Definition of a clinical strategy to enhance the efficacy, efficiency and safety of egg donation cycles with imported vitrified oocytes

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

OBJECTIVE

To assess the impact of below-benchmark (95%-100%) donor-oocyte survival rates on vitrification/warming in the laboratory and clinical outcomes of recipient cycles.

DESIGN

Retrospective cohort study.

SUBJECTS

We analyzed 12,690 vitrified-warmed donor-oocyte recipient cycles performed from 2018-2022.

EXPOSURE

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%; and very poor <50%.

MAIN OUTCOME MEASURES

The primary endpoint of the study was the total usable blastocyst rate per 2 pronuclear (2PN) zygote. Secondary endpoints were the fertilization rate, the live birth rate after the first single blastocyst transfer, and the cumulative live birth rate.

RESULTS

The mean number of warmed oocytes per intracytoplasmic sperm injection (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 number of 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%; and very poor: 43.6%), as well as the fertilization rates (benchmark: 76.8%; competence: 76.6%, below competence: 75.6%; poor: 74.7%; and very poor:75.5%). The adjusted relative risk (aRR) 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: aRR = 0.986, 95% confidence interval [CI]: 0.931-1.045; below-competence: aRR = 0.992, 95% CI: 0.929-1.059; poor: aRR = 1.103, 95% CI: 1.009-1.207; and very poor: aRR = 1.169, 95% CI: 0.963-1.419). The cumulative live birth rate decreased in lower survival groups compared with benchmark survival (benchmark: 79.2%; competence: aRR = 0.988, 95% CI: 0.961-1.015; below competence: aRR = 0.911, 95% CI: 0.880-0.944; poor: aRR = 0.802, 95% CI: 0.757-0.851; and very poor: aRR = 0.793, 95% CI: 0.693-0.907). The lower cumulative rates maintained in a subanalysis with equal metaphase-II available for ICSI (benchmark: 69.5%; competence: aRR = 0.909, 95% CI: 0.827-1.000; below competence: aRR = 0.942, 95% CI: 0.848-1.046; poor: aRR = 0.833, 95% CI: 0.7386-0.941; and very poor: aRR = 0.873, 95% CI: 0.695-1.097) CONCLUSION: 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 metaphase-II oocytes available for ICSI. Nonetheless, the surviving oocytes of a cohort seem to maintain a high competence level, with very similar laboratory outcomes, irrespective of the cohort's survival rates, as well as equal implantation potential of the resulting blastocysts.

Balancing choice and socioeconomic realities: analyzing behavioral and economic factors in social oocyte cryopreservation decisions

Purpose

This research investigates the influence of personal income, the likelihood of pregnancy from cryopreserved oocytes, and the risk of infertility, on the decision-making process of women. The study employs the economic stated preference framework alongside the Theory of Planned Behavior in order to comprehend the process of decision-making.

Design/methodology/approach

The data had been collected from women between the ages of 18 and 65 via questionnaire employing conjoint analysis (CA). Through the utilization of this methodology, the factors influencing women's choices concerning oocyte cryopreservation were quantified.

Findings

The study identified crucial factors that impact the determination to cryopreserve oocytes, such as personal financial resources, the likelihood of achieving a successful pregnancy using frozen oocytes, and the potential for infertility. The analysis reveals that a considerable number of participants perceive cryopreservation as a feasible alternative for augmenting their prospects for future procreation.

Research implications

The results validate the patterns and the ways in which personal and socioeconomic elements impact choices regarding fertility. This has the potential to inform forthcoming health policies and educational initiatives that aim to provide more comprehensive support for women's fertility decisions.

Social implications

The research highlights the necessity of policy and societal support for women who are contemplating oocyte cryopreservation. It is recommended that public health policies incorporate provisions for state financing of cryopreservation in order to safeguard reproductive autonomy and alleviate the fertility risk linked to the aging process.

Originality/value

His research is unique in that it employs the Theory of Planned Behavior and an economic stated-preference framework to analyze the dynamics of oocyte cryopreservation decisions. This work enhances the existing body of literature by drawing attention to the socio-economic persona factors that influence choices regarding fertility preservation.

