Blastocyst Formation Rate Research Articles

Micronuclei in 2-cell embryos show higher blastocyst formation rates on human embryonic development

ObjectiveMultinucleated blastomeres at the two-cell stage (2MNB) represent a frequently observed nuclear abnormality in early human embryos. This abnormality has been reported to significantly impact on the embryo’s developmental potential to reach the blastocyst stage. However, our understanding of the embryo’s developmental potential and the morphokinetics of 2MNB remains limited. This study investigates the influence of 2MNB and its subtypes on the blastocyst formation. Study designA non-interventional retrospective study was performed in the Reproductive Medical Center of the First Affiliated Hospital of Hainan Medical University, using a time-lapse incubator. The study involved the evaluation of 4416 embryos, including 628 multinucleated embryos, from 1521 intracytoplasmic sperm injection (ICSI) cycles conducted between October 2019 and October 2021. The morphokinetic characteristics of multinucleated embryos were analyzed. ResultsThe results show multinucleation was the most common abnormal mitotic event during embryo development (14.22 %) in 4416 embryos. A control group of 3210 developmentally normal embryos was used in the study. The multinucleated blastomeres caused a lower blastocyst rate (52.48 % VS 64.02 %) compared to the control group. Whereas, 2MNBcause a higher blastocyst rate thanthemat the 4-cell stage (4MNB) (58.89 % VS 43.64 %). 2MNB can be further be further divided into 2MNB1/2cell and 2MNB2/2cell based on one multinucleated blastomere or two multinucleated blastomere appeared. Time to pronuclei fading (tPNf) is significantly longer in 2MNB2/2cell compared to 2MNB1/2cell. Furthermore, the 2MNB1/2cell embryos were divided into four subgroups (Bi-: two nuclei with almost the same size, Micro-: two nuclei with varying sizes, Poly-: more than two nuclei with almost the same size, and Cluster-: more than two nuclei with varying sizes) based on the number of nuclei and relative size. The results show that the Bi- and Micro- groups had a significantly increased blastocyst rate. The Cluster-, and Poly- groups showed significantly delayed embryonic development compared to normal controls. Bi-group has significant delays at t3, t5, and t8 and the Micro-group had a significant delay only at t8. Conclusion2MNB cause higher blastocyst rate than them at 4MNB. 2MNB1/2cell shows shorter tPNf compared to 2MNB2/2cell. Moreover, the Micro-, Bi- groups had a significantly increased blastocyst rate and different kinetic parameters compared to Cluster-, Poly-groups, suggesting that it is necessary to distinguish the nucleus status within 2MNB to increase the blastocyst rate. When selecting embryos for transformation from the 2MNB1/2cell, Micro- is the best choice.

GnRH agonist-only trigger, compared to dual trigger, reduces oocyte retrieval rate in high responders without affecting cumulative live birth rate.

This study compared, in high responders undergoing IVF treatment, GnRH agonist-only trigger and dual trigger on oocyte retrieval rate and cumulative live birth rate (LBR). The aim was to determine if the GnRH agonist-only triggers had provided outcomes comparable to dual trigger, while minimizing the risk of ovarian hyperstimulation syndrome (OHSS). A retrospective, matched case-control study was conducted at Taichung Veterans General Hospital, Taiwan, including women who underwent IVF/ICSI between January 1, 2014, and December 31, 2022. Inclusion criteria were: GnRH antagonist protocol and estrogen level >3,000 pg/ml on trigger day. Exclusion criteria were: immune/metabolic diseases, donated oocytes, and mixed stimulation cycles. Propensity score matching was applied to balance age, AMH level, and oocyte number between the GnRH agonist-only and dual trigger groups. Outcomes were analyzed for patients who had complete treatment cycles, focusing on oocyte retrieval rate and cumulative LBR. We analyzed 116 cycles in the agonist-only group, and 232 cycles in the dual trigger group. No inter-group difference was found in their age, BMI, and AMH levels. The dual trigger group had a higher oocyte retrieval rate (93% vs. 80%; p <0.05), while fertilization rates, blastocyst formation rates, and cumulative LBR were comparable. Notably, no OHSS cases had been reported in the GnRH agonist-only group, compared with 7 cases in the dual trigger group. GnRH agonist-only triggers resulted in a lower oocyte retrieval rate compared to dual triggers but did not significantly affect cumulative LBR in high responders. This approach effectively reduces OHSS risk without compromising pregnancy outcomes, making it a preferable option in freeze-all strategies, despite a longer oocyte pick-up duration and a medium cost. GnRH agonist-only trigger, however, may not be suitable for fresh embryo transfers or patients with low serum LH levels on trigger day.

Taurine, alpha lipoic acid and vitamin B6 ameliorate the reduced developmental competence of immature mouse oocytes exposed to methylglyoxal

Advanced glycation end products (AGEs) are the final products of the Maillard reaction, formed through the interaction of carbohydrates and proteins. Reactive dicarbonyl compounds such as methylglyoxal (MGO) serve as precursors for AGEs formation. Elevated levels of MGO/AGEs are observed in conditions like obesity, polycystic ovarian syndrome (PCOS), and diabetes, negatively impacting oocyte development. Previous studies have shown that hydrogen sulfide, a gasotransmitter with anti-AGEs effects, is produced in a process influenced by vitamin B6. R-α-lipoic acid (ALA) inhibits protein glycation and AGEs formation while stimulating glutathione (GSH) production. Taurine mitigates oxidative stress and acts as an anti-glycation compound, preventing in vitro glycation and AGEs accumulation. This study aimed to explore the ameliorative effects of a micronutrient support (Taurine, ALA and B6: TAB) on mouse oocytes challenged with MGO. Our results indicate that MGO reduces oocyte developmental competence, while TAB supplementation improves maturation, fertilization, and blastocyst formation rates. TAB also restores cell lineage allocation, redox balance and mitigates mitochondrial dysfunction in MGO-challenged oocytes. Furthermore, cumulus cells express key enzymes in the transsulfuration pathway, and TAB enhances their mRNA expression. However, TAB does not rescue MGO-induced damage in denuded oocytes, emphasizing the supportive role of cumulus cells. Overall, these findings suggest that TAB interventions may have significant implications for addressing reproductive dysfunctions associated with elevated MGO/AGEs levels. This study highlights the potential of TAB supplementation in preserving the developmental competence of COCs exposed to MGO stress, providing insights into mitigating the impact of dicarbonyl stress on oocyte quality and reproductive outcomes.

Adipose-derived Mesenchymal Stem Cell Transplantation Improves Ovarian Function and Oocyte Quality in Aged Mice.

