Ongoing Pregnancy Research Articles

P-086 Consequences of elevated levels of DNA fragmentation and its influence on pregnancy – A multicentric cohort analysis

Abstract Study question Does an abnormal DNA Fragmentation Index impact the clinical outcomes of patients undergoing IVF treatment? Summary answer Statistical differences were seen in biochemical, implantation, clinical, and ongoing pregnancy rate in sperms with high and low DFI scores with autologous and donated oocytes. What is known already Sperm chromatin integrity is associated with embryo development and clinical outcomes of an IVF cycle. DNA Fragmentation Index (DFI) is a diagnostic tool for the detection of spermatozoa with damaged chromosomes in the ejaculate. DNA fragmentation is a significant cause of day 3 embryo arrest and the development of poor-quality embryos. The interventions associated with elevated levels of DFI are ICSI, lifestyle changes and antioxidant therapies. However, the published data regarding the potential of embryo development with high DFI is limited to the sample size thus, encouraging a need for more research in this area. Study design, size, duration The study is population-based and included 768 male patients who underwent DFI score detection across 44 centers at Indira IVF Hospital Private Limited from January 2023 to September 2023. The abstinence period for all the patients was recorded during the DFI detection. After the DFI assessment patients were classified into normal DFI score ( < =15%) (n = 203) and abnormal DFI score (>15%) (n = 565). Participants/materials, setting, methods The retrospective cohort analysis was performed on our databank on the male patients regardless of their age (21-50), ethnicity, and medical history. DFI was calculated using a Sperm Chromatin Dispersion assay. Patients were categorized into two groups: Normal DFI ( < =15%) and Abnormal DFI (>15%). The characteristics of population along with clinical outcomes were evaluated after transferring embryos fertilized with normal DFI sperm and abnormal DFI sperm. The data was analyzed and estimated by SPSS software. Main results and the role of chance Our analyses discovered that embryos fertilized with sperms of normal DFI score have significantly enhanced the likelihood of implantation compared with embryos fertilized with sperms of abnormal DFI (50.27% v/s 44.40%; p = 0.047). Simultaneously, early pregnancy was evaluated by determining the values of beta-HCG in blood, also known as biochemical pregnancy rate (BPR). The embryos fertilized with sperms of normal DFI score significantly enhanced the BPR compared with embryos fertilised with sperms of abnormal DFI (67% v/s 59.1%; p = 0.048). Clinical Pregnancy Rate (CPR) defined as presence of a heartbeat of gestational sac observed during the 6-week scan. Furthermore, it was evaluated that the CPR showed a significant enhancement in embryos fertilized with sperms of normal DFI score in comparison with embryos fertilized with sperms of abnormal DFI (65.5% v/s 57.9%; p = 0.034). However, it was noticed that male DFI score had no impact on the miscarriage rate of embryos inseminated with normal DFI score and abnormal DFI score (7.52% v/s 7.34%; p = 0.687). Moreover, the pregnancy was tracked, and it was revealed that embryos inseminated with sperms of normal DFI score significantly enhanced the ongoing pregnancy till 12 weeks compared with embryos inseminated with sperms of abnormal DFI score (60.6% v/s 53.6%; p = 0.039). Limitations, reasons for caution Embryos are known to have a self-correct mechanism to correct the presence of mosaicism in the embryos. Hence, the oocyte quality also affects the outcomes of the IVF cycle. Therefore, using a high grade of the oocyte for the patients with abnormal DFI score can be useful. Wider implications of the findings Our data suggest that abnormal DFI have an impact on the clinical outcomes of an IVF cycle. Therefore, examining the levels of DNA Fragmentation is utmost imperative for a successful pregnancy. Trial registration number not applicable

O-296 The benefits of higher concentrations of synthetic serum substitutes in post-warming embryo culture and transfer media: a retrospective study of 864 frozen blastocyst transfer cycles

Abstract Study question Does a higher concentration of synthetic serum substitutes (SSS) in post-warming embryo culture and transfer media improve clinical outcomes in frozen blastocyst transfer (FBT) cycles? Summary answer Increased SSS concentration in post-warming embryo culture and transfer media reduces miscarriage rate in FBT cycles and improves ongoing pregnancy rate in euploid blastocyst transfer. What is known already Several studies showed increased clinical pregnancy rates with the use of complex protein supplementation such as SSS in embryo culture media. Nevertheless, there is a lack of standardization on their concentrations. The range of concentrations employed is strikingly wide, spanning from 5% to 50%. Moreover, no studies investigating different SSS supplement concentrations in post-warming embryo culture and transfer media in FBT cycles are available. These uncertainties warrant further investigation in this field. Study design, size, duration This retrospective study included 864 patients undergoing vitrified-warmed euploid (n = 102) and untested (n = 762) blastocyst transfers between September 2022 and August 2023. The cohort was divided based on the concentration of SSS used in post-warming embryo culture and transfer media: 10% (n = 415) and 20% (n = 449). The exclusion criteria were ICSI-cycles performed with surgically retrieved or frozen sperm, gamete donation and vitrified-warmed oocyte cycles. Prior to embryo transfer, warmed blastocysts were cultured for 2-3 hours. Participants/materials, setting, methods Treatment allocation to 10% or 20% SSS groups followed an alternating regimen. To reduce any pre-existing differences between the two groups, a propensity-score (PS) analysis was performed, targeting unbiased treatment effect estimates. Variables included in the PS were: maternal age, maternal BMI, infertility type, transfer day, endometrial preparation, blastocyst quality, and the operators for biopsy, warming, and transfer. Main results and the role of chance Patient baseline characteristics were evenly distributed in the two study groups. After the PS-based analysis, no statistically significant differences in ongoing pregnancy rates for both overall and untested blastocyst transfers were observed between 10% and 20% SSS groups. However, the 20% SSS group exhibited a significantly lower miscarriage rate in overall FBTs [OR = 0.61, 95% CI (0.37-1.00), p-value=0.050] and a higher ongoing pregnancy rate in euploid blastocyst transfers [OR = 3.48, 95% CI (1.30-9.35), p-value=0.013]. A mild trend of an increased miscarriage rate was also observed in both euploid and untested blastocyst transfers in the 10% SSS group compared to the 20% SSS group [OR = 2.834, 95% CI (0.651-12.337), p-value=0.165; OR = 1.558, 95% CI (0.897-2.705), p-value=0.115 respectively]. Limitations, reasons for caution The study is limited by its retrospective design and a lack of randomization, although a PS-based analysis may mitigate such a weakness. Not considering live birth rate as outcome and protein concentrations higher than 20% and lower than 10% might represent other study limitations. Wider implications of the findings To our knowledge, this is the first study investigating the impact of varying protein supplementation concentrations in post-warming embryo culture and transfer media on clinical outcomes in FBTs. Our findings suggest that higher serum concentrations improve the likelihood of ongoing pregnancy, especially in blastocysts undergoing stressful manipulations such as biopsy. Trial registration number not applicable

P-459 Impact of a drop in serum estradiol levels after gonadotropin-releasing hormone (GnRH) antagonist on clinical outcomes of ovarian stimulation cycles in assisted reproductive technology (ART)

