Efficiency of aseptic open vitrification and hermetical cryostorage of human oocytes

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.

Frozen autologous and donor oocytes are associated with differences in clinical and neonatal outcomes compared with fresh oocytes: a Society for Assisted Reproductive Technology Clinic Outcome Reporting System Analysis

Objective

To study the clinical and neonatal outcomes of embryos derived from frozen oocytes relative to fresh oocytes in both autologous and donor oocyte cycles after fresh embryo transfer (ET).

Design

This is a retrospective cohort study using the Society for Assisted Reproductive Technology Clinic Outcome Reporting System database between 2014 and 2015.

Setting

The Society for Assisted Reproductive Technology Clinic Outcome Reporting System database was used to identify autologous and donor oocyte cycles that resulted in a fresh ET during 2014 and 2015.

Patients

There were 154,706 total cycles identified that used embryos derived from fresh or frozen oocytes and resulted in a fresh ET, including 139,734 autologous oocyte cycles and 14,972 donor oocyte cycles.

Interventions

Generalized linear regression models were used to compare the clinical and neonatal outcomes of frozen oocytes relative to fresh oocytes. Models were adjusted for maternal age, body mass index, smoking status, parity, infertility diagnosis, number of embryos transferred, and preimplantation genetic testing. An additional sensitivity analysis was performed to examine singleton pregnancies separately.

Main Outcome Measures

The live birth (LB) rate was the primary outcome. Secondary outcomes include pregnancy and birthweight outcomes.

Results

Differences in clinical and neonatal outcomes between fresh and frozen-thawed oocytes after fresh ET were observed. Specifically, our study found a higher incidence of high-birthweight infants after the use of frozen oocytes relative to fresh oocytes in both autologous oocytes (12.5% [frozen] vs. 4.5% [fresh], adjusted risk ratio [aRR] 2.67, 95% confidence interval [CI] 1.65-4.3) and donor oocyte cycles (6.2% [frozen] vs. 4.6% [fresh], aRR 1.42, 95% CI 1.1-1.83). This finding remained true when the analysis was restricted to singleton gestations only for both groups: autologous (17.3% [frozen] vs. 7.1% [fresh], aRR 2.77, 95% CI 1.74-4.42) and donor oocytes (9.4% [frozen] vs. 7.8% [fresh], aRR 1.38, 95% CI 1.07-1.77). Additionally, we observed a decrease in LB (aRR 0.81, 95% CI 0.77-0.85); clinical pregnancy (aRR 0.83, 95% CI 0.8-0.87); and an increase in biochemical pregnancy loss (aRR 1.22, 95% CI 1.05-1.43) after the use of frozen oocytes in donors, but not autologous cycles.

Conclusions

Our findings of an increased incidence of high-birthweight infants after the transfer of embryos derived from frozen oocytes in both autologous and donor oocyte cycles raise questions about oocyte vitrification and deserve further study. Additionally, the finding of a decreased likelihood of LB with frozen-donor oocytes compared with fresh donor oocytes is an important finding, especially because more patients are seeking to use frozen oocytes in their donor egg cycles. Future research should be directed toward these findings to optimize the use of frozen oocytes in clinical practice.

Comparing the effects of vitrification, before and after mouse oocyte in vitro maturation on developmental competence, changes in epigenetic regulators and stress oxidative response

Since the developmental stage of oocyte is a challenging issue in the success of vitrification, this study investigated the effects of vitrification, before and after in vitro maturation, on the survival and maturation rates, developmental competence and the expression levels of genes involved in apoptosis, oxidative stress and epigenetic modifications. Mouse germinal vesicle (GV) oocytes were divided into four groups: fresh in vitro matured oocytes without vitrification (fIVM), in vitro matured oocytes after vitrification (vIVM), in vitro matured oocytes before vitrification (IVMv). In addition, in vivo matured oocytes (MII) were used as control. After oocytes collection, maturation and survival rates as well as the intracellular reactive oxygen species (ROS) level were evaluated. Also, the expression level of various genes was analyzed by qRT-PCR. In addition, following artificial activation (parthenogenesis), the developmental competence of oocytes to the blastocyst stage was evaluated. A significant decrease in maturation rate and survival of vIVM oocytes was observed compared to fIVM and IVMv oocytes. Intracellular ROS levels were significantly increased in both vitrified groups compared to the fIVM group, and no significant difference between vitrified groups. Pro-apoptotic genes; BAX and Bcl2 as well as genes related to oxidative stress response Hsp1a, Hsp1b and SOD1were significantly increased in the vIVM group compared to the IVMv group. Interestingly, epigenetic regulators genes DNMT1, DNMT3a and DNMT3b were highly expressed in IVMv oocytes along with a decrease in the artificial activation rate compared to the vIVM oocytes. Our results indicated that despite observing more negative effects of vitrification before IVM on the survival rate and maturation as well as apoptosis status, less epigenetic changes in vIVM oocytes can make this process a better option in the treatment of infertility than IVM of oocytes followed by vitrification, a hypothesis that needs to be investigation in human oocytes.

Embryo ploidy in vitrified versus fresh oocytes: Is there a difference?

PURPOSE

To evaluate embryo ploidy in a cohort of patients who underwent preimplantation genetic testing for aneuploidy (PGT-A) with vitrified oocytes compared to fresh oocytes.

METHODS

Patients who underwent their first autologous oocyte vitrification and warming followed by in vitro fertilization (IVF) and trophectoderm biopsy for PGT-A between 1/1/2017 and 12/31/2021 at a single academic institution were included. Patients were compared 1:3 to age-matched controls who underwent their first IVF cycle with fresh oocytes and subsequent trophectoderm biopsy for PGT-A. The primary outcome was the proportions of euploid, mosaic, and aneuploid embryos between those using vitrified versus fresh oocytes.

RESULTS

117 patients who cryopreserved a total of 1,272 mature oocytes were included in the study and were matched with 351 controls using fresh oocytes. The average age was 36.9 ± 2.6 years, and the median interval between oocyte vitrification and warming was 38 months. There were similar numbers of mature oocytes (10.9 ± 4.9 vs. 11.1 ± 6.3, P = .67), fertilized oocytes (7.8 ± 4.0 vs. 8.7 ± 5.5, P = .10), and blastocysts per patient (5.1 ± 3.1 vs. 5.8 ± 4.3, P = .10) between those using vitrified versus fresh oocytes. In terms of embryo ploidy results, there were no statistically significant differences in rates of euploidy (40.1% vs. 41.6%), mosaicism (15.7% vs. 12.0%), or aneuploidy (44.3% vs. 46.4%) (P = .06) between the two groups.

