Cytoplasmic strings in human blastocysts: hypotheses of their role and implications for embryo selection.

STUDY QUESTION: What are the implications of the presence cytoplasmic strings (Cyt-S) and their quantity and dynamics for the pre-implantation development of human blastocysts? SUMMARY ANSWER: Cyt-S are common in human embryos and are associated with faster blastocyst development, larger expansion, and better morphological quality. WHAT IS KNOWN ALREADY: Cyt-S are dynamic cellular projections connecting inner cell mass and trophectoderm (TE) cells, that can be observed during blastocyst expansion. Their prevalence in human embryos has been estimated to be between 44% and 93%. Data relevant to their clinical implications and role in development are lacking, limited, or controversial. STUDY DESIGN, SIZE, DURATION: Retrospective study conducted at a single IVF center between May 2013 and November 2014 and involving 124 pre-implantation genetic testing for aneuploidy cycles in a time-lapse incubator with ≥1 blastocyst biopsied and vitrified (N = 370 embryos assessed). These cycles resulted in 87 vitrified-warmed single-euploid blastocyst transfers. PARTICIPANTS/MATERIALS, SETTING, METHODS: ICSI, continuous blastocyst culture (Days 5-7), TE biopsy of fully expanded blastocysts without Day 3 zona pellucida drilling, qPCR to assess uniform full-chromosome aneuploidies, and vitrification were all performed. Only vitrified-warmed euploid single-embryo-transfers were conducted. Blastocyst morphological quality was defined according to Gardner's criteria. The AI-based software CHLOE™ (Fairtility) automatically registered timings from time of starting blastulation (tSB) to biopsy (t-biopsy, i.e. blastocyst full-expansion) as hours-post-insemination (hpi), embryo area (including zona pellucida in µm2), and spontaneous blastocyst collapses. One senior embryologist manually annotated Cyt-S presence, quantity, timings, and type (thick cell-to-cell connections and/or threads). All significant associations were confirmed through regression analyses. All couples', cycles', and embryos' main features were also tested for associations with Cyt-S presence, quantity, and dynamics. MAIN RESULTS AND THE ROLE OF CHANCE: About 94.3% of the patients (N = 117/124) had ≥1 embryo with Cyt-S. Out of a total of 370 blastocysts, 55 degenerated between blastulation and full-expansion (N = 55/370, 14.9%). The degeneration rate among embryos with ≥1 Cyt-S was 10.8% (N = 33/304), significantly lower than that of embryos without Cyt-S (33.3%, N = 22/66, P < 0.01). Of the remaining 315 viable blastocysts analyzed, 86% (N = 271/315; P < 0.01) had ≥1 Cyt-S, on average 3.5 ± 2.1 per embryo ranging 1-13. The first Cyt-S per viable embryo appeared at 115.3 ± 12.5 hpi (85.7-157.7), corresponding to 10.5 ± 5.8 h (0.5-31) after tSB. Overall, we analyzed 937 Cyt-S showing a mean duration of 3.8 ± 2.7 h (0.3-20.9). Cyt-S were mostly threads (N = 508/937, 54.2%) or thick cell-to-cell connections becoming threads (N = 382/937, 40.8%) than thick bridges (N = 47/937, 5.0%). The presence and quantity of Cyt-S were significantly associated with developmentally faster (on average 6-12 h faster) and more expanded (on average 2700 µm2-larger blastocyst's area at t-biopsy) embryos. Also, the presence and duration of Cyt-S were associated with better morphology. Lastly, while euploidy rates were comparable between blastocysts with and without Cyt-S, all euploid blastocysts transferred from the latter group failed to implant (N = 10). LIMITATIONS, REASONS FOR CAUTION: Cyt-S presence and dynamics were assessed manually on seven focal planes from video frames recorded every 15 min. The patients included were mostly of advanced maternal age. Only associations could be reported, but no causations/consequences. Lastly, larger datasets are required to better assess Cyt-S associations with clinical outcomes. WIDER IMPLICATIONS OF THE FINDINGS: Cyt-S are common during human blastocyst expansion, suggesting their physiological implication in this process. Their presence, quantity and dynamics mirror embryo viability, and morphological quality, yet their role is still unknown. Future basic science studies are encouraged to finally describe Cyt-S molecular nature and biophysical properties, and Artificial Intelligence tools should aid these studies by incorporating Cyt-S assessment. STUDY FUNDING/COMPETING INTEREST(S): None. TRIAL REGISTRATION NUMBER: N/A.

