Vitrified-warmed Blastocyst Transfer Research Articles

Noneffectiveness of cryostorage duration on clinical and neonatal outcomes after single vitrified-warmed blastocyst transfers

BackgroundIn the current era of assisted reproductive technology, the strategy of single vitrified-warmed blastocyst transfer (SVBT) is acknowledged for positively impacting clinical outcomes and preventing the risk of multiple conceptions. Previous studies have indicated that blastocyst grade and the day of blastocyst positively correlate with outcomes. Moreover, storage duration has no significant effect on survival rates, clinical outcomes, and neonatal outcomes. However, some researchers express controversial opinions on cryostorage duration, and their findings suggest a negative impact on clinical outcomes. These results remain subject to controversy, and limited studies exist regarding the outcomes after SVBT. Therefore, our study aims to investigate the impact of the day of blastocyst, blastocyst grade, and blastocyst cryostorage duration on clinical and neonatal outcomes following SVBT in patients who underwent clomiphene-citrate-based minimal stimulation.Material and methodsIn this study, retrospective cohort study data collected from June 2015 to April 2023 included 2107 patients with first SVBT cycles who underwent a clomiphene-based minimal ovarian stimulation protocol or a drug-free natural protocol at the Ojinmed IVF Center. Patients were categorized into four groups based on blastocyst cryostorage duration: group 1 (< 2 months, n = 882), group 2 (3–6 months, n = 794), group 3 (7–12 months, n = 187), group 4 (13–24 months, n = 126), and group 5 (25–81 months, n = 118). The patient’s clinical and neonatal outcomes were compared with cryostorage duration after the propensity score matched.ResultMultivariable logistic regression analysis revealed that prolonged cryostorage duration insignificantly correlated with clinical outcomes. Additionally, neonatal outcomes are not correlated with cryostorage duration.ConclusionsThe patient must consider several parameters when selecting embryos for transfer, including the duration of cryostorage. Our study results show that for the first single vitrified-warmed blastocyst transfer of patients who underwent clomiphene citrate-based minimal stimulation, cryostorage duration does not affect outcomes.

O-297 Prediction of pregnancy outcomes of single vitrified-warmed blastocyst transfer using combination of an automatic classification algorithm applied on cleavage stage embryos and blastocyst morphology

Abstract Study question Does combination of embryo assessment algorithm on cleavage-stage based on the automatic annotation of morphokinetic and blastocyst morphology in embryo selection improve implantation outcomes? Summary answer Combination of embryo assessment algorithm on cleavage-stage based on the automatic morphokinetic annotation and blastocyst morphological evaluation was showed significantly predictive for implantation outcomes. What is known already Conventional morphological assessment is still the gold standard for embryo selection. Timelapse monitoring of embryo development may represent a superior way to culture and select embryos in vitro. Nowadays, time-lapse culture systems are becoming more popular, many algorithms have been developed for embryo selection based on embryo morphokinetics, providing additional information for morphological assessment. However, manual annotations of developmental events and application of algorithms can be time-consuming and subjective processes. Automation of morphokinetic annotation can be a potential approach that reduces subjectivity in embryo selection. Study design, size, duration The observational, retrospective study was conducted in a single centre between 2020-2023 and included 511 single vitrified-warmed blastocyst transfer cycles. Blastocyst selected for transfer on Day 5,6 based on conventional morphological evaluation. Embryos were evaluated on Day 3 with a score from 1 (best) to 5 (worst) (from highest to lowest developmental potential) by the automatic embryo assessment algorithm. The correlation of the algorithms scoring and pregnancy outcomes was qualified by generalized estimating equations (GEEs). Participants/materials, setting, methods Embryos were cultured in timelapse GERI incubator and classified on day 3 by automatic embryo assessment algorithm depending on four parameters: P2 (t3-t2), P3 (t4-t3), oocyte age, and number of cells. The correlation of the algorithms scoring and pregnancy outcomes was qualified by generalized estimating equations (GEEs). Three GEE model using embryo assessment algorithm, conventional morphological assessment, and a combination of both classification system as the predictor were compared. Main results and the role of chance The implantation rate was higher with lower the scores generated by the embryo assessment algorithm. A GEE model showed the negative association between higher embryo score and lower odds of implantation. The OR of Score 3; 4; 5 vs 1 were 0.335; 0.259; 0.245 (95% CI 0.194-0.580; 0.138-0.485; 0.111-0.544, P = 0.000), respectively, for implantation. The AUC of the model using embryo assessment algorithm for implantation potential = 0.641. The AUC of the model combining both embryo assessment algorithm and conventional morphological assessment for implantation potential = 0.733. The differences were statistically significant (z-statistic = 3.896, p = 0.0001). Limitations, reasons for caution The sample size was enough to confirm the ability of the model for embryo selection. However, the retrospective nature of this study may be a limitation. Wider implications of the findings Using combination of timelapse technology with automated embryo assessment and conventional morphological assessment can predict the success rates of assisted reproduction cycles. To our knowledge, this is the first study using embryo dataset from single vitrified-warmed blastocyst transfer cycles with this embryo assessment algorithm. Trial registration number not applicable

P-229 Effect of morula pattern on clinical outcomes in single vitrified-warmed blastocyst transfer cycles