Abstract Study question Does a drop in serum estradiol level after the administration of a GnRH antagonist affect outcomes in ovarian stimulation cycles in ART? Summary answer A drop in serum estradiol after administration of a GnRH antagonist is related to changes in luteinizing hormone (LH) and to inferior clinical outcomes. What is known already In recent years, the GnRH antagonist protocol has become widely used to prevent a premature LH surge during ovarian stimulation in ART, with many advantages such as immediate pituitary suppression and a lower risk of ovarian hyperstimulation. However, one phenomenon intriguing professionals monitoring these cycles and reviewing blood analyses, is the decrease in serum estradiol that occasionally occurs after the administration of the antagonist. With the natural menstrual cycle in mind, this could be an undesirable effect possibly affecting clinical outcomes. Study design, size, duration This was a non-interventional, retrospective, observational cohort study. We analyzed 1678 ovarian stimulation cycles in ART in 1143 patients. Patients were treated between January 1st 2015 and November 1st 2022. Patients were 20 to 45 years old, were stimulated with human menopausal gonadotropin (hMG) or recombinant follicle stimulating hormone (follitropin α, β or δ, corifollitropin α and follitropin α + lutropin α) and a GnRH antagonist was used for pituitary suppression in a flexible protocol. Participants/materials, setting, methods Data were extracted from medical records at a tertiary infertility clinic. The difference between serum estradiol level before and after the first antagonist administration was calculated. When this value was negative, the cycle was marked as having an estradiol drop. Influence of treatment and cycle characteristics on estradiol drop, as well as influence of the drop on clinical outcomes were analyzed using generalized linear mixed effects models. Main results and the role of chance The presence of a serum estradiol drop could be calculated in 1552 cycles, of which 153 cycles (9.9%) showed a drop. There was no significant difference in the odds on cycle cancellation between cycles with and without drop (p = 0.87). Type of gonadotrophin used was significantly associated with the presence of an estradiol drop (p < 0.0001), with hMG cycles showing the lowest amount of drops (3.0%). More estradiol drops were observed with the start of antagonist administration on day six of stimulation (10.3% of cycles), compared to starting later than day six (9.1%)(p = 0.001). Serum LH at the start of the cycle was significantly higher in cycles with estradiol drop (mean±SD=4.10±4.13IU/L) than in cycles without (3.88±2.74IU/L) (p = 0.01). Decrease in serum LH levels after antagonist administration was significantly larger in cycles with estradiol drop (-5.30±7.58IU/L versus -1.66±3.13IU/L,p<0.0001). Serum LH on the day of ovulation triggering was also lower in estradiol drop cycles (1.29±1.59IU/L versus 2.24±8.13IU/L,p=0.0007). Estradiol drop was not significantly associated with the number of oocytes retrieved, 2PN fertilized, utilization rate or embryo transfer (p-values>0.05). Ongoing pregnancy and live birth were also significantly lower in cycles with an estradiol drop (13.9%) than in cycles without (25%, p = 0.01). When correcting for age, p-values remained unchanged. Limitations, reasons for caution A limitation of the retrospective study design is that stimulation protocols and any adjustments were chosen by the treating physician according to the patient’s characteristics. The authors did adjust for different cycles per patient by using generalized mixed models. Absolute numbers of estradiol drop are low, limiting optimal multivariable analysis. Wider implications of the findings Because serum estradiol drop after GnRH antagonist administration is related to changes in LH, prospective research could focus on potential optimization of the LH serum levels which could potentially ameliorate clinical outcome. Trial registration number not applicable

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

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

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

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

P-405 Effects of intrauterine perfusion of autologous platelet-rich plasma on recurrent implantation failure in frozen-thawed embryo transfer: a meta-analysis of randomized controlled trials

Abstract Study question We aimed to evaluate the effect of the platelet-rich plasma （PRP) on pregnancy outcomes in patients with RIF undergoing frozen-thawed embryo transfer (FET). Summary answer Intrauterine infusion of PRP might have more beneficial effects on pregnancy outcomes in RIF patients undergoing FET. What is known already Immunological therapies are of great interest to specialists in reproductive medicine. The immune therapies use intrauterine infusion (i.e., PRP, PBMC, G-CSF, and hCG) for endometrial immunomodulation. Despite the limited number of publications available, the results are encouraging. In the network meta-analysis, PRP, PBMC, C-GCSF, and hCG administration all significantly increased embryo implantation and clinical pregnancy compared to controls. Additionally, PRP administration resulted in a higher live birth rate than the control. This year, more research has focused on PRP as an innovative method to treat RIF. Study design, size, duration Medline, Embase, and Cochrane Controlled Register of Trials (CENTRAL) were searched from inception to July 29, 2023. The randomized controlled trials (RCTs) reporting on pregnancy outcomes of women with RIF who were administered PRP undergoing FET were included. We conducted a meta-analysis where possible using a fixed effects model. The Cochrane Handbook was used to assess the risk of bias for RCTs. Binary outcomes were pooled using risk ratio (RR) with 95% confidence intervals (CIs). Participants/materials, setting, methods Seven RCTs were included with 1,014 RIF women. The final number of women analyzed was 508 with intrauterine infusion PRP and 506 without it. Main results and the role of chance Meta-analysis showed that compared to the controls, the women who received PRP had a significantly higher embryo implantation rate (n = 2, risk ratio (RR) 2.34, 95% CI 1.65 to 3.32; P < 0.00001, I2 = 0%), biochemical pregnancy rate (n = 5, RR 1.94, 95% CI 1.60 to 2.36; P < 0.00001, I2 = 0%), clinical pregnancy rate (n = 7, RR 2.31, 95% CI 1.89 to 2.82; P < 0.00001, I2 = 0%), ongoing pregnancy rate (n = 3, RR 2.70, 95% CI 1.79 to 4.05, P = 0.0004, I2 = 31%), and multiple pregnancy rate (n = 3, RR 2.67, 95% CI 1.07 to 6.68, P = 0.04, I2 = 0%). However, PRP was not attributable to reduce the miscarriage rate (n = 3, RR 1.15, 95% CI 0.40 to 3.35; P = 0.80, I2 = 0%). Limitations, reasons for caution The proportion of small-sample studies included has to some extent affected the validity of the results. There were some variations regarding the PRP preparation process, which may result in a variable composition and concentrations of its different contents. Wider implications of the findings Intrauterine infusion PRP in patients with RIF who underwent FET may improve the pregnancy outcomes assessed in RCTs, including clinical pregnancy and ongoing pregnancy. Therefore, we suggest that PRP be included in endometrial preparation protocols. Trial registration number not applicable

P-607 Reproductive outcomes of oocyte donors using subdermal etonogestrel implants and levonorgestrel intrauterine devices

