Looking past the appearance: a comprehensive description of the clinical contribution of poor-quality blastocysts to increase live birth rates during cycles with aneuploidy testing

Preimplantation genetic testing for aneuploidy: predictive embryonic factors

PURPOSE

In a preimplantation genetic testing for aneuploidy (PGT-A) cycle, does the blastocyst quality before biopsy, or the day of biopsy, or the embryo hatching status have an impact on either euploidy or the rate of embryo survival after freezing?

METHODS

This was a retrospective study including 6130 biopsied blastocysts coming from 1849 PGT-A cycles performed in our center (2016-2022). Embryos were categorized according to the inner cell mass and trophectoderm quality, using Gardner's scoring (excellent: AA; good: AB, BA, BB; poor: AC, CA, BC, CB, CC); the day of biopsy (5 or 6); and their hatching status (fully hatched blastocysts [FHB] or non-fully hatched blastocysts [nFHB]). The independent relationship between each group and both euploidy and survival rate was assessed.

RESULTS

Excellent-quality embryos were more euploid than both good- and poor-quality embryos (52.69%, 39.69%, and 26.21%; p < 0.001), and day 5-biopsied embryos were more euploid than day 6-biopsied embryos (39.98% and 34.80%; p < 0.001). Survival rates of excellent-quality (92.26%) and good-quality (92.47%) embryos were higher than survival rates in the poor-quality group (84.61%) (p = 0.011 and p = 0.002). Day 5-biopsied embryos survived better than day 6-biopsied embryos (93.71% vs. 83.69%; p < 0.001) and FHB had poorer survival than nFHB (78.61% vs. 93.52%; p < 0.001).

CONCLUSIONS

Excellent-quality and day 5-biopsied embryos are more prone to be euploid than good and poor or day 6-biopsied embryos, respectively. Poor-quality, day 6-biopsied embryos, and FHB have significantly lower survival after biopsy and vitrification.

Which factors affect the live birth outcome of the first single euploid frozen-thawed blastocyst transfer in couples with balanced chromosomal translocations?

Objective

The objective of this study is to investigate the factors that influence the live birth rate (LBR) of the first single euploid frozen-thawed blastocyst transfer (FBT) cycles after preimplantation genetic testing for structural rearrangements (PGT-SR) in couples with balanced chromosomal translocations (BCT).

Design

Single center, retrospective and observational study.

Methods

A total of 336 PGT-SR and the first single euploid FBT cycles between July 2016 and December 2022 were included in this study. The patients were divided into two groups according to the live birth outcomes. The parameters of the study population, controlled ovarian stimulation cycles, and FBT cycles were analyzed. Multivariable binary logistic regression was performed to find the factors that affected the LBR.

Results

The percentage of blastocysts at developmental stage Day 5 compared to Day 6 (51.8% vs. 30.8%; P<0.001) and with morphology ≥BB compared to

Conclusion

The developmental stage and morphology of blastocyst affect the live birth outcome of the first single euploid FBT in BCT carriers undergoing PGT-SR.

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Key Words

• balanced chromosomal translocations
• euploid
• frozen-thawed blastocyst transfer
• live birth
• preimplantation genetic testing for structural rearrangements (PGT-SR)

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MESH Headings

• Humans
• Female
• Pregnancy
• Retrospective Studies
• Live Birth
• Translocation, Genetic
• Adult
• Embryo Transfer/methods
• Male
• Cryopreservation
• Pregnancy Rate
• Preimplantation Diagnosis/methods
• Birth Rate
• Fertilization in Vitro/methods
• Pregnancy Outcome
• Blastocyst
• Ovulation Induction/methods

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Affiliation(s)

Ruixiao Zhang Reproductive Medicine Center, Henan Provincial People’s Hospital, Zhengzhou, China Reproductive Medicine Center, Zhengzhou University People’s Hospital, Zhengzhou, China Reproductive Medicine Center, Henan University People’s Hospital, Zhengzhou, China
Yahui Hu Reproductive Medicine Center, Henan Provincial People’s Hospital, Zhengzhou, China Reproductive Medicine Center, Zhengzhou University People’s Hospital, Zhengzhou, China Reproductive Medicine Center, Henan University People’s Hospital, Zhengzhou, China
Chenchen Cui Reproductive Medicine Center, Henan Provincial People’s Hospital, Zhengzhou, China Reproductive Medicine Center, Zhengzhou University People’s Hospital, Zhengzhou, China Reproductive Medicine Center, Henan University People’s Hospital, Zhengzhou, China
Cuilian Zhang Reproductive Medicine Center, Henan Provincial People’s Hospital, Zhengzhou, China Reproductive Medicine Center, Zhengzhou University People’s Hospital, Zhengzhou, China Reproductive Medicine Center, Henan University People’s Hospital, Zhengzhou, China

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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.

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.

Reproductive outcomes with delayed blastocyst development: the clinical value of day 7 euploid blastocysts in frozen embryo transfer cycles

Embryos of optimal development reach blastocyst stage 116 ± 2 h after insemination. Usable D7 blastocysts represent nearly 5% of embryos in IVF with acceptable pregnancy and live birth rates, however data are still limited. Therefore, this study aimed to analyze the ongoing pregnancy rate (OPR) of D7 blastocysts in single euploid frozen embryo transfer (FET) cycles. An observational study was performed including 1527 FET cycles with blastocysts biopsied on D5 (N = 855), D6 (N = 636) and D7 (N = 36). Blastocysts were classified as good (AA/AB/BA), fair (BB) or poor (AC/BC/CC/CA/CB) (Gardner scoring). FETs were performed in natural cycles (NC) or hormone replacement therapy (HRT) cycles. Patient's age differed significantly between D5, D6 and D7 blastocysts FET cycles (33.2 ± 5.6, 34.4 ± 5.3 and 35.9 ± 5.2, P < 0.001). OPRs were higher when D5 euploid blastocysts were transferred compared with D6 and D7 (56.0% vs. 45.3% and 11.1%, P < 0.001). Poor quality blastocysts were predominant in D7 blastocyst FET cycles (good quality: 35.4%, 27.2%, 5.6%; fair quality: 52.1%, 38.5%, 11.1%; poor quality: 12.5%, 34.3%, 83.3%, P < 0.001 for D5, D6 and D7 blastocysts; respectively). OPR was significantly reduced by D7 blastocyst FETs (OR = 0.23 [0.08;0.62], P = 0.004), patient's BMI (OR = 0.96 [0.94;0.98], P < 0.001), HRT cycles (OR = 0.70 [0.56;0.88], P = 0.002) and poor quality blastocysts (OR = 0.33 [0.24;0.45], P < 0.001). OPR is significantly reduced with D7 compared with D5/D6 euploid blastocysts in FET cycles. The older the patient, the more likely they are to have an FET cycle with blastocysts biopsied on D7, therefore culturing embryos until D7 can be a strategy to increase OPR outcomes in patients ≥38 years.

Oxygen concentration from days 1 to 3 after insemination affects the embryo culture quality, cumulative live birth rate, and perinatal outcomes

PURPOSE

We aimed to compare embryo development, cumulative live birth rate (CLBR), and perinatal outcomes of embryos cultured in 20% and 5% oxygen from days 1 to 3 after insemination.

METHODS

This retrospective study included patients who received in vitro fertilization (IVF) treatment between January 2015 and November 2019. Embryos of each patient were cultured at 20% or 5% oxygen from days 1-3 after insemination. The primary outcome was CLBR. Propensity score matching (PSM) was used to balance patients' baseline data in both oxygen groups.

RESULTS

In total, 31,566 patients were enrolled. After PSM, the rate of high-quality day 3 embryos was significantly lower in the 20% than in the 5% oxygen group (0.49 ± 0.33 vs 0.51 ± 0.33; adjusted β = -0.03; 95% confidence interval [CI], -0.03 to -0.02). The CLBR was significantly lower in the 20% than in the 5% oxygen group (58.6% vs. 62.4%; adjusted odds ratio = 0.85; 95% CI, 0.81-0.90). The birthweight and Z score of singletons were significantly higher in the 20% than in the 5% oxygen group (birthweight: 3.30 ± 0.50 vs. 3.28 ± 0.48; adjusted β = 0.022; 95% CI, 0.004-0.040; Z score: 0.26 ± 1.04 vs. 0.22 ± 1.01; adjusted β = 0.037; 95% CI, 0.001-0.074).