Abstract Study question Does morula pattern affect clinical outcomes in single vitrified-warmed blastocyst transfer cycles? Summary answer Ongoing pregnancy rate is statistically increased when transferring the blastocyst derived from fully compacted morula in single vitrified-warmed blastocyst transfer cycles. What is known already Time-lapse microscopy has enabled the detailed identification and measurement of dynamic events of embryo development. Recent studies have shown that the exclusion of one or more cells from the compacted morula is associated with reduced developmental competence and a decrease in pregnancy rate. Additionally, it is also associated with decreased rates of PGT-A euploid and implantation. These findings demonstrate the correlation between morula pattern and the outcomes of assisted reproductive technologies. Study design, size, duration A retrospective cohort study was performed between January 2020 and November 2023. A total of 99 single vitrified-warmed blastocyst transfer cycles (women ≥ 35 years) were analyzed. The rates of biochemical pregnancy, clinical pregnancy, implantation, miscarriage, and ongoing pregnancy were evaluated. Participants/materials, setting, methods Images of morula stage embryos were collected at 7-focal planes and every 5-minute interval using a time-lapse microscope. The morula stage embryos were divided into two groups according to their compaction patterns. Morula stage embryos without excluded or extruded cells were defined as fully compacted morula (FCM, n = 47). In contrast, Morula stage embryos with excluded or extruded cells were defined as partially compacted morula (PCM, n = 52). Main results and the role of chance There were no differences of patient characteristics between FCM and PCM regarding female age (37.8 ± 2.1 vs. 37.8 ± 1.8, p = 0.96), number of previous IVF failure (0.5 ± 1.1 vs. 0.9 ± 1.6, p = 0.23), number of retrieved oocytes (16.1 ± 4.0 vs. 14.3 ± 5.1, p = 0.14), maturation rate (86.5% vs. 89.1%, p = 0.18), fertilization rate (73.8% vs. 69.9%, p = 0.39), survival rate (100% vs. 100%, p = Not applicable), and number of transferred embryos (1.0 ± 0.0 vs. 1.0 ± 0.0, p = Not applicable), with the exception of rate of good-quality embryos on Day 3 (44.7% vs. 37.6%, p = 0.04). No statistical differences were observed in rates of biochemical pregnancy (44.7% vs. 34.6%, p = 0.31), clinical pregnancy (40.4% vs. 26.9%, p = 0.15), miscarriage (11.4% vs. 15.4, p = 0.57), and implantation (40.4% vs. 26.9%, p = 0.15) between FCM and PCM, respectively. However, FCM demonstrated a significantly increased ongoing pregnancy rate compared to PCM (29.8% vs. 11.5%, p = 0.02). Limitations, reasons for caution This study was conducted with a small sample size, which limited the generalizability of the findings. Therefore, further studies are needed with a larger sample size and more diverse populations to confirm our findings. Wider implications of the findings The compaction pattern of morula stage embryos can be an indicator for embryo selection. The blastocyst derived from fully compacted morula has the potential to improve ongoing pregnancy rate in single vitrified-warmed blastocyst transfer cycles. Trial registration number not applicable

P-134 Fatty acid supplementation during warming improves pregnancy outcomes after frozen blastocyst transfers: a propensity score-matched study

Abstract Study question Does warming with fatty acids (FAs) affect the viability of human blastocysts and pregnancy outcomes after a single vitrified-warmed blastocyst transfer (SVBT)? Summary answer FA-supplemented warming solutions promoted the blastocyst outgrowth by decreasing the degeneration of trophoblast cells and improved pregnancy outcomes after SVBTs. What is known already Vitrification is considered a well-established technique and has been used worldwide. However, previous studies demonstrated the detrimental effects of vitrification on pre-implantation development and term pregnancy in oocytes and embryos. Vitrification reduces the intracellular lipid content and decreases the competence for pre-implantation development. The FA supplementation into the warming solution restores the lipid content in the ooplasm and improves developmental competence by promoting the β-oxidation pathway in mice. Although, in humans, the FA-supplemented warming solutions reportedly improved pregnancy outcomes after vitrified-warmed cleavage-stage embryo transfers, the effectiveness of these solutions on blastocyst warming remain unclear. Study design, size, duration The experimental study included 401 discarded blastocysts. The blastocysts were warmed using the FA-supplemented (FA group) or non-supplemented (control group) solutions. The blastocyst adhesion, outgrowth area, and incidence of outgrowth degeneration were assessed. The retrospective cohort study included 4,426 treatment cycles from 4,426 women who underwent SVBTs between January 2023 and August 2023 (January–May 2023, control group; June–August 2023, FA group). Pregnancy outcomes were compared statistically between the groups. Participants/materials, setting, methods The implantation competence was experimentally examined using an outgrowth model. The blastocysts were placed on fibronectin-coated dishes and cultured for 96 hours. The embryos were designated as degenerated when the outgrowth area decreased by &amp;gt; 10%, compared with the maximum area. For the clinical study, multiple covariates that affected the outcomes were used for propensity score matching. The patients in the FA group were matched with controls using a propensity score in a 1:1 ratio. Main results and the role of chance The adhesion rate after the outgrowth culture was comparable between the control and FA groups. However, the outgrowth was larger in the FA group than in the control group. The multivariate linear regression analysis also demonstrated similar results. Furthermore, the incidence of outgrowth degeneration was significantly decreased in the FA group. Furthermore, the subgroup analyses revealed that FA-supplemented warming solutions were effective in blastocysts donated from young patients, day 5 blastocysts, and morphologically good blastocysts. For the retrospective cohort study, the implantation, clinical pregnancy, and ongoing pregnancy rates were significantly higher in the FA group than in the control group. The multivariate logistic regression analysis also demonstrated that warming with FA-supplemented solutions significantly increased the probability of ongoing pregnancies. However, the rates of early pregnancy loss and miscarriage in the first trimester were comparable between the groups. The subgroup analyses demonstrated a similar trend to in vitro experiments; the FA-supplemented solutions were more effective in good prognosis cases (young patients, day 4/5 blastocysts, and morphologically good blastocysts) than in poor prognosis cases (advanced age patients, day 6/7 blastocysts, and morphologically poor blastocysts). Limitations, reasons for caution This was a single-centre, retrospective study, necessitating further multicentre studies to ascertain the generalizability of these findings to other clinics with different protocols and/or patient demographics. Despite using propensity score matching and multivariate models to adjust for the confounders, we cannot adjust for all possible confounders. Wider implications of the findings FA-supplemented warming solutions improved pregnancy outcomes after SVBTs, particularly in patients with a good prognosis. These warming solutions could contribute to maximizing clinical outcomes, shortening treatment periods, and reducing patient burden. Trial registration number not applicable

