Euploidy Rates Research Articles

P-273 Image-based oocyte model predictive of blastocyst development correlates with ploidy status across a broad spectrum of PGT-A indications, accounting for confounding variables

Abstract Study question Does MAGENTA, an AI assessment of oocyte quality, indicate ploidy potential of the developed blastocysts in the presence of confounding variables? Summary answer MAGENTA correlates to oocytes that develop into euploid embryos across diverse demographics, highlighting its robust ability to assess oocyte quality and genetic potential. What is known already MAGENTA is a non-invasive AI-image analysis tool that assesses images of mature oocytes and provides a score from 0-10, where higher scores indicate higher chances of developing into a blastocyst. MAGENTA has also displayed a correlation to blastocyst morphological quality. The ploidy status of blastocysts plays a significant role in cycle success and is often utilized for the selection of embryos to transfer. Despite the selection of embryos based on their genetic normality, many transfers are unsuccessful. With most chromosomal errors arising in the oocyte, assessment at the gamete level is critical to improving outcomes. Study design, size, duration A retrospective study using CRM Weill Cornell Medicine data included 3,342 mature oocytes that developed into blastocysts and underwent PGT-A in 2021. Blastocysts tested as mosaic (n = 753) or inconclusive (n = 13) were excluded. Images of the oocytes were obtained immediately post-ICSI using EmbryoScope time-lapse incubators (Vitrolife, Sweden). Blastocyst morphological grades were categorized by quality: highest (ICM+TE grade A), high (ICM+TE grade A/B), medium (ICM+TE grade B), or low quality (ICM or TE grade C/D). Participants/materials, setting, methods Data was obtained from 629 patients (females 26-45 years old) with an average of 5.3 blastocysts (range 1-20) with PGT-A results per patient. MAGENTA assessed each oocyte image and provided a score (0-10), with higher scores representing a greater potential to develop into a blastocyst embryo. In this dataset, 1827 (55%) blastocysts were tested as euploid and 1515 (45%) were tested as aneuploid. PGT-A was conducted for various specific and non-specific indications in these patients. Main results and the role of chance MAGENTA was positively associated with oocytes that developed into blastocysts of increasing quality, with significance between highest and high-quality (7.4 vs 7.0,p<0.05) and medium and low-quality (6.9 vs 6.1,p<0.01). Of the blastocysts, the MAGENTA score further displayed significant differences between oocytes that developed into euploid (7.0) compared to aneuploid blastocysts (6.6) (p < 0.001;Welch’s t-test). Although MAGENTA does not predict ploidy, a threshold of 8.8 MAGENTA score was determined to best distinguish between ploidy outcomes with 61% euploidy rate above this threshold compared to 51% below, a significantly different proportion (p < 0.001;Two-Sample Proportions z-test). Therefore, oocytes scored ≥8.8 display a 19.6% relative increase in chance of developing into a euploid blastocyst. To account for female age, subgroup analysis was conducted and found MAGENTA scores to be significantly different between oocytes that developed into euploid and aneuploid blastocysts for patients <35 years old (7.2 vs 6.6, p < 0.01;Welch’s t-test) and ≥35 years old (6.8 vs. 6.5, p < 0.05;Welch’s t-test). Blastocyst morphological grade was also investigated as a confounding factor. No significant differences existed between MAGENTA scores of euploid and aneuploid blastocysts among the low, high, or highest-quality. Significantly, differences were only found within medium quality blastocysts (7.0 vs 6.6,p<0.05), which had the greatest sample size (n = 1854). Limitations, reasons for caution MAGENTA was not trained to predict euploid embryo development from images of mature oocytes. Further data is required to discern the correlation of MAGENTA to chromosomal ploidy status, apart from blastocyst quality. Additionally, investigation into sperm DNA fragmentation as a potential contributor to ploidy determination is warranted. Wider implications of the findings MAGENTA can identify oocytes of better quality that not only have higher chances of blastocyst development and higher morphological grades, but also indicates oocytes that are more likely to become euploid embryos across patients of various PGT-A indications and a broad age demographic. Trial registration number not applicable

O-089 Association of pituitary suppression method with euploid blastocyst yield in preimplantation genetic testing for aneuploidy (PGT-A) cycles

Abstract Study question Do progestin primed ovarian stimulation (PPOS) cycles have lower euploidy yield compared to pituitary suppression with gonadotropin releasing hormone (GnRH) antagonists? Summary answer The choice of pituitary suppression method has no bearing on euploid retrieval per blastocyst tested. What is known already Progestin primed ovarian stimulation cycles are an alternative to GnRH antagonists when fresh embryo transfer is not a priority. While the two approaches have been shown to be similar in terms of conventional stimulation outcomes such as mature oocyte retrieval, and blastulation rates, there is still some lingering controversy regarding cumulative pregnancy rates and the effects of progestins on embryo genetic constitution. Study design, size, duration This was a multicenter retrospective cohort study including data from two tertiary-level treatment centers. Participants/materials, setting, methods Infertile women undergoing ovarian stimulation with either progestin primed or GnRH antagonist pituitary suppression with the intention of transfer after PGT-A embryo testing with next-generation sequencing. The main outcome parameter was euploid embryo count per blastocyst tested and was modeled with mixed-effects log-binomial regression models. Results were adjusted for patient age and laboratory performing the PGT-A tests while they were not adjusted for embryo quality to avoid collider bias. Main results and the role of chance A total of 1425 PGT-A tested blastocysts from 383 cycles of 365 patients were included in the analysis. 243 cycles (63.4%) received GnRH antagonists for pituitary suppression while 140 (36.5%) received progestins. The overall euploidy rates per blastocyst tested in the GnRH antagonist and PPOS groups were 38.8% vs. 31.1%, 30.2% vs. 29.4%, 27.0% vs. 25.2%, and 13.8% vs. 14.5% for the age categories <35, 35-37, 38-40, and >40, respectively. After adjusting for the effect of female age at testing and the laboratory performing the PGT-A test, the type of pituitary suppression was not significantly associated with euploid retrieval per blastocyst tested (adjusted risk ratio: 0.94, 95% CI: 0.70 - 1.28, P = 0.701). After testing, 191 women received 233 embryo transfers. Human chorionic gonadotropin (hCG) positivity per transferred embryo was not significantly different between progestin primed and GnRH antagonist cycles (RR: 0.89, 95% CI: 0.71 – 1.08, P = 0.268). Limitations, reasons for caution This is a retrospective study with data from multiple centers with a non-standardized selection of blastocysts to be tested. In addition, the sample size and retrospective nature of the data may have biased the estimates. Wider implications of the findings The choice of pituitary suppression method does not appear to have a significant effect on euploid embryo retrieval rates or hCG positivity per transfer. The choice of medication can be based on the needs of the individual case without concern for suboptimal PGT-A outcomes. Trial registration number Not Applicable

P-199 The development time of good quality blastocysts is dependent on their genetic status in patients over 36 years old

