Does slow embryo development predict a high aneuploidy rate on trophectoderm biopsy?

The use of preimplantation genetic testing for aneuploidy: a committee opinion

The use of preimplantation genetic testing for aneuploidy (PGT-A) in the United States has been increasing steadily. Moreover, the underlying technology used for 24-chromosome analysis continues to evolve rapidly. The value of PGT-A as a routine screening test for all patients undergoing in vitro fertilization has not been demonstrated. Although some earlier single-center studies reported higher live-birth rates after PGT-A in favorable-prognosis patients, recent multicenter, randomized control trials in women with available blastocysts concluded that the overall pregnancy outcomes via frozen embryo transfer were similar between PGT-A and conventional in vitro fertilization. The value of PGT-A to lower the risk of clinical miscarriage is also unclear, although these studies have important limitations. This document replaces the document of the same name, last published in 2018.

Advanced Glycation End-Products of Follicular Fluid are Associated with Embryo Morphokinetic Parameters and ART Outcomes

Advanced glycation end products (AGEs) can disrupt antioxidant system and steroidogenesis, resulting in detrimental effects on assisted reproductive technology (ART) outcomes. This study aimed to investigate the association of AGEs in follicular fluid (FF) with morphokinetic parameters of embryos and ART outcomes. Fifty women undergoing ART treatment were studied. AGEs, glucose, 25(OH) vitamin D, malondialdehyde (MDA) levels and catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPX) activities were evaluated in FF. The expression of 3βHSD, CYP11A1, and CYP19A1 genes were analyzed in granulosa cells (GCs) by qRT-PCR technique. Morphokinetic parameters were evaluated using time-lapse technology. The FF level of AGEs was reversely associated with CAT, SOD, and GPX activities, and total and mature oocytes number, blastocyst formation rate, and high-grade embryos number, while it showed positive correlations with the FF MDA levels, the expression of steroidogenesis genes, number of immature oocytes, morphokinetic parameters, and number of low-grade embryos. Furthermore, the level of vitamin D in FF had an inverse association with AGEs and positive correlations with ART outcomes and morphokinetic parameters. Comparison between the those with positive and negative biochemical pregnancy showed no significant differences in terms of FF factors and just the expression of 3βHSD, CYP11A1, and CYP19A1 genes were higher in pregnant women (p < 0.05). AGEs could delay blastomere division and lead to an increase in the number of low-quality embryos, while vitamin D have an adverse effect on AGEs and a protective function against AGEs negative effects.

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'.

Live birth rate following frozen-thawed blastocyst transfer is higher in high-grade day 6 blastocysts than in low-grade day 5 blastocysts

Background

Day 5 (D5) blastocysts are generally given priority to transfer than day 6 (D6) blastocysts; however, which one should be prioritized to transfer when only low-grade D5 and high-grade D6 blastocysts are available?

Methods

A large retrospective cohort study was carried out to evaluate the live birth rate (LBR) following D5 and D6 blastocysts in single frozen-thawed blastocyst transfer (FBT) during January 2014 and December 2018. A multivariate logistic regression was conducted to evaluate the combined impact of expansion day (D5 and D6) and blastocyst quality (high grade/low grade) on LBR, accounting for the potential confounding factors. The biopsied blastocysts from a consecutive PGT-A case series during February 2013 to December 2021 were analyzed in a supplementary study.

Results

The LBR achieved in high-grade D6 blastocyst transfer was significantly higher than that in low-grade D5 blastocyst transfer (50.43% vs. 40.70%, aOR 1.54, 95% CI 1.05-2.26, p = 0.027). There were no significant differences in preterm birth rate, very preterm birth rate, mean live birth weight, and birth weight <1,500 g and >4,000 g between the two cohorts. As for aneuploidy analysis in PGT, there were 54.55% of euploid blastocysts (30/55) among high-grade D6 blastocysts, significantly higher than the 41.39% of euploid blastocysts (565/1,365) among low-grade D5 blastocysts (p < 0.001).

Conclusions

Our data suggest that D6 blastocysts with high morphology grading are preferred than D5 blastocysts with low morphology grading when selecting blastocyst transfer to shorten the time of conception.

Day of trophectoderm biopsy and embryo quality are associated with outcomes following euploid embryo transfer

PURPOSE

To compare clinical outcomes following transfer of euploid blastocysts of varying quality biopsied on day 5 versus day 6.

METHODS

Retrospective cohort study to evaluate embryo transfer outcomes for women undergoing autologous cryopreserved next generation sequencing euploid single embryo transfer from 10/2015 to 2/2022 at an academic IVF program. The primary outcome was live birth rate (LBR). Secondary outcomes included ongoing pregnancy rate (OPR), implantation rate (IR), and miscarriage rate (SAB rate).

