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

Planned oocyte cryopreservation: a systematic review and meta-regression analysis

BACKGROUND

Awareness of the age-related decline in fertility potential has increased the popularity of planned oocyte cryopreservation (POC). However, data regarding outcomes of POC, including rates of women returning to thaw oocytes, as well as pregnancy and live birth rates, are scarce and based mostly on small case series.

OBJECTIVE AND RATIONALE

POC was defined as cryopreservation exclusively for prevention of future age-related fertility loss. The primary outcome was live birth rate per patient. The secondary outcomes included the return to thaw rate and laboratory outcomes. A meta-regression analysis examining the association between live birth and age above 40 or below 35 was conducted.

SEARCH METHODS

We conducted a systematic database search from inception to August 2022. The search included PubMed (MEDLINE) and EMBASE. Our search strategies employed a combination of index terms (Mesh) and free text words to compile relevant concepts. The systematic review and meta-regression were undertaken following registration of systematic review (PROSPERO registration number CRD42022361791) and were reported following guidelines of Preferred Reporting Items for Systematic Review and Meta-Analyses 2020 (PRISMA 2020).

OUTCOMES

The database search yielded 3847 records. After the selection process, 10 studies, conducted from 1999 to 2020, were included. Overall, 8750 women underwent POC, with a mean cryopreservation age of 37.2 (±0.8). Of those, 1517 women returned to use their oocytes with a return rate of 11.1% (± 4.7%). The mean age at the time of cryopreservation for women who returned to use their oocytes was 38.1 (±0.4), with an average of 12.6 (±3.6) cryopreserved oocytes per woman. In a meta-analysis, the oocyte survival rate was 78.5% with a 95% CI of 0.74-0.83 (I2 = 93%). The live birth rate per patient was 28% with a 95% CI of 0.24-0.33 (I2 = 92%). Overall, 447 live births were reported. In a sub-group analysis, women who underwent cryopreservation at age ≥40 achieved a live birth rate per patient of 19% (95% CI 0.13-0.29, I2 = 6%), while women aged ≤35 years old or younger had a higher live birth rate per patient of 52% (95% CI 0.41-0.63, I2 = 7%).

WIDER IMPLICATIONS

POC emerges as a feasible option for women aiming to improve their chances of conceiving at a later reproductive age. Nonetheless, it must be acknowledged that the overall success rates of POC are limited and that the likelihood of successful live birth declines as the age at cryopreservation rises. With increasing interest in POC, the collation of comprehensive and high-quality data is imperative to clearly define the outcomes for various age groups.

REGISTRATION NUMBER

CRD42022361791.

A comparative analysis of the clinical pregnancy and perinatal outcomes between oocyte vitrification and embryo vitrification based on the propensity score matching method

PURPOSE

This study investigated the safety and effectiveness of oocyte vitrification by comparing the clinical pregnancy and perinatal outcomes between transfer cycles of vitrified oocytes and those of vitrified embryos.

METHODS

A retrospective cohort study was conducted to analyze the clinical data of patients who underwent cleavage-stage embryo transfer at the Department of Reproductive Medicine between January 2011 and June 2021. Seventy-seven transfer cycles of fresh cleavage-stage embryos developed from vitrified-thawed oocytes (oocyte vitrification group) and 2170 transfer cycles of vitrified-thawed cleavage-stage embryos developed from fresh oocytes (embryo vitrification group) were included. Further, 293 cases were selected from the embryo vitrification group after applying propensity score matching at 1:4. The primary outcomes were miscarriage rate, live birth rate, and neonatal birth weight.

RESULTS

No statistically significant differences were observed in the baseline data, pregnancy, perinatal outcomes, or neonatal outcomes for either singleton or twin births between the two groups after matching. Backwards stepwise regression was used to analyze the length of gestation. The age of female participants (β =  - 0.410, 95% CI =  - 1.339 ~  - 0.620, P < 0.001) had a statistically significant effect.

CONCLUSION

Oocyte vitrification results in similar clinical pregnancy and perinatal outcomes as does embryo vitrification; hence, it is a relatively safe assisted reproductive technique.

