Quality of embryos on day 7 after medium refreshment on day 6: a prospective trial

2021 ◽  
Vol 36 (5) ◽  
pp. 1253-1259
Author(s):  
Iris G Insogna ◽  
Andrea Lanes ◽  
Elizabeth S Ginsburg ◽  
Catherine Racowsky
Keyword(s):  
Adverse Effect ◽  
Continuous Medium ◽  
Culture Media ◽  
Prospective Trial ◽  
Blastocyst Stage ◽  
Single Step ◽  
Fresh Medium ◽  
Preimplantation Genetic Testing ◽  
Younger Women ◽  
Competing Interest

Abstract STUDY QUESTION Are embryos that fail to meet biopsy or freezing criteria on day 6 (D6) more likely to meet these criteria on day 7 (D7) if cultured in fresh medium from D6 to D7? SUMMARY ANSWER Refreshment of medium on D6 did not increase the proportion of usable embryos on D7, with an adverse effect for women ≥40 years old. WHAT IS KNOWN ALREADY Embryo development in continuous single-step medium, from fertilization to the blastocyst stage, is equivalent to that using a sequential media protocol. However, there remains a theoretical benefit of refreshing the culture environment by transitioning slowly developing D6 embryos to a fresh medium droplet of the same composition, with a renewed source of nutrients and a milieu free of metabolic toxins. STUDY DESIGN, SIZE, DURATION This was a prospective trial of culture media exposure in which embryos were randomized on D6 to remain in the same culture medium from D3 to D7 (continuous, n = 620) or be moved to fresh medium (fresh, n = 603) on D6, with re-evaluation on D7. Data were collected from IVF cycles, with or without ICSI, between 29 March 2019 and 17 February 2020. PARTICIPANTS/MATERIALS, SETTING, METHODS Embryos from 298 women, aged 18–44 years, from cycles with or without preimplantation genetic testing (PGT) that did not meet criteria for biopsy and/or freeze on D6 were included in the study. Embryos were only included if there was a minimum of two embryos meeting the inclusion criteria in any cohort. Only the first cycle undertaken by each woman in the study period from which embryos were randomized was included. MAIN RESULTS AND THE ROLE OF CHANCE A total of 1254 embryos were randomized from 312 cycles (209 non-PGT and 103 PGT) including 200 women undergoing IVF without PGT and 98 women who underwent PGT. The proportion of usable blastocysts on D7 did not differ between groups: 10.1% (61/603) in fresh versus 9.7% (60/620) in continuous medium (relative risk (RR) 1.05, 95% CI 0.74–1.47)). Embryos from women ≥40 years old had a significantly decreased likelihood of achieving a usable blastocyst on D7 after culture in fresh versus continuous medium: 3.5% versus 12.2%; RR 0.29, 95% CI 0.08–0.98. In total, 9.9% of embryos otherwise discarded on D6 met the criteria for biopsy and/or freeze on D7. LIMITATIONS, REASONS FOR CAUTION Future work investigating implantation, clinical pregnancy and miscarriage rates with D7 embryos is still needed. WIDER IMPLICATIONS OF THE FINDINGS Refreshment of medium on D6 did not increase the proportion of usable embryos on D7 overall. Younger women were more likely to develop D7 embryos after refreshment of medium on D6, while an adverse effect was seen in women ≥40 years old. However, by extending the culture of embryos to D7, additional blastocysts become available for clinical use. STUDY FUNDING/COMPETING INTEREST(S) Funding was provided through the Department of Obstetrics and Gynecology at Brigham and Women’s Hospital. I.G.I. works with Teladoc Health. A.L. has no disclosures. E.S.G. works as a consultant for Teladoc Health, and a writer and editor for UpToDate and BioMed Central. C.R. is a board member of the American Society for Reproductive Medicine and works with UpToDate. TRIAL REGISTRATION NUMBER N/A.