CONCLUSION

Culturing embryos at atmospheric oxygen concentrations from days 1 to 3 compromises embryo quality, reduces CLBR, and affects birthweight. The 5% oxygen concentration is more suitable for embryo culture in IVF laboratories to achieve successful outcomes.

The number of prior pregnancy losses does not impact euploidy rates in young patients with idiopathic recurrent pregnancy loss

PURPOSE

Our study aimed to determine the possible factors that might impact the probability of obtaining a euploid blastocyst following intracytoplasmic sperm injection (ICSI) and preimplantation genetic testing for aneuploidy (PGT-A) procedures in idiopathic recurrent pregnancy loss (RPL) patients.

METHODS

This single-center retrospective cohort analysis included 180 oocyte retrieval cycles of 166 women under 35 years old and those diagnosed with idiopathic RPL according to American Society of Reproductive Medicine (ASRM) guidelines. Trophectoderm biopsy and next-generation sequencing (NGS) were the techniques used. Patients were stratified by the number of previous losses (Group A: 2, Group B: 3, and Group C: > 3).

RESULTS

Baseline and embryological characteristics showed no statistically significant differences. The euploidy rate per analyzed blastocyst was comparable within the groups (63.3%, 58.2%, and 58.5%; p = 0.477). Logistic regression analyses confirmed that only the trophectoderm scores of A and B increased the probability of obtaining a euploid embryo [OR: 1.82, 95% CI (1.120-2.956), p: 0.016].

CONCLUSION

It is concluded that there was no correlation between the number of previous losses and the chance of finding at least one euploid embryo in ICSI cycles of women younger than 35 years.

Discard or not discard, that is the question: an international survey across 117 embryologists on the clinical management of borderline quality blastocysts

STUDY QUESTION

Do embryologists from different European countries agree on embryo disposition decisions ('use' or 'discard') about Day 7 (>144 h post-insemination) and/or low-quality blastocysts (LQB;

SUMMARY ANSWER

The prevalence of 'discard' answers was 38.7%; nevertheless, embryologists' agreement was overall just fair (Fleiss-k = 0.26).

WHAT IS KNOWN ALREADY

The utilization of LQBs and adoption of culture beyond 144 h post-insemination is increasing worldwide. Although morphology and morphokinetics are associated with embryo developmental competence, previous studies demonstrated significant interobserver variability among embryologists regarding embryo quality assessment and disposition decisions for borderline quality blastocysts.

STUDY DESIGN, SIZE, DURATION

An anonymous survey was run in a large network of IVF centers. A total of 117 embryologists from 6 European countries and 29 IVF centers filled in the survey. Randomly selected anonymous time-lapse videos of 50 Day 7 and/or LQB whole embryo preimplantation development were assessed by the embryologists. The key information on patients/cycles was provided along with each video. All cycles entailed preimplantation genetic testing for aneuploidies. Each embryologist specified whether he/she would have discarded or used ('transfer-fresh'/'cryopreserve'/'biopsy') any embryo. Inter-rater agreement was measured with Fleiss-k.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Examiners were asked about their years of experience, center location, average number of cycles and average maternal age, number of colleagues, and use of time-lapse incubators at their centers. All participants were blinded to artificial intelligence (AI) scores generated by two commercially available software packages, chromosomal diagnosis (all blastocysts were tested for aneuploidies), and clinical outcomes after vitrified-warmed euploid single blastocyst transfer. These data were known only by one embryologist not involved in the survey.

MAIN RESULTS AND THE ROLE OF CHANCE

Participants were Italian (40%, N = 47), Spanish (24%, N = 28), Portuguese (5%, N = 6), Czech (5%, N = 6), Swedish (23%, N = 27), and Icelandic (3%, N = 3). In total, 2263 (38.7%) 'discard' and 3587 (61.3%) 'use' decisions were recorded. Czech, Portuguese, and Italian embryologists expressed lower 'discard' decision rates (mean ± SD 17 ± 7%, range 8-24%; 23 ± 14% range 4-46%; and 27 ± 18% range 2-72%, respectively), while Spanish gave intermediate (37 ± 16% range 4-66%) and Nordic gave higher (67 ± 11% range 40-90%) rates. The prevalence of 'discard' answers was 38.7% out of 5850 choices (mean per embryologist: 39 ± 23% range 2-90%). Only embryologists' country and IVF group were associated with this rate. Overall agreement among embryologists was fair (Fleiss-k = 0.26). The prevalence of 'discard' responses per embryo was 37 ± 24% (range 2-87%). Only the number of sibling blastocysts influenced this rate (i.e. the larger the cohort, the higher the inclination to 'discard'). No difference was shown for the two scores between euploid and aneuploid borderline quality blastocysts, while the embryologists were, by chance, more prone to 'discard' the latter (28.3 ± 21% range 9-71% versus 41.6 ± 24.8% range 2-87%, respectively).

LIMITATIONS, REASONS FOR CAUTION

The survey included only private IVF clinics located in Europe. Moreover, a key variable is missing, namely patients' access to care. Indeed, all embryologists involved in the survey were part of the same network of private IVF clinics, while the embryo disposition decisions might be different in a public setting.

WIDER IMPLICATIONS OF THE FINDINGS

Decision-making by European embryologists regarding Day 7 embryos or LQBs is inconsistent with putative clinical consequences, especially in patients with low prognosis. Although the embryologists could make decisions independent from their local regulations, their mindset and clinical background influenced their choices. In the future, AI tools should be trained to assess borderline quality embryos and empowered with cost-effectiveness information to support embryologists' decisions with more objective assessments.

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was obtained for this study. The authors have no conflict of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

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Key Words

• Day 7 blastocysts
• artificial intelligence
• decision-making
• embryo competence
• low-quality blastocysts

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MESH Headings

• Female
• Humans
• Aneuploidy
• Artificial Intelligence
• Blastocyst/physiology
• Embryo Transfer/methods
• Maternal Age
• Retrospective Studies
• Male

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Affiliation(s)

Viviana Chiappetta IVIRMA Global Research Alliance, GENERA, Clinica Valle Giulia, Rome, Italy
Federica Innocenti IVIRMA Global Research Alliance, GENERA, Clinica Valle Giulia, Rome, Italy
Giovanni Coticchio IVIRMA Global Research Alliance, 9.baby, Bologna, Italy
Aisling Ahlström IVIRMA Global Research Alliance, LIVIO, Göteborg, Sweden
Laura Albricci IVIRMA Global Research Alliance, GENERA, Clinica Valle Giulia, Rome, Italy
Vicente Badajoz IVIRMA Global Research Alliance, GINEFIV, Madrid, Spain
Maria Hebles IVIRMA Global Research Alliance, GINEMED, Sevilla, Spain
Miguel Gallardo IVIRMA Global Research Alliance, GINEMED, Lisbon, Portugal
Francesca Benini IVIRMA Global Research Alliance, DEMETRA, Florence, Italy
Stefano Canosa IVIRMA Global Research Alliance, LIVET, Turin, Italy
Jiří Kumpošt IVIRMA Global Research Alliance, FERTICARE, Prague, Czech Republic
Katarina Milton IVIRMA Global Research Alliance, CARL VON LINNÈ KLINIKEN, Uppsala, Sweden
Diletta Montanino Oliva Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
Roberta Maggiulli IVIRMA Global Research Alliance, GENERA, Clinica Valle Giulia, Rome, Italy
Laura Rienzi IVIRMA Global Research Alliance, GENERA, Clinica Valle Giulia, Rome, Italy Department of Biomolecular Sciences, University of Urbino "Carlo Bo", Urbino, Italy
Danilo Cimadomo IVIRMA Global Research Alliance, GENERA, Clinica Valle Giulia, Rome, Italy

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Large-scale retrospective analysis of methodological factors affecting pregnancy rates after embryo transfer for in vitro fertilization

This study aimed to investigate the impact of methodological factors on pregnancy rates after embryo transfer (ET) for in vitro fertilization. This retrospective cross-sectional study was conducted between September 2020 and April 2022. A total of 2048 patients who underwent ultrasonography-guided first frozen embryo transfer (FET) or a fresh ET cycle due to infertility were included in the study. The effects of age, ET protocol (frozen or fresh), preimplantation genetic testing, number of embryos transferred (NET), and embryo fundus distance on pregnancy rate were investigated. The mean age of pregnant patients (31.51 ± 5.28) was significantly lower than that of non-pregnant patients (35.34 ± 6.39) (P < .001). Multiple regression analysis showed that women with lower age (P < .001), higher NET (P < .001), higher embryo fundus distance (P < .001), FET (P < .001), and preimplantation genetic testing (P = .012) had a significantly higher likelihood of pregnancy. Appropriate transfer depth, younger age, euploid embryo transfer, FET, and a higher NET can increase the likelihood of pregnancy. However, multiple factors must be considered when deciding the best protocol for a particular patient, including patient preference, costs and timing.