RESULTS

Five hundred and fifty-five transfers from 418 patients were analyzed. Euploid embryos biopsied on day 5 resulted in higher LBR compared to those biopsied on day 6 (62.3% vs. 49.6%; aRR 0.81 95% CI 0.65-0.996). When stratified by biopsy day and blastocyst quality, there was no difference in IR, OPR, and SAB rate for good, fair, and poor quality blastocysts biopsied on day 5 versus day 6. However, day 5 good quality embryos were associated with a higher LBR compared to day 6 good quality embryos (74.3% vs. 51.3%; aRR 0.69; 95% CI 0.48-0.999). There were no significant differences in LBR for fair and poor quality embryos biopsied on day 5 versus day 6.

CONCLUSION

Overall LBR are higher for euploid embryos biopsied on day 5 versus day 6. When stratified by embryo quality and day of biopsy, LBR are significantly higher for good quality day 5 versus day 6 embryos. When choosing between multiple euploid embryos, day 5 biopsied good quality embryos should be preferentially selected for transfer over day 6 embryos of the same quality.

The influence of morphologic grading and COS protocol on the outcomes of Day 5 versus Day 6 single fresh blastocyst transfers: a retrospective analysis of clinical outcomes from one center experience

INTRODUCTION

The purpose of this study was to evaluate whether the blastocyst morphologic grading and the protocol of controlled ovarian stimulation (COS) would influence pregnancy outcomes, aiming to provide guidance when choosing blastocyst transfer.

METHODS

The clinical data of 612 patients who received single fresh blastocyst transfer for first cycle, as well as the data of 253 patients who had already delivered were analyzed retrospectively. The patients were divided into two groups according to blastocyst formation time (D5 or D6). The following subgroup analyses were performed: (i) the morphologic grading of blastocyst and (ii) the protocol of COS.

RESULTS

We observed that D5 single embryo transfer (SET) were associated with higher clinical pregnancy rate (CPR, 59.04% vs. 31.73%, P < 0.001) and live birth rate (LBR, 43.90% vs. 24.04%, P < 0.001) than D6 SET following fresh cycle. Patients in D5 group experienced more good blastocysts transfer (45.47%vs. 13.46%, P < 0.001) and less poor blastocysts transfer (9.64%vs. 45.19%, P < 0.001) than patients in D6 group. As to early stage and good quality blastocysts, the CPR and LBR were similar between D5 and D6 group. GnRH antagonist protocol had a demonstrable inferiority comparing with the early-follicular-phase long-acting GnRH-agonist long protocol (EFLL) or the mid-luteal-phase long-acting GnRH-agonist long protocol (MLLL) with regard to the CPR and LBR in D6-SET group.

CONCLUSIONS

The analysis found that ovarian reserve of patients in D6-SET group was comparatively worse than that of patients in D5-SET group and D6-SET patients represented a subgroup of infertility patients usually having relatively poor embryo quality. The results should be interpreted with caution as the very low numbers in the respective group limited the use of statistical tests and the real significance values.

The hare and the tortoise: extreme mitotic rates and how these affect live birth

RESEARCH QUESTION

Is live birth of patients with excessive slow (no blastocyst on day 5) and fast mitotic rate (full blastocyst development on day 4) comparable to a matched control standard (blastocyst formation on day 5)?

DESIGN

In this retrospective matched (age and anti-Müllerian hormone [AMH]) case-control study rates of fertilization, blastulation, implantation, clinical pregnancy and live birth were compared in couples with male factor indication, prolonged embryo culture and fresh single morula and blastocyst transfer.

RESULTS

The rates of implantation, clinical pregnancy and live birth in the slow-developing group were significantly (P < 0.001) lower (17.6%, 13.7%, and 11.8%, respectively) compared with the fast (58.5%, 52.5%, 47.5%) and normal growing counterparts (51.5%, 42.6%, 39.6%). No differences in neonatal outcome could be observed between the three groups. Sex ratio in the fast-growing group was not different from the other cohorts.

CONCLUSIONS

Extremely slow development, as assessed by the absence of blastulation on day 5, is a negative predictor of pregnancy and live birth. In contrast, the fear that extremely fast-growing embryos may represent an aneuploid cohort of embryos is unsubstantiated. Day-4 full blastocysts can preferentially be considered for transfer.

Preimplantation Genetic Testing: Where We Are Today

BACKGROUND

Preimplantation genetic testing (PGT) is widely used today in in-vitro fertilization (IVF) centers over the world for selecting euploid embryos for transfer and to improve clinical outcomes in terms of embryo implantation, clinical pregnancy, and live birth rates.