Melatonin application during cryopreservation improves the development and clinical outcomes of human vitrified-warmed oocytes

In this clinical study, we investigated the potential of melatonin (MT) supplementation in the freeze-thaw medium used for cryopreserved human oocytes. In total, 152 patients who underwent in vitro fertilization between January 2020 and December 2022 were included and categorized into different groups as follows: the donor group, comprising 108 patients who donated their oocytes, with 34 patients using a vitrification and warming medium supplemented with MT (D-MT subgroup) and 74 patients using conventional medium without MT (D-0 subgroup); and the autologous group, comprising 38 patients who used their own oocytes, with 19 patients using medium supplemented with MT (A-MT subgroup) and 19 patients using medium without MT (A-0 subgroup). After thawing, the surviving oocytes in the D-MT and A-MT subgroups and D-0 and A-0 subgroups were cultured in a fertilization media with and without 10-9 MMT for 2.5 h, respectively, followed by intracytoplasmic sperm injection insemination, embryo culture, and transfer. The survival, cleavage, high-quality embryo, clinical pregnancy, ongoing pregnancy, and implantation rates were significantly higher in the D-MT subgroup than in the D-0 subgroup (all P < 0.05). Similarly, the survival, fertilization, high-quality embryo, and high-quality blastocyst rates were significantly higher in the A-MT subgroup than in the A-0 subgroup (all P < 0.05). These findings indicate that MT addition during cryopreservation can enhance the development of vitrified-warmed human oocytes and improve clinical outcomes.

Association between oocyte donors' or recipients' body mass index and clinical outcomes after first single blastocyst transfers-the uterus is the most affected

OBJECTIVE

To assess whether high body mass index (BMI) in either oocyte donors or recipients is associated with poorer outcomes after the first single blastocyst transfer.

DESIGN

Retrospective study including 1,394 first blastocyst single embryo transfers (SETs) conducted by 1,394 recipients during oocyte donation cycles with the gametes retrieved from 1,394 women (January 2019-July 2021). Four BMI clusters were defined for both donors and recipients (underweight: <18.5 kg; normal weight: 18.5-24.9 kg; overweight: 25-29.9 kg; and obese: ≥30 kg).

SETTING

Network of private IVF centers.

PATIENTS

A total of 1,394 recipients aged 42.4 ± 4.0 and with a BMI of 23.2 ± 3.8 kg/m2, and 1,394 donors aged 26.1 ± 4.2 and with a BMI of 21.9 ± 2.5 kg/m2.

INTERVENTION

All oocytes were vitrified at 2 egg banks and warmed at 8 in vitro fertilization clinics that were part of the same network. Intracytoplasmic sperm injection, blastocyst culture, and either fresh or vitrified-warmed SETs were conducted. Putative confounders were investigated, and the data were adjusted through regression analyses.

MAIN OUTCOME MEASURES

The primary outcome was the live birth rate (LBR) per SET according to donors' and/or recipients' BMI. The main secondary outcome was the miscarriage rate (<22 gestational weeks) per clinical pregnancy.

RESULTS

The LBR per blastocyst SET showed no significant association with donors' BMI. Regarding recipients' BMI, instead, the multivariate odds ratio was significant in obese vs. normal-weight recipients (0.58, 95% confidence interval, 0.37-0.91). The miscarriage rate per clinical pregnancy was also significantly associated with recipients' obesity, with a multivariate odds ratio of 2.31 (95% confidence interval, 1.18-4.51) vs. normal-weight patients. A generalized additive model method was used to represent the relationship between predicted LBR or miscarriage rates and donors' or recipients' BMI; it pictured a scenario where the former outcome moderately but continuously decreases with increasing recipients' BMI to then sharply decline in the BMI range of 25-35 kg/m2. The miscarriage rate, instead, increases almost linearly with respect to both donors' and recipients' increasing BMI.

CONCLUSION

Obesity mostly affects the uterus, especially because of higher miscarriage rates. Yet, poorer outcomes can be appreciated already with a BMI of 25 kg/m2 in both oocyte donors and recipients. Finer markers of nutritional homeostasis are therefore desirable; recipients should be counseled about poorer expected outcomes in cases of overweight and obesity; and oocyte banks should avoid assigning oocytes from overweight donors to overweight and obese recipients.