Abstract Study question Does the use of progesterone contraceptive devices during controlled ovarian stimulation (COS) affect ovarian response in oocyte donation cycles? Summary answer Progesterone contraceptive devices during COS did not impact ovarian response, measured by oocyte retrieval and maturity rates, in oocyte donation cycles. What is known already Subdermal etonogestrel implants and levonorgestrel intrauterine devices (L-DIU) are widely used contraceptives amongst oocyte donors. While the safe and effective use of L-DIU during COS has been documented, the impact of subdermal etonogestrel implants on ovarian response is less understood. Given their distinct mechanisms of action and varying local and systemic pharmacodynamics, a comprehensive understanding of the impact of these contraceptives on ovarian response during COS will be crucial for guiding informed clinical practice. Study design, size, duration In this retrospective cohort study, we analyzed 3,452 heterologous ICSI cycles from 1,975 oocyte donors (18-35 years), performed between March 2021 and September 2023, across two centers. We identified 40 COS in donors using contraceptive devices, either a subdermal etonogestrel implant (n = 18) or L-DIU, (n = 22). These were matched with 80 COS without a device. We primarily compared ovarian response amongst the two groups. Secondary outcomes included biochemical pregnancy, clinical pregnancy and live birth rates. Participants/materials, setting, methods We applied a propensity matching score model (PsmPy package, Python), trained on 3,388 oocyte donation cycles, for matching donors with and without contraceptive devices. Matching was based on age, BMI, anti-müllerian hormone (AMH) and antral follicle count (AFC), maintaining a 1:2 ratio. Ovarian response outcomes (oocyte retrieval and maturation rates) were analyzed using Student’s t-tests, while and clinical outcomes were evaluated using Fisher’s exact test. P-values <0.05 were considered significant. Main results and the role of chance Mean age was 26.22, BMI 24.7, AMH 2.63 ng/ml and AFC 18.77. We evaluated a total of 120 COS, leading to 176 heterologous ICSI cycles. The oocyte retrieval rate (total number of cumulus-oocyte-complexes (COCs) per total number of follicles > 14mm at final follicular scan), averaged 109.64%. We observed no differences in the number of COCs retrieved from donors with and without contraceptive devices (17.5 ±7.6 and 18.5 ± 9.6, respectively). Similarly, oocyte maturation rates (total number of MII oocytes per total number of COCs), were comparable amongst the two groups (78.6% overall, 77.6% with contraception device and 79.1% without contraception device, p > 0.05). The presence of the device did not affect biochemical pregnancy (69.7% with contraceptive device, 61.1% without contraceptive device, p > 0.05), clinical pregnancy (54.6% with contraceptive device, 52.9% with contraceptive device, p > 0.05) and ongoing pregnancy (36.4% with contraceptive device, 35.3% without contraceptive device). These results were consistent regardless of the type of device used. Limitations, reasons for caution The main limitation is the retrospective nature of the study, potentially influencing causal inferences, and that both devices were analyzed as one same group. The small subset of COS with contraceptive devices may impact statistical power. Perinatal outcomes were not analyzed. Wider implications of the findings This research provides clinicians with reassurance that the use of progesterone contraceptive devices during COS does not adversely affect clinical outcomes. These findings offer valuable insights for patient counseling, affirming the safety of contraceptive methods and encouraging further research for a more comprehensive understanding in diverse populations and clinical settings. 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 < 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 < 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-151 Endometrial preparation using CONCEIVF algorithm with intrauterine and sub-endometrial endosera administration for enhanced pregnancy rates in women with thin endometrium

Abstract Study question Could personalized regenerative medicine based strategies promote endometrial growth and receptivity in women with refractory thin endometrium resulting in successful implantation and live births? Summary answer Personalized regenerative medicine based strategies remarkably promote endometrial growth and receptivity in women with refractory thin endometrium resulting in successful implantation and live births What is known already Thin endometrium (<7mm) is considered sub-optimal for embryo transfer and associated with reduced pregnancy chances. Regenerative medicine based strategies utilizing stem cells, growth factors alone or in combination for endometrial regeneration have been proposed as futuristic clinical therapies. Data-intensive biomedical technologies in research studies reveals that humans vary widely at genetic, biochemical, physiological, exposure and behavioral levels, especially with respect to disease processes and treatment responsiveness. Hence there is a need to deeply ‘personalize,’ interventional strategies at clinical and dosage level for individual patients. Study design, size, duration In this self- controlled study, 60 women with history of more than 3 failed IVF cycles due to persistent refractory thin endometrium (<7mm) were enrolled between July 21-December 23. 42 women were treated with intrauterine administration of Endosera and 18 patients were treated with sub-endometrial administration of Endosera as suggested by CONCEIVF - Proprietary Algorithm from Seragen.. Endosera is Autologous platelet derived implantation friendly anti-inflammatory cytokines and concentrated growth factors and progenitor cells. Participants/materials, setting, methods CONCEIVF-Algorithm classifies patients (High, Moderate, Poor responders) based on age, BMI, clinical history, guiding standardized dosage routines for proliferative, secretory, implantation phases including CD 33/CD34 cells minimal threshold, are specified. Intrauterine Endosera administration, 2 or 3 times from menstrual cycle day 5 during FET, precedes embryo transfer. Sub-endometrial administration involves Endosera with endothelial progenitor cell support on cycle days 5-7, followed by embryo transfer two days after the final Endosera infusion in the subsequent cycle. Main results and the role of chance Clinical pregnancy rate was 77%(46/60), no pregnancy in 10 patients accounting for 17%. 50% (30/60) delivered healthy babies and 17%(10/60) of uneventful pregnancies are progressing. 3 patients (5%) had miscarriage between 6-8 weeks. Improvement in endometrium thickness (EMT) was 90% with mean difference of 1.9mm improvement in 54 patients. No adverse effects reported. 33 patients out of 42 conceived and 6 out of 42 patients did not conceive and 3 out of 42 patients are yet to undergo embryo transfer in the intra-uterine group. 13 patients out of 18 conceived and 4 out of 18 patients did not conceive and 1 out of 18 patient is yet to undergo embryo transfer in the sub-endometrial group. Live birth rate and on-going pregnancies are indicators of overall endometrial quality (thickness and receptivity) improvement and validates that personalization helps to achieve maximum success rate. 15 out of 60 patients who were referred to surrogacy have conceived. In women with a history of cycle cancellations due to thin endometrium, CONCEIVF algorithm recommended personalized Endosera dosages resulted in improved endometrial thickness, clinical pregnancy and live birth. Personalization holds the key for precision because now two patients are alike! Limitations, reasons for caution This prospective self-control study, contains small sample size and lacks randomized controlgroup. Our results are encouraging but large cohort of patients is needed to establish efficacy. of protocols and positive patient predictors score to strengthen Conceivf personalized recommendations. Wider implications of the findings Despite global rise in FET for diverse indications, ongoing efforts to find the optimal endometrial preparation protocol persist. Our personalized approach achieved cumulative 74% pregnancy rate (40/54 ETs done), inspiring planned randomized trials to validate results and help women with resistant thin endometrium to conceive without surrogacy. Trial registration number Not applicable

O-032 Intravenous immunoglobulin and prednisolone to women with unexplained recurrent pregnancy loss undergoing assisted reproductive technology treatment: a randomized, double-blinded, placebo-controlled trial