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

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

Effects of oocyte vitrification on gene expression in the liver and kidney tissues of adult offspring

Oocyte vitrification is an important assisted reproductive technology (ART) that preserves the fertility of unmarried patients with malignant tumors, and promotes the development of the oocyte donation program. In recent years, the effects of ART, including the vitrification of oocytes and embryos on the health of offspring, have attracted much attention; however, it is difficult to conduct long-term follow-up and biochemical evaluation in humans. In this study, we detected the effect of oocyte vitrification on gene expression in the organs of adult mice offspring by RNA sequencing for the first time. Our results showed that only a small amount of gene expression was significantly affected. Seven genes (Tpm3, Hspe1-rs1, Ntrk2, Cyp4a31, Asic5, Cyp4a14, Retsat) were abnormally expressed in the liver, and ten genes (Lbp, Hspe1-rs1, Prxl2b, Pfn3, Gm9008, Bglap3, Col8a1, Hmgcr, Ero1lb, Ifi44l) were abnormal in the kidney. Several genes were related to metabolism and disease occurrence in the liver or kidney. Besides, we paid special attention to the expression of known imprinted genes and DNA methylation-related genes in adult organs, which are susceptible to oocyte cryopreservation in the preimplantation stage. As a result, some of these transcripts were detected in adult organs, but they were not affected by oocyte vitrification. In conclusion, we first report that oocyte vitrification did not significantly change the global gene expression in offspring organs; nonetheless, it can still influence the transcription of a few functional genes. The potential adverse effects caused by oocyte vitrification need attention and further study.

A comparison of fertility preservation outcomes in patients who froze oocytes, embryos, or ovarian tissue for medically indicated circumstances: a systematic review and meta-analysis

OBJECTIVE

To compare obstetric outcomes in patients cryopreserving reproductive cells or tissues before gonadotoxic therapy.

DESIGN

A literature search was conducted following PRISMA guidelines on Embase, Medline, and Web of Science. Studies reporting obstetric outcomes in cancer patients who completed cryopreservation of oocyte, embryo, or ovarian tissue were included.

SETTING

Not applicable.

PATIENT(S)

Cancer patients attempting pregnancy using cryopreserved cells or tissues frozen before cancer therapy.

INTERVENTION(S)

Oocyte, embryo, or ovarian tissue cryopreservation for fertility preservation in cancer.

MAIN OUTCOME MEASURE(S)

The total numbers of clinical pregnancies, live births, and miscarriages in women attempting pregnancy using cryopreserved reproductive cells or tissues were calculated. A meta-analysis determined the effect size of each intervention.

RESULT(S)

The search returned 4,038 unique entries. Thirty-eight eligible studies were analyzed. The clinical pregnancy rates were 34.9%, 49.0%, and 43.8% for oocyte, embryo, and ovarian tissue cryopreservation, respectively. No significant differences were found among groups. The live birth rates were 25.8%, 35.3%, and 32.3% for oocyte, embryo, and ovarian tissue cryopreservation, respectively, with no significant differences among groups. The miscarriage rates were 9.2%, 16.9%, and 7.5% for oocyte, embryo, and ovarian tissue cryopreservation, respectively. Significantly fewer miscarriages occurred with ovarian tissue cryopreservation than with embryo cryopreservation.

CONCLUSION(S)

This enquiry is required to counsel cancer patients wishing to preserve fertility. Although the limitations of this study include heterogeneity, lack of quality studies, and low utilization rates, it serves as a starting point for comparison of reproductive and obstetric outcomes in patients returning for family-planning after gonadotoxic therapy.

Live birth and perinatal outcomes using cryopreserved oocytes: an analysis of the Human Fertilisation and Embryology Authority database from 2000 to 2016 using three clinical models

STUDY QUESTION

Are live birth (LB) and perinatal outcomes affected by the use of frozen own versus frozen donor oocytes?

SUMMARY ANSWER

Treatment cycles using frozen own oocytes have a lower LB rate but a lower risk of low birth weight (LBW) as compared with frozen donor oocytes.

WHAT IS KNOWN ALREADY

A rising trend of oocyte cryopreservation has been noted internationally in the creation of donor oocyte banks and in freezing own oocytes for later use in settings of fertility preservation and social egg freezing. Published literature on birth outcomes with frozen oocytes has primarily utilised data from donor oocyte banks due to the relative paucity of outcome data from cycles using frozen own oocytes.