Age-related decline in the number of ovulations and ovum quality are major causes of female infertility, and stem cells have been reported to be effective in tissue regeneration. However, current therapeutic modalities are inadequate. This study investigated the effects of adipose-derived mesenchymal stem cells (ASCs) on ovarian functions in aged mice. Following the characterization of ASCs using flow cytometry, the effects of ASCs on the number of ovulations, fertilization rate, and blastocyst-formation rate were investigated. In addition, the number of ovarian follicles and serum anti-Müllerian hormone (AMH) levels were examined. ASCs marked with Kusabira Orange were used to examine the location after cell administration. The quality of ovulated oocytes was analyzed using next-generation RNA sequencing. ASCs showed characteristics of mesenchymal stem cells and were distributed to various organs, including the ovarian stroma. The transplantation resulted in increased number of oocytes and ovulation in the ovaries and increased AMH values. Genetic analysis revealed improved oocyte quality and increased fertilization and blastocyst-formation rates. ASC therapy may be effective in improving fertility in older women.

Application of the blastomere count variations "skip value" in the embryo AI assessment

Objective: To explore the correlation between blastomere count variations "skip value" which extracted from by time-lapse technology (TLT) combined with artificial intelligence (AI) and morphological features of in vitro fertilization (IVF) embryo, and to test its feasibility in clinical applications. Methods: This study was a diagnostic experiment (AI reassessment of embryo transferred patients), a total of 6 545 embryos from 1 226 patients who underwent IVF at the Women and Children's Hospital of Chongqing Medical University from December 2020 to December 2021 were retrospectively analyzed, of which 2 869 embryos were attempted to cultured to blastocyst stage by TLT. The embryo dynamic map (EDM) was drawn by Embryo Viewer, a TLT recording software, based on embryo developmental kinetics. The self-developed AI embryo evaluation software identified and recorded the number of cleavages in real time during embryonic development, and compared with the EDM, the correlation between the skip value formed by the change of cleavage sphere counts and the outcomes of the embryos was analyzed. The correlation among skip value, morphological score of embryo, implantation rate and live birth rate were performed by Spearman and step-up logistic regression. The receiver operating characteristic (ROC) curve was selected for reporting there relationship of skip value and morphology. Finally, predicting power of skip value for implantation and live birth rate were performed by ROC analysis. Results: The total skip values extracted from the blastomere count of embryos (72 hours post-fertilization) were negatively correlated with abnormal cleavage, blastocyst formation rate, day 3 (D3)-cell score, uneven size and fragmentation (the β values were -0.268, -0.116, -0.213, -0.159 and -0.222, respectively; all P<0.001); positively correlated with D3-cell number (β=0.034; P<0.001); negatively correlated with blastocyst formation rate and implantation rate (OR=0.97, 95%CI: 0.93-0.99, P=0.034; OR=0.96, 95%CI: 0.93-0.98, P=0.044). The power of predicting implantation were similar between the order selection of skip values and traditional morphology criteria [area under curve (AUC): 0.679 vs 0.620]. Live birth rate were negatively correlated with female age (OR=0.91, 95%CI: 0.88-0.93; P<0.001), D3 general score (OR=0.77, 95%CI: 0.59-0.99; P=0.045) and order selection of skip values (OR=0.98, 95%CI: 0.96-0.99; P=0.038), while positively correlated with retrieved oocyte number and endometrial thickness in embryo transferred (OR=1.08, 95%CI:1.05-1.11, P<0.001; OR=1.09, 95%CI:1.06-0.12, P<0.001, respectively) from multivariate regression analysis, and the power of predicting live birth was 0.666 for AUC. Conclusions: The skip value and its order form is a systematic quantification of embryo development, correlated with embryo developmental quality and clinical outcome. It could be an addition parameter for embryo culture and selection.

What sperm parameters effect blastocyst formation and quality during ICSI with severe male infertility

Sperm-derived genetic material contributes half of the genome to the embryo, hence it’s crucial to investigate which sperm parameter influences blastocyst formation in the intracytoplasmic sperm injection (ICSI) cycles with severe male infertility. The retrospective study analyzed 296 ICSI cycles with severe oligoasthenoteratozoospermia (OAT) and 99 ICSI cycles with preimplantation genetic testing for aneuploidy (PGT-A). Following the correlation analysis, data stratifications were performed in the OAT ICSI subgroup. The results showed that the matching blastocyst in the OAT ICSI cycles had inferior sperm parameters. DFI and sperm morphology had an influence on the blastocyst formation rate and the high-quality blastocysts formation rate on Day6, but no significant effect on the blastocyst development on Day 5. The high-quality blastocysts formation rate and ratio of high-quality blastocyst on Day 6 were demonstrably better in the subgroup of the teratozoospermic morphology when DFI was within the normal range. In the case of the normal sperm morphology, no statistically significant difference was found in blastocyst development, although there were numerical differences within different DFI subgroups. It was concluded that the blastocyst quality and development declined with the decreased sperm qualities.

Enhancing the quality of inferior oocytes of buffalo for in vitro embryo production: The impact of melatonin on maturation, SCNT, and epigenetic modifications

Success of animal cloning is limited by oocyte quality, which is closely linked to reprogramming ability. The number of layers of cumulus cells is typically used to assess the quality of oocyte; a minimum of one-third of collected cumulus-oocyte complexes (COCs) are discarded as inferior oocytes because they have less cumulus cells. Melatonin, which has been recognised for its ability to sequester free radicals and perform multiple functions, has emerged as a potentially effective candidate for enhancing inferior oocytes quality and, consequently, embryo development competency. The current study investigates to improve the quality of inferior oocytes by supplementation of melatonin (10−9 M) during in vitro maturation (IVM) and subsequent cloned embryo production and its mechanism. The results indicate that melatonin supplementation significantly (p<0.05) enhances inferior oocytes maturation, reduces oxidative stress by reducing ROS levels, and improves mitochondrial function by boosting GSH levels. The melatonin treatment (10−9 M) enhances the expression of SOD, GPx1, GDF 9, BMP 15, ATPase 6, and ATPase 8 in inferior oocytes. Furthermore, melatonin treatment increases the total cell number in the treated groups, promoting cloned blastocyst formation rates derived from inferior oocytes. Furthermore, compared to the control, 10−9 M melatonin supplementation enhances H3K9ac acetylation and lowers H3K27me3 methylation in cloned blastocysts derived from inferior oocytes. In conclusion, 10−9 M melatonin supplementation during IVM increased inferior oocyte maturation and promoted cloned buffalo embryo development by lowering oxidative stress and promoting epigenetic alterations. These studies show that melatonin may improve the quality of poor oocytes and buffalo cloning.