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'.

Towards Automation in IVF: Pre-Clinical Validation of a Deep Learning-Based Embryo Grading System during PGT-A Cycles

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.

Metaphase-II oocyte competence is unlinked to the gonadotrophins used for ovarian stimulation: a matched case-control study in women of advanced maternal age

PURPOSE

An impact of different gonadotrophins selection for ovarian stimulation (OS) on oocyte competence has yet to be defined. In this study, we asked whether an association exists between OS protocol and euploid blastocyst rate (EBR) per metaphase-II (MII) oocytes.

METHODS

Cycles of first preimplantation genetic testing for aneuploidies conducted by women ≥ 35 years old with their own metaphase-II oocytes inseminated in the absence of severe male factor (years 2014-2018) were clustered based on whether recombinant FSH (rec-FSH) or human menopausal gonadotrophin (HMG) was used for OS, then matched for the number of fresh inseminated eggs. Four groups were outlined: rec-FSH (N = 57), rec-FSH plus rec-LH (N = 55), rec-FSH plus HMG (N = 112), and HMG-only (N = 127). Intracytoplasmic sperm injection, continuous blastocyst culture, comprehensive chromosome testing to assess full-chromosome non-mosaic aneuploidies and vitrified-warmed euploid single embryo transfers (SETs) were performed. The primary outcome was the EBR per cohort of MII oocytes. The secondary outcome was the live birth rate (LBR) per first SETs.

RESULTS

Rec-FSH protocol was shorter and characterized by lower total gonadotrophin (Gn) dose. The linear regression model adjusted for maternal age showed no association between the Gn adopted for OS and EBR per cohort of MII oocytes. Similarly, no association was reported with the LBR per first SETs, even when adjusting for blastocyst quality and day of full blastulation.

CONCLUSION

In view of enhanced personalization in OS, clinicians shall focus on different endpoints or quantitative effects related to Gn action towards follicle recruitment, development, and atresia. Here, LH and/or hCG was administered exclusively to women with expected sub/poor response; therefore, we cannot exclude that specific Gn formulations may impact patient prognosis in other populations.

Does increasing estrogen dose during frozen embryo transfer affect pregnancy rate?

OBJECTIVE

To assess the effect of increasing estrogen doses during hormone therapy frozen embryo transfer (HT-FET) cycles on endometrial thickness and success rates compared to patients who received fixed estrogen dose.

MATERIALS AND METHODS

A retrospective study from a university-based fertility clinic during the years 2008-2021. We compared two groups: the fixed-dose group (i.e., received 6 mg estradiol dose daily until embryo transfer) and the increased-dose group (i.e., the initial estradiol dose was 6 mg daily, and was increased during the cycle).

PRIMARY OUTCOME

clinical pregnancy rate.

RESULTS

The study included 5452 cycles of HT-FET: 4774 cycles in the fixed-dose group and 678 cycles in the increased-dose group. Ultrasound scan on days 2-3 of the cycle showed endometrial thickness slightly different between the two groups (4.2 mm in the fixed-dose and 4.0 mm in the increased-dose group, P = 0.003). The total estrogen dose was higher, and the treatment duration was longer in the increased than the fixed-dose group (122 mg vs. 66 mg and 17 days vs. 11 days, respectively; P < 0.001). The last ultrasound scan done before the addition of progesterone showed that the endometrial thickness was significantly thicker in the fixed than the increased-dose group (9.5 mm vs. 8.3 mm; P < 0.001). The clinical pregnancy rates were 35.8% in the increased-group vs. 34.1% in the fixed-dose group; P = 0.401.

CONCLUSIONS

The increased-dose group had thinner endometrium despite the higher doses of estrogen and longer treatment duration than the fixed-dose group. However, the pregnancy rates were similar between the two groups.

Live birth rate following a euploid blastocyst transfer is not affected by double vitrification and warming at cleavage or blastocyst stage

PURPOSE

To compare reproductive outcomes following a euploid embryo transfer, between those embryos vitrified-warmed twice to those vitrified-warmed once.

METHODS

We retrospectively analysed 694 single euploid frozen embryo transfer cycles following preimplantation genetic testing for aneuploidy (PGT-A). For cycles in group 1 (N = 451), embryos were biopsied for PGT-A at blastocyst stage and vitrified. For cycles in group 2 (N = 146), embryos were vitrified at blastocyst stage, before being warmed and biopsied for PGT-A and vitrified again. For cycles in group 3 (N = 97), embryos were vitrified on day-3, before being warmed, cultured to day-5 and biopsied for PGT-A and re-vitrified.

RESULTS

The pregnancy, clinical pregnancy and livebirth rate in group 2 were not statistically different to group 1 (pregnancy rate, adjusted OR 1.09, 95% CI 0.62-1.91; clinical pregnancy, aOR 0.89, 95% CI 0.58-1.37; live birth rate, aOR 0.85, 95% CI 0.56-1.28). There was also no significant difference between group 3 and group 1, with similar pregnancy rate (aOR 1.22, 95% CI 0.74-1.99), clinical pregnancy rate (aOR 1.21, 95% CI 0.75-1.96) and live birth rate (aOR 1.15, 95% CI, 0.73-1.80). There was no significant difference in miscarriage rates between all three groups. The age at the oocyte collection, embryo quality and day of biopsy were associated with pregnancy, clinical pregnancy and live birth rate.

CONCLUSION

This study suggests that vitrifying and warming embryos twice at blastocyst or at cleavage and then blastocyst stage, can lead to similar reproductive outcomes to embryos vitrified-warmed once, after a single euploid embryo transfer.

Natural cycle increases the live-birth rate compared with hormone replacement treatment for frozen-thawed single euploid blastocyst transfer

BACKGROUND

A number of studies have compared the clinical outcomes between the two endometrial preparation methods: natural cycles (NCs) and hormone replacement treatment (HRT) before frozen embryo transfer, but the results were conflicting. In order to mitigate the potential effect of embryos per se, several researchers have worked on this subject for euploid blastocyst transfer, but the results were still inconsistent. Therefore, the present study was aimed to investigate the clinical outcomes between HRT and NC for autologous single vitrified-warmed euploid blastocyst transfer based on our data.

METHODS

A total of 598 frozen-thawed single euploid blastocyst transfer cycles in the assisted reproductive center of Northwest Women's and Children's Hospital from January 2014 to May 2021 were retrospectively analyzed. Women were stratified into the NC (n = 125) or HRT (n = 473) group according to the patient's preference and the physician's guidance. Multivariate regression models and subgroup analysis were constructed to analyze the association between endometrial preparation and live birth.

RESULTS

Women in the NC group had a higher live birth rate (68.80% versus 58.35%, P = 0.034) and a lower risk of total pregnancy loss (8.51% versus 21.14%, P = 0.005) when compared with women in the HRT group. The biochemical pregnancy rate (75.20% versus 74.00%, P = 0.784) and clinical pregnancy rate (74.40% versus 69.98%, P = 0.334) were similar between the two groups (NC versus HRT). NC was associated with an increased odds of live birth compared with HRT by different multivariable analysis models (Model 1: adjusted odds ratio [aOR], 95% confidence interval [CI]: 0.57, 0.36 - 0.90; Model 2: aOR, 95%CI: 0.57, 0.35 - 0.92). In addition, the increased chance of live birth in the NC group was found in all subgroups. No major obstetrical complications and two malformation livebirths were reported.

CONCLUSIONS

In women undergoing single euploid frozen blastocyst transfers, the NC group was associated with a lower pregnancy loss rate and an ultimately higher live birth rate than the HRT group. Although HRT is convenient for both clinicians and patients, the lower live birth rate should be taken into account and NC might be the first choice of endometrial preparation method.

