Oocyte vitrification in the 21st century and post-warming fertility outcomes: a systematic review and meta-analysis

Vitrification of human blastocysts for couples undergoing assisted reproduction: an updated review

Over the past 40 years there has been a worldwide critical change in the field of assisted reproduction technology (ART), leading to the increased application of single blastocyst transfer, which is extremely important to avoid the risks of multiple pregnancy and associated complications for both mother and babies. Indeed, advancements in ART over the last few decades have been obtained thanks to several improvements, including ovarian stimulation, embryo culture conditions and, of course, progress in cryopreservation methods, especially with the application of vitrification. The ability to cryopreserve human embryos has improved significantly with vitrification compared to the initially adopted slow-freezing procedures. Since the introduction of vitrification, it has become the gold standard method to effectively cryopreserve human blastocysts. However, some new protocols are now being explored, such as the short warming procedure and even shorter exposure to the equilibration solution before vitrification, which seem to provide optimal results. Therefore, the main aim of the current narrative review, will be to illustrate the benefit of vitrification as an effective method to cryopreserve the human blastocyst and to illustrate new protocols and variations which in future may increase the performance of vitrification protocols.

Planned oocyte cryopreservation to preserve future reproductive potential: an Ethics Committee opinion

Planned oocyte cryopreservation is an ethically permissible procedure that may help individuals avoid future infertility. Because planned oocyte cryopreservation is new and evolving, it is essential that those considering using it be informed about the uncertainties regarding its efficacy and long-term effects. This replaces the document of the same name, last published in 2017.

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.

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.

Outcomes of Social Egg Freezing: A Cohort Study and a Comprehensive Literature Review

The purpose of this study is to evaluate the live birth outcome following oocyte thaw in women who underwent social egg freezing at Guy's Hospital, alongside a detailed published literature review to compare published results with the current study. A retrospective cohort study was conducted between January 2016 and March 2022 for all women who underwent egg freezing during this period. Overall, 167 women had 184 social egg freezing cycles. The mean age at freeze was 37.1 years and an average of 9.5 eggs were frozen per retrieval. In total, 16% of the women returned to use their frozen eggs. The mean egg thaw survival rate post egg thaw was 74%. The mean egg fertilisation rate was 67%. The pregnancy rate achieved per embryo transfer was 48% and the live birth rate per embryo transfer was 35%. We also noted that irrespective of age at freezing, a significantly high live birth rate was achieved when the number of eggs frozen per patient was 15 or more. Despite the rapid increase in social egg freezing cycles, the utilisation rate remains low. Pregnancy and live birth rate post thaw are encouraging if eggs are frozen at a younger age and if 15 eggs or more were frozen per patient.

The role of Hippo pathway in ovarian development

The follicle is the functional unit of the ovary, whereby ovarian development is largely dependent on the development of the follicles themselves. The activation, growth, and progression of follicles are modulated by a diverse range of factors, including reproductive endocrine system and multiple signaling pathways. The Hippo pathway exhibits a high degree of evolutionary conservation between both Drosophila and mammalian systems, and is recognized for its pivotal role in regulating cellular proliferation, control of organ size, and embryonic development. During the process of follicle development, the components of the Hippo pathway show temporal and spatial variations. Recent clinical studies have shown that ovarian fragmentation can activate follicles. The mechanism is that the mechanical signal of cutting triggers actin polymerization. This process leads to the disruption of the Hippo pathway and subsequently induces the upregulation of downstream CCN and apoptosis inhibitors, thereby promoting follicle development. Thus, the Hippo pathway plays a crucial role in both the activation and development of follicles. In this article, we focused on the development and atresia of follicles and the function of Hippo pathway in these processes. Additionally, the physiological effects of Hippo pathway in follicle activation are also explored.

[The impact of oocyte cryopreservation time in oocyte donation on the clinical success rate]

OBJECTIVES

To evaluate the impact of the cryopreservation time of vitrified oocytes on the success rates in oocyte donation cycles.

METHODS

A retrospective study was carried out on 156 cycles with donated oocytes from January 2012 to September 2021. All the cycles were sorted according to the storage time of the oocytes (25 in the group 1:<3 months, 32 in the group 2: between 3 and 6 months, 39 in the group 3: between 6 and 12 months, 38 in the group 4: between 12 and 24 months and 22 in the group 5:>24 months). Clinical outcomes after ART, survival rates at thawing and oocyte fertilization rates were compared between the different cohorts stratified according to oocyte storage duration. A binary multivariate logistic regression was performed adjusting for the identified confounders.

RESULTS

Prolonged storage time of vitrified oocytes had an effect on their survival post-thawing rates, but no significant effect was identified on fertilization rates or clinical outcomes. After adjusting for the confounders, the relationships between clinical outcomes and oocytes storage time did not reach statistical significance. Our study was characterized by a limited cohort with data from a single ART center.

CONCLUSIONS

Our study doesn't highlight any significant difference in the use of long-stored vitrified oocytes (more than 2 years) on clinical issues in ART. The conclusion of our study needs to be verified in further studies with larger cohorts.

Oocyte Cryopreservation: A 9-Year Single-Centre Experience

OBJECTIVE

Oocyte cryopreservation (OC) has increased in recent years; however, there is a paucity of published data on the use of cryopreserved oocytes and associated outcomes.

METHODS

A retrospective review of 748 OC cycles between 2013 and 2022 at a private fertility centre was performed. Outcome parameters for oocyte retrieval cycles were reviewed. For patients who returned for oocyte disposition, outcomes subsequent to oocyte re-warming, fertilization, and transfer were analyzed.

RESULTS

There were 748 OC cycles (653 elective and 95 non-elective) in 646 patients (556 elective and 90 non-elective). Patients were older at the time of freezing in the elective oocyte group compared with the non-elective group (36.5 vs. 28.8 y; P < 0.001). Sixty-five patients returned to warm and fertilize their oocytes (50 in the elective group and 15 in the non-elective group). The survival rate for warmed oocytes was 76.1% (541/711), and 66.2% of surviving oocytes were successfully fertilized, and 39.1% reached blastulation. Twenty-three patients underwent embryo transfers (10 after preimplantation genetic testing for aneuploidy), with 15 patients having at least 1 delivery or ongoing pregnancy.

CONCLUSIONS

To date, this is the largest published experience with OC in Canada. OC can lead to successful live births but does not guarantee a viable outcome for all patients. In this study, most patients with vitrified oocytes had not returned for disposition, so long-term follow-up is still required to verify the efficacy of OC.

High pressure frozen oocytes have improved ultrastructure but reduced cleavage rates compared to conventionally fixed or vitrified oocytes

Context Live birth rates are lower for cryopreserved oocytes than for fresh IVF cycles, indicating a need for improved methodologies. Aims The aim of this study was to determine if high pressure freezing (HPF) could improve both ultrastructural preservation and cryopreserved oocyte quality when compared to conventional fixation and vitrification methods. Methods Sheep oocytes and embryos were prepared by HPF or vitrification, with or without cryoprotectants. Frozen oocytes were prepared for transmission electron microscopy or warmed, in vitro fertilised and the recovery and cleavage rates recorded. Key results Blastocyst rates were similar between fresh, HPF and vitrified embryos. HPF oocytes had improved ultrastructure compared to conventional fixation or vitrification, but had poorer survival and cleavage rates compared to vitrified oocytes. Freeze-substitution of cryopreserved oocytes and transmission electron microscopy demonstrated disruption of the oocyte ultrastructure in the presence of cryoprotectants. Conclusions Superior preservation of ultrastructure was observed in HPF oocytes compared to vitrification or conventional fixation methods. In the presence of CP, both embryos and oocytes could survive HPF and warming but oocytes had reduced development. Implications The HPF method has potential to be developed and lead to improved oocyte and embryo cryopreservation and outcomes for assisted reproduction.