STUDY DESIGN, SIZE, DURATION

This was a retrospective cohort study utilising the anonymised database of the Human Fertilisation and Embryology Authority, which is the statutory regulator of fertility treatment in the UK. We analysed 988 015 IVF cycles from the Human Fertilisation and Embryology Authority (HFEA) register from 2000 to 2016. Perinatal outcomes were assessed from singleton births only.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Three clinical models were used to assess LB and perinatal outcomes: Model 1 compared frozen own oocytes (n = 632) with frozen donor oocytes (n = 922); Model 2 compared frozen donor oocytes (n = 922) with fresh donor oocytes (n = 24 706); Model 3 compared first cycle of fresh embryo transfer from frozen donor oocytes (n = 917) with first cycle of frozen embryo transfer created with own oocytes and no prior fresh transfer (n = 326). Preterm birth (PTB) was defined as LB before 37 weeks and LBW as birth weight <2500 g. Adjustment was performed for confounding variables such as maternal age, number of embryos transferred and decade of treatment.

MAIN RESULTS AND THE ROLE OF CHANCE

The LB rate (18.0% versus 30.7%; adjusted odds ratio (aOR) 0.61, 95% CI 0.43-0.85) and the incidence of LBW (5.3% versus 14.0%; aOR 0.29, 95% CI 0.13-0.90) was significantly lower with frozen own oocytes as compared with frozen donor oocytes with no significant difference in PTB (9.5% versus 15.7%; aOR 0.56, 95% CI 0.26-1.21). A lower LB rate was noted in frozen donor oocyte cycles (30.7% versus 34.7%; aOR 0.69, 95% CI 0.59-0.80) when compared with fresh donor oocyte cycles. First cycle frozen donor oocytes did not show any significant difference in LB rate (30.1% versus 19.3%; aOR 1.26, 95% CI 0.86-1.83) or PTB, but a higher incidence of LBW (17.7% versus 5.4%; aOR 3.77, 95% CI 1.51-9.43) as compared with first cycle frozen embryos using own oocytes.

LIMITATIONS, REASONS FOR CAUTION

The indication for oocyte freezing, method of freezing used (whether slow-freezing or vitrification) and age at which eggs where frozen were unavailable. We report a subgroup analysis of women using their own frozen oocytes prior to 37 years. Cumulative LB rate could not be assessed due to the anonymous nature of the dataset.

WIDER IMPLICATIONS OF THE FINDINGS

Women planning to freeze their own eggs for fertility preservation or social egg freezing need to be counselled that the results from frozen donor egg banks may not completely apply to them. However, they can be reassured that oocyte cryopreservation does not appear to have a deleterious effect on perinatal outcomes.

STUDY FUNDING/COMPETING INTEREST(S)

No specific funding was sought for the study. The authors have no relevant conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

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.

Elective oocyte cryopreservation for age-related fertility decline

PURPOSE

Women who pursue fertility at an advanced age are increasingly common. Family planning and sexual education have traditionally focused on contraception and prevention of sexually transmitted diseases. A focus should now also be placed on fertility awareness and fertility preservation. This manuscript aims to give an update on the existing evidence around elective oocyte cryopreservation, also highlighting the need for fertility education and evidence-based, individualized counselling.

METHODS

A thorough electronic search was performed from the start of databases to March 2020 aiming to summarize the existing evidence around elective egg freezing, the logic behind its use, patient counselling and education, success rates and risks involved, regulation, cost-effectiveness, current status and future perspectives.

RESULTS

Clinician-led counselling regarding reproductive aging and fertility preservation is often overlooked. Elective oocyte cryopreservation is not a guarantee of live birth, and the answer regarding cost-effectiveness needs to be individualized. The existing studies on obstetric and perinatal outcomes following the use of egg freezing are, until now, reassuring. Constant monitoring of short-term and long-term outcomes, uniform regulation and evidence-based, individualized counselling is of paramount importance.

CONCLUSIONS

Elective oocyte cryopreservation is one of the most controversial aspects of the world of assisted reproduction, and a lot of questions remain unanswered. However, women today do have this option which was not available in the past. Elective oocyte cryopreservation for age-related fertility decline should be incorporated in women's reproductive options to ensure informed decisions and reproductive autonomy.

The First Livebirth Using Warmed Oocytes by a Semi-Automated Vitrification Procedure

Background

The first successful livebirth using warmed oocytes (vitrified by the GAVI^TM system) is reported in this paper. Embryologists throughout the world have vitrified oocytes using a manual technique which is susceptible to error and variation. In this era of automated laboratory procedures, vitrification was made semi-automatic by using the GAVI^TM system.

