Prospective controlled study to evaluate laboratory and clinical outcomes of oocyte vitrification obtained in in vitro fertilization patients aged 30 to 39 years

Clinical outcomes of vitrified-warmed autologous oocyte cycles with 15-year follow-up at a single UK centre: consistent and predictable results

RESEARCH QUESTION

What were the clinical outcomes from 332 autologous vitrified- warmed oocyte cycles derived from 3182 elective autologous oocyte freeze cycles carried out between 2008 and 2022 in a single-centre series?

DESIGN

In this retrospective observational study, outcomes in 299 patients returning to use their frozen oocytes between 2015 and 2023 were analysed.

RESULTS

A total of 3328 elective oocyte vitrification cycles were performed in 2280 patients. The return rate to use oocytes was 14% (299/2171). Mean ages were 37.6 years at storage and 40 at warming. Ninety-three clinical pregnancies and 77 healthy live births were recorded. The live birth rate (LBR) was 24% (39/163) per fresh transfer and 17% (39/227) per embryo transferred. Stratified by age at freezing, the LBR per embryo transferred was 26% (12/47) in participants under 35 years, 20% (24/118) in those 35-39 years and 5% (3/62) in those 40+ years. Frozen embryo transfers (FET) achieved a 30% (24/80) LBR per embryo transfer and a 27% (24/90) LBR per embryo transferred. PGT-A for embryo selection doubled the LBR compared with FET from an untested embryo after one attempt (40% versus 21%). In patients aged over 40 years, the cumulative LBR reached 42% per patient in euploid FET.

CONCLUSION

The proportion of patients who returned to use their stored oocytes and the clinical outcomes were consistent with other recent reports and challenges the prevalent critical narrative regarding elective oocyte freezing for fertility preservation. The results are now comparable to routine IVF. Not everyone who returns to use their oocytes will conceive, but for those choosing to preserve their fertility, oocyte freezing can provide reproducible and reassuring results.

The Effect of Open and Closed Oocyte Vitrification Systems on Embryo Development: A Systematic Review and Network Meta-Analysis

Background/Objectives: Open and closed vitrification systems are commonly employed in oocyte cryopreservation; however, there is limited evidence regarding a comparison of their separate impact on oocyte competence. This study uniquely brings to the literature, data on the effect of open versus closed vitrification systems on laboratory and clinical outcomes, and the effect of cooling and warming rates. Methods: A systematic search of the literature was performed using the databases PubMed/MEDLINE and the Cochrane Central Library, limited to articles published in English up to January 2023. A network meta-analysis was conducted comparing each vitrification system versus fresh oocytes. Results: Twenty-three studies were included. When compared to fresh oocytes, both vitrification devices resulted in lower fertilization rates per MII oocyte retrieved. When comparing the two systems in terms of survival rates, no statistically significant difference was observed. However, interestingly open systems resulted in lower cleavage and blastocyst formation rates per 2 pronuclear (2PN) oocyte compared to fresh controls, while at the same time no statistically significant difference was detected when comparing closed devices with fresh oocytes. Conclusions: In conclusion, closed vitrification systems appear to exert a less detrimental impact on the oocytes' competence, which is reflected in the blastocyst formation rates. Proof of superiority of one system versus the other may lead to standardization, helping to ultimately determine optimal practice in oocyte vitrification.

The development and phase 1 evaluation of a Decision Aid for elective egg freezing

BACKGROUND

Elective egg freezing decisions are complex. We developed a Decision Aid for elective egg freezing and conducted a phase 1 study to evaluate its acceptability and utility for decision-making.

METHODS

The online Decision Aid was developed according to International Patient Decision Aid Standards and evaluated using a pre/post survey design. Twenty-six Australian women aged 18-45 years, interested in receiving elective egg freezing information, proficient in English, and with access to the internet were recruited using social media and university newsletters. Main outcomes were: acceptability of the Decision Aid; feedback on the Decision Aid design and content; concern raised by the Decision Aid, and; utility of the Decision Aid as measured by scores on the Decisional Conflict Scale and on a study-specific scale assessing knowledge about egg freezing and age-related infertility.

RESULTS

Most participants found the Decision Aid acceptable (23/25), balanced (21/26), useful for explaining their options (23/26), and for reaching a decision (18/26). Almost all reported satisfaction with the Decision Aid (25/26) and the level of guidance  it provided (25/26). No participant reported serious concerns about the Decision Aid, and most would recommend it to other women considering elective egg freezing (22/26). Median Decisional Conflict Scale score decreased from 65/100 (Interquartile range: 45-80) pre-Decision Aid to 7.5/100 (Interquartile range: 0-37.5) post-Decision Aid review (p < 0.001). Median knowledge score increased from 8.5/14 (Interquartile range: 7-11) pre-Decision Aid to 11/14 (Interquartile range: 10-12) post-Decision Aid review (p = 0.01).

CONCLUSION

This elective egg freezing Decision Aid appears acceptable and useful for decision-making. It improved knowledge, reduced decisional conflict and did not raise serious concerns. The Decision Aid will be further evaluated using a prospective randomised control trial.

STUDY REGISTRATION

ACTRN12618001685202 (retrospectively registered: 12 October 2018).