P-240 Is the intelligent Data Analysis Score (iDAScore) a reliable tool to predict pregnancy? Our center’s experience

Abstract Study question Is the intelligent Data Analysis Score (iDAScore) reliable in predicting a positive pregnancy test, clinical pregnancy and miscarriage rate after single vitrified-warmed blastocyst transfer (SVBT)? Summary answer There is a significant increase in positive pregnancy test and clinical pregnancy rates as iDAScore increases. The miscarriage rate is lower with increased iDAScore. What is known already With the improvement of assisted reproductive technology (ART), elective single embryo transfer has become a standard. Optimizing embryo selection is a major challenge to increase reproductive outcomes. The Gardner embryo grading system is widely adopted for the evaluation of blastocyst quality, but this tool is subject to inter- and intra-variability. In recent years, artificial intelligence has found diverse applications in healthcare. Based on time-laps sequences of &amp;gt; 180’000 developing embryos, iDAScore is a new deep-learning model for objective and standardized blastocyst scoring. However, its reliability in predicting pregnancy and miscarriage rates remains unknown. Study design, size, duration This monocentric retrospective pilot study was conducted from May 2023 to December 2023. A total of 206 homologous SVBT cycles from 206 patients were analyzed (one patient, one cycle). Exclusion criteria included: cycles involving preimplantation genetic testing, multiple and/or fresh blastocyst transfer, and blastocysts obtained after testicular sperm extraction. All vitrified-warmed blastocysts were scored using iDAScore version 1.0 model, ranging from 1 – 9.9. Participants/materials, setting, methods Scores were stratified into 3 groups: high-score (9.9 – 7.7), medium-score (7.6 – 5.5) and low-score (5.4 – 3.1). For each group, positive pregnancy test, clinical pregnancy and miscarriage rates were analyzed. SVBT cycles were then stratified into four maternal age groups (&amp;lt; 35, 35-37, 38-40, &amp;gt;41 years) and the same outcomes were analyzed. χ2 was used for statistics analysis. Main results and the role of chance Mean maternal age was 36.8 ± 4.9. Among the 206 vitrified-warmed blastocysts, 122 were scored as high-score, 57 as medium-score and 27 as low-score. Positive pregnancy test rate was significantly higher with increased iDAScore with 58% in the high-score group, 36.8% in the medium-score group and 17% in the low-score group (p &amp;lt; 0.0001). Clinical pregnancy rate, defined as the visualization of a fetal heartbeat at ultrasound scan, was also significantly higher with increased iDAScore, with 51.6% in the high-score group, 31.6% in the medium-score group and 17% in the low-score group (p &amp;lt; 0.0001). The miscarriage rate was lower with increased iDAScore, with 8.1% in the high-score group, 16.6% in the medium-score group and 50% in the low-score group, but this difference was not statistically significative (p 0.032). When adjusted to age group however, the miscarriage rate was found to be significantly lower in the high-score group when compared to the medium-score group (p &amp;lt; 0.0001); statistical analysis was not achieved in the low-score group due to the small sample size. Limitations, reasons for caution The major limitation of our study is its small sample size. Data collection is ongoing, to increase the study power. Additionally, many other factors, such as genetic, hormonal, metabolic and/or immunological, may play a role in achieving pregnancy. Wider implications of the findings Our results indicate that iDAScore may be a strong predictor of pregnancy and could be used as a complementary tool to the Gardner embryo grading system in the decision-making process of which blastocyst to transfer. Trial registration number N/A

P-244 Which embryo selection model should be prioritized for transfer of a single euploid blastocyst?