Review of human oocyte cryopreservation in ART programs: Current challenges and opportunities

Oocyte cryopreservation has notably increased in recent times, to become an essential part of clinical infertility treatment. Since the 1980s, many improvements in oocyte cryopreservation (OC) have been adopted, including the great advance with the application of vitrification. The commonly used vitrification protocol applies different cryoprotectants (Ethylene glycol and/or DMSO and/or PROH and sucrose and/or Trehalose) and two different steps: firstly, exposure in equilibration solution for 5-15 min, followed by a vitrification solution for 60-90 s at room temperature. The warming method includes a first step for 1 min at 37 °C and 3 subsequent steps at room temperature to remove the cryoprotectant for a total of 9-12 min. In addition, biosafety is a critical aspect to mention, and it is related to devices used during the vitrification, mainly in terms of whether the biological vitrified material comes in direct contact with liquid nitrogen (open vitrification) or not (closed vitrification), where LN2 may contain potentially contaminating viruses or pathogens. Furthermore, during early development major waves of epigenetic reprogramming take place. Recent literature suggests that epigenetic and transcriptomic profiles are sensitive to the stress induced by vitrification, including osmotic shock, temperature, rapid changes of pH and toxicity of cryoprotectants. It is, therefore, important to better understand the potential perturbations of epigenetic modifications that may be associated with the globally used vitrification methods. Therefore, we here discuss the benefits and efficiency of human oocyte vitrification; we also review the evidence surrounding oocyte cryopreservation-related epigenetic modifications and potential epigenetic dysregulations, together with long-term consequences for offspring health.

Exploring the effect of cryopreservation in assisted reproductive technology and potential epigenetic risk

Since the birth of the first baby by in vitro fertilization in 1978, more than 9 million children have been born worldwide using medically assisted reproductive treatments. Fertilization naturally takes place in the maternal oviduct where unique physiological conditions enable the early healthy development of the embryo. During this dynamic period of early development major waves of epigenetic reprogramming, crucial for the normal fate of the embryo, take place. Increasingly, over the past 20 years concerns relating to the increased incidence of epigenetic anomalies in general, and genomic-imprinting disorders in particular, have been raised following assisted reproduction technology (ART) treatments. Epigenetic reprogramming is particularly susceptible to environmental conditions during the periconceptional period and non-physiological conditions such as ovarian stimulation, in vitro fertilization and embryo culture, as well as cryopreservation procedure, might have the potential to independently or collectively contribute to epigenetic dysregulation. Therefore, this narrative review offers a critical reappraisal of the evidence relating to the association between embryo cryopreservation and potential epigenetic regulation and the consequences on gene expression together with long-term consequences for offspring health and wellbeing. Current literature suggests that epigenetic and transcriptomic profiles are sensitive to the stress induced by vitrification, in terms of osmotic shock, temperature and pH changes, and toxicity of cryoprotectants, it is therefore, critical to have a more comprehensive understanding and recognition of potential unanticipated iatrogenic-induced perturbations of epigenetic modifications that may or may not be a consequence of vitrification.

Opening the black box: why do euploid blastocysts fail to implant? A systematic review and meta-analysis

BACKGROUND

A normal chromosomal constitution defined through PGT-A assessing all chromosomes on trophectoderm (TE) biopsies represents the strongest predictor of embryo implantation. Yet, its positive predictive value is not higher than 50-60%. This gap of knowledge on the causes of euploid blastocysts' reproductive failure is known as 'the black box of implantation'.

OBJECTIVE AND RATIONALE

Several embryonic, maternal, paternal, clinical, and IVF laboratory features were scrutinized for their putative association with reproductive success or implantation failure of euploid blastocysts.

SEARCH METHODS

A systematic bibliographical search was conducted without temporal limits up to August 2021. The keywords were '(blastocyst OR day5 embryo OR day6 embryo OR day7 embryo) AND (euploid OR chromosomally normal OR preimplantation genetic testing) AND (implantation OR implantation failure OR miscarriage OR abortion OR live birth OR biochemical pregnancy OR recurrent implantation failure)'. Overall, 1608 items were identified and screened. We included all prospective or retrospective clinical studies and randomized-controlled-trials (RCTs) that assessed any feature associated with live-birth rates (LBR) and/or miscarriage rates (MR) among non-mosaic euploid blastocyst transfer after TE biopsy and PGT-A. In total, 41 reviews and 372 papers were selected, clustered according to a common focus, and thoroughly reviewed. The PRISMA guideline was followed, the PICO model was adopted, and ROBINS-I and ROB 2.0 scoring were used to assess putative bias. Bias across studies regarding the LBR was also assessed using visual inspection of funnel plots and the trim and fill method. Categorical data were combined with a pooled-OR. The random-effect model was used to conduct the meta-analysis. Between-study heterogeneity was addressed using I2. Whenever not suitable for the meta-analysis, the included studies were simply described for their results. The study protocol was registered at http://www.crd.york.ac.uk/PROSPERO/ (registration number CRD42021275329).