Ru360 protects against vitrification-induced oocyte meiotic defects by restoring mitochondrial function

Oocyte vitrification has been widely application in female fertility preservation. Recent studies found that vitrification of immature (germinal vesicle stage, GV) oocytes increased the risk of aneuploidy during meiotic maturation; however, the underlying mechanisms and the strategies to prevent this defect remain unexplored. In this study, we found that vitrification of GV oocytes decreased the first polarbody extrusion rate (90.51 ± 1.04% vs. 63.89 ± 1.39%, p < 0.05) and increased the aneuploid rate (2.50% vs. 20.00%, p < 0.05), accompanied with a series of defects during meiotic maturation, including aberrant spindle morphology, chromosome misalignment, incorrect Kinetochore-Microtubule attachments (KT-MTs) and weakened spindle assembly checkpoint protein complex (SAC) function. We also found that vitrification disrupted mitochondrial function by increasing mitochondrial Ca²⁺ levels. Importantly, inhibition of mitochondrial Ca²⁺ entry by 1 μM Ru360 significantly restored mitochondrial function and rescued the meiotic defects, indicating that the increase of mitochondrial Ca²⁺, at least, was a cause of meiotic defects in vitrified oocytes. These results shed light on the molecular mechanisms of oocyte vitrification-induced adverse effects of meiotic maturation and provided a potential strategy to improve oocyte cryopreservation protocols further.

Clinical efficacy analysis of oocyte cryopreservation: A propensity score matched study

OBJECTIVE

To investigate the effectiveness of oocyte thawing cycles in the clinical application of assisted reproductive technology (ART).

STUDY DESIGN

The clinical data of 78 cases who underwent oocyte thawing cycles in our center were retrospectively analyzed. All patients in this study received oocyte cryopreservation for the husband reason. According to patient age at egg freezing, patients were divided into three observation groups (Group A, <30 years old; Group B, 30-34 years old; Group C, ≥35 years old), and the control groups were selected by propensity score matching with fresh cycles. The clinical outcomes of each group were compared, and the clinical efficacy of oocyte thawing cycles was analyzed.

RESULTS

Clinical pregnancy outcomes of oocyte thawing cycles were not significantly different from that of fresh oocytes, but vitrification affected the number of two pronuclei zygotes developing to cleavage stage and the number of high-quality embryos, and the normal fertilization rate after thawing. The cycle cumulative live birth rate in Group C was significantly lower than those in Groups A and B. The live birth rates per egg of Groups A, B, C were 5.03%, 5.61%, and 3.57%, respectively, and the numbers of eggs per live birth were 13.72, 14.43, and 21.0, respectively.

CONCLUSIONS

The overall clinical outcomes of oocyte vitrification were similar to that of fresh oocytes, but the cleavage rate and embryo quality of frozen oocytes were slightly reduced. Freezing of oocytes in women over 35 years of age affects the clinical efficacy of ART.

Fertility awareness and attitudes among resident physicians across different specialties

PURPOSE

To evaluate knowledge of age-related fertility decline and oocyte cryopreservation among resident physicians in obstetrics and gynecology (ob-gyn) compared to residents in other specialties.

METHODS

An online survey was sent to the US residency program directors for ob-gyn, internal medicine, emergency medicine, family medicine, general surgery, pediatrics, and psychiatry. They were asked to forward the survey to their respective residents. The survey consisted of three sections: fertility knowledge, oocyte cryopreservation knowledge, and attitudes toward family building and fertility preservation. Multivariable logistic regression models were used to compare outcomes between ob-gyn and non-ob-gyn residents.

RESULTS

Of the 2,828 completed surveys, 450 (15.9%) were by ob-gyn residents and 2,378 (84.1%) were by residents in other specialties. 66.3% of respondents were female. The median number of correct answers was 2 out of 5 on the fertility knowledge section and 1 out of 3 on the oocyte cryopreservation knowledge section among both ob-gyn and non-ob-gyn residents. After adjusting for covariates, residents in ob-gyn were no more likely to answer these questions correctly than residents in other specialties (fertility knowledge, adjusted OR .97, 95% CI .88-1.08; oocyte cryopreservation knowledge, adjusted OR 1.05, 95% CI .92-1.19). Ob-gyn residents were significantly more likely than non-ob-gyn residents to feel "somewhat supported" or "very supported" by their program to pursue family building goals (83.5% vs. 75.8%, OR 1.62, 95% CI 1.23-2.14).

CONCLUSIONS

Resident physicians, regardless of specialty, have limited knowledge of natural fertility decline and the opportunity to cryopreserve oocytes. These data suggest need for improved fertility education.

The effects of vitrification on oocyte quality

Vitrification, is an ultra-rapid, manual cooling process that produces glass-like (ice crystal free) solidification. Water is prevented from forming intercellular and intracellular ice crystals during cooling as a result of oocyte dehydration and the use of highly concentrated cryoprotectant. Though oocytes can be cryopreserved without ice crystal formation through vitrification, it is still not clear whether the process of vitrification causes any negative impact (temperature change/chilling effect, osmotic stress, cryoprotectant toxicity, and/or phase transitions) on oocyte quality that translate to diminished embryo developmental potential or subsequent clinical outcomes. In this review, we attempt to assess the technique's potential effects and the consequence of these effects on outcomes.