CONCLUSIONS

Oocyte vitrification with subsequent warming, fertilization, and trophectoderm biopsy for PGT-A was not associated with adverse chromosomal competence when compared to age-matched controls utilizing fresh oocytes.

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

RESEARCH QUESTION

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

DESIGN

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

RESULTS

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

CONCLUSIONS

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

Refined Techniques for Enabling Long-Term Cryo-Repository Using Vitrification and Laser Warming

Vitrification and ultrarapid laser warming are crucial for the cryopreservation of animal embryos, oocytes, and other cells of medicinal, genetic, and agricultural value. In the present study, we focused on alignment and bonding techniques for a special cryojig that combines a jig tool and jig holder into one piece. This novel cryojig was used to obtain a high laser accuracy of 95% and a successful rewarming rate of 62%. The experimental results indicated that our refined device improved laser accuracy in the warming process after long-term cryo-storage through vitrification. We anticipate that our findings will lead to cryobanking applications that use vitrification and laser nanowarming to preserve cells and tissues from a wide range of species.

The live birth rate of vitrified oocyte accumulation for managing diminished ovarian reserve: a retrospective cohort study

BACKGROUND

Vitrified M-II oocyte accumulation for later simultaneous insemination has been used for managing POR. Our study aimed to determine whether vitrified oocyte accumulation strategy improves live birth rate (LBR) for managing diminished ovarian reserve (DOR).

METHODS

A retrospective study included 440 women with DOR fulfilling Poseidon classification groups 3 and 4, defined as the presence of serum anti-Müllerian hormone (AMH) hormone level < 1.2 ng/ml or antral follicle count (AFC) < 5, from January 1, 2014, to December 31, 2019, in a single department. Patients underwent accumulation of vitrified oocytes (DOR-Accu) and embryo transfer (ET) or controlled ovarian stimulation (COS) using fresh oocytes (DOR-fresh) and ET. Primary outcomes were LBR per ET and cumulative LBR (CLBR) per intention to treat (ITT). Secondary outcomes were clinical pregnancy rate (CPR) and miscarriage rate (MR).

RESULTS

Two hundred eleven patients underwent simultaneous insemination of vitrified oocyte accumulation and ET in the DOR-Accu group (maternal age: 39.29 ± 4.23 y, AMH: 0.54 ± 0.35 ng/ml), and 229 patients underwent COS and ET in the DOR-fresh group (maternal age: 38.07 ± 3.77 y, AMH: 0.72 ± 0.32 ng/ml). CPR in the DOR-Accu group was similar in the DOR-fresh group (27.5% vs. 31.0%, p = 0.418). However, MR was statistically higher (41.4% vs. 14.1%, p = 0.001), while LBR per ET was statistically lower (15.2% vs. 26.2%, p < 0.001) in the DOR-Accu group. There is no difference in CLBR per ITT between groups (20.4% vs. 27.5%, p = 0.081). The secondary analysis categorized clinical outcomes into four groups regarding patients' age. CPR, LBR per ET, and CLBR did not improve in the DOR-Accu group. In the group of 31 patients, accumulated vitrified metaphase II (M-II) oocytes reached a total number of ≥ 15, and CPR improved among the DOR-Accu group (48.4% vs. 31.0%, p = 0.054); however, higher MR (40.0% vs. 14.1%, p = 0.03) resulted in similar LBR per ET (29.0% vs. 26.2%, p = 0.738).

CONCLUSIONS

Vitrified oocyte accumulation for managing DOR did not improve LBR. Higher MR resulted in lower LBR in the DOR-Accu group. Therefore, the vitrified oocyte accumulation strategy for managing DOR is not clinically practical.

TRIAL REGISTRATION

The study protocol was retrospectively registered and was approved by Institutional Review Board of Mackay Memorial Hospital (21MMHIS219e) on August 26, 2021.

Comparison of oocyte vitrification using a semi-automated or a manual closed system in human siblings: survival and transcriptomic analyses

BACKGROUND

Indications of oocyte vitrification increased substantially over the last decades for clinical and ethical reasons. A semi-automated vitrification system was recently developed making each act of vitrification reproducible. In this study, we evaluated the efficiency of the semi-automated technique of oocyte vitrification by survival rate, morphometric assessment and resistance to empty micro-injection gesture as compared with a manual method. Additionally, we intended to evaluate transcriptomic consequences of both techniques using single-cell RNA-seq technology.

RESULTS

Post-warming survival rate, oocyte surfaces and resistance to empty micro-injection were comparable between semi-automated and manual vitrification groups. Both oocyte vitrification techniques showed limited differences in the resulting transcriptomic profile of sibling oocytes since only 5 differentially expressed genes were identified. Additionally, there was no difference in median transcript integrity number or percentage of mitochondrial DNA between the two groups. However, a total of 108 genes were differentially expressed between fresh and vitrified oocytes (FDR < 0.05) and showed over-represented of genes related to important cellular process.

CONCLUSIONS

Our results provide reassurance about the influence of semi-automation as compared with the manual vitrification method. Concerning oocyte vitrification itself, no tight common transcriptomic signature associated has been observed across studies.

TRIAL REGISTRATION

NCT03570073.

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.

Application of Nanoparticles and Melatonin for Cryopreservation of Gametes and Embryos

Cryopreservation of gametes and embryos, a technique widely applied in human infertility clinics and to preserve desirable genetic traits of livestock, has been developed over 30 years as a component of the artificial insemination process. A number of researchers have conducted studies to reduce cell toxicity during cryopreservation using adjuvants leading to higher gamete and embryo survival rates. Melatonin and Nanoparticles are novel cryoprotectants and recent studies have investigated their properties such as regulating oxidative stresses, lipid peroxidation, and DNA fragmentation in order to protect gametes and embryos during vitrification. This review presented the current status of cryoprotectants and highlights the novel biomaterials such as melatonin and nanoparticles that may improve the survivability of gametes and embryos during this process.

Comparison of pregnancy outcomes of 7515 same donor oocyte cycle fresh and cryopreserved-thawed oocytes in 609 donor oocyte recipient cycles: A single institution analysis

OBJECTIVE

Oocyte donation (OD) cycles have been used extensively over the last decades due to high success regarding live birth rate (LBR). We evaluated the reproductive outcomes of fresh and vitrified sibling oocytes in terms of fertilization rates, blast ratio, clinical pregnancy rates, and LBR.