Time will tell: time-lapse technology and artificial intelligence to set time cut-offs indicating embryo incompetence.

STUDY QUESTION: Can more reliable time cut-offs of embryo developmental incompetence be generated by combining time-lapse technology (TLT), artificial intelligence, and preimplantation genetics screening for aneuploidy (PGT-A)? SUMMARY ANSWER: Embryo developmental incompetence can be better predicted by time cut-offs at multiple developmental stages and for different ranges of maternal age. WHAT IS KNOWN ALREADY: TLT is instrumental for the continual and undisturbed observation of embryo development. It has produced morphokinetic algorithms aimed at selecting embryos able to generate a viable pregnancy, however, such efforts have had limited success. Regardless, the potential of this technology for improving multiple aspects of the IVF process remains considerable. Specifically, TLT could be harnessed to discriminate developmentally incompetent embryos: i.e. those unable to develop to the blastocyst stage or affected by full-chromosome meiotic aneuploidies. If proven valuable, this application would prevent the non-productive use of such embryos, thereby improving laboratory and clinical efficiency and reducing patient stress and costs due to unnecessary embryo transfer and cryopreservation. STUDY DESIGN, SIZE, DURATION: The training dataset involved embryos of PGT-A cycles cultured in Embryoscope with a single media (836 euploid and 1179 aneuploid blastocysts and 1874 arrested embryos; 2013-2020). Selection criteria were ejaculated sperm, own (not donated) fresh oocytes, trophectoderm biopsy and comprehensive-chromosome-testing to diagnose uniform aneuploidies. Out-of-sample (30% of training), internal (299 euploid and 490 aneuploid blastocysts and 680 arrested embryos; 2021-2022) and external (97 euploid, 110 aneuploid and 603 untested blastocysts and 514 arrested embryos, 2018 to early 2022) validations were conducted. PARTICIPANTS/MATERIALS, SETTING, METHODS: A training dataset (70%) was used to define thresholds. Several models were generated by fitting outcomes to each timing (tPNa-t8) and maternal age. ROC curves pinpointed in-sample classification values associated with 95%, 99% and 99.99% true-positive rate for predicting incompetence. These values were integrated with upper limits of maternal age ranges (<35, 35-37, 38-40, 41-42, and >42 years) in logit functions to identify time cut-offs, whose accuracy was tested on the validation datasets through confusion matrices. MAIN RESULTS AND THE ROLE OF CHANCE: For developmental (in)competence, the best performing (i) tPNa cut-offs were 27.8 hpi (error-rate: 0/743), 32.6 hpi (error rate: 0/934), 26.8 hpi (error rate: 0/1178), 22.9 hpi (error-rate: 1/654, 0.1%) and 17.2 hpi (error rate: 4/423, 0.9%) in the <35, 35-37, 38-40, 41-42, and >42 years groups, respectively; (ii) tPNf cut-offs were 36.7 hpi (error rate: 0/738), 47.9 hpi (error rate: 0/921), 45.6 hpi (error rate: 1/1156, 0.1%), 44.1 hpi (error rate: 0/647) and 41.8 hpi (error rate: 0/417); (iii) t2 cut-offs were 50.9 hpi (error rate: 0/724), 49 hpi (error rate: 0/915), 47.1 hpi (error rate: 0/1146), 45.8 hpi (error rate: 0/636) and 43.9 hpi (error rate: 0/416); (iv) t4 cut-offs were 66.9 hpi (error rate: 0/683), 80.7 hpi (error rate: 0/836), 77.1 hpi (error rate: 0/1063), 74.7 hpi (error rate: 0/590) and 71.2 hpi (error rate: 0/389); and (v) t8 cut-offs were 118.1 hpi (error rate: 0/619), 110.6 hpi (error rate: 0/772), 140 hpi (error rate: 0/969), 135 hpi (error rate: 0/533) and 127.5 hpi (error rate: 0/355). tPNf and t2 showed a significant association with chromosomal (in)competence, also when adjusted for maternal age. Nevertheless, the relevant cut-offs were found to perform less well and were redundant compared with the blastocyst development cut-offs. LIMITATIONS, REASONS FOR CAUTION: Study limits are its retrospective design and the datasets being unbalanced towards advanced maternal age cases. The potential effects of abnormal cleavage patterns were not assessed. Larger sample sizes and external validations in other clinical settings are warranted. WIDER IMPLICATIONS OF THE FINDINGS: If confirmed by independent studies, this approach could significantly improve the efficiency of ART, by reducing the workload and patient impacts (extended culture and cleavage stage cryopreservation or transfer) associated with embryos that ultimately are developmentally incompetent and should not be considered for treatment. Pending validation, these data might be applied also in static embryo observation settings. STUDY FUNDING/COMPETING INTEREST(S): This study was supported by the participating institutions. The authors have no conflicts of interest to declare. TRIAL REGISTRATION NUMBER: N/A.