An Eight Year Experience of Autologous Oocyte Vitrification for Infertile Patients Owing to Unavailability of Sperm on Oocyte Retrieval Day

Objective: The objective of this study was to provide a descriptive analysis of the clinical outcomes achieved in oocyte vitrification in cases where sperm was unavailable on oocyte retrieval day, and to identify predictors of oocyte survival. Methods: This retrospective cohort study used data from a university-affiliated reproductive medical center. There were 321 cycles in which some of, or all oocytes were vitrified owing to the unavailability of sperm between March 2009 and October 2017. A descriptive analysis of the clinical outcomes including both fresh embryo transfers and cryopreserved embryo transfers was provided. The ability of an individual parameter to forecast oocyte survival per thawing cycle was assessed by binary logistic regression analysis. The cumulative probability of live birth (CPLB) was estimated by using the Kaplan-Meier method according to the total number of oocytes thawed in consecutive procedures. Results: The average survival rate was 83.13%. High-quality embryo rate and blastocyst rate decreased significantly decreased significantly in vitrification oocyte group compared to fresh control oocytes. The comparison of sibling oocytes in part-oocyte-vitrified cycles shows fewer high-quality embryos developed in the vitrified group. The live birth rate per warmed-oocyte was 4.3%. Reasons for lack of sperm availability on oocyte retrieval day and serum cholesterol levels were found to be associated with oocyte survival rate in the present study. Kaplan-Meier analysis showed no significant difference in CPLB between patients ≤35 vs. >35 years. Conclusions: Oocyte vitrification is an indispensable and effective alternative when sperm are not available on oocyte retrieval day. The present study provided evidence that oocytes from infertile couples were more likely to suffer oocyte/embryo vitrification injury. Clinicians need to take this into account when advising patients in similar situations. Further studies will be necessary to clarify the correlation between serum metabolism parameters and human oocyte survival after vitrification.

Vitrification-induced activation of lysosomal cathepsin B perturbs spindle assembly checkpoint function in mouse oocytes

As the age of child-bearing increases and correlates with infertility, cryopreservation of female gametes is becoming common-place in ART. However, the developmental competence of vitrified oocytes has remained low. The underlying mechanisms responsible for reduced oocyte quality post-vitrification are largely unknown. Mouse cumulus-oocyte complexes were vitrified using a cryoloop technique and a mixture of dimethylsulphoxide, ethylene glycol and trehalose as cryoprotectants. Fresh and vitrified/thawed oocytes were compared for chromosome alignment, spindle morphology, kinetochore-microtubule attachments, spindle assembly checkpoint (SAC) and aneuploidy. Although the majority of vitrified oocytes extruded the first polar body (PB), they had a significant increase of chromosome misalignment, abnormal spindle formation and aneuploidy at metaphase II. In contrast to controls, vitrified oocytes extruded the first PB in the presence of nocodazole and etoposide, which should induce metaphase I arrest in a SAC-dependent manner. The fluorescence intensity of mitotic arrest deficient 2 (MAD2), an essential SAC protein, at kinetochores was reduced in vitrified oocytes, indicating that the SAC is weakened after vitrification/thawing. Furthermore, we found that vitrification-associated stress disrupted lysosomal function and stimulated cathepsin B activity, with a subsequent activation of caspase 3. MAD2 localization and SAC function in vitrified oocytes were restored upon treatment with a cathepsin B or a caspase 3 inhibitor. This study was conducted using mouse oocytes, therefore confirming these results in human oocytes is a prerequisite before applying these findings in IVF clinics. Here, we uncovered underlying molecular pathways that contribute to an understanding of how vitrification compromises oocyte quality. Regulating these pathways will be a step toward improving oocyte quality post vitrification and potentially increasing the efficiency of the vitrification program.

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.

Oocyte vitrification induces loss of DNA methylation and histone acetylation in the resulting embryos derived using ICSI in dromedary camel

Oocyte cryopreservation has become an important component of assisted reproductive technology with increasing implication in female fertility preservation and animal reproduction. However, the possible adverse effects of oocyte cryopreservation on epigenetic status of the resulting embryos is still an open question. This study evaluated the effects of MII-oocyte vitrification on gene transcripts linked to epigenetic reprogramming in association with the developmental competence and epigenetic status of the resulting embryos at 2-cell and blastocyst stages in dromedary camel. The cleavage rate of vitrified oocytes following intracytoplasmic sperm injection was significantly increased compared with the control (98.2 ± 2 vs. 72.7 ± 4.1%, respectively), possibly due to the higher susceptibility of vitrified oocytes to spontaneous activation. Nonetheless, the competence of cleaved embryos derived from vitrified oocytes for development to the blastocyst and hatched blastocyst was significantly reduced compared with the control (7.7 ± 1.2 and 11.1 ± 11.1 compared with 28.1 ± 2.6 and 52.4 ± 9.9%, respectively). The relative transcript abundances of epigenetic reprogramming genes DNMT1, DNMT3B, HDAC1, and SUV39H1 were all significantly reduced in vitrified oocytes relative to the control. Evaluation of the epigenetic marks showed significant reductions in the levels of DNA methylation (6.1 ± 0.3 vs. 9.9 ± 0.5, respectively) and H3K9 acetylation (7.8 ± 0.2 vs. 10.7 ± 0.3, respectively) in 2-cell embryos in the vitrification group relative to the control. Development to the blastocyst stage partially adjusted the effects that oocyte vitrification had on the epigenetic status of embryos (DNA methylation: 4.9 ± 0.4 vs. 6.2 ± 0.6; H3K9 acetylation: 5.8 ± 0.3 vs. 8 ± 0.9, respectively). To conclude, oocyte vitrification may interfere with the critical stages of epigenetic reprogramming during preimplantation embryo development.