Abstract Study question Does intravenous immunoglobulin (IVIG) and prednisolone in combination affect ongoing pregnancy rate among patients with recurrent pregnancy loss (RPL) after assisted reproductive technology (ART) treatment? Summary answer The results of this trial will provide important information about whether immunomodulatory treatment to RPL patients undergoing ART treatment can increase clinical pregnancy rate. What is known already Two retrospective cohort studies suggest that IVIG and prednisolone in combination result in a 34-37% live birth rate in RPL patients undergoing ART which is higher than the expected 12% for patients with RPL after ART. A randomized controlled trial (RCT) testing IVIG in RPL patients conceiving naturally indicated that very early administration of IVIG caused more positive effects than late administration, and prospective cohort studies suggest that treatment efficacy depends on presence of immune disturbances. No RCT has tested the IVIG/prednisolone combination starting before implantation and continued in very early pregnancy for RPL patients undergoing ART. Study design, size, duration In a randomized, double-blinded, placebo-controlled trial, patients undergoing IVF/ICSI/FET were treated with 400mg/kg IVIG and 5-10mg/day oral prednisolone or IV human albumin and oral placebo between January 2021 and March 2024. Oral treatment was administered from day one of menstrual cycle to GW 8 + 4, while IV treatment was given once in a short time interval before or after embryo transfer and repeated three times before GW 8 + 0. Primary outcome was ongoing pregnancy in GW 12 Participants/materials, setting, methods Seventy-four women <41 years old with ≥2 consecutive biochemical or clinical early pregnancy losses after ART were randomized 1:1 and underwent trial treatment along with their next IVF/ICSI/FET treatment. Patients were followed with weekly ultrasound scans in first trimester, however, if no implantation occurred, trial participation ended, and no re-entry was allowed. Exclusion criteria included antiphospholipid syndrome, BMI >35, uterine malformations, parental chromosomal translocations, AMH <4 pmol/l, drug contraindications, thyroid disease, and prior IVIG treatment. Main results and the role of chance Seventy-four patients have been randomized, and currently we are awaiting the last two patients to complete the treatment protocol before the code can be disclosed. Blinded interim analysis after inclusion of 38 patients showed no serious adverse events and an ongoing pregnancy rate of 30.0% and 9.5% (RR 1.8, 95% CI 1.0-3.1, Fisher’s exact test: p = 0.13), in the two allocation groups, respectively. Final, unblinded data on ongoing pregnancy rate, miscarriage rate and adverse events will be presented at the Congress if selected for presentation. Limitations, reasons for caution No published study has tested the same treatments in comparable patient groups which could have been the basis for the sample-size calculation, and the study is therefore at risk for being underpowered to evaluate the treatment effect in patients suffering from a combination of infertility, recurrent implantation failure, and RPL. Wider implications of the findings Blood samples were collected before first IV treatment and approximately 4 weeks later, which allow analysis for immunological disturbances and searching for biomarkers identifying those who will benefit from the treatment. This treatment could potentially increase success rate in patients undergoing ART after multiple unsuccessful treatment attempts. Trial registration number NCT04701034

P-602 Comparative analysis of recombinant human FSH and a biosimilar FSH preparation in controlled ovarian stimulation: a retrospective study of 12,952 oocyte donation and autologous cycles

Abstract Study question Does the type of FSH preparation used for ovarian stimulation, recombinant human FSH (r-hFSH) or biosimilar, influence reproductive success in oocyte donation and autologous cycles? Summary answer Ovarian response and reproductive outcomes, including live birth rates, are comparable in oocyte donation and autologous cycle, irrespective of the type of r-hFSH preparation used. What is known already Exogenous gonadotrophins, particularly FSH, have long been used in assisted reproduction, evolving from urinary to recombinant forms. The first generation of r-hFSH, including Puregon® and Gonal-f®, became available in the 1990s. However, interest in biosimilar FSH products has grown globally following the expiry of original patents. Approved by the European Medicines Agency, two r-hFSH biosimilars, Ovaleap® and Bemfola®, offer cost-effective alternatives for infertility treatments. Regulatory guidelines emphasize non-inferiority to the originator product, with clinical trials showing comparable outcomes between biosimilar and reference FSH preparations. However, debates persist regarding the efficacy and safety of r-hFSH biosimilars, particularly in achieving live births. Study design, size, duration In this retrospective cohort study, we compared reproductive outcomes following 8,429 controlled ovarian stimulations (COS) using r-hFSH Gonal-f® (n = 5,059) or the biosimilar FSH Bemfola® (n = 3,370), performed between January 2015 and December 2022 at a single fertility center. Overall, 242,978 mature (MII) oocytes were retrieved, utilized in 12,952 ICSI cycles (n = 11,421 heterologous and n = 1,531 autologous). We primarily evaluated ovarian response, measured by oocyte retrieval and maturation rates. Secondary outcomes included ongoing pregnancy and live birth rates. Participants/materials, setting, methods Participants included both oocyte donors (6,895 COS, 18-35 years) and patients using autologous oocytes (1,534 COS, 20-46 years). Univariate and multivariate analyses were performed separately across oocyte donor and patient groups. Outcomes in autologous cycles were further stratified by age. Regressions were adjusted for r-hFSH dose, antral follicle count (AFC), days of stimulation, age, BMI, use of menotropins, fertilization rates and number of embryos transferred, as appropriate. All p-values <0.05 were considered statistically significant. Main results and the role of chance Oocyte donors exhibited similar demographics (age, BMI, days of stimulation), however AFC was significantly higher in the biosimilar group compared to donors stimulated with Gonal-f® (11.31 ± 9.72 vs 7.63 ± 7.5). In patients, we observed no difference in demographic variables between study groups. A mean of 20.5 cumulus-oocyte complexes (COCs) and 15.7 MII oocytes were obtained across all COS. In oocyte donation cycles, the number of COCs retrieved was comparable between groups (22.6, Gonal-f®, 22.3, Bemfola®), however stimulation with Gonal-f® led to a slightly higher number of MII oocytes (17.6 vs 16.9, t-test p < 0.0001). Nevertheless, adjusted analyses revealed improved oocyte retrieval rates with Bemfola® (coeff 0.12, 95% CI: (0.05-0.18), p = 0.0006), while oocyte maturity rates were equivalent amongst the two groups (80% Gonal-f®, 77%, Bemfola®). Comparable results were observed in autologous cycles in terms of COCs (13.7, Gonal-f®, 12.7, Bemfola®) and number of MII oocytes (9.6, Gonal-f®, 9.0, Bemfola®). In autologous cycles, r-hFSH choice did not affect oocyte retrieval rates (coeff -3.3x10-04, 95% CI (-0,09-0,09), p > 0.05) nor oocyte maturation rates (coeff -2.7x10-04, 95% CI (-0,02-0,02), p > 0.05). Our adjusted analysis revealed comparable ongoing pregnancy and live birth rates between the study groups across all 12,952 ICSI cycles (p > 0.05 in all cases). Limitations, reasons for caution The main limitation of this study is its non-interventional retrospective cohort design, impacting generalizability to broader populations and diverse clinical settings. Despite its exploratory nature, the study’s scale, encompassing over 8,000 COS and close to 13,000 ICSI cycles, offers valuable insights into routine clinical care. Wider implications of the findings Comparable ovarian response, pregnancy and live birth rates following COS with Gonal-f® and Bemfola®, in both heterologous and autologous cycles, underscore the utility of biosimilars in ART. Our findings support the broader implications of EU’s policy on biosimilar interchangeability, ultimately enhancing patient access to a wider range of treatment options. Trial registration number not applicable

