mother after recovery from a juvenile cancer is an important part of the quality of life, several procedures to preserve fertility have been developed: ovarian surgical transposition, induction of ovarian quiescence by gonadotropin-releasing hormone agonists (GnRH-a) treatment, and oocyte and/or ovarian cortical tissue cryopreservation. Ovarian tissue cryostorage and allografting is a valuable technique that applies even to prepubertal girls; however, some patients cannot benefit from it due to the high risk of reintroducing cancer cells during allograft in cases of ovary-metastasizing neoplasias, such as leukemias or NH lymphomas. Innovative techniques are now under investigation, as in the construction of an artificial ovary made of isolated follicles inserted into an artificial matrix scaffold, and the use of stem cells, including ovarian stem cells (OSCs), to obtain neo-folliculogenesis and the development of fertilizable oocytes from the exhausted ovarian tissue. This review synthesizes and discusses these innovative techniques, which potentially represent interesting strategies in oncofertility programs and a new hope for young female cancer survivors.
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Ciclo Menstrual , Tempo para Engravidar , Gravidez , Feminino , Humanos , Análise Custo-Benefício , Fertilização in vitroAssuntos
Fertilização in vitro , Indução da Ovulação , Humanos , Gravidez , Feminino , Taxa de GravidezRESUMO
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'.
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Aborto Espontâneo , Diagnóstico Pré-Implantação , Gravidez , Feminino , Humanos , Implantação do Embrião , Blastocisto , Transferência Embrionária/métodos , Testes Genéticos/métodos , Estudos Retrospectivos , Aneuploidia , Taxa de Gravidez , Diagnóstico Pré-Implantação/métodosRESUMO
PURPOSE: To investigate whether high relative humidity conditions (HC), when using a time-lapse system (TLS) with sequential culture media, are beneficial to embryo culture, improving ongoing pregnancy rates. METHODS: We included patients undergoing their first ICSI cycle treatment from April 2021 to May 2022. Patients assigned to dry conditions (DC) or HC were 278 and 218, respectively. We used a GERI TLS, three chambers configured in humidity conditions and three in dry conditions. The effect of HC on ongoing pregnancy rate was assessed by the propensity matched sample, to reduce potential differences between women undergoing either HC or DC and reduce biased estimation of treatment effect. RESULT: After adjusting for several confounding variables and applying the propensity score (PS), no significant differences were observed in the rates of normal (2PN) and abnormal (1PN and 3PN) fertilization, blastulation, top-quality blastocysts, frozen blastocysts, ongoing pregnancies, and miscarriages. The 2-cell (t2) and 4-cell (t4) stages and cell divisions between such stages occurred earlier and were more synchronous in the in DC. CONCLUSION: These results suggest that HC conditions do not improve the rate of ongoing pregnancy and several embryological outcomes, under the conditions used in this study based on a time-lapse system and sequential culture with day 3 medium change-over.
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Desenvolvimento Embrionário , Fertilização in vitro , Gravidez , Humanos , Feminino , Taxa de Gravidez , Estudos Retrospectivos , Fertilização in vitro/métodos , Injeções de Esperma Intracitoplásmicas/métodos , Imagem com Lapso de Tempo , Pontuação de Propensão , Blastocisto , Técnicas de Cultura Embrionária/métodosRESUMO
PURPOSE: Infertility is increasing worldwide, and many couples seek IVF. Clinical management and laboratory work are fundamental in the IVF journey. Therefore, the definition of reliable key performance indicators (KPIs) based on clinical and laboratory parameters, is essential for internal quality control (IQC). Laboratory performance indicators have been identified and a first attempt to also determine clinical ones has been recently published. However, more detailed indicators are required. METHODS: An Italian group of experts in Reproductive Medicine from both public and private clinics on behalf of SIFES-MR and SIERR was established to define IVF indicators to monitor clinical performance. RESULTS: The working group built a consensus on a list of KPIs, performance indicators (PIs) and recommendation indicators (RIs). When deemed necessary, the reference population was stratified by woman age, response to ovarian stimulation and adoption of preimplantation genetic testing for aneuploidies (PGT-A). Each indicator was scored with a value from 1 to 5 and a weighted average formula - considering all the suggested parameters-was defined. This formula generates a center performance score, indicating low, average, good, or excellent performance. CONCLUSION: This study is intended to provide KPIs, PIs and RIs that encompass several essential aspects of a modern IVF clinic, including quality control and constant monitoring of clinical and embryological features. These indicators could be used to assess the quality of each center with the aim of improving efficacy and efficiency in IVF.