MATERIALS AND METHODS

This retrospective cohort study was conducted at a tertiary in vitro fertilization (IVF) center. A total of 7515 metaphase II (MII) donor oocytes from 304 donor cycles for 609 oocyte recipients undergoing embryo transfers with either fresh or cryopreserved-thawed donor oocytes. Donor cycles that provided both 12 fresh MII oocytes to be used for one recipient and at least 12 MII oocytes which were suitable for vitrification to be used for another recipient at another time were analyzed. Fertilization rates, blastocyst ratios, clinical pregnancy rates (CPR), LBR were evaluated as main outcome measures.

RESULTS

When the fresh and cryopreserved-thawed OD cycles were compared, there was no significant differences between two groups in terms of age of the recipient (41.9 ± 5.7 and 40.3 ± 6.8, p = NS), number of MII oocytes (12.1 ± 0.3 and 12.6 ± 0.8, p = NS), number of 2 pronuclear (PN) (9.1 ± 1.6 and 9.7 ± 2.0, p = NS), blastocyst ratio (58.9 ± 21.7 and 51.3 ± 21.2, p = NS) and number of transferred embryos (1.9 ± 0.3 and 1.9 ± 0.3, p = NS). There was no significant difference between fresh and cryopreserved-thawed sibling donor oocyte cycles in terms of CPR (66.8 % and 60.7 % respectively, p = NS) or LBR (59.5 % and 55.1 %, respectively; p = NS). Miscarriage and multiple gestation rates were similar between groups (p = NS). Log-binomial regression analysis revealed that the use of fresh sibling oocytes was not associated with CPR or LBR, when compared to cryopreserved-thawed oocytes.

CONCLUSIONS

There was no significant difference in terms of reproductive outcomes between sibling fresh OD and cryopreserved-thawed OD cycles.

Cryopreservation of oocytes and embryos for fertility preservation

Background: In recent years, the demand for fertility preservation for both oncologic and nononcologic reasons, as well as for personal reasons, has increased dramatically.Current Concepts: Currently, embryo and oocyte cryopreservation after ovarian stimulation are the mainstays of fertility preservation treatment in women. Embryo cryopreservation is an established and the most successful method of fertility preservation when sufficient time (approximately 2 weeks) is available to perform ovarian stimulation. Recent advances in freezing techniques (vitrification) have significantly improved the outcomes from oocyte cryopreservation that are comparable with those from embryo cryopreservation.Discussion and Conclusion: This review focuses on the indications for the two techniques of fertility preservation and their results. For women to receive timely opportunities to preserve fertility, it is necessary to raise awareness among all medical departments and the public.

Employer-based insurance coverage increases utilization of planned oocyte cryopreservation

PURPOSE

To determine the utilization of planned oocyte cryopreservation (OC) in the year immediately prior to, and the year of, insurance coverage commencement for employees at our institution.

METHODS

Patient demographics and cycle outcomes were retrospectively compared between the first OC cycles occurring in 2017 vs. 2018 according to insurance coverage and type, age, and the number of oocytes retrieved and cryopreserved. Continuous demographic variables including age, BMI, day 3 FSH and E2, AMH, gravidity, and parity were compared using student T-tests. Cycle outcomes, including the number of oocytes retrieved and cryopreserved were compared using linear regression models, adjusting for potential confounders including age, BMI, and ovarian reserve parameters.

RESULTS

Between January 2017 and December 2018, 123 patients underwent planned OC at our institution. Patient age ranged from 23 to 44 years and did not significantly differ from 2017 to 2018 (mean 34.9 vs. 35.2). There was a 12% increase in planned OC utilization from 2017 (N = 58) to 2018 (N = 65). Significantly, more patients had any insurance coverage in 2018 vs. 2017 (71.9% vs. 40.4%, p = 0.001), a 78% increase. From 2017 to 2018, the number of patients with hospital-based insurance coverage undergoing planned OC increased by a factor of 8 (5 to 41.5%, p < 0.001), while the number of self-pay patients significantly decreased (p = 0.001). No differences were found regarding cycle outcomes.

CONCLUSION

A greater proportion of women at our institution had insurance coverage for planned OC in 2018 vs. 2017. Employer-based insurance coverage for planned OC was associated with a significant increase in utilization by hospital employees.

Racial and ethnic disparities among donor oocyte banks in the United States

OBJECTIVE

To determine whether racial and ethnic distributions of oocyte donors contributing to US oocyte banks differ from the demographics of US women and donor oocyte recipients.

DESIGN

Cross-sectional study.

SETTING

United States donor oocyte banks, US census, and fertility clinics reporting to the Society for Assisted Reproductive Technology Clinic Outcome Reporting System.

PATIENTS

Oocyte donors from 12 banks, women aged 18-44 years based on the 2019 census, and US recipients of cryopreserved donor oocytes from 2012 to 2015.

INTERVENTION

None.

MAIN OUTCOME MEASURE

Proportions of donors identifying as each racial and ethnic group.

RESULTS

Of the 1,574 oocyte donors, 678 (43.1%) identified as white compared with 54.8% of US women and 69.1% of donor oocyte recipients. Proportions of donors identifying as Hispanic or two or more races were larger than those of US women and donor oocyte recipients (Hispanic: 24.1% vs. 20.8%, and 24.1% vs. 8.8%, respectively; two or more races: 16.1% vs. 2.3%, and 16.1% vs. 0.5%, respectively). African American donors were underrepresented compared with US women (8.9% vs. 14.0%) and oocyte recipients (8.9% vs. 10.8%). Although the proportion of Asian donors was similar to that of US women (7.7% vs. 7.1%), Asian donors were underrepresented compared with donor oocyte recipients (7.7% vs. 10.6%).

CONCLUSION

Racial and ethnic distribution of oocyte donors differs significantly from the demographics of US women and cryopreserved donor oocyte recipients. These data suggest a need for targeted recruitment of African American and Asian oocyte donors.

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.

Fertility and breast cancer: A literature review of counseling, preservation options and outcomes

Fertility preservation is an important issue in breast cancer patients undergoing oncological treatment. Fertility counseling is a crucial need given the physical and psychological stress experienced by patients. Cryopreservation of mature oocytes is currently the standard fertility-preserving procedure. Other options such as ovarian tissue preservation or gonadal protection during chemotherapy are still experimental, but have proven effectiveness. Prompt referral to a fertility unit is highly recommended in order to ensure quality of care. In this article, we focus on the different strategies to preserve fertility in breast cancer patients, assessing also the safety of pregnancy and breastfeeding after cancer. A systemic literature review was performed for research articles published in English in PubMed, or as abstracts from the European Society for Medical Oncology (ESMO), San Antonio Breast Cancer Symposium (SABCS) and American Society of Clinical Oncology (ASCO) annual meetings, using the search terms "breast cancer" and "fertility".