Safety of embryo cryopreservation: insights from mid-term placental transcriptional changes

BackgroundIn recent years, with benefits from the continuous improvement of clinical technology and the advantage of fertility preservation, the application of embryo cryopreservation has been growing rapidly worldwide. However, amidst this growth, concerns about its safety persist. Numerous studies have highlighted the elevated risk of perinatal complications linked to frozen embryo transfer (FET), such as large for gestational age (LGA) and hypertensive disorders during pregnancy. Thus, it is imperative to explore the potential risk of embryo cryopreservation and its related mechanisms.MethodsGiven the strict ethical constraints on clinical samples, we employed mouse models in this study. Three experimental groups were established: the naturally conceived (NC) group, the fresh embryo transfer (Fresh-ET) group, and the FET group. Blastocyst formation rates and implantation rates were calculated post-embryo cryopreservation. The impact of FET on fetal growth was evaluated upon fetal and placental weight. Placental RNA-seq was conducted, encompassing comprehensive analyses of various comparisons (Fresh-ET vs. NC, FET vs. NC, and FET vs. Fresh-ET).ResultsReduced rates of blastocyst formation and implantation were observed post-embryo cryopreservation. Fresh-ET resulted in a significant decrease in fetal weight compared to NC group, whereas FET reversed this decline. RNA-seq analysis indicated that the majority of the expression changes in FET were inherited from Fresh-ET, and alterations solely attributed to embryo cryopreservation were moderate. Unexpectedly, certain genes that showed alterations in Fresh-ET tended to be restored in FET. Further analysis suggested that this regression may underlie the improvement of fetal growth restriction in FET. The expression of imprinted genes was disrupted in both FET and Fresh-ET groups.ConclusionBased on our experimental data on mouse models, the impact of embryo cryopreservation is less pronounced than other in vitro manipulations in Fresh-ET. However, the impairment of the embryonic developmental potential and the gene alterations in placenta still suggested it to be a risky operation.

O-020 Investigating the effect of advanced sperm preparation techniques on embryo developmental potential and clinical outcomes: a network meta-analysis of randomized controlled trials

Abstract Study question Are embryological and clinical outcomes affected when employing Magnetic-Activated Cell-Sorting (MACS), Density Gradient Centrifuge (DGC)-Zeta and Microfluidic Sperm Selection (MSS) instead of DGC and Swim-Up? Summary answer MACS and MSS enhance both laboratory and clinical outcomes, while DGC-Zeta seems to improve only clinical outcomes, in comparison to conventional sperm preparation techniques. What is known already Sperm preparation techniques have been developed to enhance sperm selection process towards improving IVF laboratory and clinical outcomes. Based on centrifugation and sperm migration, DGC and swim-up constitute the standard methods for improving sperm parameters, nonetheless disregarding molecular aspects. Certain techniques, namely MACS, DCG/Zeta and MSS have been proposed to effectively select non-apoptotic sperm with intact chromatin and high DNA integrity claiming their place in routine clinical practice. Concurring on the efficacy of these adjunct methods from the standpoint of embryo developmental dynamic and clinical outcomes is both pertinent and imperative. Study design, size, duration A systematic search of the literature was performed in the database Pubmed/Medline up to December 2023. Only full-text manuscripts published in English where randomization was performed on oocytes or patients were eligible. Studies reporting on semen samples obtained by surgical techniques were excluded. A total of 20 RCTs were included in this network meta-analysis. Other reported sperm preparation techniques were excluded due to the limited number of available Randomized Controlled Trials (RCTs). Participants/materials, setting, methods All RCTs providing results on the aforementioned sperm preparation techniques were included. The outcome measures were fertilization, cleavage, blastocyst formation, clinical pregnancy, and live-birth rates. To evaluate the network estimate both direct and indirect effects were assessed. When heterogeneity was I2=0% the fixed-effects model was preferred. In any other case the random-effects model was employed. To rank the sperm preparation techniques' efficiency, the frequentist method employing the P-score was opted for. Main results and the role of chance The 20 included RCTs presented with a total of 17 different designs and 8 different combinations of sperm preparation techniques. Seventeen studies reported on fertilization rate providing no statistically significant difference between the sperm preparation techniques albeit with high heterogeneity I2=69%. Regarding cleavage rate (n = 10 studies), only MACS/DGC presented with an improved outcome when compared to DGC (RR: 1.43; 95%CI: 1.16-1.76; I2=96%). MACS/DGC presented with the highest efficiency (P-Score=0.90), followed by combination of MACS/DGC/swim-up (P-Score=0.83). Both MSS and MACS/DGC presented with significantly higher blastocyst formation rate compared to DGC (MSS: RR:1.14;95%CI:1.02-1.29; MACS: RR: 1.37; 95%CI: 1.04-1.82; I2=0%). According to P-Score, MACS/DGC was presented as the most efficient technique (P-Score=0.89) followed by MSS (P-Score=0.44). Regarding clinical pregnancy rates, the 12 studies featured low heterogeneity (I2=0). MACS/DGC presented with higher clinical pregnancy rates compared to DGC (RR: 1.30; 95%CI: 1.09-1.36) and the combination of DGC/swim-up (RR: 1.55; 95%CI: 1.12-1.95). MSS presented with enhanced results compared to swim-up (RR: 1.37; 95%CI: 1.11-1.69) and DGC-Zeta presented with higher clinical pregnancy rates compared to DGC (RR: 1.76; 95%CI: 1.28-1.92). The most efficient technique was DGC-Zeta (P-Score=0.98), followed by MACS/DGC (P-Score=0.82). Regarding live-birth rates no statistically significant difference was observed, albeit high heterogeneity was observed (I2=51%). Limitations, reasons for caution The blastocyst formation rate and the live-birth rate outcomes should be interpreted with caution due to the limited number of RCTs. The indirect effect estimates may pose as an intrinsic limitation of the network meta-analysis, especially in cases with limited direct data. Wider implications of the findings This data demonstrates that the combination of MACS/DGC provided enhanced laboratory and clinical outcomes compared to conventional techniques. Investigating sperm selection techniques that assess advanced sperm characteristics rather than parameters alone is timely and essential. To concur on optimal practice further RCTs directly comparing MSS, MACS and DGC-Zeta are required. Trial registration number Not applicable

O-186 A novel micro-insemination method, assisted sperm fusion insemination, increases the embryo utilization rate compared to conventional intracytoplasmic sperm injection