P-567 Is mosaic embryo transfer a valid alternative for patients lacking euploid embryos? a multicentric study from Argentina

Abstract Study question How does low-level mosaicism embryo transfer affect reproductive outcomes, including pregnancy rates and live birth success, compared to transfers involving euploid embryos? Summary answer Most mosaic embryo transfers do not affect reproductive outcomes, as live birth rates appear to be similar to those observed with euploid embryos. What is known already Preimplantation genetic testing (PGT) is used to identify embryonic genetic abnormalities and, ideally, select euploid embryos for intrauterine transfer, to improve clinical IVF outcomes. Chromosomal mosaicism is defined as the presence of two or more different chromosomal cell lines within an embryo. Numerous sources describe the proportion of mosaic embryos ranging from 4 to 22%. Several publications report that mosaic embryo transfer can lead to successful pregnancies and healthy deliveries, albeit at a lower frequency and with higher rates of pregnancy loss compared to euploid embryos. However, the impact of mosaicism on IVF outcomes remains a matter of controversy. Study design, size, duration Observational and retrospective multi-center study analyzed 6241 embryos from 1218 patients, across 4 IVF centers, who underwent PGT between 2016 and 2023 in a single genetics laboratory. Embryos were categorized as euploid, aneuploid, or mosaic. Patients in group A (n = 894) were transferred an euploid embryo, while in group B (n = 55), a low-grade mosaic embryo, defined as those having less than 40% (2016-2021) or 50% (2021-2023) aneuploid cells, was transferred. Participants/materials, setting, methods The embryos were biopsied and vitrified for later transfer. Blastocyst biopsy DNA was amplified using the SurePlex kit, processed with the VeriSeq kit (Vitrolife), and sequenced on a MiSeq platform. The results were analyzed using BlueFuse-Multi software. Mosaic embryo transfers were conducted only in the absence of a euploid embryo, following genetic counseling. beta-hCG levels >25 IU were considered positive, and clinical pregnancy was confirmed through ultrasound visualization of the gestational sac with heartbeat. Main results and the role of chance Among the analyzed embryos, the proportion of euploid was 46.2% (n = 2883), while mosaic embryos accounted for 19.3% (n = 1207), with 69.5% classified as low-grade and 30.5% as high-grade. Aneuploid embryos comprised 31.3% (n = 1954), and results could not be obtained for 3.2% (n = 197). Fifty-five low-grade mosaic embryos were transferred, including 19 with complete chromosomal mosaicism, 34 with segmental mosaicism, and 2 cases with 2 chromosomes involved in the mosaicism. The positive beta-hCG rate post-transfer was 50.3% for Group A, compared to 49.1% for Group B. Clinical pregnancy rates were 36.9% and 36.4%, respectively. Regarding live births, in Group A 328 (36.7%) children were born, and in Group B, 16 (29.1%), with 2 ongoing pregnancies. Conversely, pregnancy losses in Group B (9.1%) were higher compared to the euploid group (2.9%). Regarding pregnancy losses, in 3 cases no fetal heartbeats were identified, there was one miscarriage <20 weeks, and one twin gestation was lost after a normal non-invasive prenatal testing. In all cases the newborns were apparently healthy after mosaic embryo transfer, with an average gestational week at birth of 39 (37-41), and an average weight of 3197 (2900-4390) grams. Cesarean section was performed for 15/16 births, and one was born by vaginal delivery. Limitations, reasons for caution The study is limited by its retrospective nature and the small number of samples and mosaics transferred. Prenatal and postnatal tests were not conducted. Furthermore, the health of newborns was evaluated only in the initial months of life. Wider implications of the findings Mosaic embryo transfer is a valid alternative for couples lacking euploid embryos. This multicenter study adds evidence that mosaic embryo transfer does not have a clinically relevant impact on pregnancy and live birth rates, similar to what has been reported by other authors. Trial registration number ‘not applicable’

P-022 Klinefelter syndrome couples are expected higher live birth rates than unexplained NOA couples after ICSI with testicular spermatozoa

Abstract Study question What are sperm retrieval rates (SRR) by microdissection TESE (micro TESE), fertilization rates, and pre- and post- implantation development in Klinefelter syndrome (KS) couples? Summary answer In KS couples, SRR, clinical pregnancy rates (CPR) per embryo transfer (ET), and live birth rates (LBR) per patient were higher than unexplained NOA couples. What is known already Micro TESE, in combination with ICSI, is presently used to treat infertility in cases of NOA including KS, which is the most common sex-chromosome disorder among infertile males, with a prevalence of 1 in 660 men and is a frequent cause of hypogonadism and infertility. There were few reports regarding ICSI outcomes in the couples of KS. The aim of this study is to assess the prevalence and the significance including SRR by micro TESE of ICSI outcomes with embryonic development in KS couples. Study design, size, duration A retrospective study was conducted in 212 patients with non-mosaic KS and 963 unexplained NOA patients with 46, XY without past history (unexplained NOA; not including after orchidopexy, KS, cryptozoospermia, post chemotherapy, mumps orchitis, etc) who underwent micro TESE and ICSI with fresh or cryopreserved testicular spermatozoa for their wives between September 2013 to November 2023. Participants/materials, setting, methods A total of 2204 azoospermic patients were examined for chromosomal analysis. We evaluated SRR of microdissection TESE, two pronuclei (2PN) rates, blastocyst development rates, good-quality blastocyst (Grade 3BB and above on day 5 by the Gardner scoring) rates, CPR per ET, and LBR per couple patient who underwent micro TESE. We did not undergo preoperative hormonal therapy for KS patients. Statistical analysis was performed using unpaired t-tests and chi-squared tests. Main results and the role of chance We identified 212 KS out of 2204 azoospermic patients (9.6%). SRR of the first attempt micro TESE in KS (91/175=52.0%) was significantly higher than unexplained NOA (166/768=21.6%) (p < 0.001). 2PN, blastocysts development, and good-quality blastocysts rates were 49.2%, 42.9%, 16.9% in KS and 50.8, 45.8%, 21.0% in unexplained NOA respectively. Only good-quality blastocysts rate of KS was significantly lower than that of unexplained NOA (p < 0.01). Taking into account deflection of wives age, each result was calculated at their age 38 or under, but they were the same. CPR and LBR per ET in KS (42.6%, 30.4%) were significantly higher than unexplained NOA (33.1%, 23.7%) (p < 0.01, p < 0.05). The couples were 26.4% (56/212) in KS and 12.0% (116/963) in unexplained NOA (p < 0.001) who have given birth or ongoing pregnancy up to now after underwent micro TESE. That is, KS couples were significantly easier to give birth than unexplained NOA. Rates of congenital disorders had no significant difference between KS and unexplained NOA. Limitations, reasons for caution We did not show the data using ejaculated sperm with KS. The natal outcomes and development of these children has not been fully investigated, long-term follow-up of babies of the KS couples is needed. Wider implications of the findings Micro TESE is particularly helpful for KS cases, but embryonic development depend on the quality of spermatozoa. However, if a blastocyst can be obtained, the expectation of having a child is considered to be high. These results were shown to be useful in informing azoospermic couples undergoing micro TESE. Trial registration number not applicable