100 SEQUENTIAL VERSUS SINGLE-STEP MEDIUM FOR RHESUS MACAQUE EMBRYO CULTURE

2016 ◽  
Vol 28 (2) ◽  
pp. 180
Keyword(s):  
Embryonic Development ◽  
Embryo Culture ◽  
Culture Media ◽  
Blastocyst Stage ◽  
Single Step ◽  
Blastocyst Development ◽  
Equal Variance ◽  
Significant Difference ◽  
Health Studies

The nonhuman primate (NHP) is a valuable translational model for human health studies and is widely used to investigate pre-implantation embryo development. Central to these investigations is the dependency on in vitro embryo culture (IVC). Since 2001, the single-step hamster embryo culture medium (HECM) has been the accepted standard for NHP IVC. With recent advances in formula optimization for IVC in human clinics, a re-examination of optimal NHP IVC media is warranted. Thus, two types of commercially available IVC media routinely used in human applications were compared with HECM-9: Global (single-step; LifeGlobal Group, Guilford, CT, USA), and Quinns Advantage (sequential; SAGE, Trumbull, CT, USA). Normally cycling, adult rhesus monkeys (n = 3) underwent controlled ovarian stimulations, and follicles were aspirated via laparoscope. Recovered ova were fertilized in vitro and the resultant zygotes (n = 138) were cultured for 9 days in HECM-9, Global, or Quinns with 10% protein supplement at 37.5°C in humidified tri-gas (6% CO2, 5% O2, and 89% N). Single-step media (HECM-9 and Global) were refreshed every two days while embryos were cultured for Days 1–3 in Quinns Advantage Cleavage medium without being replaced and in Quinns Advantage Blastocyst medium for Days 4–9 with medium changes every 2 days. Embryos were observed for cleavage, compaction, and blastocyst development. Proportional data with equal variance and normal distribution were analysed by one-way ANOVA, and significance was determined post-hoc by the Holm-Sidak method with P < 0.05. Developmental stage data ± s.e.M are presented in Table 1; a change in superscript indicates a significant difference within the column. There was no difference in embryonic cleavage or morula compaction between the three culture media evaluated, indicating no obvious differences in their effects on embryonic development 1 to 3 days after fertilization. However, a greater proportion of blastocysts developed in Global medium compared with HECM-9, and though it was not statistically different, embryos cultured in Global tended to reach the blastocyst stage more frequently than those in Quinns. Although not significant due to large variances in each group, blastocyst expansion also tended to occur more frequently in Global medium than in HECM-9 or Quinns. Taken together, these data indicate that single-step Global is as supportive of early embryonic development as HECM-9 but is better formulated to facilitate later stage differentiation and would be better suited for use in updated standard NHP IVC protocols. Table 1.Cleavage, compaction, blastocysts, and expansion of embryos in HECM-9, Global, and Quinns media

scholarly journals ESHRE PGT Consortium data collection XVI–XVIII: cycles from 2013 to 2015†

2020 ◽  
Vol 2020 (4) ◽  
Author(s):  
E Coonen ◽  
A van Montfoort ◽  
F Carvalho ◽  
G Kokkali ◽  
C Moutou ◽  
...  
Keyword(s):  
Data Collection ◽  
Single Gene ◽  
Oocyte Retrieval ◽  
Blastocyst Stage ◽  
Data Sets ◽  
Preimplantation Genetic Testing ◽  
Testing Technology ◽  
Competing Interest ◽  
Reported Data ◽  
Data Collections