Prevalence of a Good Perinatal Outcome With Cryopreserved Compared With Fresh Donor Oocytes

OBJECTIVE

To compare the odds of a good perinatal outcome between cryopreserved and fresh donor oocytes.

METHODS

We used the Society for Assisted Reproductive Technology Clinic Outcomes Reporting System to conduct a retrospective cohort study of women undergoing donor oocyte in vitro fertilization (IVF) from 2012 to 2015. Cycles using cryopreserved embryos, a gestational carrier, or preimplantation genetic testing were excluded. The primary outcome was a good perinatal outcome, defined as a singleton live birth at 37 weeks of gestation or more with birth weight at or within 2,500 g and 4,000 g. Secondary outcomes included live birth, multiple birth, and prematurity. Generalized estimating equation models were used to test the effect of oocyte type on the primary outcome while accounting for covariates and the correlation induced by repeated cycles within a patient.

RESULTS

Of the 36,925 cycles included in the analysis, 8,381 (22.7%) used cryopreserved and 28,544 (77.3%) used fresh oocytes. The odds of a good perinatal outcome were marginally but significantly lower with cryopreserved than with fresh oocytes before and after covariate adjustment (22.0% vs 24.1%, unadjusted odds ratio [OR] 0.90, 95% CI 0.85-0.96, adjusted OR 0.88, 95% CI 0.81-0.95). Compared with fresh oocytes, cryopreserved oocytes were associated with lower rates of live birth (39.6% vs 47.7%, OR 0.75, 95% CI 0.72-0.79), multiple birth (22.3% vs 31.2%, OR 0.63, 95% CI 0.58-0.69), and prematurity (27.6% vs 30.6%, OR 0.86, 95% CI 0.79-0.94).

CONCLUSION

This retrospective national study demonstrated that the use of cryopreserved compared with fresh donor oocytes in IVF cycles is associated with marginally lower odds of a good perinatal outcome.

Single women and motherhood: right now or maybe later?

Purpose: The decision to have a child might be postponed by the lack of partner, and elective egg freezing (EEF) can afford single women more time to find a suitable companion to reach the desired family structure. Alternatively, some women decide to have a child on their own thorough in vitro fertilization (IVF) or intrauterine insemination (IUI) with donor sperm. This study investigates the motivations and personal characteristics of single women undergoing IVF/IUI or EEF.Materials and methods: This is a cross-sectional study including 281 heterosexual single women who underwent either IVF/IUI with donor sperm for solo motherhood (208) or EEF (73) in 2015 at a large fertility center. An anonymous electronic survey was sent after starting the treatment.Results: The most common reason for not having fulfilled the motherhood desire was lack of partner (72.4% IVF/IUI and 65.9% EEF). We found that women undergoing IVF/IUI report a longer motherhood desire, >10 years (71.3% vs. 54.3%), live closer to their families (75.5% vs. 56.5%), and perceive a stronger family support than women undergoing EEF (85.4% vs. 68.8%). Finally, 100% of EEF obviously knew about the possibility of IVF/IUI with donor sperm, while 59.9% of IVF/IUI knew about EEF.Conclusion: Our results underscore the relevance of family ties in the decision to undergo IVF/IUI as single women. Moreover, these women might not be fully informed about social freezing as an option to postpone motherhood. Health professionals should be aware of these differences when counseling single women on fertility choices.

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.

Social Freezing in Medical Practice. Experiences and Attitudes of Gynecologists in Germany

Surveys of the German public have revealed a high acceptance of social freezing, i.e. oocyte conservation without medical indication. Up to now, there are no investigations available on the experiences and attitudes of health professionals towards social freezing. Between August 2015 and January 2016, we surveyed gynecologists Germany-wide on the topic social freezing. Five gynecologists specialized in reproductive medicine and five office-based gynecologists in standard care were chosen for the survey. The survey was conducted with an explorative, qualitative research design. The demand for social freezing in Germany is low. With regard to their fertility age, most women attend consultations too late, they have only little previous knowledge and false expectations. The gynecologists consider it the duty of society and politics to provide for the compatibility of family and work. They relate late parenthood to disadvantages primarily for the children. A majority of the gynecologists interviewed tend to advise natural reproduction. Social freezing is often mistaken as a kind of fertility insurance. Thus, it is necessary that physicians inform women early about the possibilities and limitations of social freezing. In the first place, social freezing is not a medical or medical-ethical topic. Women consider the method as a possibility to ensure the compatibility of family and work. This compatibility should be mostly perceived as a political topic. It cannot be a medical task to solve this issue. In fact, a debate in society as a whole is necessary that includes all relevant actors.

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.

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

The Role of Oocyte Organelles in Determining Developmental Competence

The ability of an oocyte to undergo successful cytoplasmic and nuclear maturation, fertilization and embryo development is referred to as the oocyte’s quality or developmental competence. Quality is dependent on the accumulation of organelles, metabolites and maternal RNAs during the growth and maturation of the oocyte. Various models of good and poor oocyte quality have been used to understand the essential contributors to developmental success. This review covers the current knowledge of how oocyte organelle quantity, distribution and morphology differ between good and poor quality oocytes. The models of oocyte quality are also described and their usefulness for studying the intrinsic quality of an oocyte discussed. Understanding the key critical features of cytoplasmic organelles and metabolites driving oocyte quality will lead to methods for identifying high quality oocytes and improving oocyte competence, both in vitro and in vivo.

