Reproductive outcomes from ten years of elective oocyte cryopreservation

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

RESEARCH QUESTION

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

DESIGN

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

RESULTS

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

CONCLUSION

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

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 10-year follow-up of reproductive outcomes in women attempting motherhood after elective oocyte cryopreservation

STUDY QUESTION

Which reproductive treatment outcomes are observed in women who underwent elective oocyte cryopreservation (EOC) and who returned to the clinic with a desire for a child?

SUMMARY ANSWER

Whether to warm oocytes or to first use fresh own oocytes for ART depends on age upon returning, but both strategies result in favorable reproductive outcomes.

WHAT IS KNOWN ALREADY

Most affluent countries have observed a trend toward postponement of childbearing, and EOC is increasingly used based on the assumption that oocytes cryopreserved at a younger age may extend a woman's reproductive lifespan and mitigate her age-related fertility decline. Although most follow-up studies after EOC have focused on women who requested oocyte warming, a substantial proportion of women who do not conceive naturally will embark on fertility treatment without using their cryopreserved oocytes. Reports on reproductive outcomes in past EOC users are scarce, and the lack of reproductive treatment algorithms in this group of women hampers counseling toward the most efficient clinical strategy.

STUDY DESIGN, SIZE, DURATION

This retrospective observational single-center study encompasses 843 women who had elective oocyte vitrification between 2009 and 2019 at our fertility clinic. Women who underwent fertility preservation for medical or oncological reasons were excluded. This study describes the outcomes of the diverse reproductive treatment strategies performed until May 2022 in women returning to our clinic to attempt motherhood.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Using descriptive statistics, patient characteristics and data of ovarian stimulation (OS) of EOC cycles were analyzed, as well as data related to OS and laboratory data of ART in women who pursued fertility treatment with and/or without using their cryopreserved oocytes. The primary outcome was live birth rate (LBR) per patient after oocyte warming and after ART using fresh oocytes. Secondary outcomes were return rate, utilization rate of the cryopreserved oocytes, laboratory outcomes upon return, and LBR per embryo transfer. A multivariable regression model was developed to identify factors associated with the decision to thaw oocytes as the primary strategy and factors associated with ongoing pregnancy upon return to the clinic.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 1353 EOC cycles (mean ± SD, 1.6 ± 0.9 per patient) were performed. At the time of EOC, the mean age was 36.5 ± 2.8 years, mean anti-Müllerian hormone (AMH) was 2.3 ± 2.0 ng/ml, and 174 (20.6%) women had a partner. On average, 13.9 ± 9.2 mature oocytes were cryopreserved. Two hundred thirty-one (27.4%) women returned to the clinic, an average of 39.9 ± 23.4 months after EOC. Upon returning, their mean age was 40.4 ± 3.1 years, mean AMH was 1.5 ± 1.5 ng/ml, and 158/231 (68.3%) patients had a partner. As a primary approach, 110/231 (47.6%) past EOC users embarked on oocyte warming, 50/231 (21.6%) had intrauterine insemination, and 71/231 (30.7%) had ART using fresh own oocytes. Cumulative LBR (CLBR) was 45.9% (106/231) notwithstanding a miscarriage rate (MR) of 30.7% (51/166) in the entire cohort. In total, 141 women performed oocyte warming at some stage in their treatment trajectory. A subset of 90/231 (39.0%) patients exclusively had oocyte warming (41.6 ± 3.0 years, with 10.0 ± 5.2 oocytes warmed per patient). 52/231 (22.5%) patients exclusively had ART using fresh own oocytes (mean age of 39.0 ± 2.8 years, with 9.9 ± 7.4 mature oocytes retrieved per patient). CLBR was 37/90 (41.1%) in the oocyte warming-only group and 25/52 (48.1%) in the OS-only group. MR/transfer was 25.0% and 29.3% in the oocyte warming-only group and the OS-only group, respectively.

LIMITATIONS, REASONS FOR CAUTION

Both sample size and the retrospective design are limitations of this study. The decision to embark on a specific reproductive treatment strategy was based on patient preference, after counseling on their treatment options. This precludes direct comparison of the efficiency of reproductive treatment options in past EOC users in this study.

WIDER IMPLICATIONS OF THE FINDINGS

Reporting on clinical outcomes of women who underwent EOC and returned to the clinic to embark on divergent reproductive treatment strategies is mandatory to establish guidelines for best clinical practice in this growing patient population.

STUDY FUNDING/COMPETING INTEREST(S)

None.

TRIAL REGISTRATION NUMBER

N/A.

Exploring the knowledge, attitudes, and perceptions of women of reproductive age towards fertility and elective oocyte cryopreservation for age-related fertility decline in the UK: a cross-sectional survey

STUDY QUESTION

What are the knowledge, perceptions and attitudes towards fertility and elective oocyte cryopreservation (OC) for age-related fertility decline (ARFD) in women in the UK?

SUMMARY ANSWER

Awareness of OC for ARFD has reportedly improved compared to studies carried out almost a decade ago, but inconsistencies in knowledge remain regarding the rate of miscarriage amongst specific age groups, the financial costs and optimal age to undergo OC for ARFD.

WHAT IS KNOWN ALREADY

The age of first-time motherhood has increased amongst western societies, with many women of reproductive age underestimating the impact of age on fertility. Further understanding of women's awareness of their fertility, the options available to preserve it and the barriers for seeking treatment earlier are required in order to prevent the risk of involuntary childlessness.