Endometriosis-associated infertility: From pathophysiology to tailored treatment

Despite the clinically recognized association between endometriosis and infertility, the mechanisms implicated in endometriosis-associated infertility are not fully understood. Endometriosis is a multifactorial and systemic disease that has pleiotropic direct and indirect effects on reproduction. A complex interaction between endometriosis subtype, pain, inflammation, altered pelvic anatomy, adhesions, disrupted ovarian reserve/function, and compromised endometrial receptivity as well as systemic effects of the disease define endometriosis-associated infertility. The population of infertile women with endometriosis is heterogeneous, and diverse patients' phenotypes can be observed in the clinical setting, thus making difficult to establish a precise diagnosis and a single mechanism of endometriosis related infertility. Moreover, clinical management of infertility associated with endometriosis can be challenging due to this heterogeneity. Innovative non-invasive diagnostic tools are on the horizon that may allow us to target the specific dysfunctional alteration in the reproduction process. Currently the treatment should be individualized according to the clinical situation and to the suspected level of impairment. Here we review the etiology of endometriosis related infertility as well as current treatment options, including the roles of surgery and assisted reproductive technologies.

Comparing the effects of a commercial and a prototype vitrification medium on meiotic spindle morphology and survival rate of mouse oocytes

OBJECTIVE

To compare oocyte survival and meiotic spindle normality between vitrified-warmed oocytes in a mouse embryo assay using Tvitri-4 or Ingámed vitrification media.

METHODS

C57BL/6 female mice aged 8-12 weeks were submitted to superovulation with pregnant mare's serum gonadotropin and human chorionic gonadotropin (hCG) for obtaining of in vivo matured oocytes. The oocytes were randomly distributed into one of the following three groups: CTR - control (fresh oocytes); ING - oocytes vitrified-warmed in a standard commercial kit supplied by Ingámed, and T4 - oocytes vitrified-warmed in the novel prototype Tvitri-4 medium. After warming and recovery culture, oocytes were assessed with respect to survival rate (SR) and both meiotic spindle morphology and chromosome alignment of each oocyte fixed in the sagittal position after immunostaining and analysis by confocal microscopy.

RESULTS

A total of 354 mature oocytes were vitrified in ING (n=178) and T4 (n=176), out of which 299 (85%) survived after warming. Oocyte survival rates were not statistically different (p=0.08) between ING (145/178=81.5%) and T4 (154/176=87.5%). Regarding meiotic normality, there were no significant changes in the proportion of oocytes with normal meiotic spindle morphology and chromosome structure between ING (52,2%) and T4 (63.4%) after warming (RR: 0.95, 95% CI: 0.92-1.607). When the meiotic normality was assessed using the CTR group as a reference in the analysis of relative risk, no significant differences were observed between T4 (63.4%) and CTR (70.5%) (RR: 0.95, 95% CI: 0.72-1.12). On the other hand, the percentage of oocytes retaining normal meiotic spindle morphology and chromosome configuration in ING (52.2%) was lower than in the CTR group (RR: 0.95, 95% CI: 0.57-0.97).

CONCLUSIONS

The novel prototype Tvitri-4 medium was efficient in preserve survival rate and meiotic spindle normality of oocytes and, with further verification, may be able to replace commercially available media in future clinical applications.

First pregnancy in China after ovarian tissue transplantation to prevent premature ovarian insufficiency

OBJECTIVE

This article reports the first case of pregnancy after frozen-thawed ovarian tissue transplantation to prevent iatrogenic premature ovarian insufficiency in China.

METHODS

Ovarian tissue cryopreservation was performed in a patient with myelodysplastic syndrome (MDS) before multi-agent chemotherapy and hematopoietic stem cell transplantation. Two years later, she showed complete remission from MDS, and six frozen-thawed ovarian tissue strips were transplanted into the peritoneal pocket.

RESULTS

The patient's ovarian activity was restored 3 months after transplantation, and pregnancy occurred spontaneously 27 months after grafting. Until now, the pregnancy has progressed for 30 weeks, and the repeated ultrasound showed normal fetal development.

CONCLUSION

This is the first pregnancy resulting from ovarian tissue cryopreservation and transplantation in China.

Evidence-based outcomes after oocyte cryopreservation for donor oocyte in vitro fertilization and planned oocyte cryopreservation: a guideline

OBJECTIVE

To provide evidence-based recommendations to practicing physicians and others regarding the efficacy of oocyte cryopreservation (OC) for donor oocyte in vitro fertilization and planned OC.

METHODS

The American Society for Reproductive Medicine conducted a literature search, which included systematic reviews, meta-analyses, randomized controlled trials, and prospective and retrospective comparative observational studies published from 1986 to 2018. The American Society for Reproductive Medicine Practice Committee and a task force of experts used available evidence and through consensus developed evidence-based guideline recommendations.

MAIN OUTCOME MEASURE(S)

Outcomes of interest included live birth rate, clinical pregnancy rate, obstetrical and neonatal outcomes, and factors predicting reproductive outcomes.

RESULT(S)

The literature search identified 30 relevant studies to inform the evidence base for this guideline.

RECOMMENDATION(S)

Evidence-based recommendations were developed for predicting the likelihood of live births after planned OC, autologous OC in infertile women, and donor OC, as well as factors that may impact live birth rates. Recommendations were developed regarding neonatal outcomes after using fresh vs. cryopreserved oocytes in cases of autologous or donor oocytes.

CONCLUSION(S)

There is insufficient evidence to predict live birth rates after planned OC. On the basis of limited data, ongoing and live birth rates appear to be improved for women who undergo planned OC at a younger vs. older age. Although there are no significant differences in per transfer pregnancy rates with cryopreserved vs. fresh donor oocytes, there is insufficient evidence that the live birth rate is the same with vitrified vs. fresh donor oocytes. Neonatal outcomes appear similar with cryopreserved oocytes compared with fresh oocytes. Future studies that compare cumulative live birth rates are needed.

Social Freezing: Pressing Pause on Fertility

Increasing numbers of women are undergoing oocyte or tissue cryopreservation for medical or social reasons to increase their chances of having genetic children. Social egg freezing (SEF) allows women to preserve their fertility in anticipation of age-related fertility decline and ineffective fertility treatments at older ages. The purpose of this study was to summarize recent findings focusing on the challenges of elective egg freezing. We performed a systematic literature review on social egg freezing published during the last ten years. From the systematically screened literature, we identified and analyzed five main topics of interest during the last decade: (a) different fertility preservation techniques, (b) safety of freezing, (c) usage rate of frozen oocytes, (d) ethical considerations, and (e) cost-effectiveness of SEF. Fertility can be preserved for non-medical reasons through oocyte, embryos, or ovarian tissue cryopreservation, with oocyte vitrification being a new and optimal approach. Elective oocyte cryopreservation is better accepted, supports social gender equality, and enhances women's reproductive autonomy. Despite controversies, planned oocyte cryopreservation appears as a chosen strategy against age-related infertility and may allow women to feel that they are more socially, psychologically, and financially stable before motherhood.