METHODS

We report the current knowledge concerning these procedures and the results from different clinical indications in which PGT is commonly applied.

RESULTS

This paper illustrates different molecular techniques used for this purpose and the clinical significance of the different oocyte and embryo stage (polar bodies, cleavage embryo, and blastocyst) at which it is possible to perform sampling biopsies for PGT. Finally, genetic origin and clinical significance of embryo mosaicism are illustrated.

CONCLUSIONS

The preimplantation genetic testing is a valid technique to evaluated embryo euploidy and mosaicism before transfer.

Day 5 versus Day 6 blastocyst transfers: a systematic review and meta-analysis of clinical outcomes

STUDY QUESTION

Is there a difference in clinical pregnancy and live birth rates (LBRs) between blastocysts developing on Day 5 (D5) and blastocysts developing on Day 6 (D6) following fresh and frozen transfers?

SUMMARY ANSWER

D5 blastocyst transfers (BTs) present higher clinical pregnancy and LBRs than D6 in both fresh and frozen transfers.

WHAT IS KNOWN ALREADY

BT is increasingly popular in assisted reproductive technology (ART) centers today. To our knowledge, no meta-analysis has focused on clinical outcomes in both fresh and frozen BT. Concerning frozen blastocysts, one meta-analysis in 2010 found no significant difference in pregnancy outcomes between D5 and D6 BT. Since then, ART practices have evolved particularly with the wide use of vitrification, and more articles comparing D5 and D6 BT cycles have been published and described conflicting results.

STUDY DESIGN, SIZE, DURATION

Systematic review and meta-analysis of published controlled studies. Searches were conducted from 2005 to February 2018 on MEDLINE and Cochrane Library and from 2005 to May 2017 on EMBASE, Eudract and clinicaltrials.gov, using the following search terms: blastocyst, Day 5, Day 6, pregnancy, implantation, live birth and embryo transfer (ET).

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 47 full-text articles were preselected from 808 references, based on title and abstract and assessed utilizing the Newcastle-Ottowa Quality Assessment Scales. Study selection and data extraction were carried out by two independent reviewers according to Cochrane methods. Random-effect meta-analysis was performed on all data (overall analysis) followed by subgroup analysis (fresh, vitrified/warmed, slow frozen/thawed).

MAIN RESULTS AND THE ROLE OF CHANCE

Data from 29 relevant articles were extracted and integrated in the meta-analysis. Meta-analysis of the 23 studies that reported clinical pregnancy rate (CPR) as an outcome, including overall fresh and/or frozen ET cycles, showed a significantly higher CPR following D5 ET compared with D6 ET (risk ratio (RR) = 1.27, 95% CI: 1.15-1.39, P < 0.001). For CPR, calculated subgroup RRs were 2.38 (95% CI: 1.74-3.24, P < 0.001) for fresh BT; 1.27 (95% CI: 1.16-1.39, P < 0.001) for vitrified/warmed BT; and 1.15 (95% CI: 0.93-1.41, P = 0.20) for slow frozen/thawed BT. LBR was also significantly higher after D5 BT (overall RR = 1.50 (95% CI: 1.32-1.69), P < 0.001). The LBR calculated RRs for subgroups were 1.74 (95% CI: 1.37-2.20, P < 0.001) for fresh BT; 1.38 (95% CI: 1.23-1.56, P < 0.001) for vitrified/warmed BT; and 1.44 (95% CI: 0.70-2.96, P = 0.32) for slow frozen/thawed BT. Sensitivity analysis led to similar results and conclusions: CPR and LBR were significantly higher following D5 compared to D6 BT.

LIMITATIONS, REASONS FOR CAUTION

The validity of meta-analysis results depends mainly on the quality and the number of the published studies available. Indeed, this meta-analysis included no randomized controlled trial (RCT). Slow frozen/thawed subgroups showed substantial heterogeneity.

WIDER IMPLICATIONS OF THE FINDINGS

In regards to the results of this original meta-analysis, ART practitioners should preferably transfer D5 rather than D6 blastocysts in both fresh and frozen cycles. Further RCTs are needed to address the question of whether D6 embryos should be transferred in a fresh or a frozen cycle.

STUDY FUNDING/COMPETING INTEREST(S)

This work was sponsored by an unrestricted grant from GEDEON RICHTER France. The authors have no competing interests to declare.

REGISTRATION NUMBER

CRD42018080151.

Is it worth it to cryopreserve embryos with blastulation delay at day 5?