Therapeutic management in women with a diminished ovarian reserve: a systematic review and meta-analysis of randomized controlled trials.

IMPORTANCE: The clinical management of women with diminished ovarian reserve (DOR) is a challenge in the field of medically assisted reproduction. Several therapeutic strategies have been proposed, but with mixed results, mainly because the definition of DOR used was inconsistent among trials. OBJECTIVE: To investigate adjuvant treatments and protocols involving only women with DOR according to POSEIDON criteria. DATA SOURCES: We conducted a systematic search using the MEDLINE (PubMed), EMBASE, and ISI Web of Knowledge databases to identify relevant studies published up to June 2024. The review protocol was registered at http://www.crd.york.ac.uk/PROSPERO/ (registration number CRD42022346117). STUDY SELECTION AND SYNTHESIS: After duplication removal, the titles and abstracts of 4,806 articles were scrutinized, and 124 full-text articles were assessed for eligibility. In total, 38 randomized controlled trials were included in the qualitative/quantitative analysis. The following interventions were evaluated: dehydroepiandrosterone (n = 1,336), testosterone (n = 418), high- versus low-dose gonadotropin (n = 957), delayed-start protocol with GnRH antagonist (n = 398), letrozole (n = 612), clomiphene citrate (1,113), growth hormone (311), luteal phase stimulation (n = 57), dual triggering (n = 139), dual stimulation (168), luteinizing hormone (979), oestradiol pre-treatment (n = 552), and corifollitropin alfa (n = 561). RESULTS: Testosterone supplementation is associated with higher live birth rates compared with non-supplemented women among all interventions evaluated (OR 2.19, 95% CI 1.11-4.32, 4 studies, 368 patients; p = 0.02). Testosterone (WMD 0.88, 95% CI 0.03-1.72; 4 studies, n = 368 patients; p = 0.04), DHEA (WMD 0.60, 95% CI 0.07-1.13; 4 studies, n = 418 patients; p = 0.03), high-dose gonadotropin regimen (WMD -1.57, 95% CI -2.12 to -1.17; 2 studies, n = 905 patients; p < 0.0001) and delayed started protocol (WMD 1.32, 95% CI 0.74 to 1.89; 3 studies, n = 398 patients; p < 0.00001) significantly improved the total number of eggs collected. The other interventions did not produce significant improvements. CONCLUSION AND RELEVANCE: Specific interventions such as testosterone seem to correlate with a better live birth rate in women with diminished ovarian reserve; these findings should be further explored in randomized trials.

Female fertility preservation for family planning: a position statement of the Italian Society of Fertility and Sterility and Reproductive Medicine (SIFES-MR).

PURPOSE: This position statement by the Italian Society of Fertility and Sterility and Reproductive Medicine (SIFES-MR) aims to establish an optimal framework for fertility preservation outside the standard before oncological therapies. Key topics include the role of fertility units in comprehensive fertility assessment, factors impacting ovarian potential, available preservation methods, and appropriate criteria for offering such interventions. METHODS: The SIFES-MR writing group comprises Italian reproductive physicians, embryologists, and scientists. The consensus emerged after a six-month period of meetings, including extensive literature review, dialogue among authors and input from society members. Final approval was granted by the SIFES-MR governing council. RESULTS: Fertility counselling transitions from urgent to long-term care, emphasizing family planning. Age, along with ovarian reserve markers, is the primary predictor of female fertility. Various factors, including gynecological conditions, autoimmune disorders, and prior gonadotoxic therapies, may impact ovarian reserve. Oocyte cryopreservation should be the preferred method. Women 30-34 years old and 35-39 years old, without known pathologies impacting the ovarian reserve, should cryopreserve at least 12-13 and 15-20 oocytes to achieve the same chance of a spontaneous live birth they would have if they tried to conceive at the age of cryopreservation (63% and 52%, respectively in the two age groups). CONCLUSIONS: Optimal fertility counselling necessitates a long-term approach, that nurtures an understanding of fertility, facilitates timely evaluation of factors that may affect fertility, and explores fertility preservation choices at opportune intervals.