Current perspectives on social oocyte freezing

Demand for oocyte freezing in absence of a medical indication is growing as women delay childbirth and seek to extend the window of opportunity for parenthood. The optimum age for oocyte freezing is below 35 years, whereas currently the mean age of women undergoing oocyte freezing in the UK is 38 years. Nearly half of women undergoing oocyte freezing are not in a relationship. The treatment is not publicly funded and the average price for a complete oocyte freezing and thawing cycle, including annual storage fees, could reach over £7000. The live birth rate per oocyte thaw cycle is 18% and is influenced by age at the time of oocyte freezing. Women considering social oocyte freezing should be thoroughly counselled about the efficacy, limitations, cost implications and alternatives to oocyte freezing and provided with the appropriate support to enable a truly informed reproductive choice.

Systematic review of fertility preservation options in transgender patients: a guide for plastic surgeons

Transgender patients often desire to have biological children. However, their reproductive potential is often negatively impacted by gender affirming surgery (GAS) such as gender confirmation surgery (bottom surgery) and medical hormone therapy. Therefore, counselling patients on fertility preservation options before initiating gender-affirming treatments is prudent to avoid reducing their reproductive potential. A systematic review of English, Spanish, Chinese, French and Turkish languages from 2000 to December 23rd, 2019, using the preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) guidelines, was conducted. The search strategy was designed and conducted by an experienced librarian with input from the study's principle investigator. Fifteen articles that report outcomes of fertility preservation options in transgenders were included. Eight articles described options for transgender women, six reported options for transgender men and one included both transgender women and transgender men. Semen cryopreservation and oocyte cryopreservation are the most common and available methods for fertility preservation in transgenders. Physician awareness of fertility preservation options in transgender patients is crucial to ensure informed discussions regarding reproductive options in the early phase of transition.

Important parameters affecting quality of vitrified donor oocytes

For group of 281 oocytes obtained from 43 stimulated donors and cryopreserved by vitrification protocol using Cryotop and Kitazato medium we determined important parameters of oocytes collection and vitrification processes which strongly affect the probability that warmed oocytes will produce high-quality embryos for transfer. The probability to obtain high-quality embryos for transfer from vitrified and warmed oocytes was highest when two conditions were fulfilled: 1. oocytes were incubated before vitrification for 7-10 h and 2. stimulated ovaries of donors in one cycle produced a smaller number of oocytes (<7 oocytes from one donor per stimulated cycle). The probable reasons for these observations were: 1. early vitrification (less than 7 h) before final oocyte metaphase II maturation negatively affected the crucial process of post-warm remodelling of spindles and chromosomes, which reduced the fertilization and utilization rates, 2. the evaluated vitrification protocol amplifies negative impact of membrane defects of oocytes of those cohorts containing more than 6 oocytes - freezing places great demands on the integrity and elasticity of the cell membranes. The fact that cryopreservation influences a complex state of oocytes was confirmed by confocal microscopy.

Mitochondrial Dysfunction and Oxidative Stress Caused by Cryopreservation in Reproductive Cells

Mitochondria, fundamental organelles in cell metabolism, and ATP synthesis are responsible for generating reactive oxygen species (ROS), calcium homeostasis, and cell death. Mitochondria produce most ROS, and when levels exceed the antioxidant defenses, oxidative stress (OS) is generated. These changes may eventually impair the electron transport chain, resulting in decreased ATP synthesis, increased ROS production, altered mitochondrial membrane permeability, and disruption of calcium homeostasis. Mitochondria play a key role in the gamete competence to facilitate normal embryo development. However, iatrogenic factors in assisted reproductive technologies (ART) may affect their functional competence, leading to an abnormal reproductive outcome. Cryopreservation, a fundamental technology in ART, may compromise mitochondrial function leading to elevated intracellular OS that decreases sperm and oocytes' competence and the dynamics of fertilization and embryo development. This article aims to review the role played by mitochondria and ROS in sperm and oocyte function and the close, biunivocal relationships between mitochondrial damage and ROS generation during cryopreservation of gametes and gonadal tissues in different species. Based on current literature, we propose tentative hypothesis of mechanisms involved in cryopreservation-associated mitochondrial dysfunction in gametes, and discuss the role played by antioxidants and other agents to retain the competence of cryopreserved reproductive cells and tissues.

Oocyte cryopreservation - current scenario and future perspectives: A narrative review

Oocyte cryopreservation is a boon for women undergoing assisted reproductive technology. With the evolution in the technique of cryopreservation over the last three decades, there has been an exponential rise in the number of oocyte cryopreservation cycles for diverse indications. Apart from cancer patients, it has also been promoted as a mode of fertility insurance to overcome the age-related decline in fertility as well as post-surgical decline following endometriosis surgery. The objective of the review is to evaluate its clinical applications, ideal age at freezing, optimal oocyte number, freezing method of choice, efficacy, safety and recent advances. In the last decade, vitrification has surpassed slow freezing for oocyte cryopreservation. Although closed system of vitrification provides the aseptic environment, open vitrification is commonly followed in practice. Early to mid-thirties is a reasonable age group for planned oocyte cryopreservation, although it might be recommended at a younger age, in patients with diminished ovarian reserve. The patients should be motivated to preserve around 14–20 mature oocytes for successful live birth. Various studies have shown comparable fertilisation and pregnancy rates between Intracytoplasmic sperm injection with fresh and frozen-thawed oocytes. The available evidence has shown no increase in the incidence of congenital abnormalities in babies born through vitrified oocytes. In the future, image analysis using artificial intelligence, and spindle visualisation using poloscope may further enhance the outcome of oocyte cryopreservation.

'Two countries-two labs': the transnational gamete donation (TGD) programme to support egg donation

PURPOSE

To evaluate the effectiveness, efficiency, and safety of a transnational gamete donation (TGD) programme based on the shipping of vitrified donor oocytes.

METHODS

A retro-prospective observational study was conducted in the Assisted Reproductive Technology Center of the University Hospital of Florence, Italy. The study population included 622 consecutive donor oocyte cycles. A mean number of 6 vitrified oocytes per couple were shipped from two Spanish biobanks. In the receiving centre, gametes were warmed and inseminated and the subsequent embryo transfer (ET) was performed. The main outcome measurement was LBR. Secondary outcomes included oocyte survival rate, ICSI damage rate, normal fertilization, cleavage, and implantation rate (IR) in both 'fresh' and cryotransfer cycles.

RESULTS

A total number of 3536 mature oocytes were warmed with 81.4% surviving oocytes. 2PN oocytes were 1941 with an ICSI normal fertilization rate of 70.4% and a cleavage rate of 93.4%; 857 day-3 embryos were transferred in 498 women, 63 blastocysts in 44. Couples with at least one vitrified embryo were 181 (32.3%). IR was 25.1% and 33.1% for day-3 ET and blastocyst stage respectively. Crude pregnancy rate and LBR after the first ET were 35.5% and 27% correspondingly with a conservative cumulative LBR of 34% and an optimal LBR of 51.4%.