OUTCOMES

We included 372 original papers (335 retrospective studies, 30 prospective studies and 7 RCTs) and 41 reviews. However, most of the studies were retrospective, or characterized by small sample sizes, thus prone to bias, which reduces the quality of the evidence to low or very low. Reduced inner cell mass (7 studies, OR: 0.37, 95% CI: 0.27-0.52, I2 = 53%), or TE quality (9 studies, OR: 0.53, 95% CI: 0.43-0.67, I2 = 70%), overall blastocyst quality worse than Gardner's BB-grade (8 studies, OR: 0.40, 95% CI: 0.24-0.67, I2 = 83%), developmental delay (18 studies, OR: 0.56, 95% CI: 0.49-0.63, I2 = 47%), and (by qualitative analysis) some morphodynamic abnormalities pinpointed through time-lapse microscopy (abnormal cleavage patterns, spontaneous blastocyst collapse, longer time of morula formation I, time of blastulation (tB), and duration of blastulation) were all associated with poorer reproductive outcomes. Slightly lower LBR, even in the context of PGT-A, was reported among women ≥38 years (7 studies, OR: 0.87, 95% CI: 0.75-1.00, I2 = 31%), while obesity was associated with both lower LBR (2 studies, OR: 0.66, 95% CI: 0.55-0.79, I2 = 0%) and higher MR (2 studies, OR: 1.8, 95% CI: 1.08-2.99, I2 = 52%). The experience of previous repeated implantation failures (RIF) was also associated with lower LBR (3 studies, OR: 0.72, 95% CI: 0.55-0.93, I2 = 0%). By qualitative analysis, among hormonal assessments, only abnormal progesterone levels prior to transfer were associated with LBR and MR after PGT-A. Among the clinical protocols used, vitrified-warmed embryo transfer was more effective than fresh transfer (2 studies, OR: 1.56, 95% CI: 1.05-2.33, I2 = 23%) after PGT-A. Lastly, multiple vitrification-warming cycles (2 studies, OR: 0.41, 95% CI: 0.22-0.77, I2 = 50%) or (by qualitative analysis) a high number of cells biopsied may slightly reduce the LBR, while simultaneous zona-pellucida opening and TE biopsy allowed better results than the Day 3 hatching-based protocol (3 studies, OR: 1.41, 95% CI: 1.18-1.69, I2 = 0%).

WIDER IMPLICATIONS

Embryo selection aims at shortening the time-to-pregnancy, while minimizing the reproductive risks. Knowing which features are associated with the reproductive competence of euploid blastocysts is therefore critical to define, implement, and validate safer and more efficient clinical workflows. Future research should be directed towards: (i) systematic investigations of the mechanisms involved in reproductive aging beyond de novo chromosomal abnormalities, and how lifestyle and nutrition may accelerate or exacerbate their consequences; (ii) improved evaluation of the uterine and blastocyst-endometrial dialogue, both of which represent black boxes themselves; (iii) standardization/automation of embryo assessment and IVF protocols; (iv) additional invasive or preferably non-invasive tools for embryo selection. Only by filling these gaps we may finally crack the riddle behind 'the black box of implantation'.

Long-term storage of vitrified oocytes does not affect pregnancy and live birth rates: analysis of 5362 oocyte donation cycles

RESEARCH QUESTION

Does long-term storage of vitrified oocytes affect laboratory and reproductive outcomes after intracytoplasmic sperm injection?

DESIGN

Retrospective cohort study including 41,783 vitrified-warmed oocytes from 5362 oocyte donation cycles between 2013 and 2021. Five categories of storage time were established to analyse its effect on clinical and reproductive outcomes (≤1 year [reference group], 1-2 years, 2-3 years, 3-4 years and >4 years).