Abstract Study question Does a novel micro-insemination method, assisted sperm fusion insemination (ASFI), improve fertilization and embryonic development compared to conventional intracytoplasmic sperm injection (C-ICSI)? Summary answer ASFI showed comparable fertilization and blastocyst formation rates to C-ICSI, while achieving significantly higher embryo utilization rates. Furthermore, there were no degenerated oocytes after ASFI. What is known already We have reported that ASFI yielded fertilization and blastocyst rates similar to those obtained with rescue ICSI performed at 6 hours after in vitro fertilization (IVF). In ASFI, fertilization is achieved by pressing a zona pellucida (ZP)-bound sperm onto the oocyte membrane without breaking the oocyte membrane. However, there was a risk of artificial polyspermy because the sperm were pressed against the unfertilized oocytes after IVF. Moreover, it is uncertain whether fertilization occurred with sperm that penetrated into the oocyte via IVF or that were pressed against the oocyte membrane. Clarifying this requires performing ASFI of the oocyte without IVF. Study design, size, duration We prospectively evaluated the effectiveness of ASFI in a sibling oocyte study including 14 subjects from which at least two metaphase II (MII) oocytes and one immature or degenerated oocyte were retrieved. Between December 2022 and October 2023, 119 MII oocytes were obtained in 22 oocyte retrieval cycles and used in the study. Sibling MII oocytes were randomly assigned to a C-ICSI or ASFI group. The present study was approved by the local ethics committee. Participants/materials, setting, methods In the ASFI group, 10,000 motile sperm were incubated with at least one immature or degenerated oocyte for 3 hours in 100 μL of medium per patient. After incubation, the motile sperm bound to the ZP were aspirated directly using an injection pipette. The heads of these ZP-bound sperm were pressed onto the membrane of MII oocytes for 10 seconds using the injection pipette. C-ICSI was conducted using the conventional method. Main results and the role of chance The mean and standard deviation of age of the women and number of MII oocytes per cycle were 39.9 ± 2.2 years and 5.5 ± 1.8, respectively. All sperm collected from the ZP adhered to the MII oocyte membrane after ASFI. Furthermore, time-lapse imaging revealed that all sperm adhering to the MII oocyte membrane were subsequently incorporated into the oocyte. Comparison of the ASFI and C-ICSI groups did not reveal any significant differences in 2 pronuclear embryo rate (ASFI group: 85.4% vs. C-ICSI group: 71.8%), degeneration rate (0% vs. 5.6%), good-quality embryo rate at day 3 (63.4% vs. 52.9%), blastocyst formation rate (67.6% vs. 51.9%), or good-quality blastocyst (Grade 3BB and above by the Gardner criteria) formation rate (29.4% vs. 15.4%). On the contrary, the embryo utilization rate (defined as the total number of embryos transferred and cryopreserved divided by the number of MII oocytes) was significantly higher in the ASFI group compared to the C-ICSI group (47.9% vs. 25.4%, P &amp;lt; 0.05). Limitations, reasons for caution This study was limited by using the ZP for sperm selection. To expand its applicability, a method to identify sperm capable of fusing with an oocyte without using the ZP must be established. Additionally, since our sample size was small, larger studies are required to confirm our findings. Wider implications of the findings ASFI is expected to enhance the survival rate of oocytes and to increase the number of embryos available for implantation, not only compared to rescue ICSI but also C-ICSI. ASFI could aid in understanding fertilization mechanisms by enabling direct observation of oocyte-sperm fusion during the process. Trial registration number UMIN000050184

O-184 Piezo-ICSI reduces oocyte degeneration, improves ICSI success rates and has shown less dependence on the experience level of embryologists: cumulative data with 65,033 MII oocytes

Abstract Study question Dose piezo-ICSI improve the overall success rates of in ICSI operations compared with the conventional ICSI by the operators with different level of experience? Summary answer Piezo-ICSI showed lower oocyte degeneration rate during or after ICSI operations compared to the conventional ICSI for embryologists with different level of experience. What is known already Intracytoplasmic sperm injection (ICSI) with a glass micropipette can sometimes result in degeneration of the injected oocyte. Piezo-assisted ICSI has been developed as an alternative method to prevent such degeneration occurring during the procedure. It employs gentler and controlled impacts generated from the piezo electric elements attached to the injection micropipette holder to penetrate oolemma, and it does not require reciprocal aspiration of ooplasm required in the conventional ICSI. While there have been numerous study reports demonstrating the improvements in fertilization rates with piezo-ICSI, most of these studies have the limitation in the size study of population. Study design, size, duration We conducted a retrospective analysis of the ICSI results with 65,033 MII oocytes in 15,687 treatment cycles carried out between January 2018 and February 2023. ICSI were performed using the piezo-assisted equipment with flat-tip micropipettes (PIEZO PMM4G, Prime Tech Ltd., [n = 51,484, Piezo-group]) or in the conventional ICSI method with spiked-tip micropipettes (n = 13,549, C-group). Participants/materials, setting, methods Following the insemination with ICSI, the oocyte degeneration rate, fertilization rate per MII oocytes and blastocyst formation rate per 2PN embryos were evaluated in both the Piezo- and C-groups (n = 51,484 and n = 13,549, respectively). We also evaluated the degeneration rates and fertilization rates of ICSI by the operators: i.e., well-experienced embryologists (at least 10 years of experience) and less experienced embryologists (5 years or less of experience). Main results and the role of chance The fertilization and blastocyst formation rates in the Piezo-group were 83.8% (43,140/51,484) and 54.0% (23,300/43,140), respectively, which were significantly higher than the C-group (74.8% [10,132/13,549] and 36.6% [3,674/10,132], respectively, p &amp;lt; 0.01). The oocyte degeneration rate in the Piezo-group was 2.9% (1,493/51,484), which was significantly lower than the C-group (6.9% [933/13,549], p &amp;lt; 0.05). For the patients over 40 years old, the degeneration rate was also significantly lower in the Piezo-group (3.0% [632/20,770]) than the C-group (7.1% [351/4927], p &amp;lt; 0.01), while the fertilization and blastocyst formation rates were higher in the Piezo-group (82.6% [17,164/20,770] and 46.6% [7,997/17,164], respectively) than the C-group (72.8% [3,588/4,927] and 25.8% [926/3,588], respectively, p &amp;lt; 0.01). We found a marked drop in the oocytes degeneration rates in the Piezo group recorded from both well-experienced and less experienced embryologists. The degeneration rates recorded by less experienced embryologists were 2.8% (119/4,242) in Piezo-group and 8.6% (8/93) in the C group (p &amp;lt; 0.01), while the records by well-experienced embryologists were 2.7% (815/29,681) in the Piezo-group and 6.9% (555/8,037) in the C-group, respectively (p &amp;lt; 0.01). The fertilization rates of the Piezo-group by less experienced and well-experienced embryologists were 84.1%(3,569/4,242) and 83.4% (24,757/29,681), respectively, which were significantly higher the C-group (71.0％ [66/93] and 76.7％ [6,167/8,037], respectively, p &amp;lt; 0.01). Limitations, reasons for caution It is a retrospective study, in which the ICSI operations with piezo and the conventional methods were not equally assigned to the embryologists, especially, for those less experienced, thereby the number of conventional ICSI operations was more skewed to well-experienced embryologists than the less experienced colleagues. Wider implications of the findings Our results with piezo-ICSI showed a marked drop in the oocyte degeneration while achieving comparable fertilization rates amongst operators with different levels of experience. We found these as major advantages over the conventional method in standardizing the ICSI operation by filling the gap between embryologists with different length of carrier. Trial registration number Not applicable

P-227 Blastocyst rate prediction by artificial intelligence: evaluation of static oocyte images in patients and donors