In vitro fertilization and perinatal outcomes of patients with advanced maternal age after single frozen euploid embryo transfer: a propensity score-matched analysis of autologous and donor cycles.

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.

Extracellular vesicles secreted by cumulus cells contain microRNAs that are potential regulatory factors of mouse oocyte developmental competence.

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.

GnRH agonist trigger in poor prognosis patients undergoing a multicycle approach through DuoStim or consecutive stimulations: a SWOT analysis.

PURPOSE OF REVIEW: Identify the most recent and significant evidence regarding the ovulation trigger within the framework of a multicycle approach through DuoStim, providing valuable insights for improving treatment strategies in patients with a poor prognosis. RECENT FINDINGS: The trigger method plays a pivotal role in optimizing in-vitro fertilization (IVF) stimulation, influencing oocyte retrieval and maturation rates, as well as follicle recruitment in consecutive ovarian stimulations such as double stimulation. Decision-making involves multiple factors and, while guidelines exist for conventional stimulation, specific recommendations for the multicycle approach are not well established. SUMMARY: The different methods for inducing oocyte maturation underscore the need for personalization of IVF protocols. The GnRH agonist trigger induces rapid luteolysis and establishes favorable hormonal conditions that do not adversely affect the recruitment of consecutive follicular waves in the context of DuoStim. It serves as a valid alternative to hCG in freeze-all cycles. This strategy might enhance the safety and flexibility of ovarian stimulations with no impact on oocyte competence and IVF efficacy.

The metrics maze in science: navigating academic evaluation without journalistic pressures.

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.

Does recurrent implantation failure exist? Prevalence and outcomes of five consecutive euploid blastocyst transfers in 123 987 patients.

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.

Oocyte competence is comparable between progestin primed ovarian stimulation with Norethisterone acetate (NETA-PPOS) and GnRH-antagonist protocols: A matched case-control study in PGT-A cycles.

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.

Association between oocyte donors' or recipients' body mass index and clinical outcomes after first single blastocyst transfers-the uterus is the most affected.

OBJECTIVE: To assess whether high body mass index (BMI) in either oocyte donors or recipients is associated with poorer outcomes after the first single blastocyst transfer. DESIGN: Retrospective study including 1,394 first blastocyst single embryo transfers (SETs) conducted by 1,394 recipients during oocyte donation cycles with the gametes retrieved from 1,394 women (January 2019-July 2021). Four BMI clusters were defined for both donors and recipients (underweight: <18.5 kg; normal weight: 18.5-24.9 kg; overweight: 25-29.9 kg; and obese: ≥30 kg). SETTING: Network of private IVF centers. PATIENTS: A total of 1,394 recipients aged 42.4 ± 4.0 and with a BMI of 23.2 ± 3.8 kg/m2, and 1,394 donors aged 26.1 ± 4.2 and with a BMI of 21.9 ± 2.5 kg/m2. INTERVENTION: All oocytes were vitrified at 2 egg banks and warmed at 8 in vitro fertilization clinics that were part of the same network. Intracytoplasmic sperm injection, blastocyst culture, and either fresh or vitrified-warmed SETs were conducted. Putative confounders were investigated, and the data were adjusted through regression analyses. MAIN OUTCOME MEASURES: The primary outcome was the live birth rate (LBR) per SET according to donors' and/or recipients' BMI. The main secondary outcome was the miscarriage rate (<22 gestational weeks) per clinical pregnancy. RESULTS: The LBR per blastocyst SET showed no significant association with donors' BMI. Regarding recipients' BMI, instead, the multivariate odds ratio was significant in obese vs. normal-weight recipients (0.58, 95% confidence interval, 0.37-0.91). The miscarriage rate per clinical pregnancy was also significantly associated with recipients' obesity, with a multivariate odds ratio of 2.31 (95% confidence interval, 1.18-4.51) vs. normal-weight patients. A generalized additive model method was used to represent the relationship between predicted LBR or miscarriage rates and donors' or recipients' BMI; it pictured a scenario where the former outcome moderately but continuously decreases with increasing recipients' BMI to then sharply decline in the BMI range of 25-35 kg/m2. The miscarriage rate, instead, increases almost linearly with respect to both donors' and recipients' increasing BMI. CONCLUSION: Obesity mostly affects the uterus, especially because of higher miscarriage rates. Yet, poorer outcomes can be appreciated already with a BMI of 25 kg/m2 in both oocyte donors and recipients. Finer markers of nutritional homeostasis are therefore desirable; recipients should be counseled about poorer expected outcomes in cases of overweight and obesity; and oocyte banks should avoid assigning oocytes from overweight donors to overweight and obese recipients.