RESULTS

The mean number of warmed oocytes was 8.0 ± 2.5 oocytes. Oocyte storage time ranged from 3 days to 8.2 years (mean: 0.7 ± 0.9). Mean oocyte survival (90.2% ± 14.7% overall) did not significantly decrease with longer storage time after adjusting for confounders (88.9% for time >4 years, P = 0.963). A linear regression model did not show a significant effect of oocyte storage time on fertilization rate (about 70% in all time categories) (P > 0.05). Reproductive outcomes after the first embryo transfer were statistically comparable across storage times (P > 0.05 for all categories). Longer term oocyte storage (>4 years) did not affect the chances of clinical pregnancy (OR 0.700, 95% CI 0.423 to 1.158, P = 0.2214) or live birth (OR 0.716, 95% CI 0.425 to 1.208, P = 0.2670).

CONCLUSIONS

Oocyte survival, fertilization rate, pregnancy and live birth rates are not affected by the time spent by vitrified oocytes in vapour-phase nitrogen tanks.

Can Cryopreservation in Assisted Reproductive Technology (ART) Induce Epigenetic Changes to Gametes and Embryos?

Since the birth of Louise Brown in 1978, more than nine million children have been conceived using assisted reproductive technologies (ARTs). While the great majority of children are healthy, there are concerns about the potential epigenetic consequences of gametes and embryo manipulation. In fact, during the preimplantation period, major waves of epigenetic reprogramming occur. Epigenetic reprogramming is susceptible to environmental changes induced by ovarian stimulation, in-vitro fertilization, and embryo culture, as well as cryopreservation procedures. This review summarizes the evidence relating to oocytes and embryo cryopreservation and potential epigenetic regulation. Overall, it appears that the stress induced by vitrification, including osmotic shock, temperature and pH changes, and toxicity of cryoprotectants, might induce epigenetic and transcriptomic changes in oocytes and embryos. It is currently unclear if these changes will have potential consequences for the health of future offspring.

Systematic protocol and methodology needed for pre-procedure counselling of elective egg freezing patients in Singapore

Upon legalization of social egg freezing in Singapore from 2023 onwards, compulsory pre-procedure counselling is mandated for all prospective patients to enable informed choice about whether to undergo the procedure. Being a newly introduced medical procedure in Singapore, there are currently no clear directives on what pre-procedure counselling for elective egg freezing should entail. Due to pervasive media and internet influences, prospective egg freezing patients could be misled into believing that the procedure represents a guaranteed path to future motherhood, contrary to statements by professional bodies such as the American Society for Reproductive Medicine (ASRM) and the British Fertility Society (BFS). Hence, comprehensive counselling is recommended to provide women with evidence-based information (e.g. success rates of social egg freezing for women of their age) to ensure they make informed decisions and to avoid possible decision regret. For this purpose, a systematic protocol and methodology for pre-procedure counselling of women considering elective egg freezing was developed, incorporating flowcharts and decision trees that are specifically tailored to the unique sociocultural values and legal restrictions in Singapore. Questions relating to the why, what, how, where and when of the egg freezing procedure should be addressed, which could serve as a roadmap to facilitate informed decision-making by women considering elective egg freezing.

Considerations on staffing levels for a modern assisted reproductive laboratory

The duties recently performed in the embryology laboratory have deeply increased compared to those realized a couple of decades ago. Currently, procedures include conventional in vitro fertilization (IVF) and ICSI techniques, or processing of surgically retrieved sperm, embryo culture and time-lapse monitoring, blastocyst culture, as well as trophectoderm biopsy for preimplantation genetic testing and cryopreservation. These techniques require not only time, but also high knowledge level and acutely concentration by the embryologist team. The existing data indicate that an IVF laboratory need to have adequate staffing levels to perform the required daily duties, and to work in optimal conditions that are critical to assure a high quality service, as well as avoiding incidents and to provide the best outcomes. As a result, IVF clinics have invested in human resources, but there is still a large discrepancy between IVF centres on the number of embryologists employed. Currently there is no golden standard on the human resource requirements for assisted reproductive technology procedures; therefore, in this review paper we aim to provide arguments to take into account to determine the embryology staffing requirements in an embryology laboratory to assure optimal safety and efficiency of operations.