Mosaic human preimplantation embryos and their developmental potential in a prospective, non-selection clinical trial

Chromosome imbalance (aneuploidy) is the major cause of pregnancy loss and congenital disorders in humans. Analyses of small biopsies from human embryos suggest that aneuploidy commonly originates during early divisions, resulting in mosaicism. However, the developmental potential of mosaic embryos remains unclear. We followed the distribution of aneuploid chromosomes across 73 unselected preimplantation embryos and 365 biopsies, sampled from four multifocal trophectoderm (TE) samples and the inner cell mass (ICM). When mosaicism impacted fewer than 50% of cells in one TE biopsy (low-medium mosaicism), only 1% of aneuploidies affected other portions of the embryo. A double-blinded prospective non-selection trial (NCT03673592) showed equivalent live-birth rates and miscarriage rates across 484 euploid, 282 low-grade mosaic, and 131 medium-grade mosaic embryos. No instances of mosaicism or uniparental disomy were detected in the ensuing pregnancies or newborns, and obstetrical and neonatal outcomes were similar between the study groups. Thus, low-medium mosaicism in the trophectoderm mostly arises after TE and ICM differentiation, and such embryos have equivalent developmental potential as fully euploid ones.

Pregnancy Outcomes Following the First Frozen Blastocyst Transfer Among Women Aged Less Than 35 Years Old: A Retrospective Cohort Study

Background: Many guidelines have been issued regarding the number of embryos to be transferred after in vitro fertilization (IVF), but patients and clinicians may be reluctant to accept or offer a single embryo transfer due to the expected lower chance of pregnancy or live birth. This study was aimed to provide additional information on cycle outcome according to the number and quality of thawed transferred blastocysts.

Methods: A retrospective cohort study was designed to collect the data of 505 patients who performed the first frozen blastocysts transfer at Tam Anh General Hospital from June 2018 to September 2019. One good-quality embryo was transferred for 121 patients (Group 1), two good for 214 patients (Group 2), one good and one poor for 112 patients (Group 3), one good and two poor for 25 patients (Group 4), and one or two poor for 33 patients (Group 5).

Results: The pregnancy rate was 71.9%, 74.8%, 69.4%, 84.0%, and 39.4% in Group 1–5, respectively. The multiple pregnancy rate was 36.9%, 16.9%, and 32.0% in Groups 2–4, respectively, higher than Group 1 (4.9%). The live birth rate was 55.6%, 50.9%, and 60.0% in Group 2–4, respectively, but not significantly different from the Group 1 (47.9%).

Conclusions: Transferring an additional good or poor embryo, along with a good embryo, does not increase the live birth rate while the incidence of multiple pregnancies rises significantly.

A review of the pathophysiology of recurrent implantation failure

Implantation is a critical step in human reproduction. The success of this step is dependent on a competent blastocyst, receptive endometrium, and successful cross talk between the embryonic and maternal interfaces. Recurrent implantation failure is the lack of implantation after the transfer of several embryo transfers. As the success of in vitro fertilization has increased and failures have become more unacceptable for patients and providers, the literature on recurrent implantation failure has increased. While this clinical phenomenon is often encountered, there is not a universally agreed-on definition-something addressed in an earlier portion of this Views and Reviews. Implantation failure can result from several different factors. In this review, we discuss factors including the maternal immune system, genetics of the embryo and parents, anatomic factors, hematologic factors, reproductive tract microbiome, and endocrine milieu, which factors into embryo and endometrial synchrony. These potential causes are at various stages of research and not all have clear implications or immediately apparent treatment.

Inter-centre reliability in embryo grading across several IVF clinics is limited: implications for embryo selection

RESEARCH QUESTION

What is the intra- and inter-centre reliability in embryo grading performed according to the Istanbul Consensus across several IVF clinics?

DESIGN

Forty Day 3 embryos and 40 blastocysts were photographed on three focal planes. Senior and junior embryologists from 65 clinics were invited to grade them according to the Istanbul Consensus (Study Phase I). All participants then attended interactive training where a panel of experts graded the same embryos (Study Phase II). Finally, a second set of pictures was sent to both embryologists and experts for a blinded evaluation (Study Phase III). Intra-centre reliability was reported for Study Phase I as Cohen's kappa between senior and junior embryologists; inter-centre reliability was instead calculated between senior/junior embryologists and experts in Study Phase I versus III to outline improvements after training (i.e. upgrade of Cohen's kappa category according to Landis and Koch).

RESULTS

Thirty-six embryologists from 18 centres participated (28% participation rate). The intra-centre reliability was (i) substantial (0.63) for blastomere symmetry (range -0.02 to 1.0), (ii) substantial (0.72) for fragmentation (range 0.29-1.0), (iii) substantial (0.66) for blastocyst expansion (range 0.19-1.0), (iv) moderate (0.59) for inner cell mass quality (range 0.07-0.92), (v) moderate (0.56) for trophectoderm quality (range 0.01-0.97). The inter-centre reliability showed an overall improvement from Study Phase I to III, from fair (0.21-0.4) to moderate (0.41-0.6) for all parameters under analysis, except for blastomere fragmentation among senior embryologists, which was already moderate before training.

CONCLUSIONS

Intra-centre reliability was generally moderate/substantial, while inter-centre reliability was just fair. The interactive training improved it to moderate, hence this workflow was deemed helpful. The establishment of external quality assessment services (e.g. UK NEQAS) and the avant-garde of artificial intelligence might further improve the reliability of this key practice for embryo selection.

Euploid day 7 blastocysts of infertility patients with only slow embryo development have reduced implantation potential

RESEARCH QUESTION

What is the reproductive potential of embryos that achieve blastulation on day 7 followed by preimplantation genetic testing for aneuploidies (PGT-A) for infertility patients with slow embryo development?

DESIGN

This was a retrospective cohort study in a private IVF clinic of consecutive female infertility patients (n = 2966) aged 24-48 (36.3 ± 3.8) years who underwent frozen embryo transfer (FET) of a single euploid blastocyst.

RESULTS

The women underwent single euploid FET of an embryo that achieved blastulation on day 5 (n = 1880), day 6 (n = 986) or day 7 (n = 100). Day 7 embryos resulted in lower implantation and live birth rates compared with both day 5 and day 6 embryos (P < 0.001). The day 5, day 6 and day 7 groups had 68.5%, 55.2% and 36.0% live birth rates, respectively. The day 7 group was older than the day 5 group (P < 0.001); comparing age-matched cohorts, the day 7 group still had lower implantation and live birth rates (P < 0.0001 and P < 0.001, respectively). Embryo grade was unrelated to live birth rates. Day 7 embryos of expansion grade 5 or 6 or trophectoderm grade A were more likely to be euploid compared with expansion grade 3 or trophectoderm grade B.

CONCLUSIONS

Euploid day 7 embryos represented reduced implantation potential, even when controlling for maternal age. Of all day 7 embryos that underwent PGT-A, euploidy was associated with expansion grade 5 or 6 and trophectoderm grade A. These results can help providers manage patient expectations in cases where infertile women have slow embryo development.

Psychological Stress and Functional Endometrial Disorders: Update of Mechanism Insights

The human endometrium plays a vital role in providing the site for embryo implantation and maintaining the normal development and survival of the embryo. Recent studies have shown that stress is a common factor for the development of unexplained reproductive disorders. The nonreceptive endometrium and disturbed early maternal-fetal interaction might lead to infertility including the repeated embryo implantation failure and recurrent spontaneous abortion, or late pregnancy complications, thereby affecting the quality of life as well as the psychological status of the affected individuals. Additionally, psychological stress might also adversely affect female reproductive health. In recent years, several basic and clinical studies have tried to investigate the harm caused by psychological stress to reproductive health, however, the mechanism is still unclear. Here, we review the relationship between psychological stress and endometrial dysfunction, and its consequent effects on female infertility to provide new insights for clinical therapeutic interventions in the future.

Definition, diagnostic and therapeutic options in recurrent implantation failure: an international survey of clinicians and embryologists

STUDY QUESTION

What is the global variability in recurrent implantation failure (RIF) definition, investigation and therapy, currently offered to patients undergoing IVF?

SUMAMRY ANSWER

Definitions, diagnostic investigations and treatments offered to RIF patients differ widely amongst assisted reproduction healthcare professionals and clinical guidelines on RIF are urgently needed.

WHAT IS KNOWN ALREADY

RIF affects around 10% of patients undergoing IVF worldwide. There is no consensus on the definition of RIF, its diagnostic investigations or the therapeutic options, which leads to inconsistencies in clinical practice.

