Oocyte Survival Research Articles

Beyond the egg: sperm source does not impact cumulative live birth rates in autologous oocyte cryopreservation patients when adjusted for oocyte age.

To assess the impact of sperm source on cumulative live birth rate (CLBR) after oocyte thaw in autologous oocyte cryopreservation (AOC) patients. A retrospective cohort study of autologous oocyte thaw patients at an urban academic fertility center from 2006 to 2021. Patients were stratified by sperm source [partner sperm (PS) vs. donor sperm (DS)]. The primary outcome was CLBR per patient. Secondary outcomes were the oocyte survival rate and usable embryo rate. Statistics included Mann-Whitney U, Kruskal-Wallis, Fisher's exact, chi-square, two-sample t-tests, and multiple logistic regression (p < 0.05). A total of 653 patients were included; 455 (69.7%) used PS and 198 (30.3%) used DS. Time from the first AOC to the first thaw did not differ among DS and PS users (56.8 vs. 54.0months, p = 0.20). PS users were younger at AOC (37.9 vs. 38.5years, p < 0.001) and thaw (42.3 vs. 43.1years, p < 0.001). There were equivalent overall CLBRs (39.9% PS vs. 40.6% DS, p = 0.85) and CLBRs in patients < 35years at AOC (51.2% PS vs. 100% DS, p = 0.18), 35-37years at AOC (45.9% PS vs. 60.4% DS, p = 0.10), 38-40years at AOC (35.4% PS vs. 35.2% DS, p = 0.93), 41-42years at AOC (28.9% PS vs 14.3% DS, p = 0.21), and > 43years at AOC (12.5% PS vs 16.7% DS, p = 0.83) among PS and DS users. There were no significant differences in the oocyte survival (79% PS vs 80.5% DS, p = 0.08) or the proportion of patients with usable embryos (27.3% vs 27.8%, p = 0.70) between PS and DS groups. In AOC patients, CLBR, oocyte survival rate, and usable embryo rate did not differ based on sperm source.

Air pollution exposure in vitrified oocyte donors and male recipient partners in relation to fertilization and embryo quality.

Studies on air pollution and outcomes of in vitro fertilization (IVF) have focused on couples undergoing autologous IVF, in which it is challenging to disentangle maternal and paternal exposures during gametogenesis. We sought to evaluate the independent associations between air pollution exposure during oogenesis and spermatogenesis on fertilization and embryo quality in non-identified donor oocyte IVF cycles. Our study included 500 oocyte donors and 915 male recipient partners who contributed 1,095 oocyte thaw cycles (2008-2019). Daily ambient air pollutant exposure was estimated using spatio-temporal models based on residential address and averaged over folliculogenesis (i.e., three months prior to initiation of controlled ovarian stimulation), controlled ovarian stimulation, and spermatogenesis (i.e., 72days prior to oocyte thaw). We used multivariable generalized estimating equations to estimate the adjusted odds ratios (aOR) and 95% confidence intervals (CI) for an interquartile range increase in pollutant exposure in relation to the proportion of oocytes surviving thaw, oocytes fertilized, and usable embryos. Oocyte donors with higher exposure to organic carbon (OC) (aOR=0.86 95%CI 0.79,0.94) and particulate matter<10µm (aOR=0.69 95%CI 0.54,0.90) during folliculogenesis had a lower proportion of oocytes surviving thaw. During ovarian stimulation, higher particulate matter<2.5µm (aOR=0.78 95%CI 0.66, 0.91), nitrate (aOR=0.83 95% CI 0.69,0.99), and OC (aOR=0.86 95% CI 0.80,0.93) exposure was associated with a lower proportion of surviving oocytes while nitrogen dioxide (aOR=1.11 95%CI 1.00,1.23) and ozone (aOR=1.19 95%CI 1.04,1.37) exposure was associated with a higher proportion of fertilized oocytes and usable embryos. Elemental carbon (aOR=0.93 95%CI 0.87,1.00) and OC (aOR=0.95 95%CI 0.90,1.00) exposure during spermatogenesis was associated with a slightly lower proportion of usable embryos. On the day of oocyte thaw, higher ambient OC at the IVF clinic was associated with lower oocyte survival and higher ozone was associated with lower fertilization. Both maternal and paternal air pollution exposures during gametogenesis have independent, largely detrimental, effects on early embryological outcomes.

Control of sperm penetration using stereumamide A derived from Trichaptum fuscoviolaceum in the in vitro fertilization of pig oocytes.

Fungal metabolites are known to have potent and diverse properties such as antiviral, antidiabetic, antitumour, antioxidant, free radical scavenging, and antibacterial effects which can be utilized to treat diseases. In this study, we investigated the functional activity of stereumamide A (StA) derived from a culture broth of Trichaptum fuscoviolaceum during the in vitro fertilization (IVF) of pig oocytes, to determine its effects on sperm penetration. Oocytes matured in vitro were fertilized in the absence or presence of varying concentrations of StA (0-50 μg/ml StA). When StA was directly added into the IVF medium, significantly lower fertilization rates were seen with the 20 or 50 μg/ml StA (2.0-17.5%) treatments compared with those of 10 μg/ml StA or the controls (60.9-62.3%), whereas StA had no influence on the survival of oocytes and spermatozoa throughout the IVF process. For evaluating the control of sperm entry, mature oocytes were pre-incubated in a medium containing 20 μg/ml StA for 1 h, and then IVF was subsequently performed. The incidence of polyspermy was significantly reduced when oocytes were pre-incubated with StA (15.0% vs. 50.4-57.5% in controls). In conclusion, sperm penetration was inhibited in the medium in the presence of StA during IVF, while StA did not affect sperm motility and fertility competence. Fertilization was controlled when mature oocytes were incubated with StA prior to IVF, suggesting the possible use of the fungal metabolite in assisted reproductive technology for humans and animals.

Oocytes Vitrification Using Automated Equipment Based on Microfluidic Chip.