Molecular Mechanism and Prevention Strategy of Chemotherapy- and Radiotherapy-Induced Ovarian Damage

Fertility preservation is an emerging discipline, which is of substantial clinical value in the care of young patients with cancer. Chemotherapy and radiation may induce ovarian damage in prepubertal girls and young women. Although many studies have explored the mechanisms implicated in ovarian toxicity during cancer treatment, its molecular pathophysiology is not fully understood. Chemotherapy may accelerate follicular apoptosis and follicle reservoir utilization and damage the ovarian stroma via multiple molecular reactions. Oxidative stress and the radiosensitivity of oocytes are the main causes of gonadal damage after radiation treatment. Fertility preservation options can be differentiated by patient age, desire for conception, treatment regimen, socioeconomic status, and treatment duration. This review will help highlight the importance of multidisciplinary oncofertility strategies for providing high-quality care to young female cancer patients.

Employer-Sponsored Egg Freezing: Carrot or Stick?

BACKGROUND

Since 2014, many companies have followed the lead of Apple and Facebook and now offer financial support to female employees to access egg freezing. Australian companies may soon make similar offers. Employer-sponsored egg freezing (ESEF) has raised concerns and there is academic debate about whether ESEF promotes reproductive autonomy or reinforces the 'career vs. family' dichotomy. Despite the growing availability of ESEF and significant academic debate, little is known about how ESEF is perceived by the public. The aim of this study was to explore women's attitudes toward ESEF.

METHODS

Women aged 18-60 years who resided in Victoria, Australia were invited to complete an online, cross-sectional survey investigating views toward egg freezing. Associations between participant demographics and their views about ESEF were assessed using multinominal logistic regression, adjusted for age and free text comments were analyzed using thematic analysis.

RESULTS

The survey was completed by 656 women, median age 28 years (range: 18-60 years). Opinions on the appropriateness of employers offering ESEF were divided (Appropriate: 278, 42%; Inappropriate: 177, 27%; Unsure: 201, 31%). There was significantly less support for ESEF among older participants and those employed part-time (p < 0.05). While some participants saw the potential for ESEF to increase women's reproductive and career options, others were concerned that ESEF could pressure women to delay childbearing and exacerbate existing inequities in access to ARTs.

CONCLUSIONS

Our analysis revealed that while some women identified risks with ESEF, for many women ESEF is not viewed as theoretically wrong, but rather it may be acceptable under certain conditions; such as with protections around reproductive freedoms and assurances that ESEF is offered alongside other benefits that promote career building and family. We suggest that there may be a role for the State in ensuring that these conditions are met.

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.

Efficiency and efficacy of vitrification in 35 654 sibling oocytes from donation cycles

STUDY QUESTION

Is oocyte vitrification/warming as efficient and effective as using fresh oocytes in donation cycles?

SUMMARY ANSWER

IVF with vitrified donor oocytes is less efficient than using fresh oocytes, but its efficacy remains comparable to that of fresh cycles.

WHAT IS KNOWN ALREADY

Oocyte vitrification is used to preserve the reproductive potential of oocytes. A small number of randomized controlled trials carried out by experienced groups have shown that this technique provides fertilization, pregnancy, implantation and ongoing pregnancy rates comparable to those of fresh oocytes. However, large registry-based analyses have consistently reported lower live birth rates (LBRs) in cycles using vitrified oocytes. It is not clear whether this decrease may be due to the effect of vitrification per se on the oocytes or to the lower efficiency of the technique, as some of the oocytes do not survive after warming.

STUDY DESIGN, SIZE, DURATION

Retrospective cohort analysis of 1844 cycles of oocyte donation (37 520 oocytes), each donor in the study provided enough oocytes for at least one reception cycle with fresh oocytes (2561 cycles) and one reception cycle with vitrified oocytes (2471 cycles) from the same ovarian stimulation (sibling oocytes). Overall, 35 654 oocytes were considered in the analysis. All embryo transfers (n = 5032) were carried out between 2011 and 2017.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Differences in reproductive outcomes after the first embryo transfer were evaluated using Pearson's Chi-squared test and regression analysis adjusted for recipient's age, BMI, sperm origin and state, day of embryo transfer, morphological score and number of transferred embryos. We performed two additional sub-analyses, to test whether the efficiency and/or effectiveness of vitrification/warming impacts reproductive results. One analysis included paired cycles where the same number of fresh and vitrified oocytes were available for ICSI (SAME sub-analysis), while the second analysis included those cycles with a 100% survival rate post-warming (SAME100 sub-analysis).

MAIN RESULTS AND THE ROLE OF CHANCE

Baseline and cycle characteristics of participants were comparable between groups. Overall, fertilization rates and embryo morphological scores were significantly lower (P < 0.001) when using vitrified oocytes; moreover, vitrified oocytes also resulted in lower reproductive outcomes than sibling fresh oocytes using both unadjusted and adjusted analyses: ongoing pregnancy (32.1% versus 37.5%; P < 0.001; OR 0.88, 95% CI 0.77, 1.00) and live birth (32.1% versus 31.9%; P = 0.92; OR 1.16, 95% CI 0.90, 1.49). However, when the efficiency of warming was taken into account, reproductive outcomes in recipients became comparable: ongoing pregnancy (33.5% versus 34.1%; P = 0.82; OR 1.11, 95% CI 0.87, 1.43) and LBR (32.1% versus 32%; P = 0.97; OR 1.15, 95% CI 0.89, 1.48). Moreover, after selecting only cycles that, in addition to having the same number of oocytes available for ICSI, also had 100% post-warming survival rate in the vitrified group, reproductive outcomes were also comparable between fresh and vitrified oocytes: ongoing pregnancy (34.8% versus 32.4%; P = 0.42; OR 1.32, 95% CI 0.98, 1.77) and live birth (32.9% versus 31.0%; P = 0.52; OR 1.27, 95% CI 0.95, 1.71), indicating that reproductive outcomes of these cycles are affected by the efficiency of the vitrification/warming technique performed rather than the oocyte damage due to the fast cooling process to which oocytes are subjected.

LIMITATIONS, REASONS FOR CAUTION

An open vitrification system was used for all cases, and oocyte vitrification/warming was performed by experienced embryologists with consistently high survival rates; caution must be exerted when extrapolating our results to data obtained using other open vitrification systems, closed vitrification systems or to IVF units with survival rates <90%.