A comparison of live birth rates and perinatal outcomes between cryopreserved oocytes and cryopreserved embryos

PURPOSE

Prior studies suggest that pregnancy outcomes after autologous oocyte cryopreservation are similar to fresh in vitro fertilization (IVF) cycles. It is unknown whether there are differences in pregnancy and perinatal outcomes between cryopreserved oocytes and cryopreserved embryos.

METHODS

This is a retrospective cohort study comparing pregnancy and perinatal outcomes between oocyte and embryo cryopreservation at a university-based fertility center. We included 42 patients and 68 embryo transfers in patients who underwent embryo transfer after elective oocyte preservation (frozen oocyte-derived embryo transfer (FOET)) from 2005 to 2015. We compared this group to 286 patients and 446 cycles in women undergoing cryopreserved embryo transfer (frozen embryo transfer (FET)) from 2012 to 2015.

RESULTS

Five hundred fourteen transfer cycles were included in our analysis. The mean age was lower in the FOET vs FET group (34.3 vs 36.0 years), but there were no differences in ovarian reserve markers. Thawed oocytes had lower survival than embryos (79.1 vs 90.1%); however, fertilization rates were similar (76.2 vs 72.8%). In the FOET vs FET groups, clinical pregnancies were 26.5 and 30%, and live birth rates were 25 and 25.1%. Miscarriages were higher in the FET group, 8.1 vs 1.5%. There were no differences in perinatal outcomes between the two groups. The mean gestational age at delivery was 39.1 vs 38.6 weeks, mean birth weight 3284.2 vs 3161.1 gms, preterm gestation rate 5.9 vs 13.4%, and multiple gestation rate 5.9 vs 11.6%.

CONCLUSIONS

In our study, live birth rates and perinatal outcomes were not significantly different in patients after oocyte and embryo cryopreservation.

The Human Oocyte Preservation Experience (HOPE) Registry: evaluation of cryopreservation techniques and oocyte source on outcomes

BACKGROUND

This prospective, Phase IV, multicenter, observational registry of assisted reproductive technology clinics in the USA studied outcomes of first cycles using thawed/warmed cryopreserved (by slow-freezing/vitrification) oocytes (autologous or donor).

METHODS

Patients were followed up through implantation, clinical pregnancy, and birth outcomes. The main outcome measure was live birth rate (LBR), defined as the ratio of live births to oocytes thawed/warmed minus the number of embryos cryopreserved for each cycle, averaged over all thawing cycles. Clinical pregnancy rate (CPR) was also evaluated, and was defined as the presence of a fetal sac with heart activity, as detected by ultrasound scan performed on Day 35-42 after embryo transfer.

RESULTS

A total of 16 centers enrolled 204 patients; data from 193 patients were available for analyses. For donor oocytes, in the slow-freezing (n = 40) versus vitrification (n = 94) groups, respectively, CPR and LBR were significantly different: 32.4% versus 62.6%, and 25.0% versus 52.1%; outcomes from Day 3 transfers did not differ significantly. For vitrified oocytes, in the autologous (n = 46) versus donor (n = 94) group, respectively, CPR and LBR were significantly different: 30.0% versus 62.6% and 17.4% versus 52.1%. This was largely due to a significant difference in CPR with Day 5/6 transfers.

CONCLUSIONS

In two subgroup data analyses, in women who received cryopreserved oocytes from donors, CPR and LBR were significantly higher in cycles using oocytes cryopreserved via vitrification versus slow-freezing, reflecting differences in methodologies and more Day 5/6 transfers; in women who received vitrified oocytes, CPR and LBR were significantly higher in cycles using donor versus autologous oocytes with Day 5/6 transfers.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00699400 . Registered June 13, 2008.

Chapter 1 Historical Background on Gamete and Embryo Cryopreservation

This chapter describes the development of the science of cryopreservation of gametes and embryos of various species including human. It attempts to record in brief the main contributions of workers in their attempts to cryopreserve gametes and embryos. The initial difficulties faced and subsequent developments and triumphs leading to present-day state of the art are given in a concise manner. The main players and their contributions are mentioned and the authors' aim is to do justice to them. This work also attempts to ensure that credit is correctly attributed for significant advances in gamete and embryo cryopreservation. In general this chapter has tried to describe the historical development of the science of cryopreservation of gametes and embryos as accurately as possible without bias or partiality.

Egg Freezing in Childhood and Young Adult Cancer Survivors

Fertility preservation in prepubertal and young adolescent girls scheduled for chemotherapy is a demanding situation. Despite the recent impressive improvements of ovarian cortex cryopreservation, significant limitations persist. The technique remains experimental, it exposes the girl to the risks of surgery and to an iatrogenic insult to the ovarian reserve, and there is no guarantee of use because not all girls will undergo re-implantation. Moreover, it is impossible to respect all the requested conditions for a valid informed consent. The girl is minor, the time for decision is very short, and the prospect of not surviving clouds both the girl and her relatives. An alternative but neglected option is oocyte cryopreservation after the end of cancer treatments, when the girl reaches adulthood. This possibility can overcome some of the limitations of ovarian cortex freezing and may be considered for girls scheduled for a chemotherapy at low or medium risk of ovarian reserve impairment. In this case report, we describe the case of a young female patient with cancer who survived 2 chemotherapies for 2 distinct cancers and who was diagnosed with reduced ovarian reserve. The patient underwent 3 cycles of ovarian hyperstimulation and ultimately stored 19 oocytes. The success obtained in this girl suggests consideration of egg freezing as an alternative fertility-preservation procedure in prepubertal and young adolescent girls scheduled for chemotherapy. However, cryopreservation of ovarian tissue remains the only option for those scheduled for chemotherapies at high risk of ovarian reserve impairment.