Abstract Study question Is there any difference in PGT-A results between good quality blastocysts depending on whether they reach this stage on the fifth or sixth day? Summary answer In patients over 36 years old, there is a significantly higher rate of aneuploidy in embryos that reach the blastocyst stage on Day 6. What is known already The level of chromosomal abnormalities in embryos increases with maternal age, as indicated by PGT-A data. Embryo quality also correlates with aneuploidy level. The normal timeframe for blastocyst formation is considered to be between the fifth and sixth day of development. In this study, the genetic status of good quality blastocysts was examined to determine a difference in the aneuploidy rate between blastocysts formed on the fifth day compared to those formed on the sixth day.This information could provide insights into the optimal timing for blastocyst formation and its relationship to genetic abnormalities. Embryo quality also correlates with aneuploidy level Study design, size, duration The retrospective study included 513 good quality blastocysts (3-4, A-B according to the Gardner classification) after trophectoderm biopsy and obtained from fresh oocytes of 141 patients aged 23-45 years. The PGT-A data were analyzed. The analysis considered the age of the patients, with one group of patients younger than 36 years old (35 patients, 174 blastocysts), and another group aged 36 years and older (106 patients, 339 blastocysts). Participants/materials, setting, methods Trophectoderm biopsy was performed on good quality embryos as they progressed in development, either on the fifth or sixth day. PGT-A was conducted using the NGS method, and the data was processed using the chi-square test. Main results and the role of chance Among patients younger than 36 years old, 58.5% of good quality blastocysts formed by the fifth day of development. In comparison, among patients 36 years old and older, 43.0% of good quality blastocysts formed by the fifth day. The difference in the growth rate of blastocysts of the same quality between the age groups was statistically significant (p > 0.01). In patients younger than 36 years old, 75.0% of blastocysts formed by the fifth day and 66.7% of blastocysts formed by the sixth day were euploid (with no significant difference). In patients 36 years old and older, 50.5% of blastocysts formed by the fifth day were euploid, while only 19% of blastocysts formed by the sixth day were euploid. This difference in euploidy rates between the fifth- and sixth-day blastocysts was statistically significant (p > 0.01). Limitations, reasons for caution The study was conducted with a relatively small sample size, which may limit the generalizability of the results. A larger and more diverse sample would be beneficial to confirm the findings. Wider implications of the findings In patients over 36 years of age, the majority of blastocysts develop by Day 6, and there is a significant increase in aneuploidy level. This suggests that there may be a higher risk of chromosomal abnormalities in embryos that take longer to develop into blastocysts in this group. Trial registration number Not applicable

P-647 Association between PCOS phenotype-D and euploid blastocyst rate per cohort of inseminated oocytes: a matched case-control study versus idiopathic infertile women

Abstract Study question Is there any association between PCOS phenotype-D and oocyte competence defined as euploid blastocyst rate (EBR) per cohort of inseminated oocytes? Summary answer Although higher fertilization and blastulation rates were reported in PCOS phenotype-D women versus idiopathic infertile patients, the EBR per cohort of inseminated oocytes was comparable. What is known already Several studies report poorer oocyte quality and cumulative-live-birth-rate (CLBR) in hyperandrogenic PCOS phenotypes, as defined according to the Rotterdam criteria. Increased androgen concentrations in follicular fluids are indeed associated with elevated serum-LH levels, which can block dominant follicle development inducing atresia and negatively impact fertilization rates and embryo development. Limited evidence exists in phenotype-D PCOS patients, namely women characterized by oligomenorrhea, ovarian PCO morphology and absence of hyperandrogenism. Here, we report the embryological and clinical outcomes in these women during ICSI cycles with preimplantation genetic testing for aneuploidies (PGT-A) at the blastocyst stage. Study design, size, duration Retrospective propensity score matched (PSM) case-control study. Among PGT-A cycles conducted by naïve patients with own oocytes (2013-2021), we excluded FNA/TESE. 58 phenotype-D PCOS patients were identified according to the Rotterdam criteria. These patients were matched for maternal age, number of cumulus-oocyte-complexes (COCs), and sperm quality, with 58 patients with idiopathic infertility, regular cycles, normal ovarian morphology, and no sign of clinical hyperandrogenism. The primary outcome was EBR per cohort of inseminated oocytes. Participants/materials, setting, methods GnRH-antagonist ovarian stimulation, ICSI, blastocyst biopsy, qPCR/NGS-analysis to assess uniform aneuploidies and vitrified-warmed single blastocyst transfers were conducted. The PCOS and control groups were similar for age (35.6±3.0 versus 36.0±3.9 years), COCs (23.1±6.7 versus 23.5±7.6), sperm factor, primary/secondary infertility, hormonal values, BMI (23.8±5.3 versus 22.0±2.8), and duration of infertility (3.6±2.2 versus 3.6±2.0 years). All intermediate embryological and clinical outcomes were assessed as secondary endpoints. Linear/logistic regressions adjusted for confounders were conducted to confirm statistically-significant differences. Main results and the role of chance No difference was reported in maturation rates, but women with PCOS showed better fertilization rates per cohort of inseminated oocytes (76.9±15.2% versus 67.3±20.4%, Mann-Whitney-U-test<0.01), and blastulation rates per cohort of 2PN-zygotes (52±20.4% versus 43.7±20.7%, Mann-Whitney-U-test=0.03). Eventually, PCOS patients obtained more blastocysts than controls (5.8±3.1 versus 4.5±2.9, Mann-Whitney-U-test=0.02), despite similar numbers of metaphase-II oocytes in the groups (16.5±6.1 versus 16.5±7.0). All differences remained significant after adjusting for maternal age and sperm factor. Nevertheless, the euploidy rates per cohort of biopsied blastocysts were similar, thus involving comparable EBR per cohort of inseminated oocytes (21.7±14.1% versus 17.2±16%, Mann-Whitney-U-test=0.12). More patients obtained ≥1 euploid blastocyst in the PCOS versus the control group (N = 56/58, 96% versus N = 47/58, 81%, Fisher’s-exact-test=0.02), independently from maternal age, semen quality, and number of inseminated oocytes (Odds-Ratio: 6.5, 95%CI:1.3-33.7, p = 0.03). Lastly, all clinical outcomes per first vitrified-warmed euploid transfer were similar, thereby involving comparable LBRs (N = 28/54, 51.9% versus N = 26/47, 55.3% in the PCOS and control groups, p = 0.8; Odds-Ratio adjusted for blastocyst quality and day: 1.19, 95%CI:0.5-2.7, p = 0.68). Limitations, reasons for caution Although clinical hyperandrogenism was absent in both groups, biochemical hyperandrogenism was not assessed. Nonetheless, this pilot study paves the way for future more detailed investigations. 24% of cycles in the PCOS group were not concluded, therefore a CLBR comparison would be biased and was not reported. Wider implications of the findings The lower developmental competence in the control group suggests oocyte quality issues, other than chromosomal, underlying their “unexplained infertility” condition. In phenotype-D PCOS women, IVF is effective. Since >50% of this subgroup of women had already failed multiple ovulation-induction and/or intrauterine-insemination attempts, an early referral to IVF deserves further investigations. Trial registration number Not applicable

P-231 How many blastocysts are necessary to reach pregnancy with preimplantation genetic testing?

Abstract Study question What is the influence of the number of blastocysts before biopsy on the prognosis of pregnancy in preimplantation genetic testing for aneuploidy (PGT-A) cycles? Summary answer The number of pre-biopsy blastocysts seems to be a parameter that can be used as a prognostic factor for the pregnancy chance in PGT-A cycles. What is known already Advances in embryo cryopreservation techniques have allowed for a greater use of PGT. Studies showed that PGT-A has improved live birth rates while reducing the number of embryos transferred. There is a lot of information about the role of the oocyte number as a predicting factor for pregnancy rate. However, little information is available about the influence of the number of blastocysts before performing PGT-A on the chance of achieving a pregnancy. Study design, size, duration Retrospective study performed in a reproductive medicine center using the first IVF cycle from 2016 to 2023, including 682 patients with at least one blastocyst before undergoing PGT-A. All patients performed a single embryo transfer in each procedure, in up to 4 transfers. Participants/materials, setting, methods The sample was divided into four groups according to the blastocyst number: G1, 1 to 2 blastocysts (n = 324); G2, 3 to 4 (n = 197); G3, 5 to 9 (n = 137); and G4, ≥ 10 blastocysts (n = 24); each group was divided according to female age (≤ 37 and > 37) Variables: female age, and euploidy, clinical pregnancy per transfer and cumulative clinical pregnancy rates. Data were compared between groups. Statistical analysis: Chi-square test (Bonferroni correction) and Anova (p < 0.05). Main results and the role of chance The results in G1, G2, G3 and G4 were, respectively: female age, yo (40 vs. 38.4 vs. 37.2 vs. 34.7, p < 0.01); euploidy rate (34.6 vs. 67.2 vs. 83.2 vs. 100.0, p < 0.0001), clinical pregnancy rate per transfer, % (45.5 vs. 58.6 vs. 72.8 vs. 95.8 p < 0.0001 ), cumulative clinical pregnancy rate, % (15,7 vs. 39.4 vs. 60.6 vs. 95,8% p < 0.0001). Women with 1 to 2 blastocysts before biopsy had a cumulative pregnancy rate more than 3-fold lower than those with 3 to 4 blastocysts (%, 39.6 vs. 15.3, p < 0.001, OR 3.59, CI 95% 2.32 to 5.57) and more than 8-fold lower than those with 5 to 9 blastocysts (%, 60,6 vs. 15.3, p < 0.001, OR 8.42, CI 95%: 5.20 to 13.64). The comparison in each group according to female age showed that until 9 blastocysts, the younger women had a pregnancy rate higher than the older, respectively (%): G1: 30.8 vs. 12.5, p = 0.001; OR 3.1, CI 95%: 1.44 to 6.48; G2: 57.4 vs. 30.2, p < 0.001; OR 3.10, CI 95%: 1.61 to 5.98; G3: 72.6 vs. 50.7, p = 0.009. OR 2.58; IC 95%: 1.19 to 5.67; and G4: 93.8 vs. 87.5, p = 0.268. Limitations, reasons for caution As a retrospective study, data collection and filling limitations should be considered. Wider implications of the findings The number of pre-biopsy blastocysts appears to be a parameter that can be used as a prognostic factor for the pregnancy chance in PGT-A cycles. Even transferring 1 embryo, the pregnancy rate/transfer was higher with more blastocysts. In patients with less than 10 blastocysts before PGT, age influences pregnancy rates. Trial registration number Not Applicable

