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Cimadomo D, Rienzi L, Conforti A, Forman E, Canosa S, Innocenti F, Poli M, Hynes J, Gemmell L, Vaiarelli A, Alviggi C, Ubaldi FM, Capalbo A. Opening the black box: why do euploid blastocysts fail to implant? A systematic review and meta-analysis. Hum Reprod Update 2023; 29:570-633. [PMID: 37192834 DOI: 10.1093/humupd/dmad010] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Revised: 03/22/2023] [Indexed: 05/18/2023] Open
Abstract
BACKGROUND A normal chromosomal constitution defined through PGT-A assessing all chromosomes on trophectoderm (TE) biopsies represents the strongest predictor of embryo implantation. Yet, its positive predictive value is not higher than 50-60%. This gap of knowledge on the causes of euploid blastocysts' reproductive failure is known as 'the black box of implantation'. OBJECTIVE AND RATIONALE Several embryonic, maternal, paternal, clinical, and IVF laboratory features were scrutinized for their putative association with reproductive success or implantation failure of euploid blastocysts. SEARCH METHODS A systematic bibliographical search was conducted without temporal limits up to August 2021. The keywords were '(blastocyst OR day5 embryo OR day6 embryo OR day7 embryo) AND (euploid OR chromosomally normal OR preimplantation genetic testing) AND (implantation OR implantation failure OR miscarriage OR abortion OR live birth OR biochemical pregnancy OR recurrent implantation failure)'. Overall, 1608 items were identified and screened. We included all prospective or retrospective clinical studies and randomized-controlled-trials (RCTs) that assessed any feature associated with live-birth rates (LBR) and/or miscarriage rates (MR) among non-mosaic euploid blastocyst transfer after TE biopsy and PGT-A. In total, 41 reviews and 372 papers were selected, clustered according to a common focus, and thoroughly reviewed. The PRISMA guideline was followed, the PICO model was adopted, and ROBINS-I and ROB 2.0 scoring were used to assess putative bias. Bias across studies regarding the LBR was also assessed using visual inspection of funnel plots and the trim and fill method. Categorical data were combined with a pooled-OR. The random-effect model was used to conduct the meta-analysis. Between-study heterogeneity was addressed using I2. Whenever not suitable for the meta-analysis, the included studies were simply described for their results. The study protocol was registered at http://www.crd.york.ac.uk/PROSPERO/ (registration number CRD42021275329). OUTCOMES We included 372 original papers (335 retrospective studies, 30 prospective studies and 7 RCTs) and 41 reviews. However, most of the studies were retrospective, or characterized by small sample sizes, thus prone to bias, which reduces the quality of the evidence to low or very low. Reduced inner cell mass (7 studies, OR: 0.37, 95% CI: 0.27-0.52, I2 = 53%), or TE quality (9 studies, OR: 0.53, 95% CI: 0.43-0.67, I2 = 70%), overall blastocyst quality worse than Gardner's BB-grade (8 studies, OR: 0.40, 95% CI: 0.24-0.67, I2 = 83%), developmental delay (18 studies, OR: 0.56, 95% CI: 0.49-0.63, I2 = 47%), and (by qualitative analysis) some morphodynamic abnormalities pinpointed through time-lapse microscopy (abnormal cleavage patterns, spontaneous blastocyst collapse, longer time of morula formation I, time of blastulation (tB), and duration of blastulation) were all associated with poorer reproductive outcomes. Slightly lower LBR, even in the context of PGT-A, was reported among women ≥38 years (7 studies, OR: 0.87, 95% CI: 0.75-1.00, I2 = 31%), while obesity was associated with both lower LBR (2 studies, OR: 0.66, 95% CI: 0.55-0.79, I2 = 0%) and higher MR (2 studies, OR: 1.8, 95% CI: 1.08-2.99, I2 = 52%). The experience of previous repeated implantation failures (RIF) was also associated with lower LBR (3 studies, OR: 0.72, 95% CI: 0.55-0.93, I2 = 0%). By qualitative analysis, among hormonal assessments, only abnormal progesterone levels prior to transfer were associated with LBR and MR after PGT-A. Among the clinical protocols used, vitrified-warmed embryo transfer was more effective than fresh transfer (2 studies, OR: 1.56, 95% CI: 1.05-2.33, I2 = 23%) after PGT-A. Lastly, multiple vitrification-warming cycles (2 studies, OR: 0.41, 95% CI: 0.22-0.77, I2 = 50%) or (by qualitative analysis) a high number of cells biopsied may slightly reduce the LBR, while simultaneous zona-pellucida opening and TE biopsy allowed better results than the Day 3 hatching-based protocol (3 studies, OR: 1.41, 95% CI: 1.18-1.69, I2 = 0%). WIDER IMPLICATIONS Embryo selection aims at shortening the time-to-pregnancy, while minimizing the reproductive risks. Knowing which features are associated with the reproductive competence of euploid blastocysts is therefore critical to define, implement, and validate safer and more efficient clinical workflows. Future research should be directed towards: (i) systematic investigations of the mechanisms involved in reproductive aging beyond de novo chromosomal abnormalities, and how lifestyle and nutrition may accelerate or exacerbate their consequences; (ii) improved evaluation of the uterine and blastocyst-endometrial dialogue, both of which represent black boxes themselves; (iii) standardization/automation of embryo assessment and IVF protocols; (iv) additional invasive or preferably non-invasive tools for embryo selection. Only by filling these gaps we may finally crack the riddle behind 'the black box of implantation'.