Abstract Study question Which embryo selection model would be given high priority for single euploid blastocyst transfer, iDAScore® v2.0, KIDScoreTM D5 v3.2 or conventional morphological grading system? Summary answer Prioritize morphological grading over embryo score for single euploid blastocyst transfers, and reverse the priority for single non-PGT-A blastocyst transfers. What is known already The use of effective tools, such as AI, morphokinetic data and the Gardner criteria, for embryo selection within in vitro fertilization (IVF) has the potential to increase the possibility of pregnancy. Nevertheless, previous studies indicated that the best embryo these tools prioritize may be inconsistent and controversial. Therefore, this study demonstrates integrated reference tables of FHB+ rates for selecting of single embryo transfer (SET) clinically, and assess the association between iDAScore®, KIDScoreTM, traditional morphological grading and embryonic ploidy status. Study design, size, duration Retrospective study from November 2022 to October 2023 with morphokinetic parameters of time-lapse monitoring analysis involving embryos from 264 patients who underwent day-5 single vitrified-warmed blastocyst transfer with or without preimplantation genetic testing for aneuploidies (PGT-A) (total SET=264; euploid=158; non-biopsied=106) using Embryocope® Plus incubators. After SET, the rates of FHB+ of each group were analyzed. Mean female age was 35.2 years. Participants/materials, setting, methods Blastocyst morphology was scored in 3 groups: good (AA, AB, BA), average (BB), poor-quality embryos (BC, CB, CC). Blastocysts were ranked established on the scores caused by iDAScore or KIDScore. All cycles were stratified into 4 score groups (8.1-9.9, 6.1-8.0, 3.7-6.0, 1.0-3.6). Assisted hatching was conducted on day 3. Trophectoderm biopsies were performed on day 5, and examine the embryonic ploidy status using a next-generation sequencing-based PGT-A platform (Thermo/Ion GeneStudio™ S5 Prime). Main results and the role of chance In D5 non-PGT-A SET group, the FHB+ rates of good-quality embryos were higher than those of average and poor-quality embryos (49% vs. 40% vs. 0%). According to the embryo score group, the group with higher scores showed better FHB+ rates (KIDScore: 56.9% vs. 47.2% vs. 16.7% vs. 0%; iDAScore: 59.1% vs. 49.6% vs. 14.9% vs. 0%). The non-PGT-A results indicated that embryo score should be given high priority. In D5 euploidy SET group, the FHB+ rates of good-quality embryos were higher than those of average-quality embryos (78.12% vs. 56.00% vs. 44.44%). According to the embryo score group, the group with higher scores did not show distinct better FHB+ rates (KIDScore: 65% vs. 69.51% vs. 47.6% vs. 0%; iDAScore: 64.1% vs. 67.7% vs. 38.8% vs. 0%). The PGT-A results indicated that morphological grading could be given high priority. Based on the data, we hypothesized that assisted hatching might lead to distortion in embryo scores. Limitations, reasons for caution The study is limited by its retrospective single center study with small sample size of single embryo transferred even some of the groups have no embryo transfer. Therefore, a prospective multicenter validation is necessary. Wider implications of the findings This study provides distinct tables for clinical embryo selection with or without PGT-A. Our findings support the potential application of the integration of AI, morphokinetic data and embryo quality prediction systems, and indicate the possibility of making appropriate decisions in different age groups clinically. Trial registration number Not Applicable

P-181 Chromosome constitution and clinical outcome of blastocysts derived from morulae with different compaction patterns

Abstract Study question Do blastocysts with a diverse history of compaction pattern (complete or partial) have different chances to be aneuploid and to implant? Summary answer Embryos undergoing partial or complete compaction have comparable chances to be aneuploid. Euploid blastocysts with previous history of blastomere extrusion have reduced chances of implantation. What is known already Compaction at the morula stage is an essential requisite for blastocyst formation and involves blastomere flattening and establishment of tenacious cell-to-cell contacts. Incomplete compaction is associated with several upstream and downstream morphokinetic anomalies. It also affects blastocyst yield and quality and clinical outcome. However, evidence on blastocyst chromosomal constitution and implantation potential after preimplantation genetic testing for aneuploidies (PGT-A) is lacking. Study design, size, duration This retrospective cohort study assessed laboratory and clinical outcomes of 1206 blastocysts derived from 483 infertile patients undergoing ART treatment and PGT-A from January 2015 to July 2022. Three age groups (≤34, 35–38 and ≥39 years) were adopted for sub-analyses. Biopsied blastocysts were vitrified and subsequently used in single vitrified-warmed blastocyst transfers (SVBT). Participants/materials, setting, methods Embryo development was monitored by time-lapse technology (TLT), also annotating abnormal cleavages and multinucleation. Patterns of morula compaction were assessed according to previously published categories: (i) full compaction, with all blastomeres undergoing compaction (FCM); partial compaction (partially compacted morula [PCM]), with (ii) blastomeres excluded from the outset (exc-PCM) or (iii) extruded after start of compaction (ext-PCM). Embryos were assessed in relation to embryonic and clinical outcomes. PGT-A data were obtained from trophectoderm biopsies. Main results and the role of chance Average maternal age of the overall patient population was 39.0 years. The full compaction pattern (FCM) was detected in 35.7% of all embryos. Partially compacted morulae showing excluded (Exc-PCM) or extruded (Ext-PCM) cells were also observed (54.4% and 9.9%, respectively) and collectively (64.3%) were the larger fraction (P &amp;lt; 0.0001, among all groups). Of 1206 analysed blastocysts, 551 were euploid, of which 366 were used in SVBT. Aneuploidy rate in the overall blastocyst population derived from FCM, Exc-PCM and Ext-PCM was 50.8%, 55.6%, and 60.0%, respectively (P &amp;gt; 0.05). However, in the younger maternal age group (≤34 years), the aneuploidy rate of the Exc-PCM group was higher compared with FCM (39.8% vs. 25.3%, P = 0.03). In the overall population, the Ext-PCM phenotype was associated with a lower implantation rate (FCM, Exc-PCM and Ext-PCM:47.8%, 44.7%, 55.6%, and 27,6%, respectively (P = 0.04), while miscarriage rates were comparable. Finally, transferred euploid blastocysts not classified according to maternal age implanted with comparable rates, irrespective of their morphokinetic history (abnormal division, multinucleation, no morphokinetic abnormalities). Limitations, reasons for caution The study is limited by its retrospective design. Having been obtained from a single centre, the data require independent validation Wider implications of the findings This study confirms and extends our previous findings on the implications of partial compaction. Importantly, it further consolidates the notion that the embryo can develop through atypical morphokinetic patterns while often preserving its genomic integrity and implantation ability. Trial registration number Not applicable

P-143 Comparison of clinical outcomes between overnight warmed and embryo transfer day warmed blastocysts in frozen embryo transfer cycles