WIDER IMPLICATIONS OF THE FINDINGS

This is the largest cohort study comparing reproductive outcomes of vitrified and fresh sibling donor oocytes to date. We found that, when the number of oocytes available after warming is equal to the number of fresh oocytes, reproductive results including live birth are comparable. Consequently, the efficiency of vitrification must be taken into account to achieve the same reproductive outcomes as with fresh oocytes. We recommend implementing strict indicators of vitrification/warming efficiency in clinics and refining vitrification/warming protocols to maximize survival.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by intramural funding of Clínica EUGIN and by the Secretary for Universities and Research of the Ministry of Economy and Knowledge of the Government of Catalonia (GENCAT 2015 DI 048). The authors declare no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Cryopreservation of both male and female gametes leads to reduced embryo development and implantation potential

The objective of this study was to investigate the effect of oocyte and sperm cryopreservation on donated eggs submitted to intracytoplasmic sperm injection (ICSI) cycles. Medical charts of 122 oocyte recipients undergoing 152 oocyte recipient ICSI cycles, from 2017 to 2018, in a private university-affiliated in vitro fertilization (IVF) centre, were reviewed in this historical cohort study. Cycles were divided into four groups according to the gamete status: the FO/FS Group, recipients in which fresh oocytes were injected with fresh sperm (n = 19); the FO/CrS Group, recipients in which fresh oocytes were injected with cryopreserved sperm (n = 14); the CrO/FS Group, recipients in which cryopreserved oocytes were injected with fresh sperm (n = 85); and the CrO/CrS Group, recipients in which cryopreserved oocytes were injected with cryopreserved sperm (n = 34). Generalized mixed models fit by restricted maximum likelihood, followed by Bonferroni post hoc test for the comparison of means amongst groups were used to investigate the effect of cryopreservation on recipient ICSI outcomes. The results were expressed as mean differences with 95% confidence intervals and P-values. The main outcome measure was the implantation rate. Normal day 3 cleavage speed, blastocyst development and implantation rates were significantly lower in the CrO/CrS Group compared with the FO/FS Group. In conclusion, embryo developmental competence and implantation potential were reduced when vitrified oocytes were injected with frozen sperm in an egg-sharing donation programme.

Fresh oocyte cycles yield improved embryo quality compared with frozen oocyte cycles in an egg-sharing donation programme

The objective of this study was to investigate any effect of cryopreservation of donated eggs on laboratorial and clinical outcomes of intracytoplasmic sperm injection (ICSI) cycles. This retrospective cohort study included 320 oocyte recipients undergoing 307 vitrified and 119 fresh oocyte recipient ICSI cycles, participating in an egg-sharing donation programme, from 2015 to 2018, in a private university-affiliated in vitro fertilization (IVF) centre. A review of donor and recipient ICSI cycles was charted. A general mixed models fit by restricted maximum likelihood, followed by Bonferroni post hoc test was used to compare the means between fresh and warm oocyte donation groups and investigate the effect of cryopreservation on recipient ICSI outcome. The main outcome measure was blastocyst development rates. Fertilization rate, high-quality embryo rates on days 2 and 3, normal cleavage speed rates on days 2 and 3, and blastocyst development rate were significantly higher for the fresh oocyte donation cycles compared with warmed oocyte donation cycles. In the egg-sharing donation programme, fertilization and embryo developmental competence were reduced when vitrified oocytes from infertile couples were used for ICSI compared with fresh oocytes.

Cryopreservation of equine oocytes: looking into the crystal ball

Invitro embryo production has evolved rapidly in the horse over the past decade, but blastocyst rates from vitrified equine oocytes remain quite poor and further research is needed to warrant application. Oocyte vitrification is affected by several technical and biological factors. In the horse, short exposure of immature oocytes to the combination of permeating and non-permeating cryoprotective agents has been associated with the best results so far. High cooling and warming rates are also crucial and can be obtained by using minimal volumes and open cryodevices. Vitrification of invivo-matured oocytes has yielded better results, but is less practical. The presence of the corona radiata seems to partially protect those factors that are necessary for the construction of the normal spindle and for chromosome alignment, but multiple layers of cumulus cells may impair permeation of cryoprotective agents. In addition to the spindle, the oolemma and mitochondria are also particularly sensitive to vitrification damage, which should be minimised in future vitrification procedures. This review presents promising protocols and novel strategies in equine oocyte vitrification, with a focus on blastocyst development and foal production as most reliable outcome parameters.

Advances in the Treatment and Prevention of Chemotherapy-Induced Ovarian Toxicity

Due to improvements in chemotherapeutic agents, cancer treatment efficacy and cancer patient survival rates have greatly improved, but unfortunately gonadal damage remains a major complication. Gonadotoxic chemotherapy, including alkylating agents during reproductive age, can lead to iatrogenic premature ovarian insufficiency (POI), and loss of fertility. In recent years, the demand for fertility preservation has increased dramatically among female cancer patients. Currently, embryo and oocyte cryopreservation are the only established options for fertility preservation in women. However, there is growing evidence for other experimental techniques including ovarian tissue cryopreservation, oocyte in vitro maturation, artificial ovaries, stem cell technologies, and ovarian suppression. To prevent fertility loss in women with cancer, individualized fertility preservation options including established and experimental techniques that take into consideration the patient’s age, marital status, chemotherapy regimen, and the possibility of treatment delay should be provided. In addition, effective multidisciplinary oncofertility strategies that involve a highly skilled and experienced oncofertility team consisting of medical oncologists, gynecologists, reproductive biologists, surgical oncologists, patient care coordinators, and research scientists are necessary to provide cancer patients with high-quality care.

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.

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.

"Universal Warming" protocol for vitrified oocytes to streamline cell exchange for transnational donation programs: a multi-center study

PURPOSE

To investigate the clinical efficacy of a "Universal Warming" protocol, based on subsequent steps with 1 M and 0.5 M concentration of extracellular cryoprotectant (ECCP), on shipped oocytes. Oocytes are vitrified using different brands of ready-to-use kits which recommend that the use of their own warming kit and combining different vitrification/warming kits may have legal consequences for assisted reproductive (AR) centers, until this practice has been validated with clinical studies.

METHODS

Retrospective multi-center transnational observational study. Number of oocytes warmed 1.898. Vitrification performed with vitrification kit (Kitazato, Japan); warming carried out randomly with two different kits: Kitazato warming kit and Vit Kit®-Thaw (FujiFilm Irvine, USA). Warmed oocytes were assigned to 2 groups: KK (Kitazato/Kitazato) 939, and KI (Kitazato/Irvine) 959. Primary endpoint: survival rate. Secondary endpoints: fertilization rate; blastulation rate; implantation rate; live birth rate.