Oocyte vitrification has a wide range of applications in assisted reproduction and fertility preservation. It requires precise cryoprotectant agents (CPAs) loading and removal sequences to alleviate osmotic shock, which requires manual manipulation by an embryologist. In this study, a microfluidic system was developed to facilitate the precise adjustment of the CPA concentration around the oocyte by linear loading and removal of CPA. In addition, the microfluidic-based automated vitrification (MAV) device combines CPA loading/removal process, with vitrification process, thereby achieving automated oocyte vitrification. Oocytes were vitrified by Cryotop/QC manual method and MAV method. The results showed that the survival, cleavage, and blastocyst rates of oocytes were 80.44, 54.17, and 32.95% for the MAV method, which were significantly higher than Cryotop manual method (73.35, 43.73, and 23.67%) (p < 0.05). In MAV, solution injection rate during CPA loading/removal process was designed as a 1-segment, 2-segment, and 4-segment function. Accordingly, three concave loading and convex removal protocols were adopted to vitrify oocytes. Oocytes vitrified using the 4-segment function group exhibited increased survival (86.18%), cleavage (63.29%), and blastocyst (45.58%) rates compared to those vitrified using the 1-segment and 2-segment groups. The oocytes vitrification with the highest concentration of CPA, denoted as VS1-TS1, exhibited the highest survival rate after rewarming (86.18%). In contrast, the VS3-TS3 group, characterized by a CPA concentration half that of VS1-TS1, exhibited lower survival (74.14%) and cleavage (59.31%) rates, but displayed the higher blastocyst rate (50.79%) following oocyte activation. Our study demonstrates potential of the MAV device for oocyte or embryo vitrification.

Single-cell and bulk transcriptional profiling of mouse ovaries reveals novel genes and pathways associated with DNA damage response in oocytes

Immature oocytes enclosed in primordial follicles stored in female ovaries are under constant threat of DNA damage induced by endogenous and exogenous factors. Checkpoint kinase 2 (CHEK2) is a key mediator of the DNA damage response (DDR) in all cells. Genetic studies have shown that CHEK2 and its downstream targets, p53, and TAp63, regulate primordial follicle elimination in response to DNA damage. However, the mechanism leading to their demise is still poorly characterized. Single-cell and bulk RNA sequencing were used to determine the DDR in wild-type and Chek2-deficient ovaries. A low but oocyte-lethal dose of ionizing radiation induces ovarian DDR that is solely dependent on CHEK2. DNA damage activates multiple response pathways related to apoptosis, p53, interferon signaling, inflammation, cell adhesion, and intercellular communication. These pathways are differentially employed by different ovarian cell types, with oocytes disproportionately affected by radiation. Novel genes and pathways are induced by radiation specifically in oocytes, shedding light on their sensitivity to DNA damage, and implicating a coordinated response between oocytes and pregranulosa cells within the follicle. These findings provide a foundation for future studies on the specific mechanisms regulating oocyte survival in the context of aging, therapeutic and environmental genotoxic exposures.

Assessing the effect of below-benchmark vitrified/warmed donor-oocyte survival rates in subsequent laboratory and clinical outcomes

To assess the impact of below-benchmark (95-100%) donor oocyte survival rates to vitrification/warming in the laboratory and clinical outcomes of recipient cycles. Retrospective cohort study. We analyzed 12690 vitrified-warmed donor oocyte recipient cycles carried out in a network of European private IVF units from 2018-2022. All cycles analyzed used exclusively vitrified/warmed donor oocytes. The cycles were grouped according to the survival rate experienced: benchmark 95-100%; competence 85-95%; below-competence 70-85%; poor 50-70%; very poor <50%. The primary endpoint of the study was the total usable blastocyst rate per 2PN zygote. Secondary endpoints were the fertilization rate, the live birth rate after the first single blastocyst transfer, and the cumulative live birth rate. The mean number of warmed oocytes per ICSI cycle was 11.4±3.2 with a mean survival rate of 89.1%. More oocytes per cycle were consumed in the lower survival groups, yet the total oocytes available for ICSI was smaller in the below-competence, poor and very-poor survival groups. The total usable blastocyst rate was lower in the lower survival groups (benchmark: 48.9%; competence: 47.0%, below-competence: 46.0%; poor: 43.6%; very-poor:43.6%, p<0.001), as well as the fertilization rates (benchmark: 76.8%; competence: 76.6%, below-competence: 75.6%; poor: 74.7%; very-poor:75.5%, p<0.001). The adjusted relative risk of live-birth rate of the first embryo transferred was equal to the benchmark survival group in all the lower survival groups (Benchmark: 40.9%; Competence: RR=0.986, 95%CI:0.931-1.045; below-competence: RR=0.992, 95%CI:0.929-1.059; poor: RR=1.103, 95%CI:1.009-1.207; and very-poor: RR=1.169, 95%CI:0.963-1.419). The cumulative live-birth rate decreased in lower survival groups compared to benchmark survival (Benchmark: 79.2%; Competence: RR=0.988, 95%CI:0.961-1.015; below-competence: RR=0.911, 95%CI:0.880-0.944; poor: RR=0.802, 95%CI: 0.757-0.851; and very-poor: RR=0.793, 95%CI: 0.693-0.907). The lower cumulative rates maintained in a sub-analysis with equal M-II available for ICSI (Benchmark: 69.5%; Competence: RR=0.909, 95%CI:0.827-1.000; below-competence: RR=0.942, 95%CI:0.848-1.046; poor: RR=0.833, 95%CI:0.7386-0.941; and very-poor: RR=0.873, 95%CI:0.695-1.097). Lower donor-oocyte cryo-survival rates have a moderate negative impact on the blastocyst utilization rate per 2PN zygote, fertilization rate and the cumulative live-birth rates of a donation cycle, even after adjusting for equal M-II oocytes available for ICSI. Nonetheless, the surviving oocytes of a cohort seem to maintain a high competence level, with very similar laboratory outcomes, irrespectively of the cohort's survival rates, as well as equal implantation potential of the resulting blastocysts.