P-577 A randomized trial to compare the live birth rate following the progestin-primed ovarian stimulation versus the antagonist protocol in women with anticipated high ovarian responses

Abstract Study question Is there difference in the live birth rate following the progestin-primed ovarian stimulation (PPOS) versus the antagonist protocol in women with anticipated high ovarian responses? Summary answer The live birth rates of the first frozen embryo transfer following PPOS and the antagonist protocol were comparable in women with anticipated high ovarian responses. What is known already Progestin when given orally inhibits the pituitary LH surge during ovarian stimulation when taken orally i.e. progestin-primed ovarian stimulation. Two randomized trials showed similar number of oocytes for PPOS and the antagonist protocol in oocyte donation cycles. However, there is still no randomized trial to compare the live birth rate between PPOS and the antagonist protocol. Study design, size, duration This is a randomized controlled trial of 784 infertile women conducted from June 2020 and October 2021. Participants/materials, setting, methods Infertile women aged <43 years undergoing the first IVF cycle in a tertiary fertility center and having antral follicle count >15 randomly assigned in a 1:1 ratio into two groups: PPOS group and the antagonist group. Medroxyprogesterone 10 mg daily was given from the start of ovarian stimulation until the day of ovulation trigger in the PPOS group. The primary outcome was the live birth rate of the first frozen embryo transfer. Main results and the role of chance 784 women were randomly assigned into two groups: PPOS group (n = 392) and antagonist group (n = 392). Embryo transfer was either cancelled or postponed in 62 (62/392, 15.8%) women in the PPOS group and 65 (65/392, 16.6%) in the antagonist group because of no transferable embryos or no frozen embryo transfer within 6 months following randomization. The two groups were similar in demographic characteristics and number of oocytes obtained/fertilized, the number of cleaving embryos, number of good quality embryos at day 3, number of blastocysts developed and number of embryo/blastocyst frozen. There was no statistically significant difference in the live birth rate of the first frozen embryo transfer cycle between the progestin-primed ovarian stimulation and antagonist groups based on both intention to treat [37.5.0% (147/392) versus 32.7% (128/392), RR 1.148 (95% CI = 0.949–1.390), P = 0.16] and per protocol analysis [44.5% (147/330) versus 39.1.% (128/327), RR 1.138 (95%CI = 0.950–1.364), P = 0.16]. Both groups showed comparable clinical pregnancy, ongoing pregnancy, miscarriage, multiple pregnancy, ectopic pregnancy and cumulative live birth rates. Limitations, reasons for caution Women with anticipated high ovarian responses were recruited and the results may not be extrapolated to the general population seeking IVF. This is not a blind study although the live birth rate as the primary outcome is objection. The duration of the study is 6 months since randomization. Wider implications of the findings In situations in which fresh embryo transfer is not required such as oocyte/embryo freezing for fertility preservation, oocyte donation or preimplantation genetic testing, the PPOS protocol may be preferred over the antagonist protocol. Trial registration number NCT04414761

P-429 Measuring serum progesterone levels on the day of a fresh blastocyst transfer is debatable as there is no evidence for correlation with ongoing pregnancy results

Abstract Study question Does serum progesterone (P4) level on the day of a fresh blastocyst transfer relate to ongoing pregnancy rate (OPR)? Summary answer OPR after a fresh single blastocyst transfer seems not to be associated with serum P4 level on the day of transfer. What is known already Several studies have suggested an optimal serum P4 threshold for embryo transfers in frozen embryo transfer cycles. However, for fresh embryo transfers, data are scarce and conflicting. Study design, size, duration A retrospective single-center cohort study was performed on 598 complete data cycles, retained out of 631 consecutive fresh single blastocyst transfer cycles. Data were collected from patients undergoing a fresh IVF/ICSI cycle with autologous oocytes at a tertiary fertility center between June 2022 and August 2023. Participants/materials, setting, methods A total of 482 unique patients underwent one or more single fresh blastocyst transfers using micronized vaginal progesterone (MVP) 800mg BID for luteal phase support starting day after oocyte retrieval. Serum P4 levels were determined on day of transfer. The primary endpoint was OPR, positive hCG-test and early pregnancy loss (EPL) were secondary endpoints. Unadjusted and adjusted generalized estimating equations (GEE) assessed P4 level association with the endpoints, using an exchangeable working correlation matrix. Main results and the role of chance No association was identified between P4 levels on day of transfer and OPR after accounting for maternal age, blastocyst quality, P4 and estradiol level at last ultrasound, BMI and endometrial thickness. Data were grouped according to 10/50/90 and 25/50/75 percentiles, resulting in groups < = or > 27ng/ml and < = or > 40ng/ml, with omission of 90th and 75th percentile groups due to right-skewed distribution. With serum P4 levels higher than 40ng/ml, the probability of a positive hCG-test significantly increased (OR 1.79, CI 1.11-2.91; p = 0.018). No significant difference was observed in patients with serum P4 < = or > 27ng/ml (OR 1.23, CI 0.66-2.30; p = 0.506). Regarding OPR, no significant differences were observed when comparing patients with serum P4 < = or > 27/ng/ml or < = or > 40ng/ml (OR 0.88, CI 0.42-18.85; p = 0.736 and OR 1.41, CI 0.83-2.37; p = 0.203, respectively). Moreover, EPL did not significantly differ between serum P4 level groups (OR 1.93, CI 0.61-6.13; p = 0.265 and OR 1.2, CI 0.51-2.84; p = 0.674). Age (p < 0.001) and embryo quality (p < 0.001) are significantly related with OPR. Additionally, late follicular progesterone levels and OPR are significantly associated (OR 2.39, CI 1.16-4.95 in patients with P4 < = or > 27/ng/ml and OR 2.21, CI 1.07-4.55 in patients with < =40ng/ml and >40ng/ml). Limitations, reasons for caution Limitations include the retrospective design and the lack of live birth outcome data. Progesterone levels exceeding 60 ng/ml were not further analyzed to their precise value but grouped as 60 plus which did not allow to identify potential detrimental effects of very high P4 levels on treatment outcome. Wider implications of the findings Our data suggest that measuring P4 on the day of a single blastocyst transfer with MVP luteal phase support may not be indicative of OPR or the risk of EPL. This raises questions regarding the necessity for routine P4 measurements as well as the development of rescue strategies. Trial registration number ONZ-2023-0628