CONCLUSION

Imported vitrified donor oocytes retain their competence and are capable of resulting in ongoing pregnancies and healthy babies in a proportion comparable to other existing systems as egg donation with vitrification/warming in the same laboratory and transnational fresh oocyte donation.

What impact does oocyte vitrification have on epigenetics and gene expression?

Children conceived by assisted reproductive technologies (ART) have a moderate risk for a number of adverse events and conditions. The question whether this additional risk is associated with specific procedures used in ART or whether it is related to the intrinsic biological factors associated with infertility remains unresolved. One of the main hypotheses is that laboratory procedures could have an effect on the epigenome of gametes and embryos. This suspicion is linked to the fact that ART procedures occur precisely during the period when there are major changes in the organization of the epigenome. Oocyte freezing protocols are generally considered safe; however, some evidence suggests that vitrification may be associated with modifications of the epigenetic marks. In this manuscript, after describing the main changes that occur during epigenetic reprogramming, we will provide current information regarding the impact of oocyte vitrification on epigenetic regulation and the consequences on gene expression, both in animals and humans. Overall, the literature suggests that epigenetic and transcriptomic profiles are sensitive to the stress induced by oocyte vitrification, and it also underlines the need to improve our knowledge in this field.

Abrahamic traditions and egg freezing: Religious Women's experiences in local moral worlds

In this article, we elucidate how elective egg freezing (EEF) has been received within the three Abrahamic traditions-Judaism, Christianity, and Islam-and how these religion-specific standpoints have affected the EEF experiences of women who self-identify as religiously observant. Through an analysis of religious women's narratives, the study explores the "local moral worlds" of religious women who chose to freeze their eggs for non-medical reasons. It draws on ethnographic interviews with 14 women in the United States and Israel who had completed at least one EEF cycle, and who were part of a large, binational study that interviewed, between 2014 and 2016, 150 women who pursued EEF. These religious women, who were all highly educated, faced a particular challenge in finding appropriate marriage partners. Feeling pressured but still hopeful to marry and create large families, the women used EEF to extend their reproductive timelines and reduce their anxieties. As the study showed, the women reinterpreted or reconciled religious restrictions on the use of EEF in various ways, believing that their ultimate pursuit of religiously sanctioned reproduction justified the means. This study, which is the first to compare Jewish, Christian, and Muslim women's experiences of EEF, illustrates how this novel technology is now shaping the local moral worlds of religious women.

Oocyte Vitrification: A Comparative Analysis Between Fresh and Cryopreserved Oocytes in an Oocyte Donation Program

Background: Oocyte Cryopreservation has become an important part of infertility treatment for various reasons such as fertility preservation in women going for oncological treatment; in oocyte donation cycles; in eliminating several religious, ethical, and legal concerns of embryo freezing and in women who wish to delay childbirth. The newer ”vitrification” technique for freezing has further improved the success rates for actual conception than the earlier method of slow freezing. A successful oocyte freezing program can help in establishment of oocyte banks, which would help to provide compatible oocytes immediately, thus would eliminate the several problems of fresh donor cycles.

Methods: In this retrospective observational study, total 60 oocyte donation cycles were included (38 were fresh and 22 were vitrified oocytes cycle, respectively). After a thorough screening, controlled ovarian hyperstimulation for donors was performed using flexible antagonist protocol. All mature oocytes were allocated into “vitrified oocytes” and “fresh oocytes” groups. Vitrification technique using Cryotop method was used for oocyte freezing. Both clinical and laboratory outcomes of vitrified and fresh oocytes in donor cycles were compared.

Results: A total of 600 oocytes (226 “vitrified oocytes” and 374 fresh oocytes), were studied. After warming 218 oocytes survived resulting in survival rate of 96.4%. Fertilization rate and embryo formation rate was 86.2% and 93.6%, respectively. Results of frozen-thawed oocyte donor cycles were compared with fresh donation cycles. For fresh oocyte group, fertilization rate and embryo formation rate was 83.4% and 92.6%, respectively. On comparing clinical outcomes, clinical pregnancy rate was 60.5% in fresh group and 63.6% in vitrified group.

Conclusions: Both clinical and laboratory results obtained in the study suggest that oocyte cryopreservation can be performed with reproducible success, thus vitrification technique can be provided as a useful tool for achieving highly successful outcomes in an oocyte donor program.

Cost-effectiveness of social oocyte freezing in Germany: estimates based on a Markov model

PURPOSE

Is oocyte freezing for non-medical reasons-the so-called "social freezing" (SF)-cost-effective compared to standard in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) in Germany today?

METHODS

We developed a model based on three strategies for women planning to postpone pregnancy. In each strategy, women actively practiced contraception until 40 then tried to conceive naturally for 1 year. If unsuccessful, women using strategy I (oocyte cryopreservation) attempted ICSI with frozen oocytes in the 2nd year, while women using strategy II (no action) further attempted natural conception. In strategy III (IVF/ICSI), women underwent 1 year of IVF/ICSI. If still unsuccessful, each strategy was followed by attempting natural conception again until 45. We used an adaptive Markov model to estimate and compare live birth rates and cost-effectiveness measures.

RESULTS

For strategy I, cumulative live birth rates at age 45 generally declined with the woman's age at freezing and were between 71.4% (25 years) and 67.6% (38 years), while the cumulative success rate was 51.5% for strategy II and 60.8% for strategy III. The costs per live birth of egg freezing were age-dependent ranging between 22,418 € (30 years) and 25,590 € (38 years). The costs for strategy III were lower at 20,293 € per live birth.

CONCLUSION

Based on our results, social freezing in Germany may lead to additional pregnancies among women over 40 but also to significantly higher costs, since given the current live birth success rates and pricing, social freezing does not appear to be cost-effective.

ANZSREI consensus statement on elective oocyte cryopreservation

BACKGROUND

One in six Australian women and couples suffer infertility. A rising proportion relates to advanced maternal age, associated with poorer oocyte quality and in vitro fertilisation (IVF) outcomes. Internationally, oocyte cryopreservation technology applied to oocytes vitrified before 35 years provides similar live-birth statistics compared to IVF treatment using fresh oocytes. Oocyte cryopreservation is accessible in Australasian settings and elective uptake is increasing. For women accessing treatment, oocyte cryopreservation may expand future family building options.

AIMS

To develop the first Australasian Certification in Reproductive Endocrinology and Infertility (CREI) subspecialist-led consensus guideline on oocyte cryopreservation.

METHODS

The ANZSREI ACCEPT (Australasian CREI Consensus Expert Panel on Trial evidence group) met in 2017 and 2018 and identified clinical aspects of care for inclusion and review. Review of the available evidence was conducted and consensus statements prepared. Areas of dissent of expert opinion and for further research were noted.

RESULTS

Consensus was reached on definition and best practice in oocyte cryopreservation for freeze method, controlled ovarian stimulation, medical risk reduction and treatment and outcomes counselling. The term 'social egg freezing' may marginalise, stigmatise or attribute social blame to women, and there is a need to revise this to a neutral and non-judgemental term such as elective or planned oocyte cryopreservation.