Four consecutive minimal ovarian stimulation (TetraStim) is a feasible alternative to increase the number of oocytes and improve live birth rates in poor responders who do not accept oocyte donation

OBJECTIVE

To present our experience using four consecutive minimal COS (TetraStim) followed by oocyte retrieval and vitrification to increase the number of oocytes in patients with POR for whom oocyte donation is not an option.

METHODS

We performed an observational study evaluating 128 poor responders submitted to TetraStim instead of oocyte donation cycles. Patients were submitted to four consecutive minimal COS started at luteal phase, oocyte retrieval, oocyte vitrification/warming, ICSI, endometrial priming and embryo transfer. We evaluated the number of vitrified oocytes, survival rate after warming, fertilization rate, cleavage rate, number of embryos transferred, clinical pregnancy rate, miscarriage rate and live birth rate.

RESULTS

The mean age was 38.1 ± 3.1 years. A total of 791 oocytes were recovered (6.1 ± 2.7/patient), 682 (86.2%) Metaphase II (5.3 ± 2.4/patient) were vitrified, 95.3% survived warming (5.1 ± 2.3/patient), 82% showed normal fertilization after ICSI (4.2 ± 2/patient), 79.2% reached cleavage stage (3.3 ± 1.6/patient), 313 cleavage stage embryos were transferred to 115 patients (2.7 ± 0.7/patient) and 14.7% of the patients had surplus embryos that were vitrified. Clinical pregnancy rate per patient was 31.3% and live birth rate per patient was 22.6%.

CONCLUSION

To our knowledge this is the first study that demonstrates that TetraStim can be an effective alternative for patients with POR with an indication to perform IVF with donated oocytes, but do not agree to use. TetraStim is a feasible alternative to increase the number of oocytes and embryos and improve pregnancy rates with no dropouts and very low cycle cancelation rate. However, randomized controlled studies must be performed to compare TetraStim with other treatments.

Oocyte donation: not all oocyte cryobanks are the same

RESEARCH QUESTION

Is the efficacy of imported vitrified oocyte donation affected by the cryobank of origin?

DESIGN

Longitudinal cohort study, including 249 completed oocyte warming cycles from 200 recipients (January 2016-July 2020). No severe male factor was included. Vitrified oocytes were provided by three Spanish cryobanks. Primary outcome was cumulative live birth delivery rate (CLBR) per completed oocyte warming cycle.

RESULTS

After warming 1535 oocytes, 1244 survived (81.0%) and 945 fertilized (76.0%); embryo utilization rate was 65.3%. The overall CLBR per completed cycle was 47.0% but was lower in cryobank 1 (31.2%) versus cryobank 2 (56.0%, P = 0.0010) and cryobank 3 (50.8%, P = 0.0241). Multivariate logistic regression analysis identified survival of four or more oocytes as the strongest predictor for delivery (P = 0.0282). Only 202 out of 249 oocyte warming cycles had four or more survived oocytes in a proportion that was significantly lower in cryobank 1 versus cryobank 2 (70.1% versus 89.0%, P = 0.0020); comparison with cryobank 3 (81.0%) was not significant. In the 202 oocyte warming cycles, CLBR in cryobank 1 (37.0%) was lower versus cryobank 2 (58.8%, P = 0.0115) and cryobank 3 (60.8%, P = 0.0019), suggesting a reduced viability in oocytes from cryobank 1 that survived warming.

CONCLUSIONS

Differences were found in the efficacy of imported vitrified oocytes in relation to the cryobank of origin. Each centre needs to evaluate the results internally when starting a collaboration with an oocyte cryobank to establish the necessary measures to maximize treatment efficacy.

Live birth and clinical outcome of vitrification-warming donor oocyte programme: an experience of a single IVF unit

Medically assisted reproductive (MAR) treatments using donated oocytes are commonly applied in several countries to treat women who cannot conceive with their own gametes. Historically, in Italy, gamete donation has been prohibited but, in 2014, the law changed and gamete donation became allowed for couples undergoing MAR treatments. Consequently, in the last decade, there has been an increase in application of the oocyte donation programme. This study reports an egg-donation programme's clinical efficacy, based on importing donated vitrified oocytes from cryo-banks located in a foreign country. For this, we conducted a retrospective analysis of data from a single reproductive unit located in Italy (Donna Salus Women's Health and Fertility, Bozen). The study group consisted of 681 vitrified oocytes, which were warmed and culture to be replaced in 100 recipients. The survival rate after warming was 79.1% (n = 539/681), whereas the fertilization and blastulation rates were 90.2% (n = 486/539) and 47.9% (n = 233/486), respectively. Positive pregnancy test, clinical pregnancy rates, and live-birth rates per embryo transfer were 37.8%, 31.1% and 28.4%, respectively. The multiple pregnancy rate was 0.7%. This study is one of the first to report on the efficacy of a donor oocyte programme in Italy using imported vitrified oocytes. The above data may reassure women who are undertaking donation programmes using vitrified oocytes imported from commercial egg banks.