Abstract Study question Can a deep learning tool accurately predict blastocyst development from single static oocyte images across diverse patient populations? Summary answer The automatic oocyte score was directly correlated with the blastocyst formation rate in conventional treatments using patient oocytes and in the egg donation program. What is known already The implementation of artificial intelligence (AI)-based algorithms has revolutionized gamete and embryo evaluation in assisted reproduction, providing a standardized basis for clinical decisions. Despite these advances, the implementation of AI algorithms in oocyte evaluation has faced unique challenges. This study explores the predictive ability of an AI algorithm on the actual blastocyst arrival rate from static oocyte images, focusing on finding differences or similarities in these predictions between patients and donors. Study design, size, duration This retrospective cohort study analyzed 1092 static images of oocytes before ICSI. The sample included 791 donor and 301 patient oocyte images. A deep learning algorithm was employed to assess oocyte scores, categorizing them into quartiles. The study explored the correlation between oocyte scores and the actual rate of blastocyst arrival for all oocytes. The rates were also compared between patients and donors, assessing an effective cut-off point to improve the accuracy of the predictions. Participants/materials, setting, methods The oocyte images analyzed were captured with cameras connected to microinjection microscopes immediately before the ICSI procedure. Oocyte images and oocyte age were used as input data for the blind analysis performed by the deep learning-based algorithm. The algorithm predicted blastocyst arrival probability for each oocyte, and these predictions were compared with actual outcomes. This evaluation assessed the algorithm’s performance across patient and donor populations, providing valuable insights into its predictive accuracy for blastocyst arrival. Main results and the role of chance Significant differences in blastocyst formation rates were observed between quartiles of scores assigned by the artificial intelligence (AI) algorithm. Oocytes classified in Quartile 1 showed a significantly lower blastocyst arrival rate (54.63±49.99, n = 216) compared to Quartiles 3 (71.88±45.06, n = 224) and 4 (66.82±47.19, n = 220)*. In general, each increased unit in the algorithm was significantly associated with an increased probability of blastocyst formation (OR = 1.10 [95% CI: 1.02-1.16])*. The algorithm successfully predicted the blastocyst arrival rate, with an area under the curve (AUC) of 0.60 (95% CI: 0.56-0.65). When assessing differences between patients and donors, both groups exhibited similar rates in the first quartile (59.68% and 52.60%, respectively) and the three last quartiles combined (67.55% and 66.02%, respectively). However, an effective cutoff point was identified at 2.8 (between first and second quartile), where both populations experienced a notable increase in blastocyst formation rates. (*p&amp;lt;.05) Limitations, reasons for caution This project is limited by its retrospective, single-center nature and small sample size. Consequently, it would be advisable to conduct a large-scale multicenter study to confirm the conclusions of this study. Wider implications of the findings This study highlights the efficiency of the artificial intelligence algorithm in predicting blastocyst arrival from oocyte images. Establishing a cutoff point in oocyte scoring could enhance the management of the egg donation program and provide individualized guidance to patients based on the quality of their gametes. Trial registration number not applicable

O-212 A need to standardize: the use and posterior recall of toxic consumables could be avoided with the appropriate testing protocols

Abstract Study question Could the recall of toxic products have been avoided if the samples had been tested with a more sensitive Mouse Embryo Assay (MEA)? Summary answer Standardizing MEA protocols with sensitive methodologies could prevent the potential harm imparted on human embryos and avoid the need to recall initially unidentified toxic products. What is known already Dozens of consumables are used during an IVF cycle, with a potential effect on gametes/embryos in culture. Bioassays, such as the MEA, are commonly used to pinpoint embryo-toxic products/batches before their release. No strict regulations exist on how to perform these tests, although several variables have been described to play a major role on the assay’s sensitivity and its capacity to detect embryo-toxicity. Toxic products/batches that are not identified may need to be recalled. However, recalls are typically issued after the products/batches are suspected of hindering embryo development in clinical laboratories, with the loss of irreplaceable biological samples. Study design, size, duration Only in 2023, four important batch recalls have been issued by regulatory bodies or manufacturers, concerning such diverse products as oil, media, capillaries, or follicle aspiration needles (FAN). Reportedly, thousands of couples undergoing IVF cycles may have been affected by this undetected toxicity in samples that were already MEA-tested by the manufacturers or external testing laboratories, following an undisclosed methodology. Eight of these lots (2xmedia, 3xcapillaries, 2xFAN) were retested with a standardized sensitive MEA protocol. Participants/materials, setting, methods The samples were retested following a high-sensitivity and previously published protocol, using 1-cell stage embryos from a sensitive hybrid mouse strain (B6CBAF1), supplementing with 5mg/ml HSA, and maintaining a low embryo density per droplet. A total of 462 embryos were cultured, allocated to the different test groups (21 + 42 embryos for Medium 1 and 2; 63 + 84+147 embryos for Capillaries 1, 2 and 3; 42 + 42 embryos for FANs 1 and 2, respectively). Main results and the role of chance Embryos were cultured at 37.3oC, 6%CO2 and 7%O2 for 5 days (96h). The expanded blastocyst formation rate (BFR) in each group was assessed as the end-point of the assays, and an 80% was considered as the toxicity-marking threshold. When cultured in Medium 1 and Medium 2, supplemented with 5mg/ml HSA, only 0/21 (0%) and 7/63 (11.1%) of embryos reached the expanded blastocyst stage, respectively. Capillaries and FANs were tested with an indirect method, in which the samples were first incubated with a small volume of control culture medium, and the extract was used to culture the embryos. With this approach, Capillaries 1, 2 and 3 yielded a 23.8% (15/63), 22.6% (19/84) and 0.7% (1/147) BFR, respectively. Similarly, when testing FANs 1 and 2, only 66.7% (28/42) and 19.1% (8/42) of the embryos were able to form a blastocyst. Unfortunately, the recalled oil batches were not available for retest. In parallel to each test, a control group was cultured with standard culture medium without contact with any of the samples; the BFR in all control groups was above 80%. These surprisingly low results suggest that toxicity was present in these samples in high concentrations, evidencing the need for their recall. Limitations, reasons for caution The methodology used in this project successfully identified all the recalled samples as embryo-toxic. However, the same protocol might not prove equally sensitive when testing other products, as the sensitivity of the MEA has been shown to be highly dependent on numerous external factors and to vary between different toxins. Wider implications of the findings Recent events could lead to the belief that the MEA is an insensitive bioassay to assess embryo-toxicity. Far from true, attention should be paid to the specific methodology used in each case. The lack of regulations and standardization translates into huge differences in sensitivity, even leading to completely contrary results. Trial registration number not applicable

P-221 The efficiency of a PGT-A program is negatively impacted by the utilization of frozen-thawed oocytes in patients of all ages