STUDY DESIGN, SIZE, DURATION

A cross-sectional study of clinicians and embryologists was conducted between May and June 2020. The survey included 43 questions aimed at understanding participants' background and their current practice with regards to defining, investigating and managing RIF. The questions were designed by the European Society of Human Reproduction and Embryology (ESHRE) Special Interest Group (SIG) on implantation and early pregnancy following three consensus meetings.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 8579 ESHRE members from 6916 IVF centers were invited to participate using two global email calls based on their pre-specified interest in implantation and early pregnancy. SurveyMonkey and SPSS were used for data collection and analysis, respectively. Furthermore, differences were reported in the answers of European and non-European professionals, as well as between public and private settings and among clinicians clustered according to the average number of RIF patients treated per year.

MAIN RESULTS AND THE ROLE OF CHANCE

The final data set included 735 clinicians and 300 embryologist or IVF-biologists. The majority defines RIF based on the number of failed embryo transfers (ETs) with the most common threshold adopted being three ETs both fresh and frozen. More than two-thirds take lifestyle factors into account, mainly drugs, smoking and BMI. The highest consensus on which diagnostic investigations should be performed was reached for anatomical malformations and gynecological aspects focusing on hydrosalpinx, Asherman's syndrome, endometrial thickness and endometriosis. Concerning treatment of RIF patients, the highest consensus was reached for preconceptional therapies, including BMI adjustment, smoking and endometritis followed by therapies during IVF procedures.

LIMITATIONS, REASONS FOR CAUTION

The response rate was relatively low, but comparable to other surveys.

WIDER IMPLICATIONS OF THE FINDINGS

A consensus on definition, diagnosis and treatment of RIF would help to reduce costly, time-consuming and poorly validated approaches.

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was used. B.T. received support from Bayer for Clinical trials concerning endometriosis and Ferring for clinical trials concerning ovarian stimulation. She received reimbursement for travel expenses from Astropharm, Ferring. Dr Kade and is a shareholder of Reprognostics. She is a board member of the Austrian Society for Obstetrics and Gynecology (OEGGG), the associate head of the 'Reproduktionsmedizinische Zentren Baden-Württemberg' (RZBW), a member of guideline group of the German Society for Obstetrics and Gynecology (DGGG) and an editorial board member of the following journals: American Journal of Reproductive Immunology (AJRI), Archives of Gynecology and Obstetrics. All the other authors declare no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

The euploid blastocysts obtained after luteal phase stimulation show the same clinical, obstetric and perinatal outcomes as follicular phase stimulation-derived ones: a multicenter study

STUDY QUESTION

Are the reproductive outcomes (clinical, obstetric and perinatal) different between follicular phase stimulation (FPS)- and luteal phase stimulation (LPS)-derived euploid blastocysts?

SUMMARY ANSWER

No difference was observed between FPS- and LPS-derived euploid blastocysts after vitrified-warmed single embryo transfer (SET).

WHAT IS KNOWN ALREADY

Technical improvements in IVF allow the implementation non-conventional controlled ovarian stimulation (COS) protocols for oncologic and poor prognosis patients. One of these protocols begins LPS 5 days after FPS is ended (DuoStim). Although, several studies have reported similar embryological outcomes (e.g. fertilization, blastulation, euploidy) between FPS- and LPS-derived cohort of oocytes, information on the reproductive (clinical, obstetric and perinatal) outcomes of LPS-derived blastocysts is limited to small and retrospective studies.

STUDY DESIGN, SIZE, DURATION

Multicenter study conducted between October 2015 and March 2019 including all vitrified-warmed euploid single blastocyst transfers after DuoStim. Only first transfers of good quality blastocysts (≥BB according to Gardner and Schoolcraft's classification) were included. If euploid blastocysts obtained after both FPS and LPS were available the embryo to transfer was chosen blindly. The primary outcome was the live birth rate (LBR) per vitrified-warmed single euploid blastocyst transfer in the two groups. To achieve 80% power (α = 0.05) to rule-out a 15% difference in the LBR, a total of 366 first transfers were required. Every other clinical, as well as obstetric and perinatal outcomes, were recorded.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Throughout the study period, 827 patients concluded a DuoStim cycle and among them, 339 did not identify any transferable blastocyst, 145 had an euploid blastocyst after FPS, 186 after LPS and 157 after both FPS and LPS. Fifty transfers of poor quality euploid blastocysts were excluded and 49 patients did not undergo an embryo transfer during the study period. Thus, 389 patients had a vitrified-warmed SET of a good quality euploid blastocyst (182 after FPS and 207 after LPS). For 126 cases (32%) where both FPS- and LPS-derived good quality blastocysts were available, the embryo transferred was chosen blindly with a 'True Random Number Generator' function where '0' stood for FPS-derived euploid blastocysts and '1' for LPS-derived ones (n = 70 and 56, respectively) on the website random.org. All embryos were obtained with the same ovarian stimulation protocol in FPS and LPS (GnRH antagonist protocol with fixed dose of rec-FSH plus rec-LH and GnRH-agonist trigger), culture conditions (continuous culture in a humidified atmosphere with 37°C, 6% CO2 and 5% O2) and laboratory protocols (ICSI, trophectoderm biopsy in Day 5-7 without assisted hatching in Day 3, vitrification and comprehensive chromosome testing). The women whose embryos were included had similar age (FPS: 38.5 ± 3.1 and LPS: 38.5 ± 3.2 years), prevalence of male factor, antral follicle count, basal hormonal characteristics, main cause of infertility and previous reproductive history (i.e. previous live births, miscarriages and implantation failures) whether the embryo came from FPS or LPS. All transfers were conducted after warming in an artificial cycle. The blastocysts transferred after FPS and LPS were similar in terms of day of full-development and morphological quality.

MAIN RESULTS AND THE ROLE OF CHANCE

The positive pregnancy test rates for FPS- and LPS-derived euploid blastocysts were 57% and 62%, biochemical pregnancy loss rates were 10% and 8%, miscarriage rates were 15% and 14% and LBRs were 44% (n = 80/182, 95% CI 37-51%) and 49% (n = 102/207, 95% CI 42-56%; P = 0.3), respectively. The overall odds ratio for live birth (LPS vs FPS (reference)) adjusted for day of blastocyst development and quality, was 1.3, 95% CI 0.8-2.0, P = 0.2. Among patients with euploid blastocysts obtained following both FPS and LPS, the LBRs were also similar (53% (n = 37/70, 95% CI 41-65%) and 48% (n = 27/56, 95% CI 35-62%) respectively; P = 0.7). Gestational issues were experienced by 7.5% of pregnant women after FPS- and 10% of women following LPS-derived euploid single blastocyst transfer. Perinatal issues were reported in 5% and 0% of the FPS- and LPS-derived newborns, respectively. The gestational weeks and birthweight were similar in the two groups. A 5% pre-term delivery rate was reported in both groups. A low birthweight was registered in 2.5% and 5% of the newborns, while 4% and 7% showed high birthweight, in FPS- and LPS-derived euploid blastocyst, respectively. Encompassing the 81 FPS-derived newborns, a total of 9% were small and 11% large for gestational age. Among the 102 LPS-derived newborns, 8% were small and 6% large for gestational age. No significant difference was reported for all these comparisons.

LIMITATIONS, REASONS FOR CAUTION

The LPS-derived blastocysts were all obtained after FPS in a DuoStim protocol. Therefore, studies are required with LPS-only, late-FPS and random start approaches. The study is powered to assess differences in the LBR per embryo transfer, therefore obstetric and perinatal outcomes should be considered observational. Although prospective, the study was not registered.

WIDER IMPLICATIONS OF THE FINDINGS

This study represents a further backing of the safety of non-conventional COS protocols. Therefore, LPS after FPS (DuoStim protocol) is confirmed a feasible and efficient approach also from clinical, obstetric and perinatal perspectives, targeted at patients who need to reach the transfer of an euploid blastocyst in the shortest timeframe possible due to reasons such as cancer, advanced maternal age and/or reduced ovarian reserve and poor ovarian response.

STUDY FUNDING/COMPETING INTEREST(S)

None.

TRIAL REGISTRATION NUMBER

N/A.

Should we freeze it? Agreement on fate of borderline blastocysts is poor and does not improve with a modified blastocyst grading system

STUDY QUESTION

What is the inter-observer agreement among embryologists for decision to freeze blastocysts of borderline morphology and can it be improved with a modified grading system?