RESULTS

Survival was comparable between the groups: 84.6% (795/939) in group KK vs 82.1% (787/959) in group KI. Fertilization rate was lower (P = 0.027) in group KK (75.7%-602/795) than in group KI (80.4%-633/787). Blastulation and implantation and live birth rates were all statistically comparable between the study groups: blastulation rate was 58.5% (352/602) vs 57.8% (366/633); implantation rate was 41.5% (80/193) vs 45.9% (84/183); live birth rate was 52.5% (62/118) in KK and 45.0% (54/120) in KI.

CONCLUSION

The use of this "Universal Warming" protocol simplifies vitrified oocyte exchange between AR centers in different countries, and overcomes potential regulatory/commercial/availability differences affecting clinical practice.

COMPARATIVE ANALYSIS OF PROGRAMS WITH THE USE OF NATIVE AND CRYOPRESERVED OOCYTES IN IN -VIRTO FERTILIZATION PROCEDURES

This article release data about comparative survival of oocytes after freezing, fertilization, blastocyst formation and clinical results of IVF/ICSI programs in International Clinical Centre of Reproductology Persona during period from 2016 to 2019.

Human sperm vitrification: the state of the art

Sperm cryopreservation has been widely used in assisted reproductive technology (ART) and has resulted in millions of live births. Two principal approaches have been adopted: conventional (slow) freezing and vitrification. As a traditional technique, slow freezing has been successfully employed and widely used at ART clinics whereas the latter, a process to solidify liquid into an amorphous or glassy state, may become a faster alternative method of sperm cryopreservation with significant benefits in regard to simple equipment and applicability to fertility centers. Sperm vitrification has its own limitations. Firstly, small volume of load is usually plunged to liquid nitrogen to achieve high cooling rate, which makes large volume sample cryopreservation less feasible. Secondly, direct contact with liquid nitrogen increases the potential risk of contamination. Recently, new carriers have been developed to facilitate improved control over the volume and speed, and new strategies have been implemented to minimize the contamination risk. In summary, although sperm vitrification has not yet been applied in routine sperm cryopreservation, its potential as a standard procedure is growing.

The Future of Cryopreservation in Assisted Reproductive Technologies

Societal changes and the increasing desire and opportunity to preserve fertility have increased the demand for effective assisted reproductive technologies (ART) and have increased the range of scenarios in which ART is now used. In recent years, the "freeze-all" strategy of cryopreserving all oocytes or good quality embryos produced in an IVF cycle to transfer later-at a time that is more appropriate for reasons of medical need, efficacy, or desirability-has emerged as an accepted and valuable alternative to fresh embryo transfer. Indeed, improvements in cryopreservation techniques (vitrification) and the development of more efficient ovarian stimulation protocols have facilitated a dramatic increase in the practice of elective frozen embryo transfer (eFET). Alongside these advances, debate continues about whether eFET should be a standard treatment option available to the whole IVF population or if it is important to identify patient subgroups who are most likely to benefit from such an approach. Achieving successful outcomes in ART, whether by fresh or frozen embryo transfer, is influenced by a wide range of factors. As well as the efficiency of IVF and embryo transfer protocols and techniques, factors affecting implantation include maternal aging, sperm quality, the vaginal and endometrial microbiome, and peri-implantation levels of serum progesterone. The safety of eFET, both during ART cycles and on longer-term obstetric and neonatal outcomes, is also an important consideration. In this review, we explore the benefits and risks of freeze-all strategies in different scenarios. We review available evidence on the outcomes achieved with elective cryopreservation strategies and practices and how these compare with more traditional IVF cycles with fresh embryo transfers, both in the general IVF population and in subgroups of special interest. In addition, we consider how to optimize and individualize "freeze-all" procedures to achieve successful reproductive outcomes.

In-vitro development of embryos derived from vitrified-warmed oocytes is delayed compared with embryos derived from fresh oocytes: a time-lapse sibling oocyte study

RESEARCH QUESTION

Is there a difference in blastocyst formation between fresh and vitrified-warmed sibling oocytes and can this difference be attributed to changes in embryo morphokinetics?

DESIGN

Between February 2016 and December 2017, 472 metaphase II (MII) oocytes in 67 donor-recipient cycles from 27 different healthy anonymous oocyte donors were allocated for fresh transfer (FSHO) (n = 220) to a synchronous recipient (n = 36) or vitrified (VITO) (n = 252) to be warmed and transferred to another recipient (n = 31). Embryos derived from the FSHO and their sibling VITO were analysed for morphokinetic development using time-lapse imaging, blastocyst formation and clinical outcome.

RESULTS

Time-lapse analysis showed an overall delay in cleavage rate from the time of pronuclei disappearance up to the time of blastulation in the VITO compared with their sibling FSHO. Twelve morphokinetic variables were significantly different between the groups. On Day 5 significantly more FSHO embryos developed to blastocyst (expansion 1-6) and reached the full blastocyst stage (expansion 3-6) compared with the VITO embryos [53.2% (84/158) versus 40.0% (64/160); P = 0.0244 and 48.1% (76/158) versus 31.3% (50/160); P = 0.0028, respectively]. The embryo utilization rate was similar in both groups at the time of cryopreservation; 51.3% (FSHO) versus 45.0% (VITO) (P = 0.3124). The pregnancy rate per cycle was 47.2% (17/36) in FSHO patients and 48.4% (15/31) in VITO patients (P = 1). Limitations in this study: non-randomized, small study size and not powered to detect differences in clinical outcomes.

CONCLUSIONS

Timing of development is altered and blastocyst formation is delayed in embryos derived from vitrified-warmed donor oocytes compared with their fresh sibling counterparts. Although preliminary results suggest that the clinical impact of this delay may be limited, this needs further investigation in larger randomized studies.

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.

Recent Advances in Fertility Preservation and Counseling for Reproductive-Aged Women with Colorectal Cancer: A Systematic Review

BACKGROUND

The incidence of colorectal cancer among reproductive-aged women is increasing. Concerns regarding future fertility are secondary only to concerns regarding survival and may significantly impact quality of life among reproductive-aged female cancer survivors. Fertility preservation counseling reduces long-term regret and dissatisfaction among cancer survivors. Health care providers counseling patients with colorectal cancer must understand the impact of cancer treatment on future reproductive potential.

OBJECTIVE

This review aims to examine the effects that colorectal cancer treatments have on female fertility and summarize existing and emerging options for fertility preservation.

DATA SOURCES

EMBASE, National Library of Medicine (MEDLINE)/PubMed, Cochrane Review Library were the data sources for this review.

STUDY SELECTION

A systematic literature review was performed using exploded MeSH terms to identify articles examining the effect of surgery, chemotherapy, and radiation, as well as fertility preservation options for colorectal cancer on female fertility. Relevant studies were included.