Intrafollicular transfer of fresh and vitrified immature bovine oocytes

Embryo production by intrafollicular oocyte transfer (IFOT) represents an alternative for production of a large number of embryos without requiring any hormones and only basic laboratory handling. We aimed to (1) evaluate the efficiency of IFOT using immature oocytes (IFIOT) and (2) compare embryo development after IFIOT using fresh or vitrified immature oocytes. First, six IFIOTs were performed using immature oocytes obtained by ovum pickup. After insemination and uterine flush for embryo recovery, 21.3% of total transferred structures were recovered excluding the recipient's own oocyte or embryo, and of those, 26% (5.5% of transferred cumulus-oocyte complexes [COCs]) were morula or blastocyst. In the second study, we compared fresh and vitrified-warmed immature COCs. Four groups were used: (1) fresh immature COCs (Fresh-Vitro); (2) vitrified immature COCs (Vit-Vitro), with both groups 1 and 2 being matured, fertilized, and cultured in vitro; (3) fresh immature COCs submitted to IFIOT (Fresh-IFIOT); and (4) vitrified immature COCs submitted to IFIOT (Vit-IFIOT). Cumulus-oocyte complexes (n = 25) from Fresh-IFIOT or Vit-IFIOT groups were injected into dominant follicles (>10 mm) of synchronized heifers. After excluding one structure or blastocyst, the recovery rates per transferred oocyte were higher (P < 0.05) for Fresh-IFIOT (47.6%) than for Vit-IFIOT (12.0%). Blastocyst yield per initial oocyte was higher (P < 0.05) for Fresh-Vitro (42.1%) than for Fresh-IFIOT (12.9%). Vit-Vitro presented higher (P < 0.05) embryo development (6.3%), compared to Vit-IFIOT, which did not result in any extra embryo. Although IFOT did not improve developmental competence of vitrified oocytes, we achieved viable blastocysts and pregnancies produced after IFIOT of fresh bovine immature oocytes. Further work on this technique is warranted as an option both for research studies and for clinical bovine embryo production in the absence of laboratory facilities for IVF.

Production of Live Offspring from Vitrified-Warmed Oocytes Collected at Metaphase I Stage

Vitrification of matured oocytes is widely adopted in human clinics and animal research laboratories. Cryopreservation of immature oocytes, particularly those at metaphase I (MI), remains a challenge. In the present work, mouse MI oocytes denuded of cumulus cells were vitrified and warmed (V/W) either prior to (V/W-BEFORE-IVM, n = 562) or after (V/W-AFTER-IVM, n = 664) in vitro maturation (IVM). Derivative metaphase II (MII) oocytes were then used for intracytoplasmic sperm injection (ICSI). In the control groups, in vivo matured MII oocytes were used freshly (FRESH-MII, n = 517) or after V/W (MII-V/W, n = 617). In vitro and in vivo developmental competencies were compared among groups. Satisfactory blastocyst rates were achieved in V/W-BEFORE-IVM (27.5%) and V/W-AFTER-IVM (32.4%) groups, albeit as expected still lower than those from fresh-MII (56.1%) or MII-V/W (45.6%) oocytes. Similarly, the term development rates from V/W-BEFORE-IVM and V/W-AFTER-IVM were 12.4% and 16.7% respectively, acceptable but lower than those of the fresh-MII (41.2%) and MII-V/W (23.3%) groups. These data demonstrate that oocytes collected at MI stage are amenable to V/W, which can be performed before or after IVM with acceptable development rates including production of healthy pups. These findings provide useful knowledge to researchers and clinical practitioners for preservation and use of the otherwise discarded MI oocytes.

Oocyte vitrification does not affect early developmental timings after intracytoplasmic sperm injection for women younger than 30 years old

Oocyte vitrification causes a temporary disassembly of the metaphase plate and spindle, which needs time to recover after warming. As a consequence, early post-fertilization events-such as timing of second polar body extrusion-might be altered, with unknown effects on preimplantation development, timing to pronuclear breakdown, and timing of cleavages. The aim of this study was to evaluate if differences exist among these events when comparing embryos obtained from fresh-donated versus vitrified/warmed oocytes from young women. We performed a prospective study with 201 embryos from 100 fresh and 101 vitrified/warmed oocytes that were subsequently fertilized by intracytoplasmic sperm injection. Kaplan-Meier curves of each time period were generated, in which we observed that median developmental times did not differ between embryos from fresh versus vitrified/warmed oocytes among all the metrics assessed. Thus, for young women without fertility problems, no differences exist between the timing of early developmental milestones in embryos derived from fresh or vitrified oocytes, and vitrification does not affect the preimplantation development of the resulting embryos. Mol. Reprod. Dev. 83: 624-629, 2016. © 2016 Wiley Periodicals, Inc.