Antifreeze protein type I in the vitrification solution improves the cryopreservation of immature cat oocytes

Oocyte cryopreservation is not yet considered a reliable technique since it can reduce the quality and survival of oocytes in several species. This study determined the effect of different concentrations of antifreeze protein I (AFP I) on the vitrification solution of immature cat oocytes. For this, oocytes were randomly distributed in three groups and vitrified with 0 μg/mL (G0, 0 μM); 0.5 μg/mL (G0.5, 0.15 μM), or 1 μg/mL (G1, 0.3 μM) of AFP I. After thawing, oocytes were evaluated for morphological quality, and compared to a fresh group (FG) regarding actin integrity, mitochondrial activity and mass, reactive oxygen species (ROS) and glutathione (GSH) levels, nuclear maturation, expression of GDF9, BMP15, ZAR-1, PRDX1, SIRT1, and SIRT3 genes (normalized by ACTB and YWHAZ genes), and ultrastructure. G0.5 and G1 presented a higher proportion of COCs graded as I and while G0 had a significantly lower quality. G1 had a higher percentage of intact actin in COCs than G0 and G0.5 (P < 0.05). There was no difference (P > 0.05) in the mitochondrial activity between FG and G1 and they were both higher (P < 0.05) than G0 and G0.5. G1 had a significantly lower (P < 0.05) mitochondrial mass than FG and G0, and there was no difference among FG, G0, and G0.5. G1 had higher ROS than all groups (P < 0.05), and there was no difference in GSH levels among the vitrified groups (P > 0.05). For nuclear maturation, there was no difference between G1 and G0.5 (P > 0.05), but these were both higher (P < 0.05) than G0 and lower (P < 0.05) compared to FG. Regarding gene expression, in G0 and G0.5, most genes were downregulated compared to FG, except for SIRT1 and SIRT3 in G0 and SIRT3 in G0.5. In addition, G1 kept the expression more similar to FG. Regardless of concentration, AFP I supplementation in vitrification solution of immature cat oocytes improved maturation rates, morphological quality, and actin integrity and did not impact GSH levels. In the highest concentration tested (1 μg/mL), AFP maintained the mitochondrial activity, reduced mitochondrial mass, increased ROS levels, and had the gene expression more similar to FG. Altogether these data show that AFP supplementation during vitrification seems to mitigate some of the negative impact of cryopreservation improving the integrity and cryosurvival of cat oocytes.

Effects of orange peel extract (Citrus sinensis) treatment on zebrafish oocytes (Danio rerio) exposed to heat stress.

Heat stress (HS) can negatively impact oocytes by disrupting mitochondrial activity, increasing the production of reactive oxygen species, and decreasing antioxidant levels. This study investigated the impact of orange peel (OP) exposure on zebrafish oocytes (ZOs) diameter, survival rate, and germinal vesicle breakdown (GVBD) during HS. We investigated the antioxidant effect of flavonoids (concentration = 328.58 ppm) derived from OP (Citrus sinensis) added to in vitro maturation (IVM) media of ZOs (Danio rerio) under non-heat stress (NHS) and HS conditions to mimic in vivo HS conditions due to the global warming phenomenon on females. ZO in stage 3 (n = 1080) was treated with 4 μL of OP extract (not treated/control) under HS: 32°C (Heat stress 32°C solution/Heat stress 32°C orange peel [HS32S/HS32O]) and 34°C (Heat stress 34°C solution/Heat stress 34°C orange peel [HS34S/HS34O]); and NHS: 28°C (Non-heat stress solution/Non-heat stress orange peel [NHSS/NHSO]), during maturation. After 24 h of maturation, we observed the oocyte diameter, survival rate, and GVBD rate. The data were analyzed with IBM Statistics 23 software using two-way analysis of variance and Kruskal-Wallis (p < 0.05). The highest oocyte diameter data were in NHS treated with OP extract (NHSO) group (0.759 ± 0.01; mean ± standard error) compared with HS group using and without OP extract (HS32S [0.583 ± 0.02]; HS32O [0.689 ± 0.02]; HS34S [0.554 ± 0.02]; and HS34O [0.604 ± 0.02]). The survival rate of OP treated group, namely, NHSO (93% ± 3%), HS32O (85% ± 2%), and HS34O (80% ± 2%) was higher than that of the group without treatment (NHSS [83% ± 3%], HS32S [71% ± 6%], and HS34S [63% ± 3%]). ZO treated with OP extract (NHSO [93% ± 3%], HS32O [85% ± 2%], and HS34O [80% ± 2%]) showed a higher GVBD rate than the group without treatment (NHSS [83% ± 3%], HS32S [71% ± 6%], and HS34S [63% ± 3%]). It revealed that OP can enhance the oocyte diameter, survival rate, and GVBD rate of ZO under NHS and HS. Further investigation should be conducted to determine the effect of OP extract (C. sinensis) on in vivo conditions in females as an alternative treatment to face global warming.

KIT in oocytes: a key factor for oocyte survival and reproductive lifespan

The KITL-KIT interaction is known as an important initiator in oocyte activation through the downstream pathway of PI3K-AKT-FOXO3 signalling. Previous studies utilising germ cell-specific Kit mutant knockin and kinase domain knockout models with Vasa-Cre suggested the crucial role of KIT in oocyte activation at the primordial follicle stage. We utilised mice with complete postnatal deletion of KIT expression in oocytes via Gdf9-iCre and conducted analyses on ovarian follicle development, specific markers, hormone assays, and fertility outcomes. Our findings reveal contrasting phenotypes compared to previous mouse models with prenatal deletion of Kit. Specifically, postnatal deletion of Kit exhibit no defects in germ cell nest breakdown, follicle activation, and folliculogenesis during development. Remarkably, upon reaching full maturity, mice with postnatal deletion of Kit experience a complete loss of ovarian reserve, growing follicles, and ovarian function. Furthermore, mice display smaller ovarian size and weight, delayed folliculogenesis, and phenotypes indicative of primary ovarian insufficiency (POI), including elevated serum levels of FSH, reduced AMH, and absence of ovarian follicles, ultimately resulting in infertility. Additionally, the ovaries exhibit randomly distributed expression of granulosa and theca cell markers such as Inhibin α, ACVR2B, and LHR. Notably, there is the uncontrolled expression of p-SMAD3 and Ki67 throughout the ovarian sections, along with the widespread presence of luteinised stroma cells and cleaved Caspase-3-positive dying cells. These genetic studies underscore the indispensable role of KIT in oocytes for maintaining the survival of ovarian follicles and ensuring the reproductive lifespan. This work was supported by National Institutes of Health grant R01HD096042 and startup funds from UNMC (S.Y.K.).