CONCLUSION

Oocyte cryopreservation has the potential to improve cumulative live birth outcomes for women. Implementation of this guideline should facilitate an optimal approach for providing care.

Fertility preservation in patients with hematologic malignancies and recipients of hematopoietic cell transplants

Patients with hematologic malignancies and those undergoing hematopoietic cell transplantation (HCT) face a complex set of challenges when considering options for fertility preservation (FP). There are no standard options for prepubertal children, and women with hematologic malignancies may not be eligible for standard FP options. Fortunately, initial therapies for most blood cancers are not highly gonadotoxic, affording an important opportunity for postremission counseling and referrals to fertility specialists. These patients face a high risk of relapse, and many will be referred for autologous or allogeneic HCT, which carries an extremely high risk of infertility. The expanding indications for HCT to include benign hematologic disorders as well as autoimmune diseases mandate that all hematologists are familiar with these risks. Oncofertility researchers are continually pushing the boundaries of what may be possible for our patients; in the meantime, communication and shared decision-making between hematologists and patients, as well as program-building, education, and outreach are essential to ensure that these patients, many of whom will be cured, maintain all of their options for a fulfilling life after intensive therapy.

Dynactin pathway-related gene expression is altered by aging, but not by vitrification

The storage of surplus oocytes by cryopreservation (OC) is a widely used tool in assisted reproductive technology, but there is a great debate about the effects of cryopreservation on oocyte competence. It is known that OC may affect meiotic spindles but remains unclear if OC may increase the risk of aneuploidy. The aim of this study was to test the effects of OC and women aging on the expression of cytokinesis-related genes playing an important role in the segregation of chromosomes (DCTN1, DCTN2, DCTN3, DCTN6 and PLK1). Results highlighted that OC do not modify the expression of the selected genes, whereas women aging modulate the expression of all transcripts, confirming that aging is the crucial factor affecting meiosis and aneuploidy risk. A new role for Dynactin and PLK1 was shed in light, providing information on the ageing process in the oocyte which may be associated to reduced fertility.

Understanding social oocyte freezing in Italy: a scoping survey on university female students' awareness and attitudes

In Western countries, a social trend toward delaying childbearing has been observed in women of reproductive age for the last two decades. This delay is due to different factors related to lifestyle, such as the development of a professional career or the absence of the right partner. As a consequence, women who defer childbearing may find themselves affected by age-related infertility when they decide to conceive. Fertility preservation techniques are, therefore, proposed as a solution for these women. Among all possible solutions, social freezing is an alternative strongly discussed from a scientific, social and ethical point of view.A survey among 930 female students at the University of Padova (Italy) investigated their knowledge and attitudes on social egg freezing and their potential intentions regarding this procedure. To our knowledge, this is the first study to examine the level of awareness of age-related infertility in Italian young women and their attitudes regarding acceptable indications for elective oocyte freezing, their potential personal use, the circumstances in which they would then decide to use cryopreserved eggs, and their attitudes towards cost coverage and oocyte donation.Data collected in this study revealed some important points about young women and their knowledge about social oocyte freezing in Italy as compared to other European countries and the United States.Overall, 34.3% of the students reported having heard about the possibility of oocyte cryopreservation for non-medical reasons and being aware of the meaning of this procedure; only 19.5% were in favour of social egg freezing and 48.4% thought that the cost for this procedure should be borne entirely by the woman herself. Regarding egg donation, the majority of students (64.9%) would not accept donating their eggs to a known woman or couple and 42.5% would instead accept donating to a biobank.Our study shows that young Italian women are significantly less aware of age-related decline in fertility and the possibility of using social egg freezing compared to their similarly situated counterparts in other Western countries.

Social egg freezing under public health perspective: Just a medical reality or a women's right? An ethical case analysis

In recent years, a social trend toward delaying childbearing has been observed in women of reproductive age. A novel technomedical innovation was commercialized for non-medical reasons to healthy, ostensibly fertile women, who wished to postpone motherhood for various reasons such as educational or career demands, or because they had not yet found a partner. As a consequence, these women may be affected by age-related infertility when they decide to conceive, and fertility preservation techniques can be obtained through the so-called social egg freezing. This paper examines, from an ethical point of view, the impact of social egg freezing under some aspects that can involve policy making and resources allocation in public health. Due to the increasing demand for this procedure, some debated issues regard if it is reasonable to include social egg freezing in Public Healthcare System and consequently how to manage the storage of cryopreserved oocytes also from individual donors, how to support these egg banks and how to face, in the future, with the possibility that egg freezing will play a role in enabling childbearing for gays, lesbians, and unmarried persons. Social freezing may be advertised to harmonise gender differences, but we wonder if it is the proper solution to the problem or if it could also create further challenges. An ethical argumentation on these topics should address some questions that will be discussed.

Fertility preservation options in transgender people: A review

Gender affirming procedures adversely affect the reproductive potential of transgender people. Thus, fertility preservation options should be discussed with all transpeople before medical and surgical transition. In transwomen, semen cryopreservation is typically straightforward and widely available at fertility centers. The optimal number of vials frozen depends on their reproductive goals and treatment options, therefore a consultation with a fertility specialist is optimal. Experimental techniques including spermatogonium stem cells (SSC) and testicular tissue preservation are technologies currently under development in prepubertal individuals but are not yet clinically available. In transmen, embryo and/or oocyte cryopreservation is currently the best option for fertility preservation. Embryo cryopreservation requires fertilization of the transman's oocytes with a donor or partner's sperm prior to cryopreservation, but this limits his future options for fertilizing the eggs with another partner or donor. Oocyte cryopreservation offers transmen the opportunity to preserve their fertility without committing to a male partner or sperm donor at the time of cryopreservation. Both techniques however require at least a two-week treatment course, egg retrieval under sedation and considerable cost. Ovarian tissue cryopreservation is a promising experimental method that may be performed at the same time as gender affirming surgery but is offered in only a limited amount of centers worldwide. In select places, this method may be considered for prepubertal children, adolescents, and adults when ovarian stimulation is not possible. Novel methods such as in-vitro activation of primordial follicles, in vitro maturation of immature oocytes and artificial gametes are under development and may hold promise for the future.

Ten pathways to elective egg freezing: a binational analysis

PURPOSE

What are the specific pathways that lead women to freeze their eggs? In this binational study, women were asked directly about the life circumstances that led them on the path to elective egg freezing (EEF).

METHODS

From June 2014 to August 2016, 150 women (114 in the USA, 36 in Israel) who had completed at least 1 cycle of EEF were interviewed by two medical anthropologists. Study participants were recruited through four American IVF clinics (two academic, two private) and three in Israel (one academic, two private). Interviews were audio-recorded, transcribed verbatim, and entered into a qualitative data management program (Dedoose) for analysis.

RESULTS

The majority (85%) of women in the study were without partners, while 15% had partners at the time of EEF. Six pathways to EEF were found among women without partners (being single, divorced, broken up, deployed overseas, single mother, career planner), with career planning being the least common pathway to EEF. Among women with partners, four pathways to EEF were found (relationship too new or uncertain, partner not ready to have children, partner refusing to have children, or partner having multiple partners). With only one exception, the pathways and their frequencies were similar in both countries.