Ovarian stimulation for oocyte donation: a systematic review and meta-analysis

BACKGROUND

Since its introduction in the 1980s, oocyte donation (OD) has been largely integrated into ART. Lately, both demand and the indications for OD have increased greatly. Oocyte donors are healthy and potentially fertile women undergoing voluntarily ovarian stimulation (OS). Selection of the optimal type of stimulation is of paramount importance in order to achieve the most favourable outcomes for the oocyte recipients, but most importantly for the safety of the oocyte donors.

OBJECTIVE AND RATIONALE

This is the first systematic review (SR) with the objective to summarize the current evidence on OS in oocyte donors. The scope of this SR was to evaluate the OD programme by assessing four different aspects: how to assess the ovarian response prior to stimulation; how to plan the OS (gonadotrophins; LH suppression; ovulation trigger; when to start OS); how to control for the risk of ovarian hyperstimulation syndrome (OHSS) and other complications; and the differences between the use of fresh versus vitrified donated oocytes.

SEARCH METHODS

A systematic literature search was conducted in May 2020, according to PRISMA guidelines in the databases PubMed and Embase, using a string that combined synonyms for oocytes, donation, banking, freezing, complications and reproductive outcomes. Studies reporting on the safety and/or efficacy of OS in oocyte donors were identified. The quality of the included studies was assessed using ROBINS-I and ROB2. Meta-analysis was performed where appropriate. Data were combined to calculate mean differences (MD) for continuous variables and odd ratios (OR) for binary data with their corresponding 95% CIs. Heterogeneity between the included studies was assessed using I2 and tau statistics.

OUTCOMES

In total, 57 manuscripts were selected for the review, out of 191 citations identified. Antral follicle count and anti-Müllerian hormone levels correlate with ovarian response to OS in OD but have limited value to discriminate donors who are likely to show either impaired or excessive response. Five randomized controlled trials compared different type of gonadotrophins as part of OS in oocyte donors; owing to high heterogeneity, meta-analysis was precluded. When comparing different types of LH control, namely GnRH antagonist versus agonist, the studies showed no differences in ovarian response. Use of progesterone primed ovarian stimulation protocols has been evaluated in seven studies: the evidence has shown little or no difference, compared to GnRH antagonist protocols, in mean number of retrieved oocytes (MD 0.23, [95% CI 0.58-1.05], n = 2147; 6 studies; I2 = 13%, P = 0.33) and in clinical pregnancy rates among recipients (OR 0.87 [95% CI 0.60-1.26], n = 2260, I2 = 72%, P < 0.01). There is insufficient evidence on long-term safety for babies born. GnRH agonist triggering is the gold standard and should be used in all oocyte donors, given the excellent oocyte retrieval rates, the practical elimination of OHSS and no differences in pregnancy rates in recipients (four studies, OR 0.86, 95%CI 0.58-1.26; I2 = 0%). OS in OD is a safe procedure with a low rate of hospitalization after oocyte retrieval. The use of a levonorgestrel intrauterine device or a progestin contraceptive pill during OS does not impact the number of oocytes retrieved or the clinical pregnancy rate in recipients. Ultrasound monitoring seems enough for an adequate follow up of the stimulation cycle in OD. Use of fresh versus vitrified donated oocytes yielded similar pregnancy outcomes.

WIDER IMPLICATIONS

This update will be helpful in the clinical management of OS in OD based on the most recent knowledge and recommendations, and possibly in the management of women under 35 years undergoing oocyte vitrification for social freezing, owing to the population similarities. More clinical research is needed on OS protocols that are specifically designed for OD, especially in term of the long-term safety for newborns, effective contraception during OS, and treatment satisfaction.