Abstract STUDY QUESTION What are the trends and developments in preimplantation genetic testing (PGT) in 2013–2015 as compared to previous years? SUMMARY ANSWER The main trends observed in the retrospective data collections 2013–2015, representing valuable data on PGT activity in (mainly) Europe, are the increased application of trophectoderm biopsy at the cost of cleavage stage biopsy and the continuing expansion of comprehensive testing technology in PGT for chromosomal structural rearrangements and for aneuploidies (PGT-SR and PGT-A). WHAT IS KNOWN ALREADY Since it was established in 1997, the ESHRE PGT Consortium has been collecting data from international PGT centres. To date, 15 data sets and an overview of the first 10 years of data collections have been published. STUDY DESIGN, SIZE, DURATION Collection of (mainly) European data by the PGT Consortium for ESHRE. The data for PGT cycles performed between 1 January 2013 and 31 December 2015 were provided by participating centres on a voluntary basis. For the collection of cycle, pregnancy and baby data, separate, pre-designed MS Excel tables were used. PARTICIPANTS/MATERIALS, SETTING, METHODS Data were submitted by 59, 60 and 59 centres respectively for 2013, 2014 and 2015 (full PGT Consortium members). Records with incomplete or inconsistent data were excluded from the calculations. Corrections, calculations, figures and tables were made by expert co-authors. MAIN RESULTS AND THE ROLE OF CHANCE For data collection XVI/XVII/XVIII, 59/60/59 centres reported data on 8164/9769/11 120 cycles with oocyte retrieval: 5020/6278/7155 cycles for PGT-A, 2026/2243/2661 cycles for PGT for monogenic/single gene defects, 1039/1189/1231 cycles for PGT-SR and 79/59/73 cycles for sexing for X-linked diseases. From 2013 until 2015, the uptake of biopsy at the blastocyst stage was mainly observed in cycles for PGT-A (from 23% to 36%) and PGT-SR (from 22% to 36%), alongside the increased application of comprehensive testing technology (from 66% to 75% in PGT-A and from 36% to 58% in PGT-SR). LIMITATIONS, REASONS FOR CAUTION The findings apply to the 59/60/59 participating centres and may not represent worldwide trends in PGT. Data were collected retrospectively and no details of the follow-up on PGT pregnancies and babies born were provided. WIDER IMPLICATIONS OF THE FINDINGS Being the largest data collection on PGT worldwide, detailed information about ongoing developments in the field is provided. STUDY FUNDING/COMPETING INTEREST(S) The study has no external funding and all costs are covered by ESHRE. There are no competing interests declared. TRIAL REGISTRATION NUMBER N/A.

P–168 RCT comparing the effect of Continuous ( Single Step ) embryo culture system versus a Sequential embryo culture system on the outcome of IVF/ICSI cycles

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
R Singh ◽  
M Singh
Keyword(s):  
Embryo Culture ◽  
Culture System ◽  
Culture Media ◽  
Poor Quality ◽  
Blastocyst Stage ◽  
Single Step ◽  
Blastocyst Formation ◽  
Cleavage Stage ◽  
Media Systems ◽  
Single Medium