CONCLUSIONS

Partnership problems, not career planning, lead most women on pathways to EEF. These pathways should be studied in a variety of national settings, and fertility clinics should offer patient-centered care for single women pursuing EEF in the couples-oriented world of IVF.

Elective egg freezing and its underlying socio-demography: a binational analysis with global implications

BACKGROUND

What are the underlying socio-demographic factors that lead healthy women to preserve their fertility through elective egg freezing (EEF)? Many recent reviews suggest that women are intentionally postponing fertility through EEF to pursue careers and achieve reproductive autonomy. However, emerging empirical evidence suggests that women may be resorting to EEF for other reasons, primarily the lack of a partner with whom to pursue childbearing. The aim of this study is thus to understand what socio-demographic factors may underlie women's use of EEF.

METHODS

A binational qualitative study was conducted from June 2014 to August 2016 to assess the socio-demographic characteristics and life circumstances of 150 healthy women who had undertaken at least one cycle of elective egg freezing (EEF) in the United States and Israel, two countries where EEF has been offered in IVF clinics over the past 7-8 years. One hundred fourteen American women who completed EEF were recruited from 4 IVF clinics in the US (2 academic, 2 private) and 36 women from 3 IVF clinics in Israel (1 academic, 2 private). In-depth, audio-recorded interviews lasting from 0.5 to 2 h were undertaken and later transcribed verbatim for qualitative data analysis.

RESULTS

Women in both countries were educated professionals (100%), and 85% undertook EEF because they lacked a partner. This "lack of a partner" problem was reflected in women's own assessments of why they were single in their late 30s, despite their desires for marriage and childbearing. Women themselves assessed partnership problems from four perspectives: 1) women's higher expectations; 2) men's lower commitments; 3) skewed gender demography; and 4) self-blame.

DISCUSSION

The "lack of a partner" problem reflects growing, but little discussed international socio-demographic disparities in educational achievement. University-educated women now significantly outnumber university-educated men in the US, Israel, and nearly 75 other societies around the globe, according to World Bank data. Thus, educated women increasingly face a deficit of educated men with whom to pursue childbearing.

CONCLUSION

Among healthy women, EEF is a technological concession to gender-based socio-demographic disparities, which leave many highly educated women without partners during their prime childbearing years. This information is important for reproductive specialists who counsel single EEF patients, and for future research on EEF in diverse national settings.

Decision making processes of women who seek elective oocyte cryopreservation

PURPOSE

The aim of this study is to analyze women's opinions and their decision making processes regarding elective oocyte cryopreservation (OC).

METHODS

One hundred twenty-four women who had elective OC counseling at the CHA Seoul Fertility Center were asked to complete a survey after their first visit. Data collection regarding age, marital status, monthly income, occupation, religion, reproductive history, questions about the participant's view on their own fecundity, and future parenthood were included. The modified Reproductive Concerns After Cancer scale and the Decisional Conflict Scale were used for analysis.

RESULTS

The participants' mean age was 37.1 ± 4.8 years old. Eighty-six percent of the participants had regular periods. Ninety-two percent thought it was important to have their own biological offspring, and 86% were willing to pursue OC. Forty-nine percent appeared to have high DCS scores regarding making a decision of OC. Sixty-eight percent pursued OC, and the mean number of oocytes cryopreserved per patient was 10.5 ± 8.3. Multivariate analysis revealed that age was the only factor associated with high DCS scores (P = 0.002). Feeling less fertile than other women of same age and low DCS scores were the factors associated with pursuing OC (P = 0.02 and 0.004, respectively) after adjusting for possible confounding factors, including age.

CONCLUSIONS

Older women had more difficulties in making decisions about OC. Adjusting for age, women who thought that they were less fertile than other women of same age and those with lower decisional conflict were more likely to pursue OC. Further studies should focus on the validation of older women's decisional conflicts regarding OC.

Preincubation with glutathione ethyl ester improves the developmental competence of vitrified mouse oocytes

PURPOSE

Oocyte vitrification is currently used for human fertility preservation. However, vitrification damage is a problem caused by decreasing ooplasmic levels of glutathione (GSH). The GSH donor glutathione ethyl ester (GSH-OEt) can significantly increase the GSH content in oocytes. However, it is difficult to obtain oocyte from woman. To overcome this, we used mouse oocytes to replace human oocytes as a model of study.

METHODS

Oocytes from B6D2F1 mice were preincubated for 30 min with 2.5 mmol/L GSH-OEt (GSH-OEt group), without GSH-OEt preincubation before vitrification (control vitrification group) or in nonvitrified oocytes (fresh group). After thawing, oocytes were fertilized for evaluating the developmental competence of embryos in vitro and in vivo. Immunofluorescence, Polscope equipment and quantitative reverse transcription polymerase chain reaction (RT-qPCR) were used to analyze damage, including mitochondrial distribution, reactive oxygen species (ROS) levels, spindle morphology, and gene expression levels (Bcl-2, BAX, and MnSOD).

RESULTS

The rates of fertilization, 3-4 cell, blastocyst formation and expanded blastocysts were significantly higher (p < 0.05) in the GSH-OEt group (90.4%; 91.1%; 88.9% and 63.0%) than in the control (80.0%; 81.4%; 77.7% and 50.5%). Provided embryos overcame the 2-cell block and developed to the blastocyst stage, birth rates of all groups were similar. Vitrification altered mitochondrial distribution, increased ROS levels, and caused abnormal spindle morphology; GSH-OEt preincubation could improve such damage. RT-qPCR showed that the expression of Bcl-2 was lower in the control group compared with the GSH-OEt group; BAX and MnSoD expression levels were higher in the control group than in the GSH-OEt group (p < 0.05).

CONCLUSIONS

The beneficial effect of GSH-OEt preincubation occurred before the 2-cell stage.

Outcome of Oocyte Vitrification Combined with Microdissection Testicular Sperm Extraction and Aspiration for Assisted Reproduction in Men

Background

As a safety and efficacy protocol, oocyte vitrification has been widely used in IVF treatment. The aim of this study was to evaluate the outcome of ICSI-ET utilizing vitrified oocytes with sperm obtained from non-obstructive azoospermia (NOA) patients via micro-TESE.

Material/Methods

A total of 150 NOA patients underwent micro-TESE. Ten patients were unable to ejaculate and refused to accept TESA at the time of oocyte retrieval; later, these patients underwent TESA. A total of 174 obstructive azoospermia (OA) patients underwent TESA. Vitrified oocytes were used with micro-TESE in 35 cycles (group 1), and TESA in 10 cycles (group 2). Fresh oocytes were used with micro-TESE in 38 cycles (group 3) and TESA in 174 cycles (group 4).

Results

The overall sperm retrieval rate of the 150 NOA patients was 48.7% (73/150). A total of 257 cycles of ICSI-ET were conducted with testicular spermatozoa; 212 cycles utilized fresh oocytes and 45 cycles utilized vitrified oocytes. No differences were observed with fertilization (73.8%, 77.2%,72.8%, 73.6%), implantation (33.3%, 34.7%, 33.8%, 37.5%), or clinical pregnancy rates (51.4%, 60%, 52.6%, 51.7%) for groups 1 through 4, respectively (P>0.05). Developmental competence was greatest among couples using sperm obtained via TESA rather than micro-TESE, not dependent on whether vitrified or fresh oocytes were utilized. Fertilization, implantation, and clinical pregnancy rates did not differ between using fresh vs. vitrified oocytes, nor did they differ between using testicular sperm derived from men with NOA vs. men with OA.