Abstract Study question Is there any difference between clinical outcomes of overnight warmed (ONW) and embryo transfer day warmed (ETDW) blastocysts in frozen embryo transfer (FET) cycles? Summary answer ETDW blastocysts had better clinical outcomes compared to ONW blastocysts in FET cycles. What is known already Some studies reported that the resumption of mitosis in thawed cleavage-stage embryos resulted in significantly better clinical outcomes in FET cycles. Unnecessary transfer of non-functioning embryos can be avoided by incubating thawed embryos overnight to deselect embryos that developed abnormally or failed to undergo additional cleavage. The synchronisation between a viable embryo and a receptive endometrium is vital for successful implantation to take place. The optimal implantation rates occur with embryo-endometrial developmental asynchrony of ± 1.5 days or less. The implantation rates are progressively reduced when embryo-endometrial development asynchrony is greater than 3 days. Study design, size, duration This was a retrospective study involving 2368 FET cycles in KKIVF Centre, KK Women’s and Children’s Hospital, Singapore from Jan 2021 to Dec 2022. The transfer of embryos or blastocysts derived from thawed oocytes, cleavage-stage embryos, double blastocysts and cultured blastocysts from thawed cleavage-stage embryos were excluded. Only single vitrified-warmed blastocyst transfers (n = 1445) were included in this study. Participants/materials, setting, methods Cryopreserved blastocysts were routinely warmed one day before embryo transfer (ET) using Vit Kit - Warm (FUJIFILM Irvine Scientific®) and incubated overnight (ONW group). However, when ETs fell on Monday or post public holiday, vitrified blastocysts were warmed on ET day (ETDW group). Regardless of blastocyst age, surviving blastocysts were transferred into day 5 endometrium. Statistical analysis was performed using t-test or Chi-square test. Differences with P &amp;lt; 0.05 were considered as significant. Main results and the role of chance No statistical significant difference was observed in terms of maternal age distribution at the time of oocyte retrieval between ONW and ETDW groups (34.26 ± 3.29 vs. 34.49 ± 3.22, P = 0.221). Overall, clinical pregnancy rates (CPR) and live birth rates (LBR) were significantly higher in the ETDW group (CPR: 47.47% vs. 40.47%, P &amp;lt; 0.01; LBR: 34.99% vs. 28.78%, P &amp;lt; 0.05). Clinical outcomes were comparable in both ONW and ETDW groups for vitrified-warmed day 5 blastocyst transfers (CPR: 51.27% vs. 58.44%, P = 0.11; LBR: 37.06% vs. 44.81%, P = 0.07). CPR (45.02% vs. 25.71%, P &amp;lt; 0.0001) and LBR (32.03% vs. 17.45%, P &amp;lt; 0.0001) were significantly increased when vitrified day 6 blastocysts were warmed and transferred on the actual day of ET. 18.42% CPR and 13.16% LBR were achieved when vitrified-warmed day 7 blastocysts were transferred on the ET day itself. However, transfer of vitrified-warmed day 7 blastocysts in the ONW group did not result in any pregnancy. Limitations, reasons for caution Study subjects were not stratified according to patient’s age band and blastocyst quality. Age itself is an independent determinant of blastocyst quality which can affect clinical outcomes. Wider implications of the findings Warming of a vitrified blastocyst on ET day is preferred regardless of blastocyst age. However, to facilitate seamless operation in laboratory, overnight warming for vitrified day 5 blastocysts is feasible without compromising clinical outcomes. Trial registration number Not applicable

Obstetrical and neonatal outcomesafter vitrified-warmed blastocyst transfer in day 1 rescue intracytoplasmic sperm injection cycles: a retrospective cohort study.

Fertilization failure often occurs in conventional IVF cycles, and day 1 rescue ICSI is frequently recommended. In this study, the effect of rescue ICSI on obstetrical and neonatal outcomes after a single blastocyst transfer in vitrified-warmed cyclesis evaluated. This cohort study was a retrospective analysis of 703 vitrified-warmed single blastocyst transfers and 219 singletons in the r-ICSI group compared with 11,611 vitrified-warmed single blastocyst transfers in the IVF/ICSI and 4472 singletons in the IVF/ICSI group, respectively, and patients just undergoing their first IVF treatments were included in this study. Pregnancy rate (PR), live birth rate (LBR), and singleton birthweight were the primary outcome measures. Multiple linear regression analysis and logistic regression analysis were performed to evaluate the possible relationship between obstetrical and neonatal outcomes and fertilization method (including IVF, ICSI, and r-ICSI) after adjusting for other potential confounding factors. PR and the LBR were lower in the r-ICSI group compared with the IVF/ ICSI group. Singletons from the r-ICSI group had a higher Z-score and the proportion of large for gestational age (LGA) newborns was greater compared with singletons from the IVF/ICSI group. The results of the study indicated that a 31% LBR after r-ICSI is acceptable for vitrified-warmed blastocyst transfer, but the safety of transfer is a concern because of the lower PR and LBR compared with IVF/ICSI. The safety of r-ICSI newborns is also a concern because of the significantly higher birthweight and the proportion of LGA in r-ICSI group newborns compared with the IVF/ICSI group.

Impact of inclusion of a poor-quality embryo with a good-quality embryo on pregnancy outcomes in vitrified-warmed blastocyst transfers

Research questionDoes the co-transfer of a good-quality embryo and a poor-quality embryo influence pregnancy outcomes in comparison to the transfer of a single good-quality embryo in vitrified-warmed blastocyst transfer cycles? DesignThis retrospective cohort study involved a total of 11,738 women who underwent IVF/intracytoplasmic sperm injection cycles and vitrified-warmed blastocyst transfer at a tertiary-care academic medical from January 2015 to June 2022. The study population was categorized into two groups: single-blastocyst transfer (SBT; participants who underwent single good-quality embryo transfer, n = 9338) versus double-blastocyst transfer (DBT; participants who underwent transfers with a poor and a good-quality embryo, n = 2400). ResultsThe live birth rate (LBR) was significantly higher in the DBT group in comparison with the SBT group (65.6% versus 56.3%, P < 0.001). Multivariable logistic regression analysis showed that DBT was an independent predictor for LBR with a strong potential impact (adjusted odds ratio 1.55, 95% confidence interval 1.41–1.71; P < 0.001). However, the multiple birth rate was significantly higher in the good-quality embryo and poor-quality embryo group compared with patients undergoing a single good-quality embryo transfer (41.4% versus 1.8%; P < 0.001). ConclusionsIn vitrified-warmed blastocyst transfer cycles, LBR was higher following DBT with one good-quality and one poor-quality embryo compared with SBT. However, this was at the expense of a marked increase in the likelihood of multiple gestations. Physicians should still balance the benefits and risks of double-embryo transfer.