How should the best human embryo in vitro be? Current and future challenges for embryo selection.

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.

Innovative Strategies for Fertility Preservation in Female Cancer Survivors: New Hope from Artificial Ovary Construction and Stem Cell-Derived Neo-Folliculogenesis.

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.

Cryostorage management of reproductive cells and tissues in ART: status, needs, opportunities and potential new challenges.

Among the wide range of procedures performed by clinical embryologists, the cryopreservation of reproductive cells and tissues represents a fundamental task in the daily routine. Indeed, cryopreservation procedures can be considered a subspecialty of medically assisted reproductive technology (ART), having the same relevance as sperm injection or embryo biopsy for preimplantation genetic testing. However, although a great deal of care has been devoted to optimizing cryopreservation protocols, the same energy has only recently been spent on developing and implementing strategies for the safe and reliable storage and transport of reproductive specimens. Herein, we have summarized the content of the available guidelines, the risks, the needs and the future perspectives regarding the management of cryopreservation biorepositories used in ART.

Opening the black box: why do euploid blastocysts fail to implant? A systematic review and meta-analysis.

BACKGROUND: A normal chromosomal constitution defined through PGT-A assessing all chromosomes on trophectoderm (TE) biopsies represents the strongest predictor of embryo implantation. Yet, its positive predictive value is not higher than 50-60%. This gap of knowledge on the causes of euploid blastocysts' reproductive failure is known as 'the black box of implantation'. OBJECTIVE AND RATIONALE: Several embryonic, maternal, paternal, clinical, and IVF laboratory features were scrutinized for their putative association with reproductive success or implantation failure of euploid blastocysts. SEARCH METHODS: A systematic bibliographical search was conducted without temporal limits up to August 2021. The keywords were '(blastocyst OR day5 embryo OR day6 embryo OR day7 embryo) AND (euploid OR chromosomally normal OR preimplantation genetic testing) AND (implantation OR implantation failure OR miscarriage OR abortion OR live birth OR biochemical pregnancy OR recurrent implantation failure)'. Overall, 1608 items were identified and screened. We included all prospective or retrospective clinical studies and randomized-controlled-trials (RCTs) that assessed any feature associated with live-birth rates (LBR) and/or miscarriage rates (MR) among non-mosaic euploid blastocyst transfer after TE biopsy and PGT-A. In total, 41 reviews and 372 papers were selected, clustered according to a common focus, and thoroughly reviewed. The PRISMA guideline was followed, the PICO model was adopted, and ROBINS-I and ROB 2.0 scoring were used to assess putative bias. Bias across studies regarding the LBR was also assessed using visual inspection of funnel plots and the trim and fill method. Categorical data were combined with a pooled-OR. The random-effect model was used to conduct the meta-analysis. Between-study heterogeneity was addressed using I2. Whenever not suitable for the meta-analysis, the included studies were simply described for their results. The study protocol was registered at http://www.crd.york.ac.uk/PROSPERO/ (registration number CRD42021275329). OUTCOMES: We included 372 original papers (335 retrospective studies, 30 prospective studies and 7 RCTs) and 41 reviews. However, most of the studies were retrospective, or characterized by small sample sizes, thus prone to bias, which reduces the quality of the evidence to low or very low. Reduced inner cell mass (7 studies, OR: 0.37, 95% CI: 0.27-0.52, I2 = 53%), or TE quality (9 studies, OR: 0.53, 95% CI: 0.43-0.67, I2 = 70%), overall blastocyst quality worse than Gardner's BB-grade (8 studies, OR: 0.40, 95% CI: 0.24-0.67, I2 = 83%), developmental delay (18 studies, OR: 0.56, 95% CI: 0.49-0.63, I2 = 47%), and (by qualitative