Abstract Study question Is the outcome of IVF/ICSI cycles done with continuous (single step ) embryo culture system different from that with sequential embryo culture system ? Summary answer Yes the outcome of IVF / ICSI cycles done with continuous (single step ) embryo-culture system is better than that with sequential embryo-culture system . What is known already Embryo culture media are important factors in IVF, which can significantly influence the clinical outcome of IVF/ICSI cycles. However it is not clear which formulation is most optimal and whether sequential or continuous media (single step) should be favored. Sequential media complies with embryo demands based on developmental stage , taking into account metabolic changes embryos undergo in-vivo, while moving from the oviduct to the uterus. The embryos in the early cleavage stage prefer to use pyruvate to produce energy, whereas once development nears the blastocyst stage , the embryos start using glucose in the process of glycolysis . Study design, size, duration A prospective RCT was carried out at our centre between 2018–2019 and IVF-ICSI patients meeting inclusion criteria (at least six normal MII - Oocytes) were included in this study. The aim of study was to compare blastocyst formation rates after embryo-culture in two different culture media systems. 436 metaphase II Oocytes from 62 women were randomly and equally divided to be fertilized and cultured to the blastocyst stage in either sequential media or single-step media. Participants/materials, setting, methods In this prospective trial with sibling oocytes, 436 metaphase II oocytes from 62 women were randomly and equally divided to be fertilized and cultured to the blastocyst stage in either sequential media ( n = 218 MII oocytes) or a single medium ( n = 218 MII oocytes). In both groups, embryos were cultured in an interrupted fashion with media changes on day 3. Embryo transfer was performed on day 5. Main results and the role of chance Blastocyst formation rates on day 5 were significantly higher following culture in single step media 60.55% (132 / 218 ) as compared to sequential media 34.86% ( 76 / 218) . The percentage of good quality blastocysts was also significantly higher in single step media. In conclusion, culture in single step media was associated with higher blastocyst formation rates compared to sequential media , suggesting that the single medium may provide better support to the developing embryo. The proportion of poor quality embryos was significantly higher in the sequential media group. Results indicate that embryo culture in continuous media could be as efficient as embryo culture in sequential media. A significant difference observed was the proportion of poor quality embryos on day 5 , which was significantly higher when the embryos were cultured in sequential media. Our results suggest that the type of embryo culture media can influence the quality of embryos both at the cleavage stage and blastocyst stage. The use of continuous embryo culture media does not seem to cause an adverse effect; in fact, their use can lower the workload in busy IVF labs and lower the stress that embryos are exposed to during handling. Limitations, reasons for caution Although single-step-medium for extended culture has practical advantages and blastocyst formation rates appear to be higher, there is insufficient evidence to recommend either sequential or single-step media as being superior for the embryo-culture to days 5/6. Further studies comparing these two media systems in well-designed trials should be performed. Wider implications of the findings: When employing sequential media for embryo culture , it is necessary to transfer the embryos from one medium to another ( cleavage stage medium to blastocyst stage medium) which increases stress related embryo damage . Therefore, single-step media is beneficial as the embryos can develop undisturbed till blastocyst stage. Trial registration number Not applicable

Purification of Urokinase from Complex Mixtures Using Immobilized Monoclonal Antibody Against Urokinase Light Chain

1983 ◽  
Vol 49 (01) ◽  
pp. 024-027 ◽  
Author(s):  
David Vetterlein ◽  
Gary J Calton
Keyword(s):  
Monoclonal Antibody ◽  
Light Chain ◽  
Culture Media ◽  
Biological Fluids ◽  
Single Step ◽  
High Yield ◽  
Step Method ◽  
Commercial Preparation ◽  
E Coli ◽  
Tissue Culture Media

SummaryThe preparation of a monoclonal antibody (MAB) against high molecular weight (HMW) urokinase light chain (20,000 Mr) is described. This MAB was immobilized and the resulting immunosorbent was used to isolate urokinase starting with an impure commercial preparation, fresh urine, spent tissue culture media, or E. coli broth without preliminary dialysis or concentration steps. Monospecific antibodies appear to provide a rapid single step method of purifying urokinase, in high yield, from a variety of biological fluids.

scholarly journals Utilization of preimplantation genetic testing in the USA

2021 ◽  
Author(s):  
Kaitlyn Roche ◽  
Catherine Racowsky ◽  
Joyce Harper
Keyword(s):  
Genetic Testing ◽  
Older Women ◽  
State Level ◽  
Oocyte Retrieval ◽  
Preimplantation Genetic Testing ◽  
Annual Increase ◽  
Younger Women ◽  
Live Birth Rates ◽  
Significant Difference ◽  
The Usa