Case Presentation

Donor oocytes were initially vitrified using the GAVI^TM system. They remained in the clinic's oocyte bank until they were allocated to the patient. Donor oocytes were warmed as per Genea BIOMEDX protocol and inseminated to create embryos. Resulting embryos for the 42-year-old patient were cultured to the blastocyst stage, biopsied to perform PGT-A, using next generation sequencing and subsequently vitrified. The patient underwent a single euploid transfer in a frozen embryo transfer cycle which resulted in a healthy livebirth.

Conclusion

The introduction of a semi-automated system should minimize the risk to the oocytes, standardize the procedure worldwide and potentially reduce the laboratory time taken by the embryologists. This case report demonstrates the safety of the technology used for vitrification, but larger randomized studies need to be performed to demonstrate the safety and efficacy of newer technologies like the GAVI^TM system before adopting it as a standard laboratory procedure.

Fertility considerations prior to conservative management of gynecologic cancers

Fertility-sparing management of early-stage gynecologic cancers is becoming more prevalent as increasing evidence demonstrates acceptable oncologic and reproductive outcomes in appropriately selected patients. However, in the absence of randomized controlled trials, most of the commonly used treatment algorithms are based only on observational studies. As women are increasingly postponing childbearing, the need for evidence-based guidance on the optimal selection of appropriate candidates for fertility-sparing therapies is paramount. It is imperative to seriously consider the fertility potential of a given individual prior to making major oncologic treatment decisions that may deviate from the accepted standard of care. It is a disservice to patients to undergo a fertility-sparing procedure in hopes of ultimately achieving a live birth, only to determine later they have poor baseline fertility potential or other substantial barriers to conception including excess financial toxicity. Many women with oncologic diagnoses are of advanced maternal age and their obstetric and neonatal risks must be considered. In the era of advanced assisted reproductive technologies, patients should be provided realistic expectations regarding success rates while understanding the potential oncologic perils. A multidisciplinary approach to the conservative treatment of early-stage gynecologic cancers with early referral to reproductive specialists as well as maternal-fetal medicine specialists is warranted. In this review, we discuss the recommended fertility evaluation for patients with newly diagnosed, early-stage gynecologic cancers who are considering fertility-sparing management.

Planned oocyte cryopreservation (Planned OC): systematic review and meta-analysis of cost-efficiency and patients' perspective

BACKGROUND

Advances in vitrification techniques have enabled planned oocyte cryopreservation ('Planned OC').

OBJECTIVES

To explore the cost-efficiency and utilisation of planned OC, as well as patients' perspectives on the process.

SEARCH STRATEGY

A systematic search in PubMed/MEDLINE, Embase, Cochrane Database and PsychINFO, for all relevant studies published between January 2007 and December 2019.

SELECTION CRITERIA

The protocol followed PRISMA guidelines in PECO format, and was registered with PROSPERO.

DATA COLLECTION AND ANALYSIS

Two independent reviewers evaluated all manuscripts for inclusion eligibility. Authors were contacted for missing data. Included studies were assessed for risk of bias and for heterogeneity. Weighted effects were measured and plotted.

MAIN RESULTS

The search yielded 12 545 records, of which 43 were included. Planned OC is cost-efficient at 35, assuming 60% utilisation; and at 37 assuming utilising donor sperm when necessary. At 38 it is cost-efficient to defer planned OC in favour of undergoing 2 IVF cycles. Currently, utilisation of banked-oocytes within 22-58 months, is up to 15%. Nine percent of warmed banked oocytes result in life births. Online resources and treating physicians are equally important sources of information regarding planned OC. Most patients think planned OC is ideal before age 35 and are not fully aware of what the process entails and tend to overestimate the success rates. The main barrier to wider endorsement of planned OC is being wary of potential health implications or of limited success.

CONCLUSION

Planned OC is an adequate method for preserving fertility. However, knowledge gaps result in under-utilisation leading to reduced cost-efficiency.

TWEETABLE ABSTRACT

Identifying facilitators and barriers for wider adoption of banking oocytes can enhance the cost-efficiency of this modality.

Fertility-sparing treatment for early-stage epithelial ovarian cancer: Contemporary oncologic, reproductive and endocrinologic perspectives

AIM

Epithelial ovarian cancer (EOC) can be a devastating diagnosis in women of reproductive age who desire future fertility. However, in early-stage disease, fertility-sparing surgery (FSS) can be considered in appropriately selected patients.