Fatty acid supplementation during warming improves pregnancy outcomes after frozen blastocyst transfers: a propensity score-matched study

This study aimed to examine the viability of human blastocysts after warming with fatty acids (FAs) using an in vitro outgrowth model and to assess pregnancy outcomes after a single vitrified-warmed blastocyst transfer (SVBT). For the experimental study, we used 446 discarded vitrified human blastocysts donated for research purposes by consenting couples. The blastocysts were warmed using FA‐supplemented (FA group) or non-FA-supplemented (control group) solutions. The outgrowth area was significantly larger in the FA group (P = 0.0428), despite comparable blastocyst adhesion rates between the groups. Furthermore, the incidence of outgrowth degeneration was significantly lower in the FA group than in the control group (P = 0.0158). For the clinical study, we retrospectively analyzed the treatment records of women who underwent SVBT in natural cycles between January and August 2022. Multiple covariates that affected the outcomes were used for propensity score matching as follows: 1342 patients in the FA group were matched to 2316 patients in the control group. Pregnancy outcomes were compared between the groups. The rates of implantation, clinical pregnancy, and ongoing pregnancy significantly increased in the FA group after SVBTs (P = 0.0091–0.0266). These results indicate that warming solutions supplemented with FAs improve blastocyst outgrowth and pregnancy outcomes after SVBTs.

Should we should consider day 3 blastomere number during single vitrified-warmed blastocyst transfer cycle? A retrospective study

The present study investigated whether day 3 blastomere number has an effect on the clinical outcomes during single vitrified-warmed blastocyst transfer cycles. A total of 3294 vitrified-warmed single day 5 blastocyst transferred cycles were analyzed in this retrospective study from January 2018 to December 2021. The cycles were divided into ≥ 7 and < 7 blastomere groups depending on the day 3 embryo blastomere number. The clinical outcomes were compared between the two groups, moreover multivariate logistic regression analysis was conducted to investigate the correlation between the number of day 3 blastomeres and clinical outcomes. The chi-square test demonstrated that the rates of clinical pregnancy and live birth were significantly higher in the ≥ 7 blastomere group compared to the < 7 blastomere group with respect to single high-quality blastocyst transfer cycles. Conversely, these rates were similar in the two groups with respect to single low-quality blastocyst transfer cycles. These results were confirmed by multivariate logistic regression analysis. However, the miscarriage rate was higher in the < 7 blastomere group than in ≥ 7 group during low-quality blastocyst transfer cycles. These results suggested that day 3 blastomere number should be considered during single vitrified-warmed blastocyst transfer cycles. Thus, blastocsyts derived from ≥ 7 blastomere embryos are preferred when choosing the same quality blastocysts.

Human metaphase II oocytes with narrow perivitelline space have poor fertilization, developmental, and pregnancy potentials.

To analyze the fertilization, developmental, and pregnancy potentials in oocytes with narrow perivitelline space. Perivitelline space (PVS) of oocytes was evaluated at the time of ICSI, and those without sufficient PVS were judged as oocytes with narrow PVS (NPVS oocytes), and those with sufficient PVS formation were judged as oocytes with non-narrow PVS (non-NPVS oocytes). The analysis included 634 NPVS oocytes from 278 cycles and 12,121 non-NPVS oocytes from 1698 cycles. The fertilization and developmental potentials of NPVS and non-NPVS oocytes were compared by calculating odds ratios using a mixed-effects logistic regression model. We also compared the embryo transfer outcomes of those used for single vitrified-warmed blastocyst transfer after developing into the blastocyst stage. NPVS oocytes had higher odds ratios for degeneration (adjusted odds ratio [aOR], 1.555; 95% confidence interval [CI], 1.096-2.206; p = 0.0133) and 0PN (aOR, 1.387; 95% CI, 1.083-1.775; p = 0.0095), resulting in a lower 2PN rate (aOR, 0.761; 95% CI, 0.623-0.929; p = 0.0072). Even embryos with confirmed 2PN had lower odds ratios for cleavage (aOR, 0.501; 95% CI, 0.294-0.853; p = 0.0109) and blastocyst development (Gardner criteria; CC-AA) rates (aOR, 0.612; 95% CI, 0.476-0.788; p = 0.0001). Blastocysts developed from NPVS oocytes had significantly lower odds ratios for clinical pregnancy (aOR, 0.435; 95% CI, 0.222-0.854; p = 0.0156) than those developed from non-NPVS oocytes. Oocytes with NPVS have low fertilization and developmental potential, as well as low likelihood of pregnancy.