Abstract Purpose To evaluate the use of preimplantation genetic testing (PGT) and live birth rates (LBR) in the USA from 2014 to 2017 and to understand how PGT is being used at a clinic and state level. Methods This study accessed SART data for 2014 to 2017 to determine LBR and the CDC for years 2016 and 2017 to identify PGT usage. Primary cycles included only the first embryo transfer within 1 year of an oocyte retrieval; subsequent cycles included transfers occurring after the first transfer or beyond 1 year of oocyte retrieval. Results In the SART data, the number of primary PGT cycles showed a significant monotonic annual increase from 18,805 in 2014 to 54,442 in 2017 (P = 0.042) and subsequent PGT cycles in these years increased from 2946 to 14,361 (P = 0.01). There was a significant difference in primary PGT cycle use by age, where younger women had a greater percentage of PGT treatment cycles than older women. In both PGT and non-PGT cycles, the LBR per oocyte retrieval decreased significantly from 2014 to 2017 (P<0001) and younger women had a significantly higher LBR per oocyte retrieval compared to older women (P < 0.001). The CDC data revealed that in 2016, just 53 (11.4%) clinics used PGT for more than 50% of their cycles, which increased to 99 (21.4%) clinics in 2017 (P< 0.001). Conclusions A growing number of US clinics are offering PGT to their patients. These findings support re-evaluation of the application for PGT.

P–174 Globulin-rich protein supplements improve blastulation efficiency in culture and promote implantation in vitro

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
S Ojosnegros ◽  
A Seriola ◽  
E Aroca ◽  
A Godeau ◽  
D Denkova ◽  
...  
Keyword(s):  
Molecular Markers ◽  
Culture Media ◽  
Blastocyst Stage ◽  
Reproductive Age ◽  
Human Embryos ◽  
Protein Supplement ◽  
Age Cohorts ◽  
The Matrix ◽  
Basal Media ◽  
Post Implantation

Abstract Study question Can globulin-rich compared to albumin (HSA) supplements improve blastulation and support embryo development towards post implantation? Summary answer Yes, globulin supplements with clinical-grade quality increase blastulation efficiency by 20% (50% in older mothers) and support the transition of embryos towards post-implantation development. What is known already During embryonic development at the morula stage there is a metabolic transition towards glycolysis as demand from outsourced energy increases. Therefore as cleavage proceeds, the demand for nutrients in the embryo increases accordingly. With few exceptions, HSA from human plasma or recombinant origin has been the main an only protein supplement used in almost all IVF-procedures. Globulin rich supplements are available but their use is not widespread and little is known about their efficiency in post-implantation development. Study design, size, duration We have cultured more than 600 mouse embryos in continuous media containing a protein supplement#1 (PS#1), from 1-cell up to blastocyst stage. At blastocyst stage embryos were replaced into fresh media containing protein supplement#2 (PS#2). The embryos were allowed to hatch naturally and then transferred into a proprietary matrix for further development and implantation for an additional 48h. Participants/materials, setting, methods: The blastulation rate, measured for HSA-supplemented embryo cohort was compared with embryos cultured in PS#1. Hatching efficiency was reported for embryos cultured in transfer media including PS#2. Once embedded in the matrix, advanced label-free imaging techniques and custom algorithms to measure matrix implantation strength were used. Key molecular markers (i.e. OCT4, CDX2) for correct post-implantation lineage patterning were documented by conventional 3D confocal immunofluorescence imaging. Main results and the role of chance Embryos supplemented with PS#1 reached blastocyst with overall 21% higher efficiency than embryos supplemented by HSA. When separated by age cohorts, embryos obtained from older females (ex-colony breeders, &gt;14 weeks old) reached blastocyst stage with 55% higher efficiency than the same type of embryos cultured in the presence of HSA. Embryos obtained from females at optimal reproductive age reached blastocyst stage 10% more efficiently under PS#1 supplementation than with HSA. Hatching efficiency was 45% higher for embryos cultured with PS#2 than embryos supplemented with HSA. For every variable tested (e.g.% of arrested or degenerated embryos) or condition implemented (e.g. mouse basal media, human basal media from different brands, etc.) PS#1 and PS#2 outperformed, without exception, the supplementation with HSA. When embedded in the implantation matrix, the embryos cultured with PS#1 (cleavage) and transferred to PS#2 at blastocyst stage showed a remarkable implantation ability as measured by trophoblast outgrowth and matrix deformations. The embryos in PS#2 medium exerted stronger force into the matrix and also survived longer times than the embryos in HSA. PS#2 supported the transition of blastocyst towards post-implantation stages of development showing the correct lineage patterning of embryonic and extraembryonic molecular markers, including Oct4, CDx2, EOMES or GATA4. Limitations, reasons for caution This is a study based on an animal model. These observations need to be confirmed by ongoing experiments with human embryos. Wider implications of the findings: This work constitutes a proof-of-concept for the use of globulin-rich supplements as higher performance substitute of albumin in the culture of IVF embryos, both as (i) a standard protein source for culture media and (ii) as a supplement for transfer media to capacitate the embryo for implantation. Trial registration number Not applicable