analysis) some morphodynamic abnormalities pinpointed through time-lapse microscopy (abnormal cleavage patterns, spontaneous blastocyst collapse, longer time of morula formation I, time of blastulation (tB), and duration of blastulation) were all associated with poorer reproductive outcomes. Slightly lower LBR, even in the context of PGT-A, was reported among women ≥38 years (7 studies, OR: 0.87, 95% CI: 0.75-1.00, I2 = 31%), while obesity was associated with both lower LBR (2 studies, OR: 0.66, 95% CI: 0.55-0.79, I2 = 0%) and higher MR (2 studies, OR: 1.8, 95% CI: 1.08-2.99, I2 = 52%). The experience of previous repeated implantation failures (RIF) was also associated with lower LBR (3 studies, OR: 0.72, 95% CI: 0.55-0.93, I2 = 0%). By qualitative analysis, among hormonal assessments, only abnormal progesterone levels prior to transfer were associated with LBR and MR after PGT-A. Among the clinical protocols used, vitrified-warmed embryo transfer was more effective than fresh transfer (2 studies, OR: 1.56, 95% CI: 1.05-2.33, I2 = 23%) after PGT-A. Lastly, multiple vitrification-warming cycles (2 studies, OR: 0.41, 95% CI: 0.22-0.77, I2 = 50%) or (by qualitative analysis) a high number of cells biopsied may slightly reduce the LBR, while simultaneous zona-pellucida opening and TE biopsy allowed better results than the Day 3 hatching-based protocol (3 studies, OR: 1.41, 95% CI: 1.18-1.69, I2 = 0%). WIDER IMPLICATIONS: Embryo selection aims at shortening the time-to-pregnancy, while minimizing the reproductive risks. Knowing which features are associated with the reproductive competence of euploid blastocysts is therefore critical to define, implement, and validate safer and more efficient clinical workflows. Future research should be directed towards: (i) systematic investigations of the mechanisms involved in reproductive aging beyond de novo chromosomal abnormalities, and how lifestyle and nutrition may accelerate or exacerbate their consequences; (ii) improved evaluation of the uterine and blastocyst-endometrial dialogue, both of which represent black boxes themselves; (iii) standardization/automation of embryo assessment and IVF protocols; (iv) additional invasive or preferably non-invasive tools for embryo selection. Only by filling these gaps we may finally crack the riddle behind 'the black box of implantation'.

Clinical and laboratory key performance indicators in IVF: A consensus between the Italian Society of Fertility and Sterility and Reproductive Medicine (SIFES-MR) and the Italian Society of Embryology, Reproduction and Research (SIERR).

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.

Double stimulation for the management of poor-prognosis patients: where are we going?

PURPOSE OF REVIEW: The technical improvements in IVF allowed the implementation of nonconventional ovarian stimulation protocols for some specific patients. Where time is crucial, such as with oncologic patients, poor-prognosis patients, patients with low ovarian reserve, and those with advanced maternal age, access to IVF treatment is even more critical. Some of these protocols might start in the late follicular phase, luteal phase, or involve both stimulations within the same ovarian cycle. RECENT FINDINGS: Until now, published evidence showed that oocytes retrieved from unconventional protocol seem to be developmentally, genetically, and reproductively competent. Second stimulation in the same ovarian cycle after the conventional approach may represent a sound alternative to oocyte accumulation. This can be proposed in progress after careful counselling focused on the patients' chances of finding at least one euploid embryo on account of their age and of the number of blastocysts obtained after the conventional approach. SUMMARY: The adoption of these new strategies, known as double stimulation protocol, can be conceived as a real full-personalization of ovarian stimulation. Multicentre prospective RCTs are urgently needed to evaluate the efficacy, efficiency, and costs of double stimulation versus two consecutive conventional approaches with standard or mild stimulation and in a different IVF setting.