SUMMARY ANSWER

The inter-observer agreement among embryologists deciding whether to freeze blastocysts of marginal morphology was low and was not improved by a modified grading system.

WHAT IS KNOWN ALREADY

While previous research on inter-observer variability on the decision of which embryo to transfer from a cohort of blastocysts is good, the impact of grading variability regarding decision to freeze borderline blastocysts has not been investigated. Agreement for inner cell mass (ICM) and trophectoderm (TE) grade is only fair, factors which contribute to the grade that influences decision to freeze.

STUDY DESIGN, SIZE, DURATION

This was a prospective study involving 18 embryologists working at four different IVF clinics within a single organisation between January 2019 and July 2019.

PARTICIPANTS/MATERIALS, SETTING, METHODS

All embryologists currently practicing blastocyst grading at a multi-site organisation were invited to participate. The survey was comprised of blastocyst images in three planes and asked (i) the likelihood of freezing and (ii) whether the blastocyst would be frozen based on visual assessment. Blastocysts varied by quality and were categorised as either top (n = 20), borderline (n = 60) or non-viable/degenerate quality (n = 20). A total of 1800 freeze decisions were assessed. To assess the impact of grading criteria on inter-observer agreement for decision to freeze, the survey was taken once when the embryologists used the Gardner criteria and again 6 months after transitioning to a modified Gardner criterion with four grades for ICM and TE. The fourth grade was introduced with the aim to promote higher levels of agreement for the clinical usability decision when the blastocyst was of marginal quality.

MAIN RESULTS AND THE ROLE OF CHANCE

The inter-observer agreement for decision to freeze was near perfect (kappa 1.0) for top and non-viable/degenerate quality blastocysts, and this was not affected by the blastocysts grading criteria used (top quality; P = 0.330 and non-viable/degenerate quality; P = 0.18). In contrast, the cohort of borderline blastocysts received a mixed freeze rate (average 52.7%) during the first survey, indicative of blastocysts that showed uncertain viability and promoting significant disagreement for decision to freeze among the embryologists (kappa 0.304). After transitioning to a modified Gardner criteria with an additional grading tier, the average freeze rate increased (64.8%; P < 0.0001); however, the inter-observer agreement for decision to freeze was unchanged (kappa 0.301). Therefore, significant disagreement for decision to freeze among embryologists is an ongoing issue not resolved by the two grading criteria assessed here.

LIMITATIONS, REASONS FOR CAUTION

Blastocyst assessment was performed from time-lapse images in three planes, rather than with a microscope in the laboratory. The inter-observer agreement for decision to freeze may be lower for embryologists working in different clinics with different grading protocols.

WIDER IMPLICATIONS OF THE FINDINGS

The decision to freeze a blastocyst with borderline morphology is a common clinical issue that has the potential to arise for any patient during blastocyst culture. Disagreement for decision to freeze these blastocysts, and therefore clinical usability in frozen embryo transfer cycles, affects consistency in patient care due to a potential impact on cumulative live birth rates, as well as financial, emotional and time costs associated with the frozen embryo transfer cycles. We demonstrate significant disagreement for decision to freeze borderline blastocysts among embryologists using the same grading scheme within a large multisite organisation, a phenomenon which was not improved with a modified grading system. Decision-making around borderline embryos is an area requiring further research, especially as studies continue to demonstrate the reduced but modest live birth rates for low quality blastocysts (Grade C). These results provide support for emerging technology for embryo assessment, such as artificial intelligence.

STUDY FUNDING/COMPETING INTEREST(S)

None declared.

TRIAL REGISTRATION NUMBER

Not applicable.

Deep learning neural network analysis of human blastocyst expansion from time-lapse image files

RESEARCH QUESTION

Can artificial intelligence (AI) discriminate a blastocyst's cellular area from unedited time-lapse image files using semantic segmentation and a deep learning optimized U-Net architecture for use in selecting single blastocysts for transfer?

DESIGN

This platform was retrospectively applied to time-lapse files from 101 sequentially transferred single blastocysts that were prospectively selected for transfer by their highest expansion ranking within cohorts using a 10 h expansion assay rather than standard grading.

RESULTS

The AI platform provides expansion curves and raw data files to classify and compare blastocyst phenotypes within both cohorts and populations. Of 35 sequential unbiopsied single blastocyst transfers, 23 (65.7%) resulted in a live birth. Of 66 sequential single euploid blastocyst transfers, also selected for their most robust expansion, 49 (74.2%) resulted in live birth. The AI platform revealed that the averaged expansion rate was significantly (P = 0.007) greater in euploid blastocysts that resulted in live births compared with those resulting in failure to give a live birth. The platform further provides a framework to analyse fragmentation phenotypes that can test new hypotheses for developmental regulation during the preimplantation period.

CONCLUSIONS

AI can be used to quantitatively describe blastocyst expansion from unedited time-lapse image files and can be used to quantitatively rank-order blastocysts for transfer. Early clinical results from such single blastocyst selection suggests that live birth rates without biopsy may be comparable to those found using single euploid blastocysts in younger, good responder patients.

When embryology meets genetics: the definition of developmentally incompetent preimplantation embryos (DIPE)-the consensus of two Italian scientific societies

A clear definition of developmentally incompetent preimplantation embryo (DIPE) in literature is still missing, while several scientific societies are discussing this challenging topic. From both a clinical and scientific perspective, the identification of embryos unfit for reproductive purpose is crucial. This aim should be pursued in light of all diagnostic technologies for embryo evaluation, encompassing also genetic analyses, of recent implementation in IVF. The Italian context is characterized by an unusual scenario: embryos can be discarded only if not viable and cannot be used for research purposes either. Therefore, thousands of embryos, diagnosed as affected and/or aneuploid as resulting from preimplantation genetic testing (PGT) and clinically not utilizable, are cryopreserved and stored indefinitely, with important psychological, legal, and financial implications. With the aim of updating the definition of DIPE, also on the basis of the embryo genetic status, the Italian Society of Embryology, Reproduction and Research (SIERR) and the Italian Society of Human Genetic (SIGU) reviewed the literature on this topic, found a consensus, and produced a list of relevant criteria.

Should we look for a low-grade threshold for blastocyst transfer? A scoping review

Embryo quality is a key determinant of the success of IVF. Although the focus has been on selecting the best embryo for transfer, the classification of low-grade blastocysts (LGB) in existing scoring systems has received less attention. This is worrisome; embryo freezing allows optimal use of all created embryos, thus maximizing the cumulative live birth rate, which is arguably the most important outcome for infertile couples. A PubMed search was conducted in August 2020, using '((('poor-quality' OR 'poor quality') OR ('low-grade' OR 'low grade')) AND ('embryo' OR 'blastocyst')) AND ('pregnancy' OR 'live birth')'. This scoping review shows that LGB have similar euploidy and pregnancy success rates after implantation and have no adverse effects on pregnancy or perinatal outcomes. Evidence for pregnancy outcomes is lacking for different grades of LGB, with most studies clustering all LQB as one to compare with optimal blastocysts.

Association between morphologic grading and implantation rate of Euploid blastocyst

BACKGROUND

Standard morphologic evaluation has been the most widely adopted approach to embryo selection, and remains the most common strategy.The objective of the study to determine the association between the morphologic grading and implantation rate of euploid blastocysts in single frozen-thawed embryo transfer (SET) cycles.

METHODS

A total of 271 patients aged 20-40 years undergoing euploid SET from January 2017 to December 2019 were included in retrospective cohort study.The cycles were divided into three groups based on their morphologic grading before cryopreservation: good-quality (n = 58), average-quality (n = 88) and poor-quality blastocysts (n = 125). The pregnancy outcome of the three morphologic groups were analyzed and a logistic regression of implantation rate was conducted.

RESULTS

Good-quality blastocysts yielded statistically significantly higher implantation rates than poor-quality (79.31% vs. 48%; P<0.001). Planned subgroup analyses by age and the day of TE biopsy were conducted. Logistic regression analyses that adjusted for these variables identified higher implantation rates (adjusted odds ratio(aOR) = 4.083, 95% confidence interval (CI):1.836-9.082, P<0.001) for the good-quality blastocysts than for those that underwent poor-quality cycles in women aged < 35 years, but not in women aged ≥35 years (aOR = 6.074, 95% CI: 0.456-80.919, P = 0.172). The implantation rates were higher among women with good-quality blastocysts on both Day 5 and Day 6 of TE biopsy than among those with poor-quality blastocysts (Day 5, aOR = 3.294, 95% CI:1.260-8.616, P = 0.015; Day 6, aOR = 4.179, 95% CI:1.004 ~ 17.399, P = 0.049). Day 5 euploid blastocysts had no significant difference in implantation potential and early spontaneous abortion rate compared with similarly graded Day 6 euploid blastocysts.