P-359 Ten years’ experience using cryopreserved oocytes from In Vitro Maturation (IVM) or Controlled Ovarian Hyperstimulation (COH) cycles for fertility preservation in oncologic indications

Abstract Study question Is IVM a relevant option for fertility preservation in cancer patients, considering biological/clinical outcomes post-thawing, compared to COH? Summary answer This study shows that despite a significantly altered embryo morphology within the IVM group, the clinical outcomes remain comparable to those of COH. What is known already Fertility Preservation (FP) techniques are proposed to patients with cancer to provide the possibility of childbearing using their own gametes. Currently, oocyte vitrification after COH is the standard option. IVM serves as an alternative when COH is contraindicated, urgent cancer therapy is required, or in conjunction with ovarian cortex cryopreservation. Limited live births have been reported from frozen-thawed oocytes in IVM cycles of cancer survivors. Scarce data are available for comparing biological/clinical outcomes of frozen-thawed oocytes from IVM versus COH cycles in cancer survivors. Study design, size, duration This bicentric retrospective cohort study aimed to analyze the outcomes of all oocyte warming cycles in 73 cancer survivors having undergone oocyte vitrification for FP after COH and/or IVM. All of them had oocyte retrieval before the administration of gonadotoxic treatment and returned after being cured, with their oncologist agreement, for assisted reproduction treatments, between November 2012 and January 2024. Participants/materials, setting, methods Seventy-seven warming attempts followed by ICSI respectively from 37 COH and 40 IVM cycles were analyzed. Four patients benefited from an IVM and COH cycle. Survival, fertilization, top and good-quality embryos, defined at day-2 respectively as 4 and 3-5 adequate-sized blastomeres, without multinucleation with &amp;lt; 20% of cytoplasmic fragments, implantation, biochemical (hCG&amp;gt;100 UI/mL), clinical (intrauterine sac with fetal heartbeat) and live birth rates were compared using appropriate statistical tests. Main results and the role of chance The mean age and antral follicle count at the time of FP was similar in both groups. The indications for FP were breast cancer (n = 61), hematologic malignancies (n = 7), ovarian cancer (n = 3), other (n = 2). The number of cryopreserved oocytes tended to be higher in the COH group, when compared to the IVM group (8.5±7.3 vs 5.9±4.04; p = 0.16). The mean oocyte maturation rate after IVM was 68.6±23.1%. Oocyte survival, and fertilization rates were similar in COH and IVM groups, respectively (76.4±27.0% vs 76.1±22.0%; p = 0.76) and (67.1±34.3% vs 65.3±25.4%; p = 0.36). We reported a significantly better embryo quality at day-2 in the COH group when compared to the IVM group, with respectively top-quality embryos (44.0±34.2% vs 26.1±33.4%, p = 0,04) and good-quality embryos (62.2±38.0% vs 42.8±40.8%, p = 0.049), and also a significantly higher number of useful embryo in the COH group (2.7±2.6 vs 1.5±1.2, p = 0.03). Regarding clinical outcomes, the results were similar in COH and IVM groups, in terms of implantation rates (12.2±30.4% vs 15.5±35.6%; p = 0.86), biochemical (32.3% (10/31) vs 17.9% (6/28); p = 0.39), clinical pregnancies (25.8% (8/31) vs 17.9% (4/28); p = 0.54), live birth rates ( 25.8% (8/31) vs 14.3% (4/28); p = 0.34). Limitations, reasons for caution Statistical power to compare IVF outcomes after COH and IVM is limited by the few women who returned to use their frozen oocytes. The subjective nature of embryo morphology assessment. Wider implications of the findings This study is the largest evaluating frozen-warmed oocytes from IVM cycles in cancer patients, with 5 live births newly reported. A higher oocyte-yield may be necessary in IVM as the number of useful embryos is significantly lower. Novel approaches are being developed to improve maturation rates following IVM. Trial registration number Not applicable

O-272 Preimplantation genetic testing of the first polar body is useful for predicting embryo euploidy: data from 1,836 donor oocytes