scholarly journals 160EFFECTS OF EXTRACELLULAR ION CONCENTRATIONS ON IN VITRO DEVELOPMENT OF DOMESTIC CAT IVF EMBRYOS

2004 ◽  
Vol 16 (2) ◽  
pp. 202 ◽  
Author(s):  
W.F. Swanson ◽  
A.L. Manharth ◽  
J.B. Bond ◽  
H.L. Bateman ◽  
R.L. Krisher ◽  
...  
Keyword(s):  
Culture Media ◽  
Ionic Composition ◽  
Cell Number ◽  
Blastocyst Stage ◽  
Domestic Cat ◽  
Embryo Viability ◽  
Blastocyst Development ◽  
In Vitro Development ◽  
Vitro Development

Domestic cat embryos typically are cultured in media formulated for somatic cells or embryos from rodents or livestock species. Under these conditions, blastocyst development has been inconsistent and delayed relative to embryos grown in vivo, and embryo viability following transfer has been low. Our goal is to systematically define the culture requirements of the feline embryo to improve embryo development and viability. The objective of this study was to determine the ionic (NaCl, KCl, KH2PO4, and CaCl2:MgSO4) preferences of domestic cat IVF embryos. Anestral female cats were injected (i.m.) with 150IU eCG followed 84h later by 100IUhCG. Oocytes were recovered via laparoscopic follicular aspiration approximately 24h post-hCG injection (Day 0). Semen was collected from one of two males by means of an artificial vagina and washed once in HEPES-buffered IVF medium. Mature cumulus-oocyte complexes were co-incubated with 2.5–5×105 motile sperm mL−1 in IVF medium (100mM NaCl, 4.0mM KCl, 1.0mM KH2 PO4, 2.0mM CaCl2, 1.0mM MgSO4-7H2O, 25.0mM NaHCO3, 3.0mM glucose, 0.1mM pyruvate, 6.0mM L-lactate, 1.0mM glutamine, 0.1mM taurine, 1×MEM nonessential amino acids, 50μgmL−1 gentamicin, and 4.0mgmL−1 BSA) for 19 to 22h in 6% CO2 in air (38.7°C). Cumulus cells were removed and embryos cultured (8–11 embryos/50μL drop; 6% CO2, 5% O2, 89% N2, 38.7°C) in media containing 100.0 or 120.0mM NaCl, 4.0 or 8.0mM KCl, 0.25 or 1.0mM KH2PO4, and 1.0mM:2.0mM or 2.0mM:1.0mM CaCl2:MgSO4 (2×2×2×2 factorial design). The remaining components of the culture medium were identical to the IVF medium (but w/o gentamicin). Development to the blastocyst stage by Day 6, metabolism (glycolysis and pyruvate) of each blastocyst, and final cell number (Hoechst 33342 staining) of all embryos were evaluated. Final cell number of cleaved embryos and development to the blastocyst stage were analyzed using analysis of variance in the GLIMMIX macro of SAS. A total of 236 oocytes were inseminated, yielding 128 cleaved embryos (54%), including 6 blastocysts (4.7% of cleaved embryos). Cell number was not (P&gt;0.05) affected by NaCl, KCl, or KH2PO4 concentrations, but tended (P=0.057) to be higher after culture in 2.0mM:1.0mM CaCl2:MgSO4. Treatments did not significantly affect (P&gt;0.05) development to the blastocyst stage, but numerically more blastocysts were produced in 100.0mM NaCl (4/6), 8.0mM KCl (5/6), or 1.0mM KH2PO4 (5/6). Both CaCl2:MgSO4 ratios resulted in 3 blastocysts. Blastocysts contained 61.08±5.1 (mean±SEM, n=6) cells and actively metabolized glucose (glycolysis, 3.7±0.8pmol/embryo/3h or 0.06±0.01pmol/cell/3h) and pyruvate (0.75±0.27pmol/embryo/3h or 0.013±0.005pmol/cell/3h). These results suggest that the ionic composition of culture media influences the in vitro development of cat IVF embryos. (Supported by NIH grant RR15388.)