CONCLUSIONS

Blastocyst morphologic grading was associated with implantation rate for euploid embryo transfers after adjustment for potential confounders. These findings suggest that evaluating blastocyst morphology is critical when selecting the best euploid blastocyst.

Clinical Outcomes Deriving from Transfer of Blastocysts Developed in Day 7: a Systematic Review and Meta-Analysis of Frozen-Thawed IVF Cycles

This meta-analysis aimed to assess the reproductive competence of blastocysts developed on day 7 compared with blastocysts developed on day 5/6. A systematic search was carried out to select relevant studies published before January 2020. Ten retrospective observational cohort studies were included. The primary outcome was the clinical pregnancy rate (CPR). Secondary outcomes were live birth rate (LBR), euploid rate, and survival rates after thawing. Frozen-thawed day 7 blastocyst transfer was associated with a significant reduction in CPR compared to day 5/6 (OR 0.36 95% CI 0.21 to 0.62, p = 0.0002, I² = 71% and OR 0.43, 95% CI 0.32 to 0.58, p < 0.0001, I² = 17% respectively). A significantly lower proportion of LBR was found comparing blastocysts transfers in day 7 to those in day 5/6 (OR 0.21, 95% CI 0.16-0.27, p < 0.0001, I² = 0% and OR 0.34, 95% CI 0.26-0.45, p < 0.0001, I² = 0% respectively). These findings were confirmed in a subgroup of Preimplantation Genetic Testing for Aneuploidies (PGT-A)-screened blastocysts. Blastocysts biopsied in day 7 was associated with a significant decrease of euploid rate compared with day 5/6 (OR 0.47, 95% CI 0.39-0.57, p < 0.0001, I² = 69% and OR 0.68, 95% CI 0.61-0.75, p < 0.0001, I² = 19% respectively). The survival rate after thawing was not statistically different. Sensitivity analyses were also performed. This study shows an association between delayed blastulation and a poorer prognosis in terms of euploid rate and pregnancy outcomes following frozen-thawed transfers. On the other hand, the results do not support the discharge of slow-blastulation embryos.

Euploidy rates of embryos in young patients with good and low prognosis according to the POSEIDON criteria

RESEARCH QUESTION

Does an association exist between ovarian reserve, ovarian response and embryonic euploidy in female patients under age 35 years?

DESIGN

This was a retrospective analysis of intracytoplasmic sperm injection and preimplantation genetic testing for aneuploidies cycles among patients enrolled at Bahceci Fulya IVF Center between January 2016 and August 2019. A total of 133 patients in POSEIDON group 1 (suboptimal responder; female age <35 years, antral follicle count [AFC] ≥5, number of oocytes retrieved <10) (group A), 133 patients in POSEIDON group 3 (expected low responder; female age <35 years, AFC <5) (group B) and 323 in the non-low-prognosis group (female age <35 years, AFC ≥5 and number of oocytes retrieved >9) (group C) were included.

RESULTS

There was no significant difference in euploidy rate per embryo among the three groups (61.7% [145/235] for group A versus 53.5% [68/127] for group B versus 62% [625/1008] for group C; P = 0.13). The cancellation rate in cycles without a euploid blastocyst was significantly lower in group C than groups A and B (8.4% versus 12.8% and 16.5%; P = 0.034). Multivariate regression analysis indicated that the ovarian response group did not significantly affect the probability of obtaining a euploid embryo. Trophectoderm score 'C' (odds ratio 0.520, P = 0.007) and inner cell mass score 'C' (odds ratio 0.480, P < 0.001) were associated with a decreased probability of obtaining a euploid embryo.

CONCLUSIONS

These results confirm that POSEIDON group 1 and group 3 and non-low-prognosis patients have different probabilities of euploid embryos being obtained per cycle. However, euploidy rates per embryo are not affected by the patient's ovarian reserve and response.

The dawn of the future: 30 years from the first biopsy of a human embryo. The detailed history of an ongoing revolution

Following early studies showing no adverse effects, cleavage stage biopsy by zona drilling using acid Tyrode's solution, and removal of single blastomeres for preimplantation genetic testing (PGT) and identification of sex in couples at risk of X-linked disease, was performed by Handyside and colleagues in late 1989, and pregnancies reported in 1990. This method was later used for specific diagnosis of monogenic conditions, and a few years later also for chromosomal structural and/or numerical impairments, thereby establishing a valuable alternative option to prenatal diagnosis. This revolutionary approach in clinical embryology spread worldwide, and several other embryo biopsy strategies developed over three decades in a process that is still ongoing. The rationale of this narrative review is to outline the different biopsy approaches implemented across the years in the workflow of the IVF clinics that provided PGT: their establishment, the first clinical experiences, their downsides, evolution, improvement and standardization. The history ends with a glimpse of the future: minimally/non-invasive PGT and experimental embryo micromanipulation protocols. This grand theme review outlines a timeline of the evolution of embryo biopsy protocols, whose implementation is increasing worldwide together with the increasing application of PGT techniques in IVF. It represents a vade mecum especially for the past, present and upcoming operators and experts in this field to (re)live this history from its dawn to its most likely future.

Blastulation rates of sibling oocytes in two IVF culture media: an evidence-based workflow to implement newly commercialized products

RESEARCH QUESTION

An evidence-based novel commercially available continuous IVF culture medium in compliance with an efficient quality-management system is proposed.

DESIGN

Non-interventional study on sibling oocytes. Intracytoplasmic sperm injection cycles among women aged 42 years or younger that used ejaculated spermatozoa and retrieved four to eight oocytes were included. Sibling oocytes were randomized for culture in the novel Geri-medium or continuous single culture medium (CSCM). Primary outcome measure was blastulation rate per cohort of inseminated oocytes; 1182 oocytes were required to outline down to a 7% difference (power = 80%).

RESULTS

A total of 181 cohorts of sibling oocytes were included. Geri-medium (n = 631 oocytes) and CSCM (n = 643 oocytes) resulted in similar blastulation rates (mean ± SD: 42.8% ± 30.1% versus 43.1% ± 29.0%; Wilcoxon signed rank test = 0.77). Blastocysts cultured in the former (n = 275 versus n = 277) showed longer timings during preimplantation development (P < 0.01) and were poorer quality (26% versus 18%; P = 0.03). Euploidy rate was no different in cycles that underwent preimplantation genetic testing for aneuploidy (n = 113) (117/237 [49%] versus 117/249 blastocysts [47%]; P = 0.6). Ongoing implantation rate was comparable in the study arms after euploid (29/47 [63%] versus 14/ 34 [41%]; P = 0.1) or untested (12/31 [39%] versus 7/18 [39%]; P = 0.3) transfers.

CONCLUSION

Blastulation rate among cohorts of sibling oocytes cultured in the same incubator is a fast, reliable and comprehensive performance indicator to validate novel commercially available culture medium. The media tested were considered similarly efficient. The differences in blastocyst morphology and developmental timings warrant further investigation, although euploidy and ongoing implantation rates were similar.

A stepwise approach to move from a cleavage-stage to a blastocyst-stage transfer policy for all patients in the IVF clinic

STUDY QUESTION

Is a stepwise change management approach an efficacious method to move from a Day 3 transfer policy to a Day 5 transfer policy for all patients in an IVF program?

SUMMARY ANSWER

A stepwise change from a Day 3 to a Day 5 transfer policy maintained the live birth rates per oocyte collection cycle (OCC) of the IVF program, with increased single embryo transfer (SET) and reduction of twin pregnancies.

WHAT IS KNOWN ALREADY

Evidence has shown that the probability of a live birth following IVF with a fresh embryo transfer (ET) is significantly higher after blastocyst-stage transfer than after cleavage-stage transfer. Blastocyst culture and transfer are usually performed in cases of good prognosis patients but many centers keep transferring cleavage-stage embryos for most of their patients because of the higher transfer cancelation rate in a blastocyst transfer policy.