Effect of repeated vitrification of human embryos on pregnancy and neonatal outcomes

BackgroundRepeated cryopreservation of embryos should occasionally be considered when embryos were not suitable for transfer. The effect of re-cryopreservation on embryos remains contentious.MethodsThis retrospective cohort study aimed to evaluate the pregnancy and neonatal outcomes of twice vitrificated blastocyst derived from once vitrified embryos. Total 410 vitrified-warmed blastocyst transfer cycles were divided into two groups according to the times of embryo vitrification: (1) vitrified blastocysts derived from fresh blastocysts (control group, n = 337); (2) twice vitrified blastocysts derived from once vitrified embryos (n = 73). The primary outcome was live birth rate. Multivariable logistic or linear regression analysis model was performed to describe the association between embryo cryopreservation times and clinical outcomes.ResultsNo difference was observed in female age at retrieval and transfer, infertility period, body mass index (BMI), infertility type, endometrial thickness, and embryo transfer numbers between the two groups. The pregnancy outcomes of embryos in repeated cryopreservation group were comparable to those of embryos in control group, including implantation rate, clinical pregnancy rate, and live birth rate. In multivariate logistic regression analysis, the cryopreservation times did not affect the outcomes of biochemical pregnancy, clinical pregnancy, and live birth. Moreover, there was no difference in gestational age, birthweight and sex ratio of singleton newborns between groups. After correcting several possible confounding variables, no significant association was observed between cryopreservation times and neonatal birthweight.ConclusionIn conclusion, pregnancy and neonatal outcomes achieved with twice vitrified blastocyst transfer were comparable to those achieved with vitrified blastocyst transfer in control group.

Prioritized single vitrified blastocyst to be warmed between grades 3 or 4 blastocyst on day 5 transfer cycles.

Selecting the optimal blastocyst to implant during cryopreservation and warming is critial for in vitro fertilization success. Therefore, the aim of this study was to explore which blastocyst should be prioritized to be thawed when facing a single vitrified blastocyst on day 5 transfer. A retrospective study including 1,976 single vitrified-warmed blastocyst transfer cycles was conducted from January 2016 to December 2020. We found that grade 4 vitrified blastocyst had a higher clinical pregnancy (60.64% vs. 49.48%, P < 0.001) and live birth rates (50.12% vs 39.59%, P < 0.001) than the grade 3 vitrified blastocyst. However, no statistical difference was found between groups in miscarriage rate, birth weight, or gestational age. Besides, the grade 4 vitrified-thawed blastocyst had significant potential to develop into grade 6 blastocyst after further culturing for 16 h (73.68% vs. 48.60%, P < 0.001). The grade 6 transferred blastocyst was markedly higher in both clinical pregnancy rate (61.88% vs. 51.53%, P < 0.001) and live birth rate (50.91% vs. 40.46%, P < 0.001) compared to grade 5 transferred blastocyst. Grade 4 vitrified blastocyst is recommended when facing single vitrified blastocyst on day 5 transfer. More importantly, the "embryonic escape hypothesis" was firstly proposed to reveal the findings.

Clinical and neonatal outcomes of complete zona pellucida removal by laser-assisted hatching after single vitrified-warmed blastocyst transfer.

Laser-assisted hatching (LAH) is a widely used and unavoidable technique in assisted reproductive technology after frozen embryo transfer (FET). We aimed to investigate the safety and efficacy of completely ZP (zona pellucida) removed by an assisted laser group compared to an intact group after FET. This retrospective study involved 320 SVBT single vitrified-warmed blastocyst transfers of 213 patients who underwent clomiphene citrate (CC) based minimal stimulation protocol. This study compared 160 SVBT with ZP that were completely removed using laser-assisted (laser beams of 10-15, a wavelength of 1.48μm, and duration of 1.8-2.2ms) to 160 cases of intact SVBT. Fisher's exact test, chi-squared test, and logistic regression are used for statistical analysis. The women's age, cause of infertility, BMI, transferred embryo day, insemination methods, and blastocyst grade were not significantly different between two groups. The implantation rate (66.2% vs. 51.2%, P < 0.01), the clinical pregnancy rate (CPR, 52.5% vs. 39.3%, P = 0.01), and the live birth rate (LBR, 43.7% vs. 29.3%, P < 0.01) were significantly higher in the completely ZP removed than the intact group. In logistic regression analysis, the laser-assisted hatching group showed about 2 times higher implantation rate and CPR and LBR than the control group. But miscarriage, gestational weeks, gender, birth weight, and twin births were insignificant between two groups. Our study suggests ZP free embryo transfer by assisted laser is more effective and safer than intact embryo transfer.

#273 : Comparative Analysis of Pregnancy Predictive Potential Using the Deep Learning Blastocyst Scoring Model Calculated from the Single Focus Blastocyst Image and Time-Lapse Image Sequences

Background and Aims: Artificial Intelligence (AI) based embryo evaluation may objective and reduce inter-observer disagreement. Most commercially available AI models use blastocyst morphokinetics from time-lapse monitoring (TLM). Lifewhisperer (LW, FUJIFILM) is an AI-scoring model that uses a single-focus blastocyst image at a single-time point. LW may be more acceptable to many facilities than the TLM model as it does not require a time-lapse incubator. This study analyzed the predictive ability of LW for pregnant embryos and compared it to an AI model based on morphokinetics (iDAscore, Vitrolife) to assess their usefulness. Methods: This retrospective single-center study analyzed 666 vitrified-warmed blastocyst transfer cycles from January 2019 to December 2022. Inclusion criteria were blastocysts that developed within 5 days from insemination (maximum 120 h) using EmbryoScope+ (Vitrolife), intracytoplasmic sperm injection (ICSI) cycle, and a single-blastocyst transfer cycle. LW score (1.0–9.9) was calculated from single-focus blastocyst images taken before vitrification, while iDAScore (1.0–9.9) was calculated from time-lapse image sequences taken at 11 focal every 10 min after ICSI. We calculated the odds ratio for pregnancy and ROC analysis to compare these models. Results: The mean score was higher in pregnant blastocysts than in non-pregnant blastocysts in both models (LW: 7.47 vs. 6.72, p&lt;0.01; iDAScore: 8.50 vs. 8.04, p&lt;0.01, Willcoxon-test). The odds ratio (95% confidence interval) for pregnancy was 1.19 (1.10–1.28) for LW and 1.48 (1.27–1.74) for iDAScore, with the odds for clinical pregnancy increasing with higher scores (p&lt;0.01). ROC curve analysis showed that the AUC values were 0.60 for LW and 0.62 for iDAScore. There was no significant difference in the predictive ability for pregnant blastocysts (p=0.51). Conclusions: LW allowed objective score calculation from a single focus at single time point blastocyst images without TLM. Moreover, in day 5 blastocyst, LW and iDAscore had comparable predictive pregnancy ability.