New methods for cooling and storing oocytes and embryos in a clean environment of -196°C

It is well documented that oocyte vitrification using open systems provides better results than closed systems. However, its use is limited owing to risks of contamination posed by direct exposure to liquid nitrogen and cross-contamination when stored in liquid nitrogen tanks. A device that produces clean liquid air (CLAir) having similar a temperature as liquid nitrogen and a sterile storage canister device (Esther) that keeps samples sealed in their own compartment while in regular liquid nitrogen tanks were developed. The following experiments were performed: temperature measurements, bioburden tests, vitrification and storage experiments with mice embryos and human oocytes. Results showed similar cooling rates for liquid nitrogen and liquid air. Bioburden tests of CLAir and Esther showed no contamination, while massive contamination was found in "commercial" liquid nitrogen and storage canisters. Mice blastocysts had a survival rate of over 90%, with 80% hatching rate after vitirification in CLAir and 1 week storage in Esther, similar to the fresh (control) results. Human oocytes vitrified in CLAir and in liquid nitrogen for three consecutive vitrification/warming cycles showed 100% survival, seen as re-expansion in both groups. These new systems represent a breakthrough for safe vitrification using open systems and a safe storage process generally.

The total pregnancy potential per oocyte aspiration after assisted reproduction-in how many cycles are biologically competent oocytes available?

PURPOSE

While stimulation of women prior to assisted reproduction is associated with increased success rates, the total biological pregnancy potential per stimulation cycle is rarely assessed.

METHODS

Retrospective sequential cohort study of the cumulative live birth rate in 1148 first IVF/ICSI-cycles and 5-year follow up of frozen embryo replacement (FER) cycles were used. Oocyte number, number of embryos transferred, and cryopreserved/thawed and transferred embryos in a FER cycle were registered for all patients. Children per oocyte and per transferred embryo and percentage of cycles with births were calculated.

RESULTS

We obtained 9529 oocytes. Embryos (2507) were transferred in either fresh or FER cycles, resulting in 422 births and 474 live born children. Median age of the women was 32.5 years (range 20-41.5 years). In total, 34.3 % of all cycles ended with a live birth while in 65.7 % of the cycles, no oocytes were capable of developing into a child. The average number of oocytes needed per live born child after transfer of fresh and thawed embryos was 20 as only 5.0 % of oocytes aspirated in the first IVF/ICSI cycle had the competence to develop into a child.

CONCLUSIONS

In our setting, overall 5.0 % of the oocytes in a first cycle were biologically competent and in around 2/3 of all cycles, none of the oocytes had the potential to result in the birth of a child.

Effects of Different Maturation Systems on Bovine Oocyte Quality, Plasma Membrane Phospholipid Composition and Resistance to Vitrification and Warming

The objective of this study was to evaluate the effects of different maturation systems on oocyte resistance after vitrification and on the phospholipid profile of the oocyte plasma membrane (PM). Four different maturation systems were tested: 1) in vitro maturation using immature oocytes aspirated from slaughterhouse ovaries (CONT; n = 136); 2) in vitro maturation using immature oocytes obtained by ovum pick-up (OPU) from unstimulated heifers (IMA; n = 433); 3) in vitro maturation using immature oocytes obtained by OPU from stimulated heifers (FSH; n = 444); and 4) in vivo maturation using oocytes obtained from heifers stimulated 24 hours prior by an injection of GnRH (MII; n = 658). A sample of matured oocytes from each fresh group was analyzed by matrix associated laser desorption-ionization (MALDI-TOF) to determine their PM composition. Then, half of the matured oocytes from each group were vitrified/warmed (CONT VIT, IMA VIT, FSH VIT and MII VIT), while the other half were used as fresh controls. Afterwards, the eight groups underwent IVF and IVC, and blastocyst development was assessed at D2, D7 and D8. A chi-square test was used to compare embryo development between the groups. Corresponding phospholipid ion intensity was expressed in arbitrary units, and following principal components analyses (PCA) the data were distributed on a 3D graph. Oocytes obtained from superstimulated animals showed a greater rate of developmental (P<0.05) at D7 (MII = 62.4±17.5% and FSH = 58.8±16.1%) compared to those obtained from unstimulated animals (CONT = 37.9±8.5% and IMA = 50.6±14.4%). However, the maturation system did not affect the resistance of oocytes to vitrification because the blastocyst rate at D7 was similar (P>0.05) for all groups (CONT VIT = 2.8±3.5%, IMA VIT = 2.9±4.0%, FSH VIT = 4.3±7.2% and MII VIT = 3.6±7.2%). MALDI-TOF revealed that oocytes from all maturation groups had similar phospholipid contents, except for 760.6 ([PC (34:1) + H]+), which was more highly expressed in MII compared to FSH (P<0.05). The results suggest that although maturation systems improve embryonic development, they do not change the PM composition nor the resistance of bovine oocytes to vitrification.