P-527 Low sperm motility and elevated sperm DNA fragmentation index (DFI) are associated with increased rates of embryo aneuploidy in patients with advanced reproductive age

Abstract Study question Is there a correlation between the paternal age, sperm characteristics, and the prevalence of chromosomal abnormalities in embryos generated through in vitro fertilization (IVF)? Summary answer A correlation exists between advanced paternal age, suboptimal sperm parameters, and elevated rates of embryo aneuploidy in individuals of advanced reproductive age. What is known already The exact mechanisms underlying the relationship between paternal age, sperm quality and embryo ploidy, although a subject of considerable research in assisted reproduction, are not fully elucidated. Some reports, including our group’s, suggest that paternal age may influence sperm quality and segmental embryo aneuploidy, while others suggest a potential association between high DFI(DNA Fragmentation Index) and an increased likelihood of embryo aneuploidy. Studies also show that sperm with optimal motility and fertilization competence are more likely to contribute to the development of euploid embryos, while data on the effect of abnormal sperm parameters on embryo ploidy is scarce and conflicting. Study design, size, duration This was a retrospective cohort study performed in the Reproductive Genetics Department, CReATe Fertility Centre, Toronto, Canada, between January 2019-December 2023. A total of 7628 blastocysts from 1512 cycles (1392 patients) were analyzed using high resolution NGS PGT-A. Sperm motility, concentration and DFI data, as well as, IVF cycle parameter data were collected. In addition, age of gamete providers and any relevant clinical, laboratory and demographic data were obtained for statistical analysis. Participants/materials, setting, methods Embryos were allocated into two groups by oocyte-provider age: OP-≤33 years and OP-≥34 years. Each group was divided into two sub-groups by paternal age: SP-≤39 years (n = 4570); SP-≥40 years (n = 3058). Multiple logistic/ordinal regressions were conducted to evaluate Segmental abnormalities and Segmental mosaicism between these age groups in relation to sperm DFI (GOOD ≤15%; FAIR 15-30%; POOR ≥30%), Motility (HIGH >40%; LOW <40%) and Count (LOW <5 mil/ml; MEDIUM 5-15 mil/ml; HIGH >15 mil/ml). Main results and the role of chance PGT-A analysis of 7628 embryos showed 51.5% euploidy, 36.7% aneuploidy and 11.8% mosaicism. In the OP-≤33 group, there were no significant differences between the two paternal age groups for euploidy, aneuploidy or mosaicism rates. In the OP-≥34 group, decreasing euploidy rates (p < 0.0001 and increasing aneuploidy rates (p < 0.0001) were observed between the two paternal age groups, while mosaicism rates were not different, an expected oocyte age-effect result. No significant differences in aneuploidy rates were observed for each of the sperm parameters (DFI, motility, count) in the groups of the OP-≤33 with SP-≤39, OP-≤33 with SP-≥40 and OP-≥34 with SP-≤39. In the group of OP-≥34 with SP-≥40, in patients with LOW motility vs. HIGH motility the aneuploidy rates were higher (56.8% vs.50.6%, p = 0.005) and euploidy rates were lower (33.8% vs.38.4%, p = 0.03). Each sperm parameter in each age group was further analyzed for chromosomal segmental abnormalities and segmental mosaicism. Higher rates of segmental abnormalities were seen in LOW motility groups with POOR-DFI compared to GOOD DFI in OP-≤33 with SP-≤39 (3.2% vs. 7.4%, p = 0.03). Limitations, reasons for caution The main limitation was the retrospective nature of this study; however, multiple regression analyses were conducted to limit potential bias by adjusting for sperm and oocyte characteristics. In addition, PGT-A analysis cannot provide information on origin of the aneuploidy and all conclusions are deduced from indirect associations to paternal age. Wider implications of the findings The identified associations could stimulate further research into exploring the molecular/cellular processes involved in fertilization, early embryonic development, and the potential impact of sperm-related factors on the chromosomal stability of developing embryos. The broader implications of these findings extend to clinical practice, patient counseling, technological advancements, and ethical considerations. Trial registration number not applicable

P-012 Euploid and good-quality blastocysts using testicular sperm from men with high sperm DNA fragmentation (SDF), oligozoospermia, and previous failed ICSI with ejaculated sperm

Abstract Study question Are euploid rate and blastocyst quality improved when testicular sperm is used in patients with elevated SDF and poor semen parameters or/and previous ICSI failure? Summary answer The use of testicular spermatozoa in non-azoospermic males does preserve blastocyst ploidy while favoring the proportion of good-quality embryos available for the couple. What is known already Sperm extracted from the testicle has been proposed as a strategy to improve reproductive outcomes in couples with elevated DNA fragmentation in the ejaculate and with severe male infertility or previous ICSI failure. Different studies and meta-analyses show to increase pregnancy and live birth rates, and one of the reasons could be the lower genetic damage of spermatozoa retrieved from the testicle. However, there is little information on the effect on the quality of the embryos generated and their ploidy since the use of testicular sperm tends to have a higher rate of aneuploidy. Study design, size, duration This is a prospective, blinded, randomized, and controlled trial conducted in a private university-affiliated IVF center between October 2020 and June 2023. In each patient (n = 6), oocytes were randomly microinjected by sperm from the testis (T-ICSI) or ejaculate (E-ICSI) assigned in a 1:1 ratio. All males had an SDF>30% (measured by Sperm Chromatin dispersion (SCD) test), severe oligozoospermia, and/or a previous ICSI failure. Participants/materials, setting, methods Males underwent testicular sperm extraction (TESE) to obtain spermatozoa, which were frozen along with an ejaculated semen sample obtained previously on the same day. Women were <38 years old with good ovarian reserve (antral follicle count>10). SDF level was compared between both sources. The primary outcome was the euploid rate (among a total number of biopsied embryos). Secondary outcomes were fertilization rate, blastocyst rate, good-quality blastocyst rate, and ongoing pregnancy rate per embryo transfer (ET). Main results and the role of chance Mean ejaculated SDF was 44.83±16.6 (IC95% 27.5 -62.2), while mean women age was 31.8±2.9 (28.76-34.9). An average of 14.5±5.8 metaphase II oocytes were microinjected per patient. A total of 87 oocytes were randomized to the T-ICSI group (n = 45) or E-ICSI group (n = 42). There was a 14% difference between the SDF of testicular (44.7% (31.3-58.0) and ejaculated sperm (58.5% (37.6-79.4) (p = 0.2). The fertilization rate was slightly lower in the T-ICSI group (53.3% (38.1-68.1) compared to the E-ICSI group (61.9 (61.8-76.0) (p = 0.6). A total of 21 embryos reached the blastocyst stage, being the blastocyst arrival rate per correctly fertilized oocyte 41.7% (10/24) (22.8-63.1) for T-ICSI and 42.3% (11/26) (24.0-62.8) for E-ICSI (p = 1.0). Of them, a higher proportion of good-quality blastocysts was found in the T-ICSI (29.2% (13.4-51.6)) group than in the E-ICSI (19.2% (7.3-40.0)) group, although the difference was not statistically significant. In addition, the euploidy rate was comparable between the T-ICSI (60% (27.4-86.3)) and E-ICSI (63.6% (31.6-87.6)) groups (p = 1.0). Seven embryos were transferred in 6 ET, three in each study group. Only one of the ET in the E-ICSI group resulted in pregnancy (33.3% (1.8-87.5), while the three transfers in the T-ICSI group resulted in an ongoing pregnancy (100% (31.0-100)) (p = 1.0). Limitations, reasons for caution Despite being a randomized controlled trial, the number of subjects recruited is small; it is necessary to increase the number of cases to obtain results with greater statistical power. TESE is a technique that is not risk-free, so its performance should be evaluated in terms of its cost-benefit for patients. Wider implications of the findings The use of less genome-damaged testicular spermatozoa in non-azoospermic males seems to be a reliable strategy for couples with high ejaculated SDF and severe oligospermia and/or previous ICSI failures. However, although we have found an improvement, remains to be statistically confirmed with more cases. Trial registration number NCT04795440