Abstract Study question Can preimplantation genetic testing of the first polar body (PGT-1BP) accurately identify donor oocytes that will produce euploid embryos? Summary answer Oocyte chromosomal status determined through PGT-1BP had a strong association with embryo euploidy. What is known already Aberrant meiosis during oocyte development leads to aneuploidy, diminished embryo quality, and ultimately, poor reproductive outcomes. Preimplantation genetic testing for aneuploidies (PGT-A) is increasingly employed in donor oocyte cycles, detecting blastocyst euploidy rates ranging from 30% to 80%. However, this variability, together with the clinical and patient resources required to generate blastocysts, support the need for alternative approaches. Oocyte chromosomal status can safely be determined with PGT-1PB. This strategy has shown that 20–30% oocytes obtained from donors with proven fertility are aneuploid, allowing clinicians and patients to make informed reproductive decisions. Study design, size, duration In this prospective study, PGT-1BP was performed on 1,836 fresh donor oocytes collected between September 2017 and January 2022. Vitrified-thawed euploid oocytes were grouped according to donor age (n = 714, n = 554, and n = 568 from 20–24, 25–29, and 30–34-year-old donors, respectively). Oocyte survival and chromosomal status, fertilization through ICSI, blastocyst use and euploidy status were analyzed. Participants/materials, setting, methods Oocytes were derived from donors (n = 115) whose oocytes previously led to at least one live birth. First polar body biopsies were performed 2 hours after in vitro maturation, which corresponds to 38 hours post-hCG trigger. PGT-1BP and PGT-A analyses were performed on the Illumina platform. Oocyte and embryology data as well as the association between oocyte and embryo chromosomal status was evaluated using Mann-Whitney U test. Main results and the role of chance The post-thawing viability rates for the biopsied oocytes were 98.2%, 99.5%, and 96.5% for the three age groups, respectively. Donor oocyte euploidy significantly decreased with advancing age (81.9% vs. 76.9% vs. 70.0%, respectively; p ≤ 0.05). The rate of blastocyst use was comparable across age groups (68.1% vs. 71.7% vs. 68.7%, respectively; p &amp;gt; 0.05). Blastocysts derived from euploid oocytes maintained their euploid status in 88.7%, 90.1%, and 85.6% of cases, respectively. Euploid oocyte-euploid blastocyst matching rates were 89.2%, 90.1%, and 88.1%. Limitations, reasons for caution Although PGT-1BP may not guarantee euploid embryos, it could allow clinicians and couples to make informed decisions about proceeding with fertilization and embryo culture. The associations between euploidy rate of embryos derived from euploid donor oocytes should be confirmed in further studies with larger cohorts. Wider implications of the findings Selecting euploid oocytes with a high probability of becoming euploid embryos may increase the odds of achieving a successful pregnancy at the first attempt. This approach is cost-effective, could prevent unnecessary emotional distress for patients, and is an attractive option for couples with limited sperm available for IVF/ICSI. Trial registration number not applicable

P-217 Keep calm and carry on: assessing the effect of below-benchmark vitrified/warmed donor oocyte survival rates in subsequent laboratory and clinical key performance indicators

Abstract Study question When we experience below benchmark donor oocyte survival rates, are the laboratory and clinical outcomes of the recipient cycle affected? Summary answer Donor-oocyte cryo-survival rates below the benchmark (95-100%) result in slightly lower laboratory KPIs, equivalent live birth rates (LBR) and lower cumulative LBR (CLBR) per cycle. What is known already The use of vitrified/warmed donor oocytes allows overcoming many logistic challenges, but it is hindered by the loss of oocytes due to degeneration after warming. The 2012 Vienna Consensus established the benchmark rate of oocyte survival at 95-100%, competency level at &amp;gt; 85%. Results of &amp;lt; 85% cryo-survival are considered below competency, &amp;lt;70% can be considered poor, and &amp;lt;50% very poor. Below-benchmark rates of survival may not only limit the number of donor oocytes for the cycle, but they can also translate into lower per-oocyte cycle KPIs if the lower survival correlates with lower performance of the surviving oocytes. Study design, size, duration We analyzed 12690 vitrified-warmed donor oocyte recipient cycles, encompassing a total 144793 vitrified/warmed donor oocytes, carried out in a network of European private IVF units from 2018-2022. Cycles with PGT-A and spermatozoa from testicular biopsy were excluded. The primary endpoint of the study was the blastocyst utilization rate per 2PN zygote. Secondary endpoints were fertilization rate, live birth rate after the first single blastocyst transfer (SET-LBR) of each cycle, and cumulative LBR (CLBR). Participants/materials, setting, methods In all cases, fertilization was carried out by ICSI, and embryos were cultured to the blastocyst stage at low oxygen tension. Blastocysts with good or fair quality (A, B &amp; C by ASEBIR Criteria) were considered usable (transferred + cryopreserved blastocyts / zygotes). Differences in proportions were analyzed using chi-square and the adjusted odds ratio (OR) was calculated using multivariable logistic regression. Main results and the role of chance Baseline donor and patient characteristics such as age, stimulation duration and dose, total donor oocytes per cycle, male factor, and fresh/frozen/donor spem were compared between groups and adjusted for when necessary. The mean number of warmed oocytes per cycle was 11.4±3.22 with a mean survival rate of 89.2%. More oocytes per cycle were consumed in the lower survival groups, yet the total oocytes available for ICSI was smaller in the below competency, poor and very poor survival groups. There were differences in the proportion of usable blastocysts per zygote amongst the survival rate groups (benchmark: 48.9%; competence: 47.0%, below-competence: 46.0%; poor: 43.6%; very-poor:43.6%, p &amp;lt; 0.001). Fertilization rates also differed between survival groups (benchmark: 76.9%; competence: 76.5%, below-competence: 75.6%; poor: 74.7%; very-poor:75.4%, p &amp;lt; 0.001) The adjusted odds ratio of live birth on the first SET of the cycle was not lower to the benchmark survival group in all the lower survival groups (Benchmark: 40.9%; Competence: OR:0.995; 95%CI:0.971-1.018; below-competence: OR:0.996; 95%CI:0.970-1.023; poor: OR:1.044; 95%CI:1.003-1.086, and very-poor: OR:1.069; 95%CI:0.976-1.170). The CLBR decreased in lower survival groups, with 80.8% for the benchmark survival group, 80.3% (p = 0.539) for competence, 76.2% (p &amp;lt; 0.001) for below-competence, 72.5% (p &amp;lt; 0.001) for poor, and 74.8% (p = 0.056) for very-poor. Limitations, reasons for caution These results are limited to a donor-oocyte population. Wider implications of the findings Lower oocyte-cryo-survival rates resulted in a lower total number of usable blastocysts obtained for the recipient, and consequently, lower CLBR. However, the competence of surviving oocytes is encouraging, with laboratory KPIs in very close range irrespectively of the cohort survival rates, and similar implantation potential of the obtained blastocysts. Trial registration number not applicable

P-371 It’s worth the freeze: outcomes from thawing electively cryopreserved oocytes are comparable in patients with reduced vs normal ovarian reserve at the time of cryopreservation