Abstract Study question Are there any differences in the use of fresh or frozen-thawed oocytes in a PGT-A program? Summary answer While euploidy rates are comparable, the efficiency of a PGT program is adversely impacted when utilizing frozen-thawed oocytes. What is known already Oocyte vitrification has become one of the key assisted reproduction procedures. Some studies have reported rates of embryonic development, clinical pregnancy, and embryo implantation comparable between fresh and cryopreserved oocytes in egg donor patients. Vitrified oocyte accumulation before the blastocyst biopsy is a commonly used strategy in PGT programs to enhance the chances of obtaining a euploid blastocyst with the patient’s own oocytes. Further research is needed to assess the impact of frozen-thawed oocytes on aneuploidy and the efficiency of PGT programs. Study design, size, duration We conducted a retrospective comparison of 777 PGT-A cycles, using either fresh or frozen-thawed oocytes, regarding embryo development (fertilization rates, blastocyst formation, and rates of good-quality blastocysts), PGT outcomes (euploidy and mosaicism rates), and the overall efficiency of the PGT cycle, measured as the number of euploid blastocyst per available mature oocytes, between April 2018 and November 2023. The study groups were stratified based on the age of the patients (≤35 and &amp;gt;35 years old). Participants/materials, setting, methods PGT-A cycles were categorized into two groups: patients who utilized fresh oocytes (n = 641) and those who utilized frozen-thawed oocytes (n = 136). A total of 6,370 fresh oocytes and surviving oocytes from the initially vitrified ones (972 out of 1,153) were fertilized and cultured to the blastocyst stage, at which point biopsies were performed. The biopsied cells were subjected to NGS screening, and statistical data analysis was conducted using the Chi-square test, with significance set at P &amp;lt; 0.05. Main results and the role of chance In the group of patients aged ≤35 years old, significant differences were observed when comparing PGT cycles using fresh or frozen-thawed oocytes in terms of the fertilization rate (78.4% vs. 72.0%), blastocyst formation rate (47.4% vs. 37.7%), and the efficiency of the PGT cycle (24.0% vs. 16.0%), corresponding to a 33.3% reduction in efficiency. No differences were observed between fresh and frozen-thawed oocytes regarding euploidy rate (64.6% vs. 68.4%), mosaicism rate (4.9% vs. 5.1%), and the percentage of good-quality embryos (60.0% vs. 56.1%). Similarly, in patients aged &amp;gt;35 years old, fertilization (81.5% vs. 73.5%), blastocyst formation (40.5% vs. 33.4%), and the efficiency of the PGT cycle (11.7% vs. 7.2%), which correspond to a 38.5% reduction in efficiency, were improved when using fresh oocytes. No differences were observed regarding euploidy (35.6% vs. 35.3%) or mosaicism rate (3.8% vs. 5.3%), and the percentage of good-quality embryos (55.2% vs. 54.7%). The oocyte survival rate was 84.3%. Limitations, reasons for caution Our study is limited by its sample size and retrospective design, as well as the inclusion of a non-selected and general infertile population, which could amplify the impact of confounding variables. Wider implications of the findings We found that the utilization of frozen-thawed oocytes reduces the PGT program efficiency by decreasing fertilization and blastocyst formation rates. This suggests that the oocyte accumulation strategy should be approached with caution. However, vitrification did not lead to an increase in the rates of aneuploidy, mosaicism, or poor-quality blastocysts. Trial registration number NOT APPLICABLE

P-594 Retrospective comparative study of follitropin delta vs follitropin alfa in progestin-primed ovarian stimulation (PPOS) protocol in IVF

Abstract Study question Could the individualized fixed-dose algorithm with follitropin delta show a similar pregnancy rate to conventional dosing with follitropin alfa in PPOS protocol? Summary answer Individualized fixed-dose algorithm with follitropin delta showed a similar pregnancy rate to follitropin alfa In PPOS protocol. What is known already Follitropin delta (REKOVELLE, Ferring Pharmaceuticals, Switzerland) is the first human cell line driven recombinant follicle-stimulating hormone (FSH) with an individualized fixed-dose algorithm based on serum AMH level and body weight. Follitropin alfa is a Chinese hamster ovarian cell driven recombinant FSH and its dosing is adjusted according to follicular response during the stimulation period. There was no significant difference between follitropin delta and follitropin alfa in terms of pregnancy rate under GnRH antagonist protocol. Study design, size, duration A retrospective analysis of 355 patients aged under 40 years who underwent ovarian stimulation in PPOS protocol using follitropin delta or follitropin alfa and on whom frozen-thawed single blastocyst transfer was conducted between August 2021 and November 2023 was performed. Participants/materials, setting, methods 193 cycles of women who used follitropin delta were compared to 162 cycles of women who used follitropin alfa. The following clinical outcomes on each treatment group were analyzed: chemical pregnancy rate (serum β hCG), clinical pregnancy rate (gestational sac), ongoing pregnancy rate(gestational sac and fetal heartbeat), serum E2 level at trigger day, cycle proportion of ≥ 10 oocytes retrieval, blastocyst formation rate, cycle proportion of ≥ 5 blastocysts and cycle proportion of ≥ 2 good quality blastocysts. Main results and the role of chance Baseline demographics in the follitropin delta group and the follitropin alfa group were not significantly different: age, 33.9 ± 3.5 years vs 34.5 ± 3.2 years; body weight, 53.5 ± 8.3 kg vs 53.8 ± 5.9 kg; number of previous IVF cycles, 0.2 ± 0.6 vs 0.3 ± 0.7; serum AMH level, 5.5 ± 2.9 ng/mL vs 5.3 ± 3.8 ng/mL, respectively. The chemical pregnancy rate (69.9% vs. 64.8%, P = 0.308), clinical pregnancy rate (58.0% vs. 56.2%, P = 0.748) and ongoing pregnancy rate (51.8% vs. 46.3%, P = 0.338) were comparable between the follitropin delta group and the follitropin alfa group. The individualized follitropin delta treatment resulted in a smaller cycle proportion of ≥ 10 oocytes retrieval (77.7% vs. 90.8%, P &amp;lt; 0.001) with lower serum E2 level at trigger day (3273 ± 1577 pg/mL vs. 3927 ± 1732 pg/mL, p &amp;lt; 0.001). However, the blastocyst formation rate was significantly higher in the follitropin delta group (75.5% vs. 68.7%, p &amp;lt; 0.001). Moreover, the cycle proportion of ≥ 5 blastocysts (71.0% vs. 76.4%, P = 0.286) and the cycle proportion of ≥ 2 good quality blastocysts (51.8% vs. 60.3%, P = 0.115) were comparable between the groups. Limitations, reasons for caution This is a non-controlled, retrospective study. Wider implications of the findings Follitropin delta in its individualized fixed-dose regimen could have the potential to decrease the risk of OHSS by minimizing excessive ovarian response, whereas a similar pregnancy rate to conventional dosing regimen could be expected due to the number of good quality blastocysts secured. Trial registration number not applicable

P-228 Competence of injected MI versus MII sibling oocytes in terms of normal fertilization, blastocyst development and euploidy