P-259 Luteal phase in dual stimulation. Do we have the same outcomes in morphokinetics, laboratory, clinical and genetic parameters?

Abstract Study question Do luteal phase (LF) embryos have the same outcomes in laboratory and morphokinetics parameters and clinical and genetic rates that follicular phase (FF) embryos? Summary answer Laboratory outcomes, ploidy and clinical rates result similar between two phases. In morphokinetic analysis we obtained significant differences in the duration of visible pronuclei. What is known already Dual stimulation (DS) protocols are being proposed as a useful strategy in patients with poor prognosis, particularly in cases of low response or low ovarian reserve. Nevertheless, there is still a lack of solid evidence for their use. In this context, it is interesting to analyse if the embryos from the LF achieve the same results as those from the FF. Our previous studies have shown comparable data, although they included vitrified oocytes. To avoid the impact of vitrification, we only review those cycles with fresh oocytes. A morphokinetic analysis is also added to compare their development. Study design, size, duration This multicentre retrospective evaluated 81 cycles of DS and PGT-A in patients with some poor prognostic feature (Antimüllerian hormone <1ng/ml, antral follicle count <6, poor response, >39 years) with 161 pick-ups between January 2022-August 2023 (81 in FF and 80 in LF). A total of 398 embryos were biopsied (195 from FF and 203 from LF) and 59 frozen embryo transfers were performed (33 in FF and 26 in FL) between January 2022-December 2023. Participants/materials, setting, methods We compared several parameters between the two groups including gamete age, oocyte number, MII number, fertilization rate, blastocyst quality, biopsy rates, and genetic results. Additionally, clinical outcomes after embryo cryotransfer were also studied. We compared classical morphokinetic parameters as well. We performed this preliminary analysis on 226 embryos (99 FF, 127 LF) in two ways: comparing FF and LF embryos as two groups and comparing by patient within the same cycle in a paired analysis. Main results and the role of chance The average age of the patients was 40.5 (±2.3). No significant differences were found in terms of oocytes retrieved per patient (8.7 ±4.9 vs 9.2±5.9), maturity (7.2 ±4 vs 7.7±4.3) or number of embryo biopsied (6.54 ±3.9 vs 6.9±4.4). After genetic analysis, euploidy rate was found to be lower in LF compared to FF although not statistically significant (23.6% and 28.6%). Aneuploidy (67.4% vs 71.4%) and mosaicism rates (22.3% vs 19.1%) were also comparable between the two groups. In the same way, we did not find any statistically significant differences in the day of transfer, quality of the embryo transfer, neither pregnancy rates (54.5% vs 50%) nor life birth rate (54.5% vs 38.5%). In the preliminary morphokinetic analysis we only obtained significant differences in the time in which pronuclei were visible, being greater in the FF (16±3h vs 15±3h, p = 0.005/p=0.004 after adjusting for confounding variables). In addition, it appears that the pronuclei of the FF embryos tend to take longer to disappear. Also, these FF embryos complete the third cell cycle in a slower way than LF embryos, although none of these comparisons are statistically significant (p = 0.065 and p = 0.068). In the paired analysis we didn’t find any statistically significant difference. Limitations, reasons for caution This study is limited by its retrospective nature. Validation by a prospective study is recommended. Regarding morphokinetics, it is necessary to increase the number of embryos analysed to increase the statistical power of the study. Wider implications of the findings It is interesting to analyse LF embryos’ morphokinetics since there are few studies in this regard. Moreover, it is still unclear whether the oocytes obtained from the LF cycles are the result of the second stimulation or a persist effect of the first one, which could somehow affect embryo development. Trial registration number Not applicable

P-216 Whole genome amplification (WGA) of spent culture media may not be a reliable marker of blastocyst prioritization for transfer

Abstract Study question Does the success or failure of DNA amplification from spent culture media of good-quality blastocysts correlate with their ploidy status and clinical pregnancy outcomes? Summary answer Samples with successful DNA amplification exhibited similar rates of euploidy and clinical pregnancy rates compared to spent culture samples with failed DNA amplification. What is known already Studies have detected DNA in spent culture media/blastocoelic fluid (BF) from fully developed blastocysts. After amplification, this DNA is sequenced to provide information on their ploidy status. Some authors reported simply detection of amplified DNA as an indicator of blastocyst viability, so that spent culture media/BF with DNA amplification derive from abnormal embryos, and failed DNA amplification from euploid blastocysts. Along with this line of rationale, some authors associated DNA amplification failure with higher clinical pregnancy rates. Reproducibility of such findings is warranted which may stem from various factors, such as culture conditions, amplification methods and statuses of blastocysts analysed. Study design, size, duration This preliminary set of results is part of a cohort (nonselective) ongoing study, from which 62 patients participated so far from two tertiary IVF centers during the period of January 2022 until October 2023. Only ICSI patients aged <43-year-old with >6 mature oocytes were included. Single frozen blastocyst transfers were performed blinded to the results of the whole genome amplification (WGA) and/or DNA sequencing and pregnancy outcomes recorded. Participants/materials, setting, methods Embryos were singly cultured into 20µl GTL-media in Embryoscope+ incubator (Vitrolife). On day 3, embryos were washed repeated times and placed into new culture dish. Spent media was collected from ≥BL4BB blastocysts (Gardner) on days 5/6 after laser collapse prior vitrification. DNA from culture medium were amplified using MALBAC (Yikon-Genomics). After WGA, DNA was quantified using Qubit 3.0 fluorometer (cut-off of 0.6 ng/µl) and then subjected to next-generation sequencing (NGS) with Illumina MiSeq platform. Main results and the role of chance A total of 104 spent culture media samples were analysed from individual blastocysts. About 70% of samples of spent media had amplified DNA and were sequenced further. From those sequenced samples, 55% resulted in euploidy and 45% in abnormal ploidy status. Embryo transfers took place from blastocysts cultured in 82/104 samples. A total of 36 (44%) clinical pregnancies were obtained from 82 transfers/samples from which, 78% derived from samples with DNA amplification and 22% from samples with failed DNA amplification. Outcomes of clinical pregnancies were verified for both conditions, samples with DNA amplification or failed DNA amplification. A total of 28/55 (51%) samples with DNA amplification resulted in clinical pregnancies, while only 30% (8/27) of failed DNA amplification samples did so (P = 0.06). Positive predictive values (PPV) and negative predictive values (NPV) of ploidy status of sequenced samples in relation to ongoing pregnancy and live birth rates are ongoing. Limitations, reasons for caution The limited sample size. Wider implications of the findings The presence of DNA in the spent culture media may offer an attractive alternative as a non-invasive test for aneuploidy. Research is still ongoing and challenging. Nevertheless, truncating the test at DNA amplification phase seems not a reproducible methodology to serve as a criterion to prioritize embryos for transfer. Trial registration number This research project is financially supported by Theramex Birth Grant program, a competitive grant supporting IVF research in Europe.