Abstract Study question For patients coming back to use oocytes derived from elective cryopreservation, does their initial ovarian reserve predict thaw survival, embryos’ developmental milestones and pregnancy success? Summary answer Thaw survival, fertilization rate, embryo development and pregnancy success rates do not vary significantly according to AMH level at initial cryopreservation. What is known already Increasing numbers of patients are electing to cryopreserve oocytes for future use. AMH (Anti Mullerian Hormone) is an ovarian reserve marker often assessed prior to initiation of treatment that predicts response to fertility treatment and the resulting oocyte yield. However, it is not known whether oocytes derived from a patient with compromised ovarian reserve (perhaps over multiple treatment cycles) will fare as well as that of a patient with normal ovarian reserve and a higher per cycle oocyte yield. Our study seeks to shed light on whether a lower initial AMH level negatively impacts the prognosis of the thawed oocytes. Study design, size, duration We included in our retrospective study all oocyte thaw cycles resulting from electively cryopreserved oocytes since 1996 at a single academically affiliated fertility center. 325 patients completed a total of 510 thaw cycles. 315 cycles were excluded from analysis for no AMH information. 6376 oocyte cryopreservation cycles were performed over that timeframe. The primary outcomes were laboratory statistics including oocyte survival, fertilization and embryo blastulation rates, while the secondary outcome was cumulative live birth rates. Participants/materials, setting, methods AMH categories of &amp;lt; 1, 1-2 and &amp;gt; 2 were selected to stratify reduced, low-normal, and normal ovarian reserves, respectively. 70.7% inseminated oocytes with partner sperm while the remaining 29.3% used donor sperm. Mean age at time of oocyte cryopreservation was 36.5 (range 27.5 to 46.2) while mean age at time of oocyte thaw was 39.2 (range 27.7 to 47.5). The statistical analysis was performed using ANOVA for mean comparisons and chi-squared for pregnancy data. Main results and the role of chance Average oocyte yield per cryopreservation cycle was significantly different across AMH groups (7.7 oocytes in AMH &amp;lt; 1, 10.5 oocytes in AMH 1-2, and 17.2 oocytes in AMH &amp;gt; 2, p &amp;lt; 0.01). The number of treatment cycles completed was highest in patients with AMH &amp;lt; 1 at 1.26 cycles. Oocyte survival (mean 89.0%), fertilization rate (mean 75.3%), and blastocyst conversion rate (mean 62.4%) did not vary significantly across AMH groups. Time to oocyte use was not significantly impacted by AMH at the time of initial testing. Those with reduced AMH &amp;lt; 1 came back earlier to utilize the oocytes (787 days), vs 1141 days for patients with AMH 1-2 and 1021 days for patients with AMH &amp;gt; 2. However, this difference was not statistically significant, p = 0.4. The rate of PGT-A euploid embryos did not vary between groups (38.8% in AMH &amp;lt; 1, 45.3% in AMH 1-2, 53.0% in AMH &amp;gt; 2, p = 0.07). Clinical pregnancy, miscarriage rate, and live birth rate in the first transfer cycle was not impacted by AMH. Total cumulative live birth rate was not correlated with AMH (31.6% in AMH &amp;lt; 1, 44.4% in AMH 1-2, 47.8% in AMH &amp;gt; 2, p = 0.48). Limitations, reasons for caution This data was collected at a single fertility center and thus has limited generalizability. 8.0% of patients came back to utilize their oocytes, which varies widely across the published literature. 60.6% of patients did not have AMH assessed as part of their pre-treatment testing and were excluded from analysis. Wider implications of the findings Although reduced ovarian reserve impacts oocyte yield, many studies find no impact on resulting oocyte quality, embryo development and pregnancy success rates. Those with compromised AMH have comparable oocyte thaw outcomes to those with normal ovarian reserve, though more oocyte cryopreservation cycles may be needed to achieve a successful outcome. Trial registration number N/A

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

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

P-141 Elevating human oocyte vitrification and warming to a new level: fast, efficient, and effective

Abstract Study question Due to the rising trend for oocyte cryopreservation and increasing demand, there is an urgency to make oocyte vitrification and warming protocols more efficient. Summary answer Oocyte vitrification and warming can be done successfully in 4 minutes, reducing the time of commonly used current protocols by up to 25 minutes. What is known already Vitrification and warming of oocytes is widely used in many IVF clinics worldwide and routinely utilized as a dominant technique for fertility preservation and freezing of donor as well as autologous oocytes in many clinical settings. Outcome data using cryopreserved oocytes is comparable to fresh oocytes. However, vitrification and warming of human oocytes can be time consuming. Usually, vitrification of oocytes is done in about 11-16 minutes, and warming requires another 11 minutes. Also, it is a common practice to load not more than 2 oocytes per carrier at time of vitrification. Study design, size, duration From November 2022 to November 2023, 504 germinal vesicles (GV) and 207 metaphase I (MI) oocytes, which did not convert into mature oocytes at day of oocyte retrieval, were vitrified in Vit Kit Freeze (FujiFilm Irvine Scientific, USA), and RapidVit Oocyte (Vitrolife, Sweden). Their survival rates were compared, and as an additional viability indicator, post-warming developmental capabilities were evaluated after 24 and 48hrs of culture in Global High Protein (LifeGlobal, USA). Participants/materials, setting, methods A group of 4 GV or MI oocytes was vitrified at room temperature for 1 minute in Equilibration solution (ES) and 1 minute in Vitrification solution (VS), loaded on a S-Cryolock (Biotech, USA) and then plunged into liquid nitrogen. Warming was done at 37ºC in 0.5M sucrose for 1 minute and Wash solution (WS) for another minute. Post warming, GV and MI oocytes were cultured for developmental evaluation. Statistical significance was defined as P &amp;lt; 0.05. Main results and the role of chance There was no statistically significant difference in the survival rate of GV oocytes between Irvine (209/219; 95.4%), and Vitrolife media (270/285; 94.7%; P = 0.72). The survival of MI oocytes was also comparable and not significantly different between both media; Irvine: 103/106; 97.2%, vs Vitrolife: 96/101; 95.0%; P = 0.43). Because of the similar survival rates of oocytes in both groups, for the developmental potential and conversion rates, oocytes of both groups were combined. Of the 504 GV, 479 survived (95.0%) and after 24hrs of culture, 441 converted to MI (92.1%). After a culture of 48hrs, 56.5% (249/441) converted to metaphase II (MII) oocytes. Combining the vitrified and warmed MI oocytes from both groups, 96.1% (199/207) survived the warming, and after 24hrs of culture, 168 (84.4%) converted to MII oocytes. Vitrification and warming of oocytes at different developmental stages can be done with a short exposure time to hypertonic (ES/VS) and hypotonic (0.5M sucrose) solutions in a total of 4 minutes. Limitations, reasons for caution Immature oocytes were used as study material to evaluate a new protocol with significantly reduced vitrification and warming times. At this moment we cannot provide data on fertilization, embryo development, and blastocyst formation. Wider implications of the findings Oocytes are exposed to less suboptimal temperatures during dehydration and rehydration and help to maintain their developmental potential. Loading 4 oocytes per carrier combined with the decrease in time resulted in increased efficiency. Warming in 0.5M instead of 1M sucrose contributes positively to survival and allows earlier resumption of functionality. 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-472 Oocyte cryopreservation for social reasons in women ≥ 40 years who decline oocyte donation: anticipated outcomes, myth dispelling, and addressing concerns