This is a retrospective study over a 5-year period. In total, 3139 embryos were individually cryopreserved (Cryotop®) and warmed using the Kitazato vitrification/warming kit. They were classified into three categories based on their expansion degree. Transfer, implantation and pregnancy rates were assessed for each embryo category and compared using SPSS (Statistical Package for the Social Sciences) software. In total, 1139 couples enrolled in infertility treatment programme benefitted from embryo vitrification at day 5. After warming, embryos belonging to the three categories showed similar success rates. Although there was a trend towards better outcomes when grade 3 embryos were transferred, the differences did not reach statistical significance: implantation rates (n fetal sac/n embryo transferred) grade 1: 21.9%, grade 2: 22.7% and grade 3: 30.3% (=0.19). Pregnancy rate (n clinical pregnancy/n transfer) (21.9%, 22.7%, 30.3%, respectively; P=0.11). Miscarriage rate was not statistically different in the three categories (14.5%, 20.4%, 20%, respectively, P=0.51). Our overall results show that it is worth vitrifying slow kinetics embryos as they provide a non-negligible chance to give rise to a pregnancy.

Extended culture of poor-quality supernumerary embryos improves ART outcomes

PURPOSE

The aims of this study were to investigate the possible benefits of extending the culture of poor-quality day-2 embryos (PQE) versus good-quality embryos (GQE) and to identify factors associated with pregnancy and live birth when transferring frozen-thawed blastocysts originating from GQE and PQE.

METHODS

This is a retrospective cohort follow-up study performed between November 2012 and February 2015 at the IVF Laboratory Unit of Cochin University Hospital (Paris, France) including 3108 day-2 supernumerary embryos resulting from 1237 IVF/ICSI cycles.

RESULTS

Total blastulation rate was 67.2% from GQE and 48.7% from PQE. Percentage of good-quality blastocysts was 60.7 and 47.9% respectively including 14.7 and 7.3% top-quality blastocysts. A total of 150 blastocysts originating from GQE and 729 from PQE were frozen, and then, 37 and 164 were thawed and transferred respectively resulting in 19 (51.4%) and 61 (37.9%) clinical pregnancies with 13 (35.1%) deliveries from GQE and 32 (19.9%) from PQE (p = 0.046) without any difference in neonatal outcomes. Quality of blastocysts that resulted in live birth was similar in the two groups. Women < 35 years old and day-5 blastocyst expansion were predictive of pregnancy and live birth.

CONCLUSIONS

(i) PQE are able to reach the blastocyst stage, to implant, and to give healthy babies and (ii) women age and day of blastocyst expansion are predictive of pregnancy and live birth.

Elective single blastocyst transfer in advanced maternal age

PURPOSE

The purpose of this study was to investigate reproductive outcomes following elective single blastocyst transfer (eSBT) compared with those of double blastocyst transfer (DBT) in advanced maternal age.

METHODS

This was a retrospective cohort study performed at an academic fertility center. All women aged 40 and over for whom in vitro fertilization (IVF) cycles were performed and in whom embryo culture was extended to the blastocyst stage were reviewed for possible inclusion. Exclusion criteria included the following: women with >3 previous IVF cycles, the use of donor or frozen oocytes, preimplantation genetic diagnosis/preimplantation genetic screening cycles, and cycles in which embryos did not reach the blastocyst stage on day 5. The study included 310 women; 148 were included in the eSBT group and 162 were included in the DBT group. Live birth rate (LBR) was the main outcome. Outcomes were analyzed using logistic regression, controlling for confounders. These confounders were embryo expansion, embryo quality, and the number of previous IVF cycles.

RESULTS

The mean age of the whole group was 41 ± 0.91 years, and the LBR was 21.6%. The eSBT group and the DBT group achieved similar clinical pregnancy rates (33 vs. 33%) (OR 1.04; 95%CI, 0.62-1.75) and LBRs (20 vs. 22.8%) (OR 1.43; 95% CI, 0.78-2.64). The multiple birth rate was lower in the eSBT group (0 vs. 16%, p = 0.02). The subgroup of women who had elective DBT (eDBT) achieved a higher LBR (20 vs. 30.6%) (OR 2.32; 95% CI, 1.16-4.68) and a higher multiple birth rate (0 vs. 22%, p = 0.001). Cycles with early blastocyst transfers were associated with lower LBRs compared with cycles with fully expanded blastocyst transfers (11 vs. 24%, p = 0.02).

CONCLUSION

The results of this study indicate that eSBT is associated with similar LBRs compared to the entire DBT cohort; however, when supernumerary blastocysts are available for cryopreservation, eDBT is associated with both higher LBRs and a higher number of multiple births. Studies assessing the cumulative LBR in advanced maternal age after single blastocyst transfer and subsequent frozen-thawed blastocyst transfers are needed.