STUDY DESIGN, SIZE, DURATION

In January 2012, a Day 5 embryo culture and blastocyst transfer policy including vitrification of supernumerary Day 5 blastocysts were implemented in a stepwise approach. The retrospective descriptive single-center analysis involving a preintervention phase consisted of Day 3 ETs and Day 3 slow freezing from 2010 until 2012. The postintervention phase involved a 6-year period from 2012 until 2017 in which three consecutive changes in the transfer policy were made, each over a 2-year period, based on the number of zygotes on Day 1. The primary outcome was live birth delivery rate per OCC during the stepwise change.

PARTICIPANTS/MATERIALS, SETTING, METHODS

All patients with at least one zygote available on Day 1 were scheduled for a fresh transfer, either on Day 3 or 5. Cycles with preimplantation genetic testing, freeze-all and oocyte donation cycles and cycles with a Day 2 transfer in the preintervention period were excluded. In the preintervention group, all cycles were scheduled for Day 3 transfer (n = 671 OCC) and slow freezing of the remaining Day 3 embryos. In the postintervention period, three periods were analyzed: period 1 (n = 1510 OCC; 1–9 zygotes: Day 3 transfer and >9 zygotes: Day 5 transfer); period 2 (n = 1456 OCC; 1–4 zygotes: Day 3 transfer and >4 zygotes: Day 5 transfer) and period 3 (n = 1764 OCC; Day 5 transfer). All remaining embryos underwent extend culture and were vitrified on Day 5, if developed to at least an early blastocyst. Data were analyzed using a mixed regression model with patient as a random factor.

MAIN RESULTS AND THE ROLE OF CHANCE

In the preintervention group, all OCC were scheduled for a Day 3 transfer. In period 1, period 2 and period 3, 20.9%, 61.5% and 100% of the OCCs were scheduled for a Day 5 transfer, respectively. More transfers per OCC were canceled in the postintervention period 2 and period 3 compared to the preintervention period (5.3% and 18.7% versus 3.4%, respectively; P < 0.0001). The mean number of embryos used per transfer decreased gradually after the introduction of the Day 5 transfer policy, from 1.62 ± 0.65 in the preintervention group to 1.12 ± 0.61 in period 3 (P < 0.0001). The percentage of SET cycles increased from 48.4% in the preintervention group to 54.6%, 73.8% and 87.8% in period 1, period 2 and period 3, respectively (P < 0.0001). The mean number of cryopreserved surplus embryos was significantly lower in period 3 compared to the preintervention group (1.29 ± 1.97 versus 1.78 ± 2.80; P < 0.0001).

Pregnancy and live birth delivery rate per fresh transfer, respectively, were significantly lower in the preintervention group (26.7% and 19.1%) as compared to period 3 (39.3% and 24.2%) (P < 0.0001). Twin pregnancy rate decreased gradually from 11.0% to 8.2%, 5.7% and 2.5% in the preintervention group, period 1, period 2 and period 3, respectively (P < 0.0001). Live birth rate and cumulative live birth delivery rates per OCC were significantly higher in group 2 compared to the preintervention period (25.6% and 35.8% versus 18.5% and 25.9%, respectively). Similar live birth and cumulative live birth delivery rates per OCC were achieved between the preintervention period and period 3 (18.5% and 25.6% versus 19.7% and 24.9%; respectively).

LIMITATIONS, REASONS FOR CAUTION

The primary limitation is the retrospective design of the study. The allocation of the cycles was done by the number of zygotes available without taking into account both embryological and clinical prognostic factors. Furthermore, the analysis was restricted to cycles where the standard transfer policy was followed. Embryos which were in the morula or compaction stage were not vitrified or cultured to Day 6, which could have contributed to the slight, not statistically significant, drop in live birth rate per OCC in group 3.

WIDER IMPLICATIONS OF THE FINDINGS

Live birth and cumulative live birth delivery rate per OCC in an unselected patient population is maintained in a Day 5 transfer policy compared to a Day 3 transfer policy. Additionally, a significantly reduction in twin pregnancy rate and a significant increase in SET were observed in a Day 5 transfer policy. For centers wanting to make the step from Day 3 to Day 5, this study provides a practical stepwise change management approach.

STUDY FUNDING/COMPETING INTEREST(S)

None.

TRIAL REGISTRATION NUMBER

None.

Pronuclear and blastocyst morphology are associated age-dependently with embryo ploidy in in vitro fertilization cycles

This retrospective study aimed to assess the relationship between standard markers of embryo morphology, maternal age and blastocyst ploidy determined by trophectoderm (TE) biopsy and Next-generation Sequencing (NGS). A total of 774 oocytes and embryos from 288 PGT-A cycles were scored for pronuclear, cleavage stage and blastocyst morphology. Pronuclear oocytes aligned between the nuclei and presenting equal number of nucleolus precursor bodies (NPBs) were designated Z1, oocytes showing equal number of NPBs, but not aligned, as Z2 while Z3 oocytes had an unequal number of NBPs between the nuclei or NPBs aligned in one nucleus and non-aligned in the other. Pronuclear oocytes with unequal-sized or non-aligned nuclei were designated Z4. Blastocysts were graded as BL1 (AA, AB or BA), BL2 (BB or CB) and BL3 (BC or CC) based on the combination of inner cell mass (ICM) and TE scores. Pronuclear and blastocyst morphology were correlated with aneuploidy in a < 40-year-old group (p < 0.01 and p < 0.05, respectively), but not in those ≥40 years. Interestingly, BL3 blastocysts classified as Z1 or Z3-Z4 on day-1 had different aneuploidy rates (BL3/Z1 = 46.7% vs. BL3/Z3-Z4 = 90.0%, p < 0.05). In summary, our data showed that pronuclear and blastocyst morphology are associated with blastocyst ploidy in younger patients. This may help embryo selection for embryo transfer and decision-making on which blastocysts should be biopsied in PGT-A cycles.

Trophectoderm biopsy for preimplantation genetic test and technical tips: A review

BACKGROUND

Recently, the Japan Society of Obstetrics and Gynecology initiated a clinical study of preimplantation genetic test for aneuploidy. There will be a great need for a standardized embryo biopsy technique in Japan. However, the gold standard trophectoderm (TE) biopsy procedure has not been established, and this review outlines the clinical use of TE biopsy.

METHODS

Based on literature, the method and associated techniques for TE biopsy, a dissection method of TE cells from blastocysts, were investigated.

MAIN FINDINGS

Two TE biopsy methods are used, namely assisted hatching (herniating) and non-assisted hatching (direct suction); however, it is not clear which of these methods is superior. It is critical to understand whether the flicking or pulling method is beneficial.

CONCLUSION

Non-assisted hatching biopsy method may cause blastocyst collapse with a higher probability, and it may extend the biopsy time. The biopsy procedure should be performed within 3 minutes, and thus direct TE suction may have greater disadvantages. It is a fact that pulling method of TE dissection with laser pulse is simple; however, excess laser shots may induce a higher frequency of mosaicism. It is important to understand that each technique of TE biopsy has benefits and disadvantages.

Do patient factors influence embryologists' decisions to freeze borderline blastocysts?

RESEARCH QUESTION

To investigate whether patient factors influence the decision to freeze a blastocyst with low implantation potential.

DESIGN

This experimental study assessed 170 practicing embryologists from a variety of countries who were recruited via an online survey. Participants were currently practicing embryologists, who grade blastocysts as part of this role. The survey presented decision-making 'vignettes' to participants. These included specific patient information, as well as an image of an expanded blastocyst that was of borderline quality for inner cell mass and trophectoderm, for which the embryologist selected whether or not to freeze. High/low maternal age, the presence/absence of other top quality blastocysts, and the presence/absence of previously unsuccessful IVF cycles were systematically varied within the patient information in a 2 × 2 × 2 design. Participants reported how likely they would be to freeze a particular blastocyst on a scale of 1 (Extremely Unlikely) to 7 (Extremely Likely), and whether or not they would ultimately freeze each blastocyst (Yes or No).

RESULTS

Lower maternal age, no other high-quality blastocysts within the cohort, and multiple unsuccessful IVF cycles were associated with greater likelihood of recommending to freeze (P < .001). Furthermore, significant interactions among all three patient factors were noted.

CONCLUSION

This study provides evidence suggesting that when faced with an uncertain blastocyst, factors pertaining to the patient (maternal age, the presence/absence of other top quality blastocysts, and the presence/absence of previously unsuccessful IVF cycles) influence the decision to freeze.