Developmental competence and neonatal outcomes of nonpronuclear zygotes following single vitrified-warmed blastocyst transfers using propensity score matching analysis.

To investigate developmental competence and neonatal outcomes of nonpronuclear (0PN) zygotes following single vitrified-warmed blastocyst transfers (VBT). The clinical, laboratorial and neonatal data of 996 patients with ≤ 38years who underwent blastocyst culture and single VBT were retrospectively analyzed. The pregnancy and neonatal outcomes of VBT were compared between 0PN and 2PN blastocysts using propensity score matching (PSM). Moreover, Day 3 (D3) embryo development and blastocyst formation were compared between 0PN and 2PN zygotes. There were no significant differences in clinical pregnancy rate (CPR), live birth rate (LBR) and neonatal outcomes of VBT between the 0PN and 2PN blastocysts irrespectively of whether PSM was used. However, early abortion rate (EAR) was higher in blastocysts from 0PN D3 embryos > 10 cells (p < 0.05) before PSM. Moreover, the early developmental competence of 0PN zygotes was different from that of 2PN zygotes presenting higher percentages of D3 embryos ≤ 6 cells (p < 0.01) and > 10 cells (p < 0.01), lower available blastocyst formation rate (ABFR) (p < 0.01) and good-quality blastocyst formation rate (GBFR) (p < 0.01) in D3 embryos with 4-6 cells. ABFR and GBFR increased with cell number when compared among embryos with 4-6 cells, 7-10 cells and > 10 cells, irrespectively of 0PN or 2PN embryos. The early developmental competence of 0PN zygotes was different from that of 2PN zygotes, but did not influence pregnancy and neonatal outcomes following VBT. ABFR and GBFR increased with cell number, irrespectively of 0PN or 2PN embryos.

Spontaneously hatching human blastocyst is associated with high development potential and live birth rate in vitrified-warmed single blastocyst transfer: A retrospective cohort study.

To investigate the effect of hatching status on predicting pregnancy outcomes in single vitrified-warmed blastocyst transfer (SVBT) by objectively subdividing pre-implantation blastocysts according to hatching status. This retrospective study included 817 SVBT cycles performed between January 2016 and December 2017. Transferred embryos were categorized according to their hatching status as follows: group I (n = 147), non-hatching blastocysts; group II (n = 484), hatching blastocysts; and group III (n = 186), completely hatched blastocysts. Hatching blastocysts (group II) were then classified based on the ratio of the blastocystic diameter outside and inside the zona pellucida into early (n = 185), mid- (n = 103), and late (n = 196) hatching stages. Implantation rate (IR), clinical pregnancy rate (CPR), live birth rate (LBR), multiple pregnancy rate (MPR), miscarriage rate, and neonatal outcomes were evaluated. For groups I, II, and III, respectively, the results were as follows: IR (28.6%, 43.6%, and 53.8%; P < 0.001), CPR (27.9%, 42.8%, and 53.2%; P < 0.001), and LBR (23.1%, 32.0%, and 42.5%; P < 0.001). Group III had better IR, CPR, and LBR. Among hatching blastocysts, late-hatching blastocysts had the highest IR (33.5%, 46.6%, and 51.5% for early, mid-, and late hatching, respectively; P = 0.002) and CPR (33.0%, 45.6%, and 50.5%; P = 0.002), with a tendency for a higher rate of LBR. Neonatal outcomes were not influenced by the hatching status. Advanced hatching status is positively associated with a higher rate of clinical pregnancy and live birth with no negative effects on neonatal outcomes. Additionally, the quantitative classification of hatching status was found to be predictive of pregnancy outcomes.

Comparison of 1-year cumulative live birth and perinatal outcomes following single blastocyst transfer with or without preimplantation genetic testing for aneuploidy: a propensity score-matched study.

We evaluated whether preimplantation genetic testing for aneuploidy (PGT-A) could increase the cumulative live birth rate (CLBR) in patients with recurrent implantation failure (RIF) and recurrent pregnancy loss (RPL). The clinical records of 7,668 patients who underwent oocyte retrieval (OR) with or without PGT-A were reviewed for 365days and retrospectively analyzed. Using propensity score matching, 579 patients in the PGT-A group were matched one-to-one with 7,089 patients in the non-PGT-A (control) group. Their pregnancy and perinatal outcomes and CLBRs were statistically compared. The live birth rate per single vitrified-warmed blastocyst transfers (SVBTs) significantly improved in the PGT-A group in all age groups (P < 0.0002, all). Obstetric and perinatal outcomes were comparable between both groups regarding both RIF and RPL cases. Cox regression analysis demonstrated that in the RIF cases, the risk ratio per OR was significantly lower in the PGT-A group than in the control group (P = 0.0480), particularly in women aged < 40years (P = 0.0364). However, the ratio was comparable between the groups in RPL cases. The risk ratio per treatment period was improved in the PGT-A group in both RIF and RPL cases only in women aged 40-42years (P = 0.0234 and P = 0.0084, respectively). Increased CLBR per treatment period was detected only in women aged 40-42years in both RIF and RPL cases, suggesting that PGT-A is inappropriate to improve CLBR per treatment period in all RIF and RPL cases.