P–581 The day of blastocyst biopsy and the chromosomal constitution. Evaluation of 5125 embryos by Next Generation Sequency (NGS)

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
P E Villanuev. Zúñiga ◽  
J Huayhua ◽  
L Noriega-Hoces ◽  
G Llerena ◽  
J Noriega-Portella ◽  
...  
Keyword(s):  
Maternal Age ◽  
Blastocyst Stage ◽  
Chromosome Constitution ◽  
Lower Probability ◽  
Next Generation ◽  
Preimplantation Genetic Testing ◽  
Mosaic Embryo ◽  
Blastocyst Biopsy ◽  
Registration Number ◽  
Next Generation Sequencing Ngs

Abstract Study question Is there a relationship between the day of blastocyst biopsy and the results NGS analysis? Summary answer Embryos biopsied on day 6 or 7 are associated with the increased probability of being an aneuploidy embryo and less likely to be mosaic embryo. What is known already There is controversy about whether an embryo that reaches the blastocyst stage on day 5 has a higher chance of being euploid than embryos which are biopsied later. In our study, chromosome constitution was evaluated by next-generation sequencing (NGS)-based preimplantation genetic testing for aneuploidy (PGT-A) and confounding factors were eliminated. Study design, size, duration Data was collected retrospectively from June 2016 to January 2020 Participants/materials, setting, methods In total, 5125 blastocyst (day 5=2914, day 6 N = 2154 and day7 N = 57), generated from 1318 cycles were analysed with PGT-A. The chromosome constitution for each embryo was classified as euploid, aneuploid and mosaic. A multilevel model was made and associations betwwen variables by logistic regression were adjusted according to maternal age, SART blastocyst grade, fertilization method, biopsy operator and blastocyst stage. Main results and the role of chance The mean maternal age was 36.2 ± 4.2. Euploid rate was 62.1% and 37.9% (day 5 and day 6–7 respectively), aneuploidy rate was 47.0% and 53.0% (day 5 and day 6–7, respectively), mosaicism rate was 59.6% and 40.4% (day 5 and day 6–7, respectively) (p &lt; 0.001). Embryos biopsied on day 6–7 have a significantly lower probability to be euploid and mosaicism than embryos biopsied on day 5 ((OR = 0.76 [0.68–0.86]); (OR = 0.84 (0.73 – 0.96) respectively) (p &lt; 0.001). On the contrary, embryos biopsy on day 5 were significantly more likely to be euploid than day 6–7 (OR = 1.63[1.42–1.86]) (p &lt; 0.001). Limitations, reasons for caution The results observed in this study should be confirmed using a larger number of samples. For the NGS analysis, a chromosome with a variation between 20 to 80% was considered mosaic. Wider implications of the findings: The present study revealed that embryos that reach blastocyst classified as full to hatched on day 5 are more like to be euploid compared to slow growing embryos. Trial registration number non-clinical trials

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