Deliveries from trophectoderm biopsied, fresh and vitrified blastocysts derived from polar body biopsied, vitrified oocytes

This longitudinal study reports preliminary findings of six patients who underwent first polar body biopsy followed by oocyte vitrification. All oocytes were warmed, inseminated by intracytoplasmic sperm injection and cultured to blastocyst. All suitable blastocysts underwent trophectoderm biopsy for aneuploidy screening, and supernumerary blastocysts were vitrified. Euploid blastocysts were transferred either fresh or in a subsequent programmed cycle. Of the 91 metaphase II oocytes, 30 had euploid first polar bodies. Development to blastocyst was more likely in oocytes with a euploid first polar body (66.7% versus 24.6%; P < 0.001). Nineteen euploid blastocysts were produced: 10 from oocytes with a euploid first polar body and nine from oocytes with an aneuploid first polar body. Five out of six patients (83%) had a live birth or ongoing pregnancy at the time of analysis. Eleven euploid blastocysts have been transferred and seven implanted (64%). Although the chromosomal status of the first polar body was poorly predictive of embryonic ploidy, an association was found between chromosomal status of the first polar body and development to blastocyst. Further study is required to characterize these relationships, but proof of concept is provided that twice biopsied, twice cryopreserved oocytes and embryos can lead to viable pregnancies.

Age-related infertility

Oocyte number and quality decrease with advancing age. Thus, fecundity decreases as age increases, with a more rapid decline after the mid-30s. Patients more than 35 years old should receive prompt evaluation for causes of infertility after no more than 6 months of attempted conception. Patients with abnormal tests of ovarian reserve have a poorer prognosis and may need more expedited and aggressive treatment. Although oocyte donation is the best method to overcome age-related infertility, other treatment options may help women proceed quicker toward pregnancy. Patients at an advanced age should be counseled and evaluated before undergoing infertility treatments.

l-carnitine supplementation during vitrification of mouse germinal vesicle stage-oocytes and their subsequent in vitro maturation improves meiotic spindle configuration and mitochondrial distribution in metaphase II oocytes

STUDY QUESTION

How does l-carnitine (LC) supplementation during vitrification and in vitro maturation (IVM) of germinal vesicle stage (GV)-oocytes improve the developmental competence of the resultant metaphase II (MII) oocytes?

SUMMARY ANSWER

LC supplementation during both vitrification of GV-oocytes and their subsequent IVM improved nuclear maturation as well as meiotic spindle assembly and mitochondrial distribution in MII oocytes.

WHAT IS KNOWN ALREADY

Vitrification of GV-oocytes results in a lower success rate of blastocyst development compared with non-vitrified oocytes. LC supplementation during both vitrification and IVM of mouse GV-oocytes significantly improves embryonic development after IVF.

STUDY DESIGN, SIZE, DURATION

GV-oocytes were collected from (B6.DBA)F1 and B6 mouse strains and subjected to vitrification and warming with or without 3.72 mM LC supplementation. After IVM with or without LC supplementation, the rate of nuclear maturation and the quality of MII oocytes were evaluated. At least 20 oocytes/group were examined, and each experiment was repeated at least three times. All experiments were conducted during 2013-2014.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Extrusion of the first polar body in IVM oocytes was observed as an indication of nuclear maturation. Spindle assembly and chromosomal alignment were examined by immunostaining of α-tubulin and nuclear staining with 4,6-diamidino-2-phenylindole (DAPI). Mitochondrial distribution and oxidative activity were measured by staining with Mitotracker Green Fluorescence Mitochondria (Mitotracker Green FM) and chloromethyltetramethylrosamine (Mitotracker Orange CMTMRos), respectively. ATP levels were determined by using the Bioluminescent Somatic Cell Assay Kit.

MAIN RESULTS AND THE ROLE OF CHANCE

LC supplementation during both vitrification and IVM of GV-oocytes significantly increased the proportions of oocytes with normal MII spindles to the levels comparable with those of non-vitrified oocytes in both mouse strains. While vitrification of GV-oocytes lowered the proportions of MII oocytes with peripherally concentrated mitochondrial distribution compared with non-vitrified oocytes, LC supplementation significantly increased the proportion of such oocytes in the (B6.DBA)F1 strain. LC supplementation decreased the proportion of oocytes with mitochondrial aggregates in both vitrified and non-vitrified oocytes in the B6 strain. The oxidative activity of mitochondria was mildly decreased by vitrification and drastically increased by LC supplementation irrespective of vitrification in both mouse strains. No change was found in ATP levels irrespective of vitrification or LC supplementation. Results were considered to be statistically significant at P < 0.05 by either χ(2)- or t-test.

LIMITATIONS, REASONS FOR CAUTION

It remains to be tested whether beneficial effect of LC supplementation during vitrification and IVM of GV-oocytes leads to fetal development and birth of healthy offspring after embryo transfer to surrogate females.

WIDER IMPLICATIONS OF THE FINDINGS

This protocol has the potential to improve the quality of vitrified human oocytes and embryos during assisted reproduction treatment.

STUDY FUNDING/COMPETING INTEREST

Partially supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant and Mitacs Elevate Postdoctoral Fellowship, Canada.

Oocyte banking for anticipated gamete exhaustion (AGE) is a preventive intervention, neither social nor nonmedical

The scope of female fertility preservation through cryopreservation of oocytes or ovarian cortex has widened from mainly oncological indications to a variety of fertility-threatening conditions. So far, no specific universally accepted denomination name has been given to cryopreservation of oocytes or ovarian cortex for the prevention of age-related fertility decline. We argue that the commonly used phrases 'social' and 'nonmedical freezing' to denote the indication for cryopreservation are not entirely correct. We suggest 'AGE banking', as this has not only the advantage of being catchy but also depicts the exact indication for the strategy, anticipated gamete exhaustion.