P-262 Clinical viability of oocytes with micronuclei at fertilisation

Abstract Study question Does the presence of micronuclei at fertilisation impact on embryo potential? Summary answer Embryos displaying micronuclei at fertilisation exhibit decreased utilisation rates and lower euploidy rates, however are capable of resulting in clinical pregnancies. What is known already The appearance of two pronuclei defines normal fertilisation. With advances in imaging techniques, a range of pronuclei phenotypes can now be identified in more detail, including additional micronuclei. Micronuclei are smaller satellite structures appearing around the pronuclei. Previous studies have determined that embryos containing two primary pronuclei and one micronuclei are generally diploid and can develop to blastocyst stage. However, these studies were limited in sample size, did not have consistent imaging techniques and assessed only the presence or absence of micronuclei, not their size or number. Study design, size, duration Retrospective cohort analysis in a single, large IVF centre including all oocytes entering culture between January 2022 and December 2023 (n = 33,237). All embryos were cultured in Embryoscope+ using Vitrolife sequential media at 6% CO2 and 5% O2. ICSI and naturally inseminated oocytes were included. All embryos were cultured to day 5/6 before determining suitability for transfer, freezing and/or genetic testing. Participants/materials, setting, methods During routine daily annotation, embryologists assessed fertilised oocytes for the presence of micronuclei. This study re-examined all embryos annotated as displaying micronuclei and further assessed: number of micronuclei, their position (‘apposed’ or ‘distant’ from the pronuclei, and in the case of > 1 micronuclei ‘clustered’ or ‘spread’) along with the area (μm2) of the two largest micronuclei and area (μm2) of primary pronuclei using Embryoscope+ software. Clinical pregnancy was defined as presence of a gestational sac. Main results and the role of chance Micronuclei were observed in 0.45% (n = 149/33,237) of all oocytes assessed. The majority of these presented as one additional nuclei 92.60% (n = 138), 7.38% (n = 11) showed two additional nuclei and 0.67%(n = 1) had multiple (more than 2) micronuclei. All micronuclei appeared apposing a primary pronucleus. In the event of multiple micronuclei, 82% were clustered whereas 9% was spread throughout the around the primary pronuclei. The average area of the largest micronuclei in each oocyte was 80.33μm2 ± 26.81.The mean area of all micronuclei was 76.80μm2, approximately 16% of the size of primary pronuclei measured, 465.09μm2. The utilisation rates of embryos derived from micronuclei fertilisation were 28.18% (N = 42) compared to 49%, n = 4118 of 2PN derived embryos. All but one of these presented two primary pronuclei and one additional micronuclei, with the remaining embryo displaying two micronuclei. Twelve of these embryos were transferred (in a fresh stimulated cycle (n = 5) or a subsequent frozen embryo transfer cycle (n = 7), resulting in four clinical pregnancies, however only one ongoing clinical pregnancy. PGT testing was performed on 19 embryos, with only two, 6.67% returning a euploid results, 68.42% resulting an aneuploid, of the remaining four embryos, 2 achieved a mosaic result and 2 received a no result. Limitations, reasons for caution As the occurrence of micronuclei is rare, only a limited number of embryos were available for analysis. Furthermore, this study was conducted in a large single laboratory and can not account for differences in culture conditions between laboratories. Inter-operator variability among initial fertilisation annotations could not be excluded. Wider implications of the findings By creating a definition of the micronuclei measurement, it provides safeguard for micronuclei to be assessed in culture. The data presented here can help guide clinical decisions where micronuclei are present. Trial registration number not applicable

P-439 Analysis of Products of Conception (POC) using Whole Genome Next Generation Sequencing (NGS) in pregnancy loss after euploid or mosaic embryo transfer

Abstract Study question What is the outcome of genetic assessment for fetal chromosomal aberrations in miscarriages after euploid/mosaic embryo transfers (ET)? Summary answer POC testing should be recommended in patients with E/M-ET to screen for chromosomal aberrations occurring post-implantation or beyond the detection limit of PGT-A testing What is known already Spontaneous abortion is the most common complication of pregnancy, affecting approximately 15% of clinically recognized pregnancies. Although the etiology is diverse, fetal chromosomal aberrations account for 50-70% of first trimester miscarriages. Assessment of the fetal chromosomal composition is recommended by ACOG guidelines and aids in counselling and management of patients’ reproductive options. The value of this assessment in patients with miscarriage after euploid/mosaic ET has not evaluated. At the same time there is generally a lack of follow-up studies to examine the accuracy of PGT-A testing and investigate the rates of post-implantation errors causing miscarriage. Study design, size, duration This retrospective study had REB approval. This study was performed at the CReATe Fertility Centre and its Reproductive Genetics Laboratory in Toronto, Canada, between January 2019-December 2023.We evaluated the molecular karyotype of POC samples from first trimester <12GW miscarriages after ART: IVF-PGT-group euploid (E) and mosaic (M) embryo transfers (ET) and IVF-group; IUI and natural conception-NC groups; while controlling for maternal cell contamination (MCC) by high-resolution whole genome NGS. Participants/materials, setting, methods 549 POC samples from early miscarriages after fertility treatment were obtained by suction-dilatation-and curettage. Selection of fetal tissue/chorionic villi (4 representative samples for each case) was performed under a dissecting microscope. Maternal and paternal DNA was obtained to test for MCC. MCC was determined by testing maternal/gestational carrier and fetal DNA (fDNA) with highly informative STRs (AmpFLSTR Identifiler kit). Whole genome low-pass NGS (0.1xcoverage) was performed using the Illumina platform and analyzed with NxClinical Software. Main results and the role of chance Fetal tissue was obtained from 90.7% (498/549) of tested samples and the rest had MCC (9.3%, 51/549): IVF-PGT-A(n = 183), IVF(n = 92), IUI(n = 46) and NC(n = 173). The overall mean maternal age was 37±3.2years. The average gestational age at D&C was 8w4d (range 5w-12w6d). Overall, NGS analysis of fDNA showed 44.6% male and 55.3% female fetuses, 57.6% (287/498) were euploid, 39.5% (197/498) were aneuploid and 1.8% (9/498) were mosaic. In IVF-PGT-A group there were 169 POC from euploid ET and 14 from mosaic ET. 98.2% (n = 166/169) of POCs from IVF-PGT-A euploid-ETs were confirmed as euploid, and 3 had confined placental mosaicism (CPM) (trisomy-11, trisomy-4, monosomy-X). POC from mosaic-ET (n = 14), showed CPM in 3/14(21.4%): TE mosaicism was confirmed in 1/14(7.1%), 2/14(14.3%) had CPM differing from the PGT-A result, 11/14(78.6%) were euploid. POC euploidy rate in IVF (no PGT-A) group was 59.8%(55/92), in IUI 34.8%(16/46) and in NC 24.3%(42/173). In NC group CPM was detected in 1.7%(3/173). The frequency of aberrations detected in POC(n = 197) were: T22, 16.5%; T16,12.9%; T15, 11.3%; T20, 5.2%; T8, 3.6%; T7, T9 and T13, 3.1%; T10 and T14, 2.6%; T18 and T21, 2.1%; T12, 1.5%; 1% of each T2, T4 and T11; monosomy-X,6.7% and 11.3% triploid (69,XXY or 69,XXX). Limitations, reasons for caution MCC is relatively high in POC samples from early pregnancies (9.3%) and controlling for it is warranted. Although 4 representative samples of placental tissue were tested, the true extent and existence of CPM may not be captured correctly. Wider implications of the findings NGS analysis of POC from first trimester miscarriages after fertility treatment would improve diagnostic accuracy, and could aid in patient counselling and management. We observed high PGT-A accuracy (100% for gender) and 98.2% for fetal ploidy with CPM rate of 1.8% (which is lower than observed after CVS (4%)). Trial registration number not applicable

O-294 Human oocyte survival, early embryo development, metabolic fingerprinting, and pregnancy outcomes following ultra-rapid or standard vitrification and thawing