P-723 Egg-conomized frozen embryo transfer

Abstract Study question Is home-based monitoring of ovulation cost effective compared with hospital-controlled ovulation in women undergoing frozen embryo transfer in the natural cycle? Summary answer Home-based monitoring to time frozen-embryo-transfer is cost-effective compared to hospital-controlled ovulation, as it results in lower cost with no difference in ongoing pregnancy rates. What is known already Women undergoing frozen embryo transfer treated by home-based monitoring of ovulation or hospital-controlled ovulation have comparable ongoing pregnancy rates. We found no differences in secondary outcomes, including the risk of undetected ovulation. Complete home-based monitoring of ovulation with LH hormone kits is feasible and requires no hospital visits at lower costs since ultrasound monitoring and hCG injection are no longer needed. Both consequences imply potentially lower costs after home-based monitoring of ovulation. Study design, size, duration We performed an economic evaluation of home-based monitoring of ovulation compared with hospital-controlled ovulation in a national multicentre randomised controlled trial in women undergoing frozen embryo transfer (ANTARCTICA-2 RCT Dutch TrialRegister Trial NL6414). 1464 women were randomly assigned between April 10, 2018, and April 13, 2022, with 732 allocated to home-based monitoring and 732 to hospital-controlled monitoring. All randomized patients were included according to the intention-to-treat principle. Participants/materials, setting, methods We performed a cost-effectiveness analysis from a hospital and societal perspective. We compared the direct medical costs of home-based monitoring of ovulation and hospital-controlled ovulation during one cycle until an ongoing pregnancy occurred. Direct medical costs included digital ovulation tests, transvaginal ultrasound monitoring of the dominant follicle followed by hCG trigger, hormone measurements in blood, treatment for miscarriage or ectopic pregnancy. Nonparametric bootstrapping was used to calculate cost estimates and differences with 95% confidence intervals. Main results and the role of chance Ongoing pregnancy rates were 20·8% in the home-based monitoring group and 20·9% in the hospital-controlled group (risk ratio [RR] 0·99 [90% CI 0·81 to 1·22]; risk difference [RD] -0·14 [90% CI -3·63 to 3·36]). No differences in ectopic pregnancies or miscarriages were found. Home-based monitoring required less travelling to the hospital, less ultrasounds by doctors or nurses, less hormone measurements in blood, and less medication (hCG injections). Mean direct medical costs per woman in the home-based monitoring of ovulation group and in the hospital-controlled ovulation group were €752 versus €991, respectively, with a mean difference of €239. The ICER consistently showed home-based monitoring to be less costly with no difference in effectiveness. Consequently, the cost difference from a societal perspective was larger. The mean costs per woman in the home-based monitoring of ovulation group and in the hospital-controlled ovulation group were €787 versus €1395, respectively, with a mean difference of €607 in favour of home-based monitoring. Limitations, reasons for caution We report on one cycle per women. Women usually undergomultiple frozen-embryo-cycles. This is of importance for clinical decision making aboutimplementation of home-based monitoring, since the cumulative benefit of multiple cycles perwoman should be taken into account. Wider implications of the findings The results of our trial show that home-based monitoring time frozen embryo transfer is equally effective but less costly compared with hospital-controlled ovulation. In this era of climate change and shortages of hospital staff and waiting lists, any process that takes less human labour is important. Trial registration number Dutch Trial Register (Trial NL6414)

P-285 Serum progesterone level may not impact ongoing pregnancy rate (OPR) in patients with endometriosis undergoing frozen-warmed-blastocyst transfer employing hormone replacement treatment (HRT) with subcutaneous progesterone

Abstract Study question Do serum progesterone (P4) levels on frozen embryo transfer (FET)-1 day impact OPRs in patients with endometriosis undergoing HRT-FET with subcutaneous progesterone (sc P)? Summary answer In HRT cycles employing sc P, serum P4 levels on FET-1 day do not affect OPRs in patients with or without endometriosis. What is known already In HRT-FET cycles employing vaginal P, reproductive outcomes are improved by serum P4 monitoring and employing a rescue protocol, if needed. However, there is paucity of data for the need of serum P4 monitoring in HRT cycles employing sc P. Endometriosis is associated with P4 resistance. There is only one study evaluating the impact of serum P4 levels on reproductive outcomes in patients with endometriosis; in this study lacking a control group and employing vaginal P gel 90 mg/12 hours supplemented by daily 50 mg intramuscular P, a threshold of 37.1 ng/ml has been reported for improved live birth rates. Study design, size, duration Retrospective cohort study. 451 consecutive patients undergoing their first HRT- vitrified warmed blastocyst transfer during November 2021-June 2023 at Anatolia IVF Centre were included. 44 patients had endometriosis with surgical and/or ultrasound findings and the remaining 407 patients did not harbor endometriosis. The presence of adenomyosis was an exclusion criterion. Following 10-12 days of 6 mg/day estradiol valereate use, sc P 25 mg/12hours (Prolutex, Ibsa) was administered. The primary outcome measure was OPR. Participants/materials, setting, methods Serum P4 levels were measured 4-5 hours after morning administration of sc P on FET-1 day. The impact of serum P4 on OPRs was assessed at various percentiles adjusting for female age, body mass index, prior birth, preimplantation genetic testing for aneuploidy, number/grade of blastocysts transferred. Multivariate regression models were performed in the whole cohort incorporating polynomial P4 terms and endometriosis interactions; optimal model for OPR prediction was selected using the lowest Akaike Information Criteria. Main results and the role of chance Patients with (27/44, 61.4%) and without (214/407, 52.6%) endometriosis had comparable OPRs. In the endometriosis group, the 10th, 50th, and 90th percentiles of serum P4 were 15.6, 25.1, and 35.4 ng/ml, respectively, compared to 14.9, 23.5, and 35.6 ng/ml in the non-endometriosis group. In the endometriosis group, the OPRs were 60.0%, 66.7%, 56.3%, and 60.0% for the <10p, 10-50p, 50-90p, >90p groups, respectively. These figures were 46.3%, 50.3%, 56.8%, and 51.2%, in the non-endometriosis group, respectively. In the endometriosis group, taking the 50-90p group as the reference, the adjusted odds ratios (aORs) for OPR of < 10p, 10-50p, and >90p groups were 1.24 [0.03, 50.45], 1.77 [0.31, 10.24], and 2.08 [0.05, 80.23], respectively. In the non-endometriosis group, the respective aORs were 0.85 [0.40, 1.79], 0.80 [0.49, 1.29], and 0.72 [0.34, 1.50]. In the multivariate regression analysis to determine the optimal model, neither serum P4 levels (aOR for linear term: 1.11 [0.98, 1.26]; for quadratic term: 0.998 [0.996, 1.00]) nor the diagnosis of endometriosis (OR: 1.48 [0.74, 2.98]) significantly predicted ongoing pregnancy after adjusting for confounders. Additionally, the optimal model did not include the interaction term, suggesting that endometriosis does not significantly modify the impact of serum P4 levels on OPRs. Limitations, reasons for caution The study’s limitations include retrospective study design, a limited sample size of the endometriosis cohort, absence of laparoscopy for endometriosis exclusion in the non-endometriosis group, and lack of data on endometriosis phenotypes. Wider implications of the findings In HRT-FET cycles employing sc P 25 mg/12hours neither serum P4 nor the presence of endometriosis have an impact on OPRs. Endometriosis may not modify the impact of serum P4 on OPRs suggesting a lack of P resistance in such cycles or the overcoming of P resistance by this regimen. Trial registration number not applicable

P-412 Elevated progesterone levels after hormone replacement therapy (HRT) for frozen embryo transfer (FET) does not impair IVF outcomes, a retrospective study