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Affiliation(s)
- Danilo Cimadomo
- 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
| | - Alessandro Conforti
- Department of Neuroscience, Reproductive Science and Odontostomatology, Federico II University, Naples, Italy
| | - Eric Forman
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Columbia University Irving Medical Centre, New York, NY, USA
| | | | - Federica Innocenti
- IVIRMA Global Research Alliance, GENERA, Clinica Valle Giulia, Rome, Italy
| | - Maurizio Poli
- Centrum voor Kinderwens, Dijklander Hospital, Purmerend, The Netherlands
- Juno Genetics, Rome, Italy
| | - Jenna Hynes
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Columbia University Irving Medical Centre, New York, NY, USA
| | - Laura Gemmell
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Columbia University Irving Medical Centre, New York, NY, USA
| | - Alberto Vaiarelli
- IVIRMA Global Research Alliance, GENERA, Clinica Valle Giulia, Rome, Italy
| | - Carlo Alviggi
- Department of Public Health, Federico II University, Naples, Italy
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Wu TF, Chen MJ, Lee MS, Huang CC, Ho ST, Cheng EH, Lee TH. Comparison of clinical outcome between day 5 and day 6 single blastocyst transfers in cycles undergoing preimplantation genetic testing for aneuploidy. Taiwan J Obstet Gynecol 2023; 62:429-433. [PMID: 37188448 DOI: 10.1016/j.tjog.2023.03.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/15/2023] [Indexed: 05/17/2023] Open
Abstract
OBJECTIVE In vitro fertilization (IVF) treatment has gradually adopted the practice of culturing embryos until the blastocyst stage on the D5 or D6 as the standard approach. PGT-A is commonly used in vitro fertilization (IVF). This study aimed to evaluate the clinical outcomes of frozen embryo transfers (FETs) using single blastocyst transfers (SBTs) on the fifth (D5) or sixth (D6) day of development in cycles that underwent preimplantation genetic testing for aneuploidy (PGT-A). MATERIALS AND METHODS The patients who had at least one euploid or mosaic blastocyst of good quality determined by PGT-A results and received single embryo transfer (SET) cycles were included in the study. In this study, the live birth rate (LBR) and neonatal outcomes were compared after the transfer of single biopsied D5 and D6 blastocysts in frozen embryo transfer (FET) cycles. RESULTS A total of 527 frozen-thawed blastocyst transfer (FET) cycles (8449 biopsied embryos were analyzed). No significant difference in the implantation rate (IR), clinical pregnancy rate (CPR), and live birth rate (LBR) between the transfers of D5 and D6 blastocysts. Birth weight was the only perinatal outcome that showed a significant difference between the D5 and D6 groups. CONCLUSION The study confirmed that the transfer of a single euploid or mosaic blastocyst, regardless of whether it was on the fifth (D5) or sixth (D6) day of development, can lead to promising clinical results.
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Affiliation(s)
- Ting-Feng Wu
- Division of Infertility, Lee Women's Hospital, Taichung, Taiwan; Department of Obstetrics and Gynecology, Taichung Veterans General Hospital, Taichung, Taiwan
| | - Ming-Jer Chen
- Department of Obstetrics and Gynecology, Taichung Veterans General Hospital, Taichung, Taiwan; School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan.
| | - Maw-Sheng Lee
- Division of Infertility, Lee Women's Hospital, Taichung, Taiwan; Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan; Department of Obstetrics and Gynecology, Chung Shan Medical University Hospital, Taichung, Taiwan.