Abstract Study question Is the injection of immature MI oocytes as effective as injection of their siblings mature MII oocytes regarding normal fertilization, blastocyst development and euploidy? Summary answer MI oocytes show a lower rate of fertilization, a similar blastulation rate, and a slightly lower rate of euploidy compared to their MII sibling oocytes. What is known already Although several studies have been performed on immature MI oocytes evaluating their developmental competence after intracytoplasmic sperm injection (ICSI), all have been performed on oocytes that extruded the first polar body by the time of injection. ICSI is typically performed on MII oocytes which have completed the process of maturation. Some laboratories also inject MI oocytes, nevertheless, they are generally not used due to the lack of required molecular and cellular changes to support normal development. However, there is limited research on the reproductive potential of oocytes in MI. Consequently, our current practices are founded on assumptions. Study design, size, duration This is a retrospective, observational study of 168 oocytes injected in MI and 839 sibling oocytes injected in MII from 82 ICSI cycles with Preimplantation Genetic Testing for Aneuploidies (PGT-A) performed in a single IVF clinic between April 2018 and December 2023. All PGT-A cycles included in this study contained at least one MI oocyte injected. Participants/materials, setting, methods After oocyte retrieval and denudation, the oocytes were classified as MII, MI or GV. MI oocytes with extruded polar body by the moment of ICSI were reclassified as MII. All MII and MI oocytes were inseminated and the embryos that reached blastocyst stage were biopsied on day 5, 6 or 7. Normal fertilization rate, blastocyst formation rate and euploidy rate were compared between MI-derived embryos and their MII-derived siblings. Main results and the role of chance A total of 1,094 oocytes were retrieved from 83 ICSI cycles with PGT-A, comprising 839 (76.7%) MII, 168 (15.4%) MI y 87 (7.9%) VG. The normal fertilization rate was significantly higher in oocytes injected at MII compared to MI (76.9% vs 53.0%, P &amp;lt; 0.001). The rates of abnormal fertilization in MII and MI oocytes were as follows: 1 PN 0.8% vs 0.6%, P = 0.342; 3PN 2.6% vs 1.2%, P = 0.075; 0 PN 19.7% vs 45.2%, P &amp;lt; 0.001. Interestingly, the blastulation rate of zygotes with normal fertilization was very similar between both groups (46.4% vs 43.8%, P = 0.708), as well as the proportion of biopsied blastocysts on day 5 (74.2% vs 71.8%, P = 0.858), on day 6 (23.1% vs 25.6%, P = 0.946), and on day 7 (2.7% vs 2.6%, P = 0.594). The euploidy rate of the 298 biopsied MII-derived blastocyst was 36.2%, compared with 23.1% of the 39 MI-derived blastocysts biopsied (P = 0.077). Despite the limited sample size, it is noteworthy that three out of the four euploid blastocysts derived from MI oocytes, which were transferred in single embryo transfers, successfully led to pregnancy resulting in one healthy live birth, one ongoing pregnancy and one miscarriage at 9 weeks of pregnancy. Limitations, reasons for caution While this study provides valuable insights into the developmental competence of MI oocytes, it is not exempt from certain limitations, such as its retrospective nature, limited sample size and ethical considerations regarding the injection of putative immature oocytes. Wider implications of the findings MI oocytes showed lower fertilization rates compared to their MII siblings. However, once fertilized, MI-derived embryos had similar blastulation rates and a trend towards lower euploidy rates. Our study suggests that MI oocytes may result in successful pregnancies and live birth, but further research is needed to validate these findings. Trial registration number Not applicable

O-195 Decreased embryo developmental potential and lower cumulative pregnancy rate in males with multiple morphological abnormalities of the sperm flagella

Abstract Study question Is there any association between the multiple morphological abnormalities of the sperm flagella (MMAF) patients and the comprehensive outcomes of assisted reproductive technology (ART) cycles? Summary answer Patients with MMAF presented compromised ART outcomes, including lower embryo developmental potential and impaired clinical outcomes, compared with the cohort of oligoasthenospermia. What is known already Several studies have reported a positive intracytoplasmic sperm injection (ICSI) outcome in the MMAF cohort, and others have opposite opinions. The association between MMAF and ART outcomes is still controversial and open for debate. Furthermore, the neonatal outcomes and the information regarding the mutations of MMAF patients were incomplete. Study design, size, duration A retrospective cohort study of MMAF patients was performed at a reproductive medicine center in China between January 2014 and July 2022. Participants/materials, setting, methods Thirty-eight MMAF individuals were recruited based on a typical MMAF phenotype (abnormal sperm flagella, including short, absent, coiled, bent, and/or irregular flagella) and 131 couples with male infertility undergoing in vitro fertilization (IVF)/ICSI treatments over the same period were included as the control pool. Whole exome sequencing (WES) was performed to confirm the genetic pathogenesis of MMAF. Main results and the role of chance Pathogenic variants in known genes of DNAH1, DNAH11, CFAP43, FSIP2, and SPEF2 were identified in MMAF patients. The ART outcomes, including the fertilization rate, 2PN cleavage rate, blastocyst formation rate, and available blastocyte rate, were all significantly lower in the MMAF group than those in the control group (P&amp;lt;0.05). Moreover, the CLPR in the MMAF group was lower than that in the control group according to the embryo transfer times (68.6% vs. 86.5%, P=0.033) and complete cycles (66.7% vs. 84.2%, P=0.020), while no significant differences were found in the neonatal outcomes. Limitations, reasons for caution The sample size was limited due to the low incidence of MMAF and WES was not performed in all MMAF patients. Further exploration of the potential genetic mutations or underlying mechanisms in patients without identified mutations was needed. Moreover, long-term follow-up of neonates needs to be addressed in the future. Wider implications of the findings The current study identified the causative genetic mutations which were partly obligated to the pathogenesis of MMAF and presented the relationship between MMAF and compromised ART outcomes. These results may provide evidence support for clinicians in genetic counseling and clinical instruction in specific MMAF patients. Trial registration number the National Key Research &amp; Development Program of China (2021YFC2700603)

P-233 Embryo transfer timing and clinical pregnancy success: a retrospective study

Abstract Study question The aim of this study is to compare the clinical outcome of day5 versus day6 genetically normal blastocyst transfers. Summary answer 1000 oocytes were analyzed showing a highly significant difference in the number of normal embryos and clinical pregnancy rates in day5 versus day6 blastocysts What is known already studies have shown that day 5 embryos have a higher pregnancy rate compared to day 6 embryos, some studies had only euploid embryos transferred and others did not have any genetic testing done on embryos. No study had a sample size as large as 1760 and the number of embryos studied was a limiting factor in their results. Study design, size, duration The study is a retrospective cross-sectional chart review with multivariate analysis, data from January 2019 up to February 2023 were extracted. 1760 patients were recruited, 1000 in the day5 group and 760 in the day6 group. The data recorded for each patient included maternal age, body mass index (BMI), anti-Müllerian hormone (AMH) level, number, prenatal genetic diagnostic testing, frozen embryo transfer, sperm parameters, and pregnancy status. Participants/materials, setting, methods All embryos were genetically tested for aneuploidy before transfer, using next-generation sequencing technology to rule out 24-chromosome aneuploidies (1-22, X, Y). All patients who have single embryo transfer, frozen embryos and pre-implantation genetic diagnosis (PGD) were included in the study. Continuous variables were expressed as mean with standard deviation and categorical variables as numbers and frequencies (percentages). Statistical differences between groups were estimated using the chi-square or Fisher’s test. All analyses were performed using SAS studio. Main results and the role of chance 1,000 cycles were analyzed for Day 5 and 760 for Day 6 embryo. The number of blastocysts formed, and genetically diagnosed embryos significantly favor the Day 5 group. There’s a significant difference in the number of normal embryos, with the Day 5 group having more. There is a highly significant difference in clinical pregnancy rates. On the other hand, the differences in biochemical pregnancies are not statistically significant. The occurrence of ectopic pregnancies shows no significant difference. Additionally, there is no statistically significant difference in the rates of miscarriage. There is a highly significant difference in blastocyst formation rates, with Day 5 embryos. This indicates that Day 5 embryos have a significantly higher likelihood of forming blastocysts compared to Day 6 embryos. Implantation: Day 5 embryos have an implantation rate of 62.0% compared to 49.7% for Day 6 embryos. Day 5 embryos exhibit a significantly higher likelihood of successful implantation. Euploid: The difference in euploid rates is statistically significant, albeit with a lower p-value of 0.0236. Day 5 embryos have a rate of 59.6%, while Day 6 embryos have a rate of 56.0%. Day 5 embryos are associated with a lower likelihood of being aneuploid Limitations, reasons for caution Limitation of this study is that we do not have data available regarding complications during pregnancy in the day 5 versus day 6 groups and we had no data regarding the the live birth rate between the two groups. Wider implications of the findings This study has the potential to revolutionize worldwide discussions during IVF consultations. With the large sample size we can provide for the first time a statistically significant difference in the percentage of success when transferring a day5 (61%) versus day6 (49%) euploid embryo. Trial registration number not applicable