METHODS

This is a narrative descriptive review of the recent literature on FSS for EOC from oncologic, reproductive and endocrinologic perspectives.

RESULTS

The recurrence rate following FSS performed for stage I EOC in published retrospective studies collectively is 13% but ranges from 5 to 29%, while mortality ranges from 0 to 18%. Five-year disease-free survival following FSS is over 90% but decreases with higher stage and grade. Recurrences following FSS are more likely to be localized with a more favorable prognosis compared to recurrences following radical surgery. Adjuvant chemotherapy is recommended in women with high-risk disease, and strategies to minimize gonadotoxicity during chemotherapy such as gonadotropin-releasing hormone (GnRH) agonists may be considered. Oocyte, embryo and/or ovarian cryopreservation can also be offered to patients desiring future biologic children. Reproductive outcomes following FSS, including pregnancy and miscarriage rates, resemble those of the general population, with a chance of successful pregnancy of nearly 80%.

CONCLUSION

In retrospective data, FSS appears to be oncologically safe in stage IA and IC grade 1-2 non-clear cell EOC. In patients with grade 3 tumors or clear cell histology, treatment can be individualized, weighing a slightly higher risk of recurrence with fertility goals. A multidisciplinary approach with oncology and reproductive endocrinology may be of utility to help these patients achieve their fertility goals.

What will the future hold for artificial organs in the service of assisted reproduction: prospects and considerations

Assisted reproduction provides a wide spectrum of treatments and strategies addressing infertility. However, distinct groups of infertile patients with unexplained infertility, congenital disorders, and other complex cases pose a challenge in in vitro fertilization (IVF) practices. This special cohort of patients is associated with futile attempts, IVF overuse, and dead ends in management. Cutting edge research on animal models introduced this concept, along with the development of artificial organs with the aim to mimic the respective physiological functions in reproduction. Extrapolation on clinical application leads to the future use of infertility management in humans. To date, the successful clinical application of artificial reproductive organs in humans is not feasible because further animal model studies are required prior to clinical trials. The application of these artificial organs could provide a solution to infertility cases with no other options. This manuscript presents an overview on the current status, future prospects, and considerations on the potential clinical application of artificial ovary, uterus, and gametes in humans. This paper presents how the IVF practice landscape may be shaped and challenged in the future, along with the subsequent concerns in assisted reproductive treatments.

Recommendations for assessing ovarian health and fertility potential in survivors of childhood cancer

Most children diagnosed with cancer survive for many years after treatment. However, the fertility potential of these patients may suffer due to their oncologic therapies. Certain chemotherapies and radiation are more likely to be detrimental to gonadal function, and put patients at risk of acute or premature ovarian failure. Prepubertal cancer patients will need different follow-up and testing from their post-pubertal counterparts. This review will present evidence to help patients, family members and physicians determine who is most at risk of ovarian insufficiency and how to monitor childhood cancer survivors. It will discuss the impact of age at diagnosis and cancer therapies on reproductive outcomes, and guide caregivers and patients on monitoring gonadal function after therapy.

Young Women with Breast Cancer: Fertility Preservation Options and Management of Pregnancy-Associated Breast Cancer

BACKGROUND

Breast cancer is the most common malignancy diagnosed in women of childbearing age. A breast cancer diagnosis in this young patient population can be uniquely complex to navigate when considering the potential impact of fertility loss associated with specific gonadotoxic therapies. Another unique challenge for young breast cancer patients is pregnancy-associated breast cancer (PABC), which occurs in approximately 1 of every 3000 pregnancies. Pregnancy adds a layer of complexity to breast cancer treatment planning as many therapies can affect the developing fetus. These two clinical challenges require nuanced multidisciplinary approaches to facilitate optimal treatment outcomes. We sought to review and summarize the management strategy options for both fertility preservation and PABC.

METHODS

A guideline and literature review was performed for fertility preservation, young patients with breast cancer, and pregnancy-associated breast cancer.

RESULTS

Fertility preservation options, both established and experimental, are detailed. Suggested clinical practice guidelines for PABC are also presented, which delineate breast cancer treatment recommendations based on pregnancy trimester.

CONCLUSION

A multidisciplinary approach to patient care, including oncologists and early referral to reproductive specialists, can provide young breast cancer patients with options for fertility preservation. Under the guidance of a multidisciplinary treatment team, PABC can also be diagnosed and treated to permit the best possible outcomes for the mother and the developing fetus.