| | - Chun-Chia Huang
- Division of Infertility, Lee Women's Hospital, Taichung, Taiwan
| | - Shu-Ting Ho
- Division of Infertility, Lee Women's Hospital, Taichung, Taiwan
| | - En-Hui Cheng
- Division of Infertility, Lee Women's Hospital, Taichung, Taiwan
| | - Tsung-Hsien Lee
- Division of Infertility, Lee Women's Hospital, Taichung, Taiwan; Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan; Department of Obstetrics and Gynecology, Chung Shan Medical University Hospital, Taichung, Taiwan
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Yu G, Ma S, Liu H, Liu Y, Zhang H, Zhang W, Wu K. Comparison of clinical outcomes of frozen-thawed D5 and D6 blastocysts undergoing preimplantation genetic testing. J Transl Med 2022; 20:545. [DOI: 10.1186/s12967-022-03762-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 11/06/2022] [Indexed: 11/28/2022] Open
Abstract
Abstract
Background
This study aimed to analyze the clinical outcomes of blastocyst which undergo the preimplantation genetic testing (PGT) transplantation from frozen-thawed D5 and D6. In addition, the effect of blastocyst grade on clinical and neonatal outcomes was also investigated in this study.
Methods
The pregnancy and miscarriage rates of 1130 cycles of frozen embryo transfer, including 784 D5 frozen embryos and 346 D6 frozen embryos in the Reproductive Hospital of Shandong University from January to December 2020 were analyzed. Gardner blastocyst scoring was used for blastocyst evaluation.
Results
The pregnancy rate of D5 blastocyst was significantly higher, whereas the miscarriage rate of D5 blastocyst was lower, than that of D6 blastocyst tissue biopsy. No significant difference was observed in birth weight and low birth weight of D5 blastocyst and D6 blastocyst, preterm birth, gestational age, and neonatal sex. Frozen-thawed D5 blastocysts have higher pregnancy success rates and lower miscarriage rates compared to D6 blastocysts.
Conclusion
Therefore, both blastocyst grade and embryo biopsy date must be considered when transferring frozen embryos.
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Lane SL, Reed L, Schoolcraft WB, Katz-Jaffe MG. Euploid day 7 blastocysts of infertility patients with only slow embryo development have reduced implantation potential. Reprod Biomed Online 2021; 44:858-865. [PMID: 35337737 DOI: 10.1016/j.rbmo.2021.08.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 08/04/2021] [Accepted: 08/26/2021] [Indexed: 10/20/2022]
Abstract
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.
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Affiliation(s)
- Sydney L Lane
- Colorado Center for Reproductive Medicine, Lone Tree CO, USA
| | - Laura Reed
- Colorado Center for Reproductive Medicine, Lone Tree CO, USA
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Rao DG, Mantravadi KC, Sharanappa VK. Euploid Day-5 Blastocysts Versus Euploid Day-6 Blastocysts — Will the Reproductive Outcomes Differ? An Observational Study. FERTILITY & REPRODUCTION 2021. [DOI: 10.1142/s2661318221500055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Background and objective: Day-5 blastocyst embryos are usually chosen for assisted reproductive therapy. We compared the reproductive outcomes of the euploid blastocysts developed on Day 5 versus Day 6. Methods: This single-center, retrospective observational study analyzed patients aged 25–45 years, who underwent intracytoplasmic sperm injection from December 2014 to November 2018. Depending on the day of trophectoderm biopsy, patients were categorized into Day-5 and Day-6 groups. Percentages of euploid embryos were calculated for both groups, and elective single euploid blastocysts were transferred in a frozen embryo transfer (FET) cycles. The study endpoints were the comparisons of the reproductive outcomes including clinical pregnancy rate (CPR), implantation rate (IR), miscarriage rate (MR), and live birth rate (LBR) between Day-5 and Day-6 euploid FET groups. Results: A total of 801 embryos from 184 patients were evaluated [Day 5 ([Formula: see text]=769); Day 6 ([Formula: see text]=32); 42.45% were euploid] with the rate of euploidy in Day-5 and Day-6 groups at 42.52% and 40.62%, respectively. A total of 126 patients underwent FET with 126 elective single euploid embryos (Day 5: 117; Day 6: 9). For Day-5 versus Day-6 groups, a significantly higher IR (61.54% vs. 44.44%; [Formula: see text] = 0.0531), CPR (61.54% vs. 44.44%; [Formula: see text] = 0.0531), and LBR (61.54% vs. 33.33%; [Formula: see text] = 0.0014) were reported. Multivariate analysis on ANOVA suggested, comparable pregnancy rates at Day 5 and Day 6 ([Formula: see text] = 0.728). Conclusions: Day-5 euploid blastocysts seem to offer better reproductive outcomes than Day-6 euploid blastocysts. Further research is recommended to evaluate the reproductive outcomes of Day-6 blastocysts.
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Affiliation(s)
- Durga Gedela Rao
- Oasis Fertility, Reproductive Medicine, Hyderabad, Telangana, India
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