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Infertilidade , Medicina Reprodutiva , Feminino , Humanos , Consenso , Infertilidade/terapia , Itália , Fertilidade , Fertilização in vitro , ReproduçãoRESUMO
Human embryos are very frequently affected by maternally inherited aneuploidies, which in the vast majority of cases determine developmental failure at pre- or post-implantation stages. However, recent evidence, generated by the alliance between diverse technologies now routinely employed in the IVF laboratory, has revealed a broader, more complex scenario. Aberrant patterns occurring at the cellular or molecular level can impact at multiple stages of the trajectory of development to blastocyst. In this context, fertilization is an extremely delicate phase, as it marks the transition between gametic and embryonic life. Centrosomes, essential for mitosis, are assembled ex novo from components of both parents. Very large and initially distant nuclei (the pronuclei) are brought together and positioned centrally. The overall cell arrangement is converted from being asymmetric to symmetric. The maternal and paternal chromosome sets, initially separate and scattered within their respective pronuclei, become clustered where the pronuclei juxtapose, to facilitate their assembly in the mitotic spindle. The meiotic spindle is replaced by a segregation machinery that may form as a transient or persistent dual mitotic spindle. Maternal proteins assist the decay of maternal mRNAs to allow the translation of newly synthesized zygotic transcripts. The diversity and complexity of these events, regulated in a precise temporal order and occurring in narrow time windows, make fertilization a highly error-prone process. As a consequence, at the first mitotic division, cellular or genomic integrity may be lost, with fatal consequences for embryonic development.
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Núcleo Celular , Zigoto , Gravidez , Feminino , Humanos , Núcleo Celular/metabolismo , Desenvolvimento Embrionário/genética , Cromossomos , Mitose , Fuso AcromáticoRESUMO
Preimplantation genetic testing for aneuploidies (PGT-A) is arguably the most effective embryo selection strategy. Nevertheless, it requires greater workload, costs, and expertise. Therefore, a quest towards user-friendly, non-invasive strategies is ongoing. Although insufficient to replace PGT-A, embryo morphological evaluation is significantly associated with embryonic competence, but scarcely reproducible. Recently, artificial intelligence-powered analyses have been proposed to objectify and automate image evaluations. iDAScore v1.0 is a deep-learning model based on a 3D convolutional neural network trained on time-lapse videos from implanted and non-implanted blastocysts. It is a decision support system for ranking blastocysts without manual input. This retrospective, pre-clinical, external validation included 3604 blastocysts and 808 euploid transfers from 1232 cycles. All blastocysts were retrospectively assessed through the iDAScore v1.0; therefore, it did not influence embryologists' decision-making process. iDAScore v1.0 was significantly associated with embryo morphology and competence, although AUCs for euploidy and live-birth prediction were 0.60 and 0.66, respectively, which is rather comparable to embryologists' performance. Nevertheless, iDAScore v1.0 is objective and reproducible, while embryologists' evaluations are not. In a retrospective simulation, iDAScore v1.0 would have ranked euploid blastocysts as top quality in 63% of cases with one or more euploid and aneuploid blastocysts, and it would have questioned embryologists' ranking in 48% of cases with two or more euploid blastocysts and one or more live birth. Therefore, iDAScore v1.0 may objectify embryologists' evaluations, but randomized controlled trials are required to assess its clinical value.