P-609 Impact of low versus air oxygen tension on the oocyte maturation in PCOS women undergoing capacitation IVM: a sibling oocyte pilot study

Abstract Study question Does low or air oxygen tension improve the oocyte maturation rate in biphasic capacitation IVM (CAPA-IVM)? Summary answer Low oxygen tension resulted in a lower maturation rate and two-pronuclei fertilization rate compared with air oxygen tension in the CAPA-IVM culture. What is known already CAPA-IVM, with a pre-maturation step, improves the competence of oocytes matured in-vitro. The current CAPA-IVM culture condition is under air oxygen concentration. However, the impact of oxygen tension on in-vitro oocyte maturation needs to be better understood, and it remains uncertain whether the maturation process aligns with in-vivo conditions. Study design, size, duration A sibling oocyte pilot study of 416 cumulus-oocyte complexes (COCs) recruited from fifteen polycystic ovary syndrome (PCOS) women was performed at IVFMD, My Duc Phu Nhuan Hospital, Ho Chi Minh City, Vietnam from November 2023 to January 2024. The study was approved by the Institutional Ethics Committee (22/23/DD-BVMD, dated October 12th, 2023) and conducted according to Good Clinical Practice and Declaration of Helsinki 2002 principles. All participants provided written informed consent. Participants/materials, setting, methods Women (18–37 years) diagnosed with PCOS undergoing CAPA-IVM were recruited. At collection, COCs from each woman were divided into two groups based on the oxygen tension used in the two steps of CAPA-IVM culture, low oxygen tension (5% O2, 6% CO2 at 37 °C) and air oxygen tension (20% O2, 6% CO2 at 37 °C). Embryos were cultured to blastocyst stage. Primary outcome was the oocyte maturation rate. Secondary outcomes were embryology outcomes. Main results and the role of chance A total of 416 COCs from fifteen eligible women were assigned to the low oxygen (207 COCs) and air oxygen tension (209 COCs) groups. Mean age and body max index were 29.0±2.5 years and 22.6±2.6, respectively. The maturation rate was significantly lower in the low oxygen group compared to the air oxygen group (54.1% vs. 66.5%, p = 0.01, respectively). The two-pronuclei fertilization rate per COC was significantly decreased in the low oxygen group compared to the air oxygen group (35.7% vs. 49.3%, p = 0.005, respectively). Rates of day-3 embryos, blastocyst formation rate, and good quality blastocyst rate were also lower but not significant in the low oxygen tension group as compared to the air oxygen tension group. Limitations, reasons for caution The study’s limitations include a relatively small sample size and a single ethnicity group. There was a lack of data on clinical outcomes after transferring embryos from the study. Wider implications of the findings Oocyte maturation rate and two-pronuclei fertilization rate were significantly lower when oxygen tension was reduced in the process of CAPA-IVM culture. Therefore, air oxygen tension should be considered as a standard for oocyte culture in the pre-maturation step of CAPA-IVM. Trial registration number NCT06087354

P-210 A new insight into the effects of systemic lupus erythematosus on oocyte and embryo development and female fertility

Abstract Study question Does SLE affect oocyte and embryo development and female fertility in female patients? Summary answer Patients with SLE present worse outcomes in oocyte and embryonic development, thus yielding compromised female fertility and clinical pregnancy. What is known already Systemic lupus erythematosus (SLE) is often associated with adverse reproductive outcomes. However, it’s currently unclear regarding the role of SLE in oocyte and embryonic development. Also, it’s controversial whether SLE hurts fertility. There is a lack of comprehensive understanding and assessment of fertility in patients with SLE. Study design, size, duration This study retrospectively investigated oocyte and embryo development, ovarian reserve, and clinical outcomes in SLE patients who underwent in vitro fertilization (IVF) treatment from January 2013 to September 2022 at the University Hospital. Participants/materials, setting, methods In this study, we collected data from 34 SLE patients who were previously diagnosed and in remission for a total of 44 IVF cycles and matched 102 infertile women with a total of 148 IVF cycles by Propensity Score Matching (PSM) of 1:3 ratio. We then evaluated baseline characteristics, ovarian reserve, IVF laboratory outcomes, and clinical outcomes between the two groups. Main results and the role of chance After PSM matching, baseline characteristics including age, infertility types, and duration, as well as infertility causes overall coincided between the two groups. Anti-müllerian hormone (AMH) was significantly lower in the SLE group vs comparison (1.9 vs. 3.3 ng/mL, P=0.001). The SLE group performed a significant reduction in available embryo rate (76.6% vs. 86.0%, P=0.001), good-quality blastocyst formation rate (35.1% vs. 47.0%, P=0.003), and blastocyst formation rate (51.0% vs. 67.7%, P=0.001) compared to the comparison. As for clinical outcomes, the implantation rate in the SLE group was notably lower (37.9% vs. 54.9%, P=0.022). The CLBR following every embryo-transfer procedure was distinctly lower (41.2% vs 68.6%, P=0.016) in the SLE group vs comparison. Also, the conservative and optimal CLBRs following every complete cycle procedure were significantly reduced in the SLE group vs the comparison (P=0.001, both) Limitations, reasons for caution It’s a retrospective and single-center study, which is relevant to an inevitable risk of bias. Due to its special population selection, the sample size of this study is quite small. Wider implications of the findings This study provides data support to explore further the impact of SLE or other autoimmune diseases on female fertility, and it also calls for more attention to be given to these special patients by reproductive physicians. Comprehensive fertility assessment and individualized fertility guidance are recommended for patients with SLE. Trial registration number TJ-IRB20211280