Abstract Study question Is ultra-rapid vitrification and thawing superior to standard vitrification in terms of preserving oocyte viability, embryo competence and enhancing pregnancy outcomes? Summary answer Ultra-rapid vitrification and thawing preserves oocyte viability and embryo quality as confirmed by their euploidy, non-invasive biomarkers in the culture media, and favorable pregnancy outcomes. What is known already Cryopreservation and vitrification protocols for oocytes and embryos have varying cooling rates, cryoprotectant chemical composition and concentration. While vitrification avoids intracellular ice crystal formation, the elevated concentrations of cryoprotectants may be cytotoxic. Over the past 20 years, parameters for vitrification protocols were optimized to improve efficiency and viability of human oocytes and embryos, however few studies have evaluated the metabolic and secretome profiles in addition to embryology and pregnancy outcomes, particularly following ultra-rapid vitrification and thawing. Mid-infrared spectroscopy is a great option for characterizing environmental components and metabolic profiles using the more spectrally complex fingerprint region from 1450-500 cm-1. Study design, size, duration This prospective study included 1,214 donor oocytes collected between January 2022 and November 2023. Sibling oocytes were assigned to standard or ultra-rapid vitrification and thawing. Corresponding blastocysts underwent the same type of vitrification following trophectoderm biopsies for PGT-A. Spent embryo culture fluid was collected on day 1, 3, and 5 for spectroscopy and PCR analysis, as well as on day 6 for metabolic fingerprinting. Clinical pregnancy was assessed 5 days following single embryo transfer. Participants/materials, setting, methods Vitrified oocyte survival was assessed one hour after thawing. Secretome profiling of day 1, 3, and 5 embryos was conducted by Attenuated Total Reflection Fournier Transform Infrared (ATR-FTIR) spectroscopy. Metabolic profiling of blastocysts (day 6) was conducted by Fournier Transform Infrared (FTIR) spectroscopy. Embryology and pregnancy data together with lipid, protein, and nucleic acid expression profiles were evaluated using the Shapiro-Wilk test followed by the student t-test (parametric variables) or the Mann-Whitney U-Test (non-parametric variables). Main results and the role of chance There was 100% survival in oocytes subject to ultra-rapid vitrification-thawing (n = 531) compared to 94.5% in oocytes that underwent standard vitrification (n = 634). There were no significant differences in the fertilization rates following intracytoplasmic sperm injection (81.3% with ultra-rapid and 83.2% with standard vitrification) or potential to reach day 3 of embryo development[RL1]. Ultra-rapid vitrification-thawing produced significantly more blastocysts than standard vitrification-thawing (67.3% vs. 53.0%, respectively) but both techniques had similar euploidy rates (61.8% vs. 61.4%, respectively; p > 0.05). Spectra in the 4000-450 cm-1 region revealed there were no significant differences in lipid and protein expression profiles of day 1, 3, 5 and 6 embryos. The similar result obtained for the culture media for day 1,3,5 and 6 day embryo development with no significant difference. Day 3 blastomere biopsy samples and Day5, Day 6 trophectoderm biopsy sample showed no significant differences for total protein concentration, lipid and nucleic acid experssion profiles in both group.This finding was corroborated by PCR analysis showing no significant difference in nucleic acid profiles. Finally, clinical pregnancy rates were 65.22% with ultra-rapid and 56.5% [RL2] with standard vitrification. (p < 0.05) Limitations, reasons for caution While both our ultra-rapid and standard vitrification-thawing protocols appear to preserve embryo competence to the blastocyst stage and euploidy, future studies should evaluate whether RNA expression levels are altered with these approaches. Wider implications of the findings This study shows competent and euploid embryos can be generated following ultra-rapid vitrification and provides embryo metabolites that can serve as non-invasive biomarkers for the identification of healthy embryos before embryo transfer. Trial registration number NA

O-322 What is the number of IVF cycles needed to produce at least one euploid blastocyst in patients of all ages with varied AMH levels

Abstract Study question How many cycles are needed to get at least one blastocyst in patients of different AMH levels and varied ages? Summary answer Age and AMH determine the number of cycles, which ranges from 1 cycle in young patients up to 10 cycles in over-44-year-old patients. What is known already AMH secretion by ovarian granulosa cells initiates during the 36th week of gestation in pre-antral and antral follicles. This persists throughout a woman’s reproductive lifespan. AMH serves as a biomarker for assessing ovarian reserve and forecasting the ovarian response to stimulation. AMH is strongly associated with the quantity of antral follicles and the production of oocytes. AMH can be utilised to determine the initial dosage of FSH in an IVF cycle, as well as serving as a quantitative indicator of the number of oocytes produced. Study design, size, duration In this retrospective cohort study, data was collected from 16,417 ICSI cycles with Preimplantation Testing for Aneuploidy (PGT-A) conducted at three referral fertility centers from Jan 2019 to Dec 2023. We excluded cycles without serum AMH, endocrinopathies or recurrent pregnancy loss, males with total sperm count of less than 5 million and total motility less than 30%, and those with parental chromosomal abnormalities. Participants/materials, setting, methods Patients were stratified into three different categories of AMH (ng/ml), low (< 1.1 ng/mL), intermediate (>1.1 to < 3.0 ng/mL) and high (> 3.0 ng/mL). Each category was subdivided into 6 age sub-categories as follow (< 35), (35 to < 38), (38 to < 40), (40 to < 42), (42 to < 44), (> 44). All of the cycles underwent blastocyst stage biopsy and PGT-A utilising next generation sequencing (NGS). Main results and the role of chance Euploidy rate was statistically insignificant for all AMH levels in the same age group. However, euploid embryo numbers vary significantly. Euploid embryos numbers are shown in low, medium, and high AMH by age group. In the (<35) years was 1.9±1.5, 2.9±2.3, and 4.7±3.5, p < 0.0001. In the (35 to > 38) years was 1.3±0.8, 2.1±1.8, and 3.2±2.6, p < 0.0001. In the (38 to > 40) years was 0.9±0.8, 1.7±1.4, and 2.6±1.7, p < 0.0001. In the (40 to > 42) years was 0.6±0.5, 0.9±0.7, and 1.5±1.4, p < 0.0001. In the (42 to > 44) year was 0.26±0.2, 0.49±0.38, and 0.6±53, p < 0.0001. In the (≥44) years was 0.10±0.10, 0.23±0.21, and 0.40±0.37, p = 0.0170. We calculated the number of cycles needed to produce at least one grade BB or higher euploid blastocyst from the mean number of euploid embryos per cycle: The number of cycles is presented in low, medium, and high AMH. In the (<35) and (35 to > 38), 1 cycle is needed. In (38 to > 40) years, 2 cycles, 1 cycle and 1 cycle. In the (40-42) group 2 cycles, 2 cycles and 1 cycle. In the (42 to < 44) group 4 cycles, 3 cycles and 2 cycles. In the (≥44) group 10 cycles, 5 cycles and 3 cycles. Limitations, reasons for caution The retrospective nature of the study is the main limitation. Wider implications of the findings The study offers valuable insights for patient counselling regarding the required number of cycles to achieve euploid embryos, as well as for financial budgeting for both patients and insurance companies. Trial registration number Not applicable

P-059 Euploidy and mosaics rates using microfluid sperm selection techniques (Zymot-ICSI®)