MAIN OUTCOME MEASURES

The primary outcome was the effect of colorectal cancer treatment on fertility.

RESULTS

There are limited data regarding the impact of colorectal surgery on fertility. The gonadotoxic effects of chemotherapy on reproductive capacity depend on age at the time of chemotherapy administration, cumulative chemotherapy, radiation dose, type of agent, and baseline fertility status. Chemotherapy-induced risks for colorectal cancers are considered low to moderate, whereas pelvic radiation with a dose of 45 to 50 Gray induces premature menopause in greater than 90% of patients. Ovarian transposition may reduce but not eliminate the damaging effect of radiation on the ovaries. Embryo and oocyte cryopreservation are considered standard of care for women desiring fertility preservation, with oocyte cryopreservation no longer being considered experimental. Ovarian tissue cryopreservation remains experimental but may be an option for select patients. The use of gonadotropin-releasing hormone agonists remains controversial and has not been definitively shown to preserve fertility.

LIMITATIONS

The limitations of this review are the lack of randomized controlled trials and high-quality studies, as well as the small sample sizes and the use of surrogate fertility markers.

CONCLUSION

Reproductive-aged women with colorectal cancer benefit from fertility preservation counseling before the initiation of cancer treatment.

For whom the egg thaws: insights from an analysis of 10 years of frozen egg thaw data from two UK clinics, 2008-2017

PURPOSE

To better understand the characteristics of patients who returned to thaw their frozen eggs to attempt conception and their outcomes.

METHODS

A retrospective analysis of clinical records for all own egg thaw patients in two UK fertility clinics across 10 years, 2008-2017.

RESULTS

There were 129 patients who returned to thaw their eggs, of which 46 had originally frozen their eggs for social reasons and 83 for a variety of clinical, incidental, and ethical reasons (which we have called "non-social"). Women who had frozen their eggs for social reasons were single at time of freeze, with an average age of 37.7. They kept their eggs in storage for just under 5 years, returning to use them at the average age of 42.5. 43.5% were single at time of thaw, and 47.8% used donor sperm to fertilise their eggs. Women whose eggs were frozen for non-social reasons were almost all (97.6%) in a relationship at both time of freeze and thaw. They had an average age of 37.2 at first freeze and 37.6 at thaw, having kept their eggs in storage for an average of 0.4 years. Overall, there was a 20.9% success rate among women attempting conception with frozen-thawed eggs.

CONCLUSIONS

Despite widespread assumptions, many women attempting conception with thawed eggs had not initially frozen them for social reasons. Women who froze their eggs for social reasons presented distinctly and statistically different characteristics at both time of freeze and thaw to women whose eggs were frozen for non-social reasons.

A brief history of oocyte cryopreservation: Arguments and facts

The term "cryopreservation" refers to the process of cooling cells and tissues and storing them at subzero temperatures in order to stop all biological activity and preserve their viability and physiological competences for future use. Cooling to subzero temperatures is not a physiological condition for human cells; this is probably due to the high content of water in the living matter, whose conversion to ice crystals may be associated with severe and irreversible damage. Among reproductive cells and tissues, metaphase II oocytes are notably vulnerable to cryopreservation, mainly because of their large size, low surface area to volume ratio, relatively high water content and presence of the meiotic spindle. As human biological systems lack efficient internal defense mechanisms against chilling injuries, it is of the utmost importance to supply adequate external support, in terms of cryoprotectant additives, appropriate cooling/warming rates, and suitable long-term storage. Over the years, scientists have proposed different cryopreservation strategies in the effort to achieve an optimized recipe ensuring cell survival and, at the same time, maintenance of the physiological functions and abilities necessary to continue life. However, despite the first success obtained in the 1980s with frozen oocytes, it was not until recently that notable improvements in the cryopreservation technique, thanks to the advent of vitrification, allowed a breakthrough of this fine procedure.

Cryopreservation and microfluidics: a focus on the oocyte

Cryopreservation of gametes and embryos has played a critical role in successful assisted reproductive technologies in rodents, domestic farm species, endangered species and humans. With improved success, and changing needs, the utility of gamete or embryo cryopreservation has escalated. In this review we address some of the foundational history of mammalian cryobiology, species-specific utilities, fundamental understandings of cryoprotectant agents and their use in slow-rate freezing and vitrification, and expand on the recent success and uses of oocyte vitrification and warming. In the area of female gamete cryopreservation, emphasis will be placed on not just cell survival, but also perceived and measured affects of cryopreservation on intracellular structures and functions that affect subsequent completion of meiosis with chromatin segregation fidelity, normal fertilisation and embryonic developmental competence. We compare and contrast data from cow, mouse and humans with a focus on using species-comparative developmental biology to guide future studies for improving methodologies for all species. The application of the relatively new technology microfluidics is discussed in relation to moving gradually (i.e. changing the solution over cells in an automated fashion) compared with the stepwise manual movement of cells through changing solution currently used. This use of microfluidics to change the way cells are exposed to cryoprotectant agents can provide new insights into the effects of osmotic stress and cellular strain rates previously unappreciated, precise methods of computational and biological data acquisition and appreciation of morphometric changes to cellular structure in response to different osmotic stresses and strain rates achieved with varying cryoprotectant exposures. Collectively, these devices and methodologies provide a means of achieving incremental improvement of oocyte and zygote cryopreservation with normalised and improved developmental competence. Finally, we look to the past and the future to acknowledge the accomplishment of leaders in the field of mammalian gamete and embryo cryobiology, their inspirational works, their tireless dissemination of information and the potential of new technologies in bioengineering to improve the efficiency and safety of gamete and embryo cryopreservation.

Advances in Fertility Preservation for Young Women With Cancer

Female patients of reproductive age with cancer often require treatment that can compromise their future fertility. Treatment-related infertility is an important cancer survivorship issue and is associated with depression and diminished quality of life. Recent advances in reproductive health care provide the opportunity to preserve fertility prior to the initiation of cancer therapy. Clinical guidelines recommend that oncology providers counsel patients about the risk of treatment-related infertility and fertility preservation options, and that they refer those who are interested in fertility preservation to fertility specialists. Guidelines endorse the use of assisted reproductive techniques (ART) provided by reproductive endocrinologists to preserve fertility in young female patients with cancer. In addition, ovarian suppression with gonadotropin-releasing hormone (GnRH) agonists may be considered for ovarian protection during chemotherapy. This article reviews currently available and emerging ART for fertility preservation in female patients of reproductive age with cancer and current data supporting the use of ovarian suppression for ovarian protection during chemotherapy in this population. We also review the uptake of fertility services and discuss barriers to fertility preservation in female patients of reproductive age with cancer.