Conclusions

Vitrified oocytes combined with micro-TESE showed similar clinical efficacy when compared with fresh oocytes.

Untapped Reserves: Controlling Primordial Follicle Growth Activation

Even with the benefit of assisted reproductive technologies (ART), many women are unable to conceive and deliver healthy offspring. One common cause of infertility is the inability to produce eggs capable of contributing to live birth. This can occur despite standard-of-care treatment to maximize the recovery of eggs from growing ovarian follicles. Dormant primordial follicles in the human ovary are a 'reserve ' that can be exploited clinically to overcome this problem. We discuss how controlling primordial follicle growth activation (PFGA) can produce increased numbers of high-quality eggs available for fertility treatment(s). We consider the state of the art in interventions used to control PFGA, and consider genetic and epigenetic strategies on the horizon that might improve compromised oocyte quality to increase live births.

No. 356-Egg Freezing for Age-Related Fertility Decline

OBJECTIVE

To provide a comprehensive review and evidence based recommendations for Canadian fertility centres that offer social egg freezing.

OUTCOMES

In social egg freezing cycles we evaluated thawed oocyte survival rates, fertilization rates, embryo quality, pregnancy rates, and live birth rates. We also review how these outcomes are impacted by age, ovarian reserve, and the number of eggs cryopreserved. Finally, we discuss the risks of social egg freezing, the alternatives, the critical elements for counselling and informed consent, and future reporting of egg freezing outcome data.

EVIDENCE

Published literature was reviewed through searches of MEDLINE and CINAHL using appropriate vocabulary and using key words ("oocyte cryopreservation," "egg freezing," "egg vitrification," "social egg freezing," and "elective egg freezing"). Results included systematic reviews, randomized controlled trials, controlled clinical trials, and observational studies. Expert opinion based on clinical experience, descriptive studies, or reports of expert committees was also included to discuss aspects of egg freezing not currently rigorously studied.

VALUES

The evidence obtained was reviewed and evaluated by the Clinical Practice Guideline (CPG) Committees of the Canadian Fertility and Andrology Society (CFAS) under the leadership of the principal authors.

BENEFITS, HARMS, AND COSTS

Implementation of this guideline should assist the clinician to develop an optimal approach in providing counselling for egg freezing while minimizing harm and improving patient outcomes during treatment.

VALIDATION

These guidelines have been reviewed and approved by the membership of the CFAS and by the CPG Committees of CFAS and The Society of Obstetricians and Gynaecologists of Canada (SOGC).

SPONSORS

CFAS and SOGC.

RECOMMENDATIONS

What women want? A scoping survey on women's knowledge, attitudes and behaviours towards ovarian reserve testing and egg freezing

OBJECTIVE

We aimed to investigate women's knowledge, attitudes and behaviours towards ovarian reserve testing and egg freezing for non-medical reasons in the general population.

STUDY DESIGN

This was a cross-sectional survey study of 663 women aged 18-44 years which assessed female perception of ovarian reserve testing and oocyte cryopreservation. An online forum was used to deliver the survey through the use of two social media sites. Participants were recruited through the technique of "snowballing", whereby existing study subjects recruited others from among their acquaintances. The data collected was analyzed using SPSS to explore descriptive statistics and frequencies relating to the participants' knowledge, attitudes and behaviour towards the practices of ovarian reserve testing and oocyte cryopreservation. Categorical variables were analyzed using Chi-squared; a p-value of <0.05 was considered significant.

RESULTS

A majority (60%) of women surveyed had knowledge of ovarian reserve testing. 64.8% would be interested in having testing performed. Younger women (<30 years of age) were more interested in checking their ovarian reserve (75.8% vs. 59.1%, p<0.0001). Single women were also more likely to be interested, (73.6% v's 62.1%, p=0.022). 89.7% of women surveyed were aware of oocyte cryopreservation. 72.2% agreed that they would consider freezing their eggs to preserve fertility. There was no significant difference in the numbers of single women compared to women in a relationship who would consider egg freezing to preserve fertility (75.7% v's 71.2%, p=0.347, or in younger (<30years) compared to older women, (74.7% v's 71.1%, p=0.387). A majority (62.1%) of study participants believed that it is a woman's right to postpone pregnancy for social reasons and to freeze her eggs, with no significant difference in options noted between younger and older women.

CONCLUSIONS

Knowledge of ovarian reserve testing and oocyte cryopreservation for non-medical reasons were higher than in previous studies, possibly reflecting increasing awareness of these issues among the general public. Additionally, we demonstrated that the women, in our study, were very open to the use of these modern technologies in an attempt to avoid unintended childlessness.

Safety and efficiency of oocyte vitrification

As the oocyte is the starting point for a new life, artificial reproductive technology (ART) techniques should not affect the (ultra) structural and functional integrity, or the developmental competence. Oocyte vitrification -one of the most significant achievements in human ART during the past decade- should therefore be a safe and efficient technique. This review discusses the principles and developments of the existing and future techniques, applications possibilities and safety concerns. The broad range of vitrification media and devices that are currently available, show differences in their effects on the oocyte ultrastructure and preimplantation development. It is not yet fully decided whether this has an influence on the obstetric and neonatal outcome, since only limited information is available with different media and devices. For autologous oocytes, the obstetric and neonatal outcomes appear promising and comparable to pregnancies obtained with fresh oocytes. This however, is not the case for heterologous fresh or vitrified oocytes, where the immunological foreign foetus induces adverse obstetric and neonatal outcomes. Besides the oocyte vitrification process itself, the effect of multiple stimulations (for oocyte banking or for oocyte donors), seems to influence the possibility to develop gynaecological cancers further in life. Automated vitrification/warming should offer a consistent, cross-contamination free process that offers the highest safety level for the users. They should also produce more consistent results in survival, development and clinical pregnancies between different IVF clinics.

Vitrification of Human Germinal Vesicle Oocytes: before or after In Vitro Maturation?

BACKGROUND

The use of immature oocytes derived from stimulated cycles could be of great importance, particularly for urgent fertility preservation cases. The current study aimed to determine whether in vitro maturation (IVM) was more successful before or after vitrification of these oocytes.

MATERIALS AND METHODS

This prospective study was performed in a private in vitro fertilization (IVF) center. We collected 318 germinal vesicle (GV) oocytes from 104 stimulated oocyte donation cycles. Oocytes were divided into two groups according to whether vitrification was applied at the GV stage (group 1) or in vitro matured to the metaphase II (MII) stage and then vitrified (group 2). In the control group (group 3), oocytes were in vitro matured without vitrification. In all three groups, we assessed survival rate after warming, maturation rate, and MII-spindle/chromosome configurations. The chi-square test was used to compare rates between the three groups. Statistical significance was defined at P<0.05 and we used Bonferroni criterion to assess statistical significance regarding the various pairs of groups. The Statistical Package for the Social Sciences version 17.0 was used to perform statistical analysis.