Abstract Study question Can Zymot-ICSI® influence the mosaic embryos rate? Is the degree of doble strands DNA fragmentation (dsSDF) affecting euploidy and mosaicism outcomes? Summary answer The use of Zymot-ICSI® in seminal samples induces a decrease in aneuploid embryos, and an increase in euploid and/or mosaic embryos independently of the dsSDF. What is known already It has been demonstrated that sperm with higher motility exhibit superior genomic integrity, establishing a direct relationship between dsSDF and the capacity for embryonic development and implantation. In a previous study focused on investigating differences in a various biopsy techniques and their impact on the genetic outcome of the embryos, an increase in the number of mosaic embryos was identified. The main objective of this study is to ascertain whether sperm selection using these techniques, specifically the use of Zymot-ICSI®, increase the euploidy rate in patients with altered fragmentation indices, and its relations with mosaics distribution. Study design, size, duration A retrospective study analyzed a total of 684 biopsied embryos in 2021, of which 339 came from seminal samples without COMET test, and 345 embryos came from seminal samples that underwent the COMET test, analysing the sperm DNA fragmentation with one DNA strand (ssSDF) and double DNA strands (dsSDF). Genetics analysis of these 345 embryos were divided into 3 groups according to the techniques used in the sperm selection before ICSI (dsSDF: <60; 60-80; >80). Participants/materials, setting, methods Differences between Swim-up/gradients(Sw/G)(n = 513) and Zymot-ICSI®/Sperm-Slow(n = 171) were assessed. 309 embryos without COMET prior to ICSI, underwent Sw/G, 5 sperm-slow and 20 Zymot-ICSI® (both prophylactically). In cases where fragmentation was high and Zymot-ICSI®(n = 98) could not be performed before ICSI for low sample quality, Sperm-slow(n = 10) or Sw/G(n = 199) techniques (with normal or altered fragmentation) were used. The existence of variations in the type of mosaicism (Simple/Complex) was also analysed with respect to the sperm selection technique used and dsSDF. Main results and the role of chance No significant differences were observed between the different sperm selection techniques used (regardless of the degree of dsSDF), in terms of euploidy, aneuploidy and mosaic values (p:0.861). According to the dsSDF, the usefulness of Zymot-ICSI® versus Sw/G is shown, decreasing the percentage of aneuploid embryos IF < 60 (20% vs 44.1%); IF > 80 (28.6% vs 43.8%), increasing the percentage of euploid embryos in IF < 60% (60% vs 46.5%) and maintaining them in IF > 80 (52.4% vs 50%). However, an increase in mosaics was observed in all the groups studied (depending on the sperm selection technique Zymot-ICSI® vs Sw/G) but independently of the dsSDF: <60: 20% vs 9.30%; 60-80: 13.4% vs 9.62%; >80: 18.2% vs 5.88%. No differences were found between the different types of mosaic embryos (simple or complex) between the different groups according to the dsSDF (p > 0.1), but there was a trend towards a decrease in complex mosaic embryos and an increase in simple mosaic embryos when using Zymot-ICSI® versus Sw/G (Complex Mosaic: 13% vs 23.2%; Simple Mosaic 87% vs 76.8%). Limitations, reasons for caution Although there is a trend towards an increase in mosaic embryos, the difference is not significant, probably due to the low number of samples in some cases. Wider implications of the findings Use of Zymot-ICSI® in seminal samples induces a decrease in aneuploid embryos, and an increase in euploid and/or mosaic embryos. The increase in mosaic embryos after the use of Zymot-ICSI® occurs independently of the dsSDF, observing a tendency towards a decrease in mosaic-complex embryos and an increase in simple embryos. Trial registration number Not applicable

O-152 Pre-implantation genetic testing for aneuploidies (PGT-A) improves reproductive outcomes in advanced maternal age patients undergoing IVF/ICSI: a multicentre retrospective cohort study with propensity score matching

Abstract Study question In patients > 37 years undergoing IVF/ICSI, does PGT-A improve live birth rates (LBR) and cumulative live birth rates (CLBR)? Summary answer In advanced maternal age women with ≥1 embryo to transfer, PGT-A improves the live birth and cumulative live birth rates. What is known already The age-related rate of aneuploidy remains a major cause of IVF failure. Therefore, PGT-A has been proposed as a method to select embryos with the highest implantation potential. Previous studies have shown that women younger than 37 years old do not benefit from PGT-A given the comparable outcomes in terms of implantation, clinical pregnancy, and live-birth rates. Moreover, PGT-A may also be inherently ineffective given the risk of mitotic mosaicism, sampling errors and misinterpretation of results. However, we are currently lacking solid scientific evidence to support whether this approach benefits advanced maternal age women. Study design, size, duration A multicenter retrospective cohort study was conducted including 9328 patients >37y undergoing their first IVF/ICSI cycle with an oocyte retrieval performed between 1/01/2013-31/07/2021 in a multinational private fertility clinic. The study group (n = 4664) included patients who performed PGT-A. The control group included patients without PGT-A (n = 4664) and was selected by propensity score matching adjusted for age at oocyte retrieval, number of oocytes retrieved and year of oocyte retrieval. Participants/materials, setting, methods The primary outcome was CLBR (delivery of at least one live birth per started cycle, including the fresh and subsequent frozen embryo transfer cycles). The secondary outcomes were LBR and time to pregnancy. The analysis was conducted including all patients with an initiated cycle of ovarian stimulation and also per embryo transfer. Comparisons are presented as adjusted odd-ratios (adjOR) and 95% confidence intervals (95%CI) following multivariable logistic regression (LBR) or cox regression (CLBR) analysis. Main results and the role of chance Patients in the PGT-A group had more oocytes retrieved (11.03±6.82 vs 9.24±6.15, p < 0.001), and a higher number of available blastocysts (2.82±2.21 vs 1.22±2.00, p < 0.001). In the PGT-A group, 13.153 embryos were analysed, with an euploidy rate of 29.30% (n = 3854). In total, 49.83% (n = 2324) patients did not undergo embryo transfer due to unavailable euploid embryos. Considering all patients that initiated ovarian stimulation, the PGT-A group presented a higher unadjusted CLBR per started cycle (27.38% vs 21.81%, p < 0.001). Considering only patients who underwent embryo transfer, a total of 5934 embryo transfers were analysed (n = 3166 in the control group and n = 2768 in the PGT-A group). Following multivariable logistic regression analysis, LBR and CLBR were significantly higher in the PGT-A group (respectively, adjOR 1.56 [95% CI 1.38-1.77], adjOR 1.53 [95% CI 1.39-1.68]). Following the transfer of 5 embryos, the CLBR was approximately 100% in the PGT-A group and 74.51% in the control group. Survival analysis was also perfomed to assess the impact of PGT-A on time to pregnancy. Despite the fact that from 6 months onwards the CLBR was higher in the PGT-A group, the median time to pregnancy was higher in the PGT-A group (3.27 (95%CI 3.16-3.40) vs 2.74 months (95%CI 2.57-3.03). Limitations, reasons for caution This study is limited by its retrospective design and low number of women with more than 3 embryos transferred. Also, the fact that only the first IVF/ICSI cycle was analysed provides a proper patient counselling in this specific context but does not provide data on repeated cycle outcomes. Wider implications of the findings Our findings suggest that, in women older than 37 years with at least one available embryo to biopsy, performing PGT-A may improve the reproductive outcomes in terms of LBR and CLBR, providing a useful clinical tool for embryo selection. Trial registration number not applicable

P-188 Growth variance score (GVS): a morphokinetic-based model with capability to distinguish euploid from aneuploid embryos

Abstract Study question Does longitudinal growth of euploid embryos differ from aneuploids? Summary answer Euploid embryos had significantly lower growth variance score (GVS), indicating steadier growth when observed with time-lapse monitoring, compared to aneuploid embryos. What is known already A major quest for optimizing embryo selection is the identification of morphokinetic parameters to distinguish euploid from aneuploid embryos. Although some studies have identified altered morphokinetic parameters related to embryo ploidy, outcomes were not reproducible, and could not provide sufficient evidence to apply it. Moreover, longitudinal changes during this temporal process of embryo development, their reference standards, and the impact of such changes on embryonic fate remains unknown. Aiming to develop a growth variance model, using the reference ranges of embryonic morphokinetic growth as a single growth trajectory might provide a better additive value to distinguish euploid from aneuploid embryos. Study design, size, duration This observational, retrospective cohort study was performed in a tertiary referral IVF centre between December 2020 and March 2023. The study included a total of 677 blastocysts from 147 cycles tested for Preimplantation Genetic Testing for aneuploidy (PGT-A) by next generation sequency (NGS). All embryos were monitored by time-lapse (TL) system during culture. Participants/materials, setting, methods Growth variance score (GVS) is a measure of embryonic growth pattern calculated using the TL morphokinetic reference ranges (from tPB2 until tEB), developed for euploid embryos. Higher GVS scores indicate more erratic growth while lower scores indicate steadier growth. Trophectoderm (TE), inner cell mass (ICM), and expansion grade were assessed immediately before biopsy using Gardner’s criteria. Euploid and aneuploid blastocysts were compared in terms of ICM, TE grade, day of biopsy and GVS score. Main results and the role of chance Among tested blastocysts, 383 were euploid (56.6%) and 294 of them were abnormal (43.4%). Euploid embryos had significantly lower GVS compared to aneuploid embryos (mean difference: 0.30 lower, 95% CI: 0.16 to 0.45; P < 0.001). Among day 5 biopsies, euploids had significantly lower GVS compared to aneuploids (mean difference: 0.27 lower, 95% CI: 0.04-0.51; P = 0.019). Among Day 6+ biopsies, euploids also had lower GVS compared to aneuploids, but the difference did not reach statistical significance (mean difference: 0.09 lower, 95% CI: -0.08-0.28, P = 0.30). Regression analysis showed GVS was significantly and independently associated with euploidy after adjusting for day of biopsy and morphological grade (aOR: 0.83, 95% CI: 0.70 – 0.99; P = 0.048). We compared two embryo selection modalities, the first one using morphology and biopsy day, the second one incorporating GVS to morphology and biopsy day. In 90% (95% CI: 87.2 – 92.8%) of the cycles, both modalities made a concordant selection by choosing the same embryo as the best. In the remaining 10% (95% CI: 6.4% - 14.7%) of the cycles, they made a discordant choice and the euploidy rate of embryos chosen by the combination of GVS and morphology were higher by 20.4% (95% CI: -0.06 to 44.0%, P = 0.060). Limitations, reasons for caution To confirm its reproducibility in other clinical and laboratory settings, GVS should be replicated with larger sample sizes and in external cohorts. Wider implications of the findings The GVS model might emerge as a valuable prognostic tool to select euploid blastocysts within patient’s own pool of embryos. GVS could be easily incorporated into laboratory work-flow when a time-lapse monitor is available to prioritize embryos for transfer, given external validations are successful. Trial registration number Not applicable