Abstract Study question Is oocyte vitrification a reproductive viable alternative for women aged over 40 who decline oocyte donation? Under what specific conditions? Summary answer Oocyte vitrification could be considered as an acceptable alternative in this patient cohort, with patients being adequately informed about the realistic possibilities. What is known already In Argentina, legislation on Assisted Reproduction Technologies endorses assisted reproductive treatments employing women’s own oocytes up to the age of forty-four. This legislative framework has resulted in an increased number of such procedures for women over 40 who decline oocyte donation, as well as a rise in those women in this age group who wish to postpone maternity for social reasons. There are scarce published studies presenting reproductive outcomes using vitrified and thawed autologous oocytes in this specific demographic. Study design, size, duration This retrospective observational study, conducted between January 2008 and December 2023, involved 299 patients aged 40 and above who underwent 356 cycles of autologous oocyte cryopreservation (1.2 cycles per patient). Statistical analysis utilized the InStat GraphPad statistical package, including one-way ANOVA and two-tailed Student’s t-test as required. Participants/materials, setting, methods Eighty-seven patients thawed their oocytes and performed 95 ICSI procedures followed by 75 embryo transfers. The primary outcome was the live birth rate, with secondary outcomes including oocyte survival rate, fertilization rate, implantation rate, clinical pregnancy rate, and miscarriage rate. Vitrification and thawing of oocytes were performed using the Cryotop method. Main results and the role of chance Average age: 41.4± 1.8 years. Average vitrified oocytes: 4.5 ± 3.9 [1-24]. 29.1%(87/299) patients thawed their eggs. Average age at thawing:44.0± 2.7 years [41-50]. Average storage time until use was 2.6 ± 1.9 years. 465 oocytes were thawed (4.9 ± 3.0 oocytes per patient). 31.0% used a donor semen sample and 69% used their partne’s semen sample. Survival rate was 87.1%(405/465). Fertilization rate was 74.3% (301/405). Cleavage rate was 98.0 % (295/301). 78.9% (75/95) of ICSI procedures had embryo transfer (1.9 ± 0.6 embryos per patient). Implantation rate was 8.9% (13/146). Clinical pregnancy rate per transfer was 17.3% (13/75). Miscarriage rate was 23.1% (3/13). Miscarriage rate per transfer was 4.0% (3/75). Live birth rate per transfer was 13.3% (10/75), 11.5% (10/87) per patient who thawed their oocytes and 10.5% (10/95) per ICSI procedure performed. Live birth rate per cryopreserved oocyte was 2.1% (10/465) in the general population and 9.1% (10/110) in those women who achieved at least clinical pregnancy. Women who achieved a healthy live birth had a greater number of vitrified oocytes (7.1 ± 3.1) than those who did not achieve pregnancy (4.9 ± 3.0) (p = 0.02). Limitations, reasons for caution This retrospective study’s conclusions are pertinent to a well-defined group of patients, specifically women aged over 40 who decline oocyte donation and have undergone oocyte vitrification. Wider implications of the findings Despite the absence of an assurance for a live birth through oocyte vitrification in this cohort, offering clear counsel grounded in variables such as the number of retrieved oocytes and age at the moment of cryopreservation allows for informed communication of realistic possibilities for those patients who decline oocyte donation. Trial registration number na

O-085 Oocyte cryopreservation: a comprehensive analysis of live birth rate by age and indication of treatment provides reassurance for young cancer patients

Abstract Study question Does the outcome of oocyte cryopreservation vary across different age groups and treatment indications, i.e. cancer diagnosis, other medical conditions or non medical fertility preservation? Summary answer Live birth rate (LBR) is significantly influenced by a woman's age, although not by indication of treatment. What is known already OC is increasingly applied in assisted reproduction, although little is about the outcomes, including livebirth according to indication. Study design, size, duration Retrospective cohort study analyzing all OC and subsequent warmed oocyte cycles in two fertility centers - Melbourne IVF and the Royal Women’s Hospital, Melbourne, Australia, between the years 2014 to 2022. Participants/materials, setting, methods Women undergoing autologous IVF treatment using vitrified and warmed oocytes. Outcome of stimulation cycles and warmed oocyte cycles were assessed according to women’s age at OCP (≤ 35 years, 35-40 years and ≥ 40 years) and treatment indication- cancer diagnosis, other medical conditions and non medical. Main results and the role of chance 2689 women underwent a total of 3801 cycles of OC, comprising 702 cycles for cancer diagnosis (18.6%), 1146 cycles for other medical (30.5%), and 1953 cycles for non-medical (50.9%). Regardless of indication, younger age groups exhibited a higher median number of mature oocytes: &amp;lt;35 (11, 8-17), 35-40 (9, 6-11), and &amp;gt;40 (6, 3-9) (H(2)=15.1, p &amp;lt; 0.05). Among 582 warmed oocytes cycles, the &amp;gt;40 group demonstrated lower rate cycles with at least one good-quality blastocyst (76.7%) compared to 35-40 (87.1%) and &amp;lt;35 (87.2%), p &amp;lt; 0.05. Cumulative live birth rates (cLBR) were also lower in the &amp;gt;40 age group (14.9%) compared to 35-40 (34.9%) and &amp;lt;35 (46.5%), p &amp;lt; 0.01. When analyzing cycles by indication, patients with cancer had lower oocyte survival rate (80.8% vs 84.8% in other medical and 82.1% in non medical, p &amp;lt; 0.01). Nonetheless, no differences in rate of cycles with at least one good quality embryo rates (cancer diagnosis 87.2%, other medical 82.1% and non medical 89.3%, p = 0.06). Patients with cancer diagnosis had higher clinical miscarriage rate (25%) compared with other medical (7%) and non medical (10.5%), p &amp;lt; 0.01. However, cLBR did not differ between the indication groups (29.7% in cancer diagnosis, 35% in other medical and 38.1% in non medical, p = 0.5. Limitations, reasons for caution Retrospective data collection. Wider implications of the findings Our study offers comprehensive data that may assist patients desiring OC, and provides reassurance that even with a cancer diagnosis, outcomes are as favorable as those having non-medical OC. Given the substantial impact of age, health care providers should, when possible, advise to complete this procedure at a young age. Trial registration number Not applicable