STUDY DESIGN, SIZE, DURATION

A hyperlink to a cross-sectional survey was posted on social media (Instagram) between 25 February 2021 and 11 March 2021.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Women from the general population aged 18-50 years were invited to complete the survey.

MAIN RESULTS AND THE ROLE OF CHANCE

In total, 5482 women fulfilled the inclusion criteria and completed the survey. The mean age of participants was 35.0 years (SD 10.25; range 16-52). Three quarters (74.1%; n = 4055) disagreed or strongly disagreed they felt well informed regarding the options available to preserve their fertility, in case of a health-related problem or ARFD. The majority overestimated the risk of miscarriage in women aged ≥30 years old, with 14.5% correctly answering 20%, but underestimated the risks in women ≥40, as 20.1% correctly answered 40-50%. Three quarters (73.2%; n = 4007) reported an awareness of OC for ARFD and 65.8% (n = 3605) reported that they would consider undergoing the procedure. The number of women who considered OC for ARFD across age groups were as follows: 18-25 (8.3%; n = 300), 26-30 (35.8%; n = 1289), 31-35 (45.9%; n = 1654), 36-40 (9.6%; n = 347), 41-45 (0.3%; n = 13), and 46-50 (0.1%; n = 2). The majority of women (81.3%; n = 4443) underestimated the cost of a single cycle of OC for ARFD (<£5000). Furthermore, 10.4% (n = 566) believed a single cycle would be adequate enough to retrieve sufficient oocytes for cryopreservation. Approximately 11.0% (n = 599) believed OC for ARFD may pose significant health risks and affect future fertility. Less than half agreed or strongly agreed that the lack of awareness regarding OC for ARFD has impacted the likelihood of pursuing this method of fertility preservation further (41.4%; n = 2259).

LIMITATIONS, REASONS FOR CAUTION

Results from cross-sectional studies are limited as interpretations made are merely associations and not of causal relationships. The online nature of participant recruitment is subject to selection bias, considering women with access to social media are often from higher socioeconomic and education backgrounds, thus limiting generalizability of the findings.

WIDER IMPLICATIONS OF THE FINDINGS

Further education regarding the financial costs and optimal age to undergo elective OC to increase the chances of successful livebirth are required. Clinicians should encourage earlier fertility counselling to ensure that OC is deemed a preventative measure of ARFD, rather than an ultimate recourse to saving declining fertility.

STUDY FUNDING/COMPETING INTEREST(S)

No funding was required for this article. There are no conflicts of interests to declare.

TRIAL REGISTRATION NUMBER

N/A.

Planned Oocyte Cryopreservation: A Review of Current Evidence on Outcomes, Safety and Risks

Although oocyte cryopreservation was initially used as a fertility preservation strategy for medical indications, it is now is increasingly used to circumvent age-related infertility. Outcomes following planned oocyte vitrification, also known as elective egg freezing, are limited. Current studies show higher success rates for individuals undergoing fertility preservation treatment under age 35. Additionally, while freezing 20 oocytes is optimal to achieve pregnancy, freezing at least 8-10 oocytes is recommended. While fertility is not guaranteed, current evidence demonstrates that planned oocyte vitrification is an overall safe, low risk method of fertility preservation to reduce the risk for age-related infertility.

Post-trigger luteinizing hormone concentration to positively predict oocyte yield in the antagonist protocol and its association with genetic variants of LHCGR

BACKGROUND

The concentration of human chorionic gonadotropin (hCG)/ luteinizing hormone (LH) after triggering is generally accepted as a predictor of the normal ovarian response to the trigger, but few studies have explored the distribution model of concentration and its impact on oocyte yield. Genetic variations in LHCGR, known as a receptor for hCG and LH, also play a role in oocyte maturation and retrieval. The objective of the study was to investigate the impact of concentrations of hCG/LH after triggering on oocyte yield and its association with genetic variants of LHCGR.

METHODS

A retrospective cohort study including 372 antagonist IVF cycles, in which 205 received the recombinant hCG trigger and 167 received the gonadotropin-releasing hormone agonist (GnRH-a) trigger, was conducted. The post-trigger concentrations of hCG/LH and the LHCGR N312S (rs2293275) genotype were evaluated in patients to analyse the impact of these factors on oocyte yield.

RESULTS

The oocyte retrieval rate (ORR) increased significantly among the low-, medium- and high-hCG-concentration groups (0.91 ± 0.25, 0.99 ± 0.23 and 1.08 ± 0.19, P < 0.001) and among the low-, medium- and high-LH-concentration groups (0.80 ± 0.29, 0.95 ± 0.21 and 1.07 ± 0.19, P < 0.001). The Pearson correlation coefficient between the post-trigger hCG concentration and ORR was 0.242 (P < 0.001), and that between the LH concentration and ORR was 0.454 (P < 0.001). After adjustment for confounding factors, high post-trigger LH concentrations remained associated with the significantly higher ORRs (adjusted R2 = 0.541, P < 0.001). Patients with the AG genotype of LHCGR N312S were more likely to have low post-trigger LH concentrations (46.10 IU/L versus 60.91 IU/L, P < 0.001) and a significantly lower ORR (0.85 versus 0.96, P = 0.042) than patients with the GG genotype after the GnRH-a trigger.

CONCLUSIONS

The post-trigger LH concentration can positively predict oocyte yield in antagonist IVF cycles, and patients with the AG genotype of LHCGR rs2293275 could have a suboptimal oocyte yield using the GnRH-a trigger.

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.

Realities and Hopes in Social Freezing: A Developing Practice to Stop Reproductive Ageing

The Article Abstract is not available.