Telomerase activity, telomere length, and the euploidy rate of human embryos

Background Telomeres maintain chromosome stability, while telomerase counteracts their progressive shortening. Telomere length varies between cell types, with leukocyte telomere length (LTL) decreasing with age. Reduced telomerase activity has been linked to reproductive issues in females, such as low pregnancy rates and premature ovarian failure, with recent studies indicating correlations between telomere length in granulosa cells and IVF outcomes. Objectives The study aims to explore the relationship between telomere length, telomerase activity, and euploid blastocyst rate in infertile women undergoing IVF/ICSI PGT-A cycles. Methods This prospective study involves 108 patients undergoing controlled ovarian stimulation and PGT-A. Telomere length and telomerase activity were measured in peripheral mononuclear cells and granulosa cells (GC), respectively. Results The telomere repeat copy number to single gene copy number ratio (T/S) results respectively 0.6 ± 0.8 in leukocytes and 0.7 ± 0.9 in GC. An inverse relationship was found between LTL and the patient’s age (p < .01). A higher aneuploid rate was noticed in patients with short LTL, with no differences in ovarian reserve markers (p = .15), number of oocytes retrieved (p = .33), and number of MII (p = 0.42). No significant association was noticed between telomere length in GC and patients’ age (p = 0.95), in ovarian reserve markers (p = 0.32), number of oocytes retrieved (p = .58), number of MII (p = .74) and aneuploidy rate (p = .65). Conclusion LTL shows a significant inverse correlation with patient age and higher aneuploidy rates. Telomere length in GCs does not correlate with patient age or reproductive outcomes, indicating differential telomere dynamics between leukocytes and granulosa cells.

The comparision among euploidy of preimplantation blastocysts in different controlled ovary stimulation (COH) protocols.

To compare differences in euploidy rates for blastocysts in preimplantation genetic testing for aneuploidy (PGT-A) cycles after gonadotropin-releasing hormone agonist (GnRH-a) long and short protocols, GnRH-antagonist (GnRH-ant) protocol, progestin-primed ovarian stimulation and mild stimulation protocols, and other ovary stimulation protocols. This was a retrospective cohort study from the Assisted Reproductive Medicine Department of Shanghai First Maternity and Infant Hospital. A total of 1657 PGT-A cycles with intracytoplasmic sperm injection after different controlled ovary hyperstimulation protocols were analyzed, and a total of 3154 embryos were biopsied. Differences in euploidy rate per embryo biopsied, embryo euploidy rate per oocyte retrieved and cycle cancellation rate were compared. For the PGT-A cycles, the euploidy rate per embryo biopsied was lower in the GnRH-ant protocol than in the GnRH-a long protocol (53.26 vs. 58.68%, respectively). Multiple linear regression showed that the GnRH-ant protocol was associated with a lower euploidy rate per embryo biopsied (β = -0.079, p = 0.011). The euploidy rate per embryo biopsied was not affected by total gonadotropin dosage, duration of stimulation and number of oocytes retrieved. The embryo euploidy rate per oocyte retrieved was similar in all protocols and was negatively correlated with the total number of oocytes retrieved (β = -0.003, p = 0.003). Compared with the GnRH-a long protocol, the GnRH-ant protocol was associated with a lower euploidy rate per embryo biopsied. The total gonadotropin dosage, duration of stimulation and number of oocytes retrieved did not appear to significantly influence euploidy rates.

Formation of the first plane of division relative to the pronuclear axis predicts embryonic ploidy

Research questionIs there a relationship between the pronuclear axis and the first cleavage plane formation in human pronuclear-stage embryos, and what are the effects on ploidy and clinical pregnancy rates? DesignTransferred embryos were followed up until their prognoses. A total of 762 embryos formed two cells and reached the blastocyst stage after normal fertilization in a time-lapse incubator. Embryos were classified into three groups: group A: embryos in which the first plane of division was formed parallel to the axis of the pronucleus; group B: embryos in which cases of oblique formation were observed; and group C: embryos in which cases of perpendicular formation were observed. ResultsThe euploidy rate was significantly higher in groups A and B than those in group C (P < 0.01), whereas the aneuploidy rate was significantly higher in group C (P < 0.01) than in groups A and B. No differences were found between the three groups in frequency of positive HCG-based pregnancy tests, frequency of clinical pregnancies, miscarriage rates or delivery rates. ConclusionsThe formation pattern of the first plane of division relative to the pronuclear axis was a predictor of embryonic ploidy, with a reduced rate of euploidy and a high probability of aneuploidy observed when the first plane of division was perpendicular to the pronuclear axis.

Prediction of embryo euploidy and pregnancy outcome by blastocyst morphology and development speed for women receiving single embryo transfer

Background Selection of high-quality blastocysts is the most important factor determining the success of assisted reproductive technology. The objective of this study is to assess the values of blastocyst morphological quality and development speed for predicting euploidy and clinical pregnancy outcome. Methods A total of 155 preimplantation genetic testing cycles including 959 blastocysts and 154 euploid blastocyst transfer cycles conducted between January 2018 and December 2019 were retrospectively analysed. The associations of blastocyst morphological quality and development speed (D) with chromosomal status, clinical pregnancy rate, early miscarriage rate, and ongoing pregnancy rate were evaluated by univariate and multivariate regression. Results The euploidy rate of development speed D5 blastocysts was significantly greater than that of D6 blastocysts (61.4% vs. 38.1%, P < 0.001), and the euploid rate of morphologically high-grade blastocysts was significantly greater than that of non-high-grade blastocysts. Development speed D5 (OR = 1.6, 95% CI 1.2–2.2, P = 0.02) and high-grade morphology (OR = 2.1, 95% CI 1.5–2.9, P = 0.01) were independent predictors of euploidy. The ongoing pregnancy rate of D5 blastocysts was significantly higher than that of D6 blastocysts (62.3% vs. 43.8%, P = 0.04). Transfer of euploid blastocysts with high-grade morphology resulted in a greater ongoing pregnancy rate than transfer of non-high-grade euploid blastocysts (60.7% vs. 43.2%, P = 0.049). Alternatively, D6 development speed was an independent risk factor for early pregnancy loss after euploid blastocyst transfer. Multivariate regression analysis adjusting for confounding factors identified maternal age, blastocyst development speed, and blastocyst morphological grade as independent predictors of euploidy but not of clinical pregnancy. Conclusion The recommended sequence of embryo transfer based on the present study is D5 high-grade > D6 high-grade > D5 non-high-grade > D6 non-high-grade.