RESULTS

There was no significant difference in the survival rate after vitrification and warming of GV (93.5%) and MII oocytes (90.8%). A significantly higher maturation rate occurred when IVM was performed before vitrification (82.9%) compared to after vitrification (51%). There was no significant difference in the incidence of normal spindle/ chromosome configurations among warmed oocytes matured in vitro before (50.0%) or after (41.2%) vitrification. However, a higher incidence of normal spindle/chromosome configurations existed in the in vitro matured oocytes which were not subjected to vitrification (fresh oocytes, 77.9%).

CONCLUSION

In stimulated cycles, vitrification of in vitro matured MII oocytes rather than GV oocytes seems to be more efficient. This approach needs to be verified in nonstimulated fertility preservation cases.

State of the art on oocyte cryopreservation in female cancer patients: A critical review of the literature

During the last decades, important advances in therapeutic options have led to increased survival rates in cancer patients; however, cancer treatments are associated with several potential adverse effects including infertility in those diagnosed during their reproductive years. A proper discussion about fertility preservation options before the use of therapies with potential gonadotoxicity (i.e. oncofertility counseling) is standard of care and should be offered to all patients of childbearing age. Temporary ovarian suppression with LH-RH analogs, oocyte and embryo cryopreservation are standard strategies for fertility preservation in female cancer patients. Oocyte cryopreservation should be preferred to embryo cryopreservation when this latter is prohibited by law, avoided for ethical or religious issues and in single women refusing sperm donation. Despite the increasing use of this strategy, data are still lacking about the efficacy and safety of the procedure in female cancer patients, with most of the evidence on this regard deriving from infertile non-oncologic women. This article aims at critically review the available evidence about the success of oocyte cryopreservation in female cancer patients with the final goal to further improve the oncofertility counseling of these women.

Oocyte, embryo and blastocyst cryopreservation in ART: systematic review and meta-analysis comparing slow-freezing versus vitrification to produce evidence for the development of global guidance

BACKGROUND

Successful cryopreservation of oocytes and embryos is essential not only to maximize the safety and efficacy of ovarian stimulation cycles in an IVF treatment, but also to enable fertility preservation. Two cryopreservation methods are routinely used: slow-freezing or vitrification. Slow-freezing allows for freezing to occur at a sufficiently slow rate to permit adequate cellular dehydration while minimizing intracellular ice formation. Vitrification allows the solidification of the cell(s) and of the extracellular milieu into a glass-like state without the formation of ice.

OBJECTIVE AND RATIONALE

The objective of our study was to provide a systematic review and meta-analysis of clinical outcomes following slow-freezing/thawing versus vitrification/warming of oocytes and embryos and to inform the development of World Health Organization guidance on the most effective cryopreservation method.

SEARCH METHODS

A Medline search was performed from 1966 to 1 August 2016 using the following search terms: (Oocyte(s) [tiab] OR (Pronuclear[tiab] OR Embryo[tiab] OR Blastocyst[tiab]) AND (vitrification[tiab] OR freezing[tiab] OR freeze[tiab]) AND (pregnancy[tiab] OR birth[tiab] OR clinical[tiab]). Queries were limited to those involving humans. RCTs and cohort studies that were published in full-length were considered eligible. Each reference was reviewed for relevance and only primary evidence and relevant articles from the bibliographies of included articles were considered. References were included if they reported cryosurvival rate, clinical pregnancy rate (CPR), live-birth rate (LBR) or delivery rate for slow-frozen or vitrified human oocytes or embryos. A meta-analysis was performed using a random effects model to calculate relative risk ratios (RR) and 95% CI.

OUTCOMES

One RCT study comparing slow-freezing versus vitrification of oocytes was included. Vitrification was associated with increased ongoing CPR per cycle (RR = 2.81, 95% CI: 1.05-7.51; P = 0.039; 48 and 30 cycles, respectively, per transfer (RR = 1.81, 95% CI 0.71-4.67; P = 0.214; 47 and 19 transfers) and per warmed/thawed oocyte (RR = 1.14, 95% CI: 1.02-1.28; P = 0.018; 260 and 238 oocytes). One RCT comparing vitrification versus fresh oocytes was analysed. In vitrification and fresh cycles, respectively, no evidence for a difference in ongoing CPR per randomized woman (RR = 1.03, 95% CI: 0.87-1.21; P = 0.744, 300 women in each group), per cycle (RR = 1.01, 95% CI: 0.86-1.18; P = 0.934; 267 versus 259 cycles) and per oocyte utilized (RR = 1.02, 95% CI: 0.82-1.26; P = 0.873; 3286 versus 3185 oocytes) was reported. Findings were consistent with relevant cohort studies. Of the seven RCTs on embryo cryopreservation identified, three met the inclusion criteria (638 warming/thawing cycles at cleavage and blastocyst stage), none of which involved pronuclear-stage embryos. A higher CPR per cycle was noted with embryo vitrification compared with slow-freezing, though this was of borderline statistical significance (RR = 1.89, 95% CI: 1.00-3.59; P = 0.051; three RCTs; I2 = 71.9%). LBR per cycle was reported by one RCT performed with cleavage-stage embryos and was higher for vitrification (RR = 2.28; 95% CI: 1.17-4.44; P =  0.016; 216 cycles; one RCT). A secondary analysis was performed focusing on embryo cryosurvival rate. Pooled data from seven RCTs (3615 embryos) revealed a significant improvement in embryo cryosurvival following vitrification as compared with slow-freezing (RR = 1.59, 95% CI: 1.30-1.93; P < 0.001; I2 = 93%).

WIDER IMPLICATIONS

Data from available RCTs suggest that vitrification/warming is superior to slow-freezing/thawing with regard to clinical outcomes (low quality of the evidence) and cryosurvival rates (moderate quality of the evidence) for oocytes, cleavage-stage embryos and blastocysts. The results were confirmed by cohort studies. The improvements obtained with the introduction of vitrification have several important clinical implications in ART. Based on this evidence, in particular regarding cryosurvival rates, laboratories that continue to use slow-freezing should consider transitioning to the use of vitrification for cryopreservation.

Evolution of human oocyte cryopreservation: slow freezing versus vitrification

PURPOSE OF REVIEW

The purpose is to determine the efficiency and efficacy of oocyte cryopreservation by slow freezing versus vitrification, recent data collected from the Italian National Assisted Reproductive Technology Register during the period 2009-2014 will be presented and reviewed. The data on oocyte cryopreservation were also compared with the results obtained with embryo cryopreservation and relative IVF with fresh oocytes.

RECENT FINDINGS

During the period 2009-2014 preservation of oocytes by vitrification had a significantly higher survival rate, implantation, and pregnancy rate than slow freezing; however, there are still large variations in success rates among centers in relation to the number of procedures performed.

SUMMARY

Vitrification has now become the method of choice for oocyte cryopreservation because of better results than slow freezing, but still requires a more standardized utilization. The transfer of fresh or cryopreserved embryo still shows a statistically significant better performance than transfers with embryos obtained with cryopreserved oocytes. Only in a few centers with much experience in cryopreservation are the results between transfers of frozen embryos or embryos obtained from oocyte cryopreservation comparable.