P-781 Managing a change of provider bank in a vitrified oocyte donation program

Abstract Study question Does a change in provider bank affect the outcomes of a vitrified oocyte donation program and require laboratory and clinical adjustments? Summary answer In a vitrified oocyte donation program, a change in the provider bank does not affect patients’ outcomes nor require laboratory or clinical adjustments. What is known already Imported vitrified oocyte donation programs are a valuable strategy to provide oocyte donation treatments in settings were donor availability is low or absent. Little is known about how to a change in the provider oocyte bank should be managed in terms of laboratory or clinical adjustments in order not to jeopardize patients’ outcomes. Study design, size, duration Longitudinal cohort study conducted in a Tertiary IVF Center (Centro Scienze Natalità, IRCCS Ospedale San Raffaele, Milan, Italy) between September 2019 and October 2023. Participants/materials, setting, methods All couples undergoing their first imported vitrified oocyte donation cycle were included (n = 235). Oocytes (6 to 9 per cycle) were purchased from one bank (Bank A, Spain, EU) until December 2022 and then from a different bank (Bank B, Spain, EU) from January to October 2023. Single blastocyst-stage embryo transfer policy was adopted in all patients and the cumulative outcomes of patients treated with oocytes purchased from Bank A and Bank B were compared. Main results and the role of chance The number of provided oocytes was higher in Bank B compared to Bank A (8.0 ± 0.8 vs 6.5 ± 0.7, Mean ± SD, p &amp;lt; 0.01). Oocyte survival rates at thawing (87.2 ± 17.2 vs 91.2 ± 16.1 %, Mean ± SD), fertilization rates (75.7 ± 20.8 vs 78.4 ± 28.7, Mean ± SD) and blastulation rates (49.0 ± 28.0 vs 54.5 ± 27.5, Mean ± SD) were stable between Bank A and Bank B respectively, resulting in a higher number of blastocysts available for transfer in cycles performed with oocytes from Bank B compared to Bank A (3.5 ± 2.0 vs 2.4 ± 1.5, Mean ± SD, p &amp;lt; 0.01). Cumulative outcomes showed an improvement in cycles performed with Bank B compared to Bank A (implantation rates 73.8 % vs 62.6 %, ongoing pregnancy rates 69.8 % vs 56.3 %), despite not reaching a statistically significant difference. On multivariate logistic regression, the number of blastocysts available for transfer (OR 2.1, 1.7 -2.7 95% CI, p &amp;lt; 0.01) but not the Bank providing the vitrified oocytes (OR 0.99, 0.40 – 2.43) resulted as significant predictor of ongoing pregnancy. Limitations, reasons for caution Longer follow-up might strengthen our results, as several cycles performed with Bank B are still ongoing and cumulative live-birth rates cannot be currently calculated. In addition, the two banks used are located in the same country. Whether these results also apply to banks located in different settings needs further investigation. Wider implications of the findings Our results reassure about the possibility to manage a vitrified oocyte donation program using oocytes from different banks without jeopardizing patients’ outcomes and without the need for laboratory and clinical adjustments. Trial registration number not applicable

The Roles of GDF-9, BMP-15, BMP-4 and EMMPRIN in Folliculogenesis and In Vitro Fertilization.

Growth differentiation factor 9 (GDF-9) contributes to early ovarian development and oocyte survival. Higher concentrations of GDF-9 in follicular fluid (FF) are associated with oocyte nuclear maturation and optimal embryo development. In in vitro fertilization (IVF), GDF-9 affects the ability of the oocyte to fertilize and subsequent embryonic development. Bone morphogenetic protein 15 (BMP-15) is involved in the regulation of ovarian function and affects oocyte development. During IVF, BMP-15 contributes to the formation of competent blastocysts. BMP-15 may play a role in embryo implantation by affecting endometrial receptivity. Bone morphogenetic protein 4 (BMP-4) is involved in the regulation of follicle growth and development and affects granulosa cell (GC) differentiation. In relation to IVF, BMP-4 is important for embryonic development, influences cell fate and differentiation, and plays a role in facilitating embryo-endometrial interactions during the implantation process. Extracellular matrix metalloproteinase inducer (EMMPRIN) is associated with ovulation and follicle rupture, promotes the release of mature eggs, and affects the modification of the extracellular matrix of the follicular environment. In IVF, EMMPRIN is involved in embryo implantation by modulating the adhesive properties of endometrial cells and promotes trophoblastic invasion, which is essential for pregnancy to occur. The purpose of the current article is to review the studies and recent findings of GDF-9, BMP-15, BMP-4 and EMMPRIN as fundamental factors in normal follicular development and in vitro fertilization.