Postponing Pregnancy Through Oocyte Cryopreservation for Social Reasons: Considerations Regarding Clinical Practice and the Socio-Psychological and Bioethical Issues Involved

Oocyte freezing for 'social reasons' refers to women of reproductive age who are aiming to prolong, protect and secure their fertility. The term emerged to describe application of the highly promising technique, namely vitrification on oocytes retrieved through controlled ovarian stimulation (COS) from women intending to preserve their fertility for social reasons. These women opt to cryopreserve their oocytes at a point in their life when they need to postpone childbearing on the grounds of so called 'social' reasons. These reasons may include a highly driven career, absence of an adequate partner, financial instability, or personal reasons that make them feel unprepared for motherhood. This is a sensitive and multifaceted issue that entails medical, bioethical and socio-psychological components. The latest trend and the apparent increase noted on oocyte freezing for 'social reasons' has prompted our team of fertility specialists, embryologists, obstetricians, gynecologists and psychologists to proceed with a thorough, critical and all-inclusive comprehensive analysis. The wide range of findings of this analysis involve concerns of embryology and epigenetics that shape decisions made in the IVF laboratory, issues regarding obstetric and perinatal concerns on the pregnancy concluding from these oocytes and the respective delivery management and neonatal data, to the social and bioethical impact of this trend's application. This literature review refers to matters rising from the moment the 'idea' of this option is 'birthed' in a woman's thoughts, to proceeding and executing it clinically, up until the point of the pediatric follow up of the children born. We aim to shed light to the controversial issue of oocyte freezing, while objectively exhibit all aspects regarding this complex matter, as well as to respectfully approach how could the prospect of our future expectations be shaped from the impact of its application.

Reproductive aging and elective fertility preservation

Reproductive aging is a natural process that occurs in all women, eventually leading to reproductive senescence and menopause. Over the past half century there has been a trend towards delayed motherhood. Postponing reproduction can increase the chance of a woman remaining involuntarily childless as well as an increase in pregnancy complications in those that do achieve pregnancy at advanced maternal age. Despite the well-documented decrease in fecundity that occurs as a woman ages, reproductive aged women frequently overestimate the age at which a significant decline in fertility occurs and overestimate the success of assisted reproductive technologies (ART) to circumvent infertility. Oocyte cryopreservation enables women to achieve genetically related offspring in the event that they desire to postpone their childbearing to an age after which a significant decline in fertility occurs or in circumstances in which their reproductive potential is compromised due to medical pathology. Available success rates and safety data following oocyte cryopreservation have been reassuring and is not considered experimental according to the American Society for Reproductive Medicine and the European Society for Human Reproduction and Embryology. This review article will focus on an evidence-based discussion relating to reproductive aging and oocyte cryopreservation.

Testing the efficacy and efficiency of a single "universal warming protocol" for vitrified human embryos: prospective randomized controlled trial and retrospective longitudinal cohort study

Purpose

To study the efficacy and efficiency of a “universal warming protocol” for vitrified human embryos, based on subsequent steps with 1 and 0.5 M concentration of extracellular cryoprotectant (ECCP).

Method

Two studies on patients undergoing fertility treatments via ICSI: a prospective randomized controlled trial (RCT) and a retrospective cohort study (CS). Setting: Private assisted reproductive (AR) center.

RCT: duration 01/03/2017–01/10/2017; 315 embryos at blastocyst stage obtained from 169 patients. Each patient’s embryos were first randomized for vitrification with two different kits: Vitrification Kit (Kitazato, Japan) and Sage Vitrification Kit (Origio, Denmark). The embryos were randomly warmed with either Kitazato (K) or Sage (S) warming kits, specifically: group A (KK), group B (KS), group C (SK), and group D (SS). Primary outcome measure: survival rate (number of embryos surviving per number of embryos warmed). Secondary: implantation rate (number of embryos implanted per number of embryos transferred).

CS: duration 01/01/2013–31/12/2015 embryos from patients’ own oocytes; 10/04/2015–31/07/2017 embryos from donors’ oocytes. A total of 1055 embryos vitrified at cleavage stage obtained from 631 warming cycles: 847 of these obtained from patients’ own oocytes, 208 egg-donation-derived embryos. Each patient’s embryos were vitrified and warmed in various combinations of three different vitrification/warming kits: Kitazato (K), Sage (S), or made in-house in our laboratory (H). Vitrification/warming kits from different manufacturers are routinely used in our AR center, and the warming procedures are randomly performed with any available kit on a “first-in-first-out” basis, irrespective of the kit used for vitrification. Group names: KK, KS, SK, SS, SH, HK, HS, HH (embryos from patients’ own oocytes); eKK, eKS, eSK, eSS (egg-donation-derived embryos).

Results

Cryo-survival rates were comparable in all study groups.

RCT. Group A 99.0% (96/97), group B 98.8% (83/84), group C 98.4% (61/62), and group D 98.6% (71/72).

CS. Embryos from patients’ own oocytes: KK 96.4% (54/56), KS 100.0% (13/13), SK 98.8% (80/81), SS 97.2% (174/179), SH 97.6% (40/41), HK 95.2% (20/21), HS 99.5% (187/188), and HH 97.4% (261/268). Egg-donation-derived embryos: eKK 100.0% (91/91), eKS 98.4% (60/61), eSK 100.0% (26/26), and eSS 96.7 (29/30).

Implantation was generally comparable in all study groups—exceptions were in CS: KS vs. SK (P = 0.049), SS (P = 0.012), HS (P = 0.010), HH (P = 0.025); and SH vs. SS (P = 0.042), HS (P = 0.035).

Conclusion

Worldwide, millions of embryos have been cryopreserved using different vitrification kits; these studies establish that it is possible to combine different kits for vitrification and warming using a universal warming protocol. This can optimize costs, simplify lab routines, and favor embryo exchange between IVF centers.

RCT registration number

ISRCTN12342851.

[Birth weight and frozen embryo transfer: State of the art]

The aim of this study was to update our acknowledgment if there is a link between assisted embryo cryopreservation and epigenetics in human? Animal studies have demonstrated epigenetics consequence and especially imprinting disorders due to in vitro culture. In human, it is important to note that after frozen embryo transfer birth weight is significantly increased by 81 to 250g. But these studies cannot identify the reasons of such difference. This review strongly suggests that embryo cryopreservation is responsible for birth weight variations but mechanisms not yet elucidated. Epigenetics is probably one of these but to date, none study is able to prove it. We have to be attentive on a possible link between assisted reproductive technology (ART) and epigenetics reprogrammation.