Abstract Study question Does high serum progesterone (P) level on the day of FET after hormone replacement therapy affect IVF outcomes? Summary answer The supraphysiological serum progesterone levels on the day of FET after HRT do not impair reproductive outcomes. What is known already A proper synchronization between embryo and the endometrium is still required by controlling the timing and the dosage of exposure to exogenous hormones. Previous observational studies have highlighted the negative effects of serum hormone levels at the minimum threshold during FET cycles. However, based on existing research, the relationship between progesterone levels on FET day and pregnancy outcomes as well as the certain dose of progesterone ideally to achieve pregnancy and a live birth are debatable topics Study design, size, duration This is an observational, retrospective and cohort study including 7539 FET cycles that were performed under artificial endometrial preparation with HRT using exogenous estradiol and progesterone (vaginal, subcutaneous and intramuscular) between January 2017 and December 2022. Both euploid FET from autologous oocyte ICSI-PGT-A cycles (n = 1822) or FET from ICSI cycles using donated oocytes (n = 5724) were considered. Participants/materials, setting, methods Women were divided into three groups according to P4 level on the day of FET:P<20 ng/ml (n = 6623),P≥20-40 ng/ml (n = 770) and P > 40 ng/ml (n = 146).All ET were performed at the blastocyst stage.The primary outcome was live birth rate (LBR). Secondary outcomes evaluated were biochemical, clinical, and ongoing pregnancy, and miscarriage rate (MR) calculated per FET.Categorical variables were compared between groups with Fisher’s exact test. Logistic regression models adjusted (AOR) with several confounders. Main results and the role of chance There were no significant differences in baseline characteristics of the study population. The mean of P4 level was 15,66 ng/ml. Female age was P < 20:38.7 ±3.1, P ≥ 20-40: 39.0 ±3.0, and P > 40: 38.1 ±2.9 (p = 0.53) years old. The group with the highest progesterone levels always found lower biochemical pregnancy even no statistically significant [64.6% (P < 20) vs 63.7% (P ≥ 20-<40) vs 61.1% (P > 40); p = 0.62]; in clinical pregnancy [56.3% (P < 20) vs 56.8% (P ≥ 20-<40) vs 51.4% (P > 40); p = 0.5] and in ongoing [47.0% (P < 20) vs 47.0% (P ≥ 20-<40) vs 41.8% (P > 40); p = 0.47] pregnancy rates. The MR was also higher in the group with higher progesterone, although not significantly: 16.2% (P < 20) vs 15.0% (P ≥ 20-<40) vs 18.0% (P > 40) (p = 0.60). No statistically significant differences were reported for live birth rate, 41.8% (P < 20) vs 40.3% (P ≥ 20-<40) vs 34.2% (P > 40) (p = 0.2). The multivariate analysis showed an increased risk of miscarriage when P > 40ng/ml, aOR= 1.14 (0.75-1.74) (p = 0.55) whereas no such association was found with P4 ≥20-40 ng/ml, aOR=0.92 (0.74-1.15) (p = 0.46). Additionally, the probability of live birth is similar when the patient was P > 40 (aOR= 0.77 (0.51-1,15) (p = 0.20)) than when P ≥ 20-<40 (aOR=0.94 (0.79-1,11) (p = 0.47) compared with the references group. Limitations, reasons for caution The retrospective design and different female factors for IVF were included in the study leading to a possible biased population although the adjusted analysis. Different routes of progesterone administration were considered in the study. Currently, we don’t report the timing between the last P4 administration and dosage on the FET. Wider implications of the findings This information is useful for clinicians who monitor progesterone levels prior to FET to avoid reaching high levels that would undermine the chances of achieving a newborn. Trial registration number Not Applicable

P-680 Comparison of ovarian hyperstimulation syndrome (OHSS) rates resulting from conventional dosing versus personalized dosing of follitropin delta in ovarian stimulation, analysis of RITA, ESTHER-1 trials

Abstract Study question To compare OHSS rates with conventional dosage of follitropin delta in the RITA-1 and RITA-2 trials (hereafter ‘RITA’) to personalized dosing in the ESTHER-1 trial. Summary answer RITA and ESTHER-1 had similar efficacy and OHSS rates despite differences in dosing regimens, possibly due to differences in fresh transfer cancellation rates. What is known already Follitropin delta is a human cell-line derived follicle stimulating hormone whose fixed dosage in ovarian stimulation, personalized based upon body weight and serum anti-Müllerian hormone (AMH) and body weight, has been shown to be safe and effective in Gonadotrophin Releasing Hormone (GnRH) antagonist ovarian stimulation protocols. In the present trial, conventional dosing of follitropin delta allowing for dose revisions has been evaluated in GnRH antagonist ovarian stimulation protocols to demonstrate the broad utility of this gonadotrophin therapeutic and to address United States (US) regulatory considerations. Study design, size, duration RITA were randomized, double-blind, controlled, US multicentre trials of follitropin delta. The primary endpoint was cumulative ongoing pregnancy rate after fresh/frozen transfers within 12 months of cycle start. 1058 women 18-42 years randomized 10:1 to follitropin delta or placebo. ESTHER-1 was a randomized, European multicentre, assessor-blind, noninferiority trial of follitropin delta. The primary endpoints were fresh transfer ongoing pregnancy and implantation rates. 1329 women 18-40 years randomized 1:1 to follitropin delta or follitropin alfa. Participants/materials, setting, methods In RITA, 12 µg/day, 15 µg/day dosages were used for 4 days: 18-34 or 35-42 years, respectively, with 3 µg dose adjustments thereafter depending on response. Human chorionic gonadotropin (hCG) was used if < 20 follicles of ≥ 12 mm and estradiol level <3,000 pg/mL. Else, agonist trigger and fresh transfer cancellation; ≥20 oocytes retrieved also cancelled fresh transfer. In ESTHER-1, hCG was used if < 25 follicles of ≥ 12 mm. Else, agonist trigger, and fresh transfer cancellation. Main results and the role of chance The ongoing pregnancy rate per fresh transfer with follitropin delta was 41.9% in RITA and 36.3% in ESTHER-1. The primary efficacy endpoint was met for all 3 trials. Rates and severity defined by Golan criteria of OHSS observed in RITA and ESTHER-1 were similar, respectively for: all OHSS, any grade (3.1% versus 3.5%), Grade 1 (0.3% versus 0.5%), Grade 2 (0.8% versus 0.9%), Grade 3 (1.8% versus 1.1%), Grade 4 (0.2% versus 0.6%), and Grade 5 (0.1% versus 0.5%). The rate of early OHSS, defined as onset ≤9 days after trigger of final follicular maturation, was also similar, respectively for any grade (2.2% versus 2.6%), Grade 1 (0.3% versus 0.3%), Grade 2 (0.6% versus 0.9%), Grade 3 (1.1% versus 0.8%), Grade 4 (0.1% versus 0.3%) and Grade 5 (0.1 % versus 0.3%). However, the fresh transfer cancellation rate was >3x higher in RITA (35.2%) than in ESTHER-1 (11.1%). Limitations, reasons for caution Other reasons for transfer cancellation in all trials included adverse events or no blastocyst available for transfer; however, no significant differences were observed. A placebo comparator was selected for RITA to meet regulatory requirements for double-blinding; women with ≤3 oocytes retrieved were offered support for treatment outside of the trials. Wider implications of the findings Stimulation with follitropin delta is effective and associated with low rates of OHSS when used with either conventional or personalized dosing. However, stricter criteria for the use of hCG as trigger and allowance of fresh transfer may be required with conventional dosing to maintain this safety profile. Trial registration number NCT01956110, NCT03740737, NCT03738618

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