Immediate versus delayed frozen embryo transfer in women following a failed IVF-ET attempt: a multicenter randomized controlled trial

Immediate versus delayed single blastocyst transfer following the first stimulated IVF cycle in the freeze-all strategy: a study protocol for a randomised controlled trial

INTRODUCTION

In recent years, the use of frozen embryo transfers (FET) has rapidly increased following the freeze-all strategy due to the advantages of increased maternal safety, improved pregnancy rates, lower ectopic pregnancy rates and better obstetric and neonatal outcomes. Currently, there is still no good scientific evidence to support when to perform FET following a stimulated in vitro fertilisation (IVF) cycle in the freeze-all strategy.

METHODS/ANALYSIS

This will be a randomised controlled trial. A total of 828 women undergoing their first FET following their first stimulated IVF cycle in the freeze-all strategy will be enrolled and randomised into one of the following groups according to a computer-generated randomisation list: (1) the immediate group, in which FET will be performed in the first menstrual cycle following the stimulated IVF cycle; or (2) the delayed group, in which FET will be performed at least in the second menstrual cycle following the stimulated IVF cycle. The primary outcome will be live birth, which is defined as the delivery of any infants at ≥22 gestational weeks with heartbeat and breath.

ETHICS/DISSEMINATION

Ethical approval was granted by the Ethics Committee of Assisted Reproductive Medicine at the Shanghai JiAi Genetics & IVF Institute (JIAI E2019-15). Written informed consent will be obtained from each woman before any study procedure is performed, according to good clinical practice. The results of this trial will be disseminated in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NCT04371783.

The optimal timing of frozen-thawed embryo transfer: delayed or not delayed? A systematic review and meta-analysis

Background

The use of frozen embryo transfer (FET) has grown exponentially over the past few years. However, in clinical practice, there are no specific criteria as to whether a delay of at least one menstrual cycle is required for an FET after a failed fresh ET or a freeze-all cycle.

Objective

Through the effects on live birth rate (LBR), clinical pregnancy rate (CPR) and pregnancy loss rate (PLR), to determine whether FET requires a delay of at least one menstrual cycle after fresh ET failure or a freeze-all cycle.

Methods

The search was conducted through PubMed, Web of Science, CNKI, and Wanfang databases for terms related to FET timing as of April 2023. There are no restrictions on the year of publication or follow-up time. Women aged 20 to 46 with any indication for in vitro fertilization and embryo transfer (IVF-ET) treatment are eligible for inclusion. Oocyte donation studies are excluded. Except for the case report, study protocol, and abstract, all original studies are included.

Results

In 4,124 search results, 19 studies were included in the review. The meta-analysis includes studies on the adjusted odds ratio (OR) and 95% confidence interval (CI) of reported live birth rate (LBR), clinical pregnancy rate (CPR), and pregnancy loss rate (PLR), 17 studies were retrospective cohort study, and 2 studies were randomized controlled trial, a total of 6,917 immediate FET cycles and 16,105 delayed FET cycles were involved. In this meta-analysis, the combined OR of LBR was [OR = 1.09, 95% CI (0.93–1.28)], the combined OR of CPR was [OR = 1.05, 95% CI (0.92–1.20)], and the combined OR of PLR was (OR = 0.96, 95% CI 0.75–1.22). There was no statistical significance between the two groups.

Conclusion

Overall, delaying FET by at least one menstrual cycle has no advantage in LBR, CPR, or PLR. So, flexible scheduling of FETs is available to both doctors and patients.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42020161648.

Psychosocial wellbeing shortly after allocation to a freeze-all strategy compared with a fresh transfer strategy in women and men: a sub-study of a randomized controlled trial

STUDY QUESTION

Is the psychosocial wellbeing affected in women and men shortly after allocation to a freeze-all strategy with postponement of embryo transfer compared to a fresh transfer strategy?

SUMMARY ANSWER

In general, psychosocial wellbeing (i.e. emotional reactions to the treatment, quality-of-life, infertility-related stress, and marital benefit) was similar in women and men allocated to a freeze-all versus those allocated to a fresh-transfer strategy 6 days after disclosure of treatment strategy (i.e. 4 days after oocyte retrieval), although women in the freeze-all group reported a slightly higher degree of depressive symptoms and mood swings compared to women in the fresh transfer group.

WHAT IS KNOWN ALREADY

The use of a freeze-all strategy, i.e. freezing of the entire embryo cohort followed by elective frozen embryo transfer in subsequent cycles has increased steadily over the past decade in assisted reproductive technology (ART). This strategy essentially eliminates the risk of ovarian hyperstimulation syndrome and has proven beneficial regarding some reproductive outcomes in subgroups of women. However, patients experience a longer time interval between oocyte retrieval and embryo transfer, hence a longer time to pregnancy, possibly adding additional stress to the ART treatment. So far, little focus has been on the possible psychosocial strains caused by postponement of embryo transfer.

STUDY DESIGN, SIZE, DURATION

This is a self-reported questionnaire based sub-study of a multicentre randomized controlled trial (RCT) including 460 women and 396 male partners initiating their first, second, or third treatment cycle of invitro fertilisation or intracytoplasmic sperm injection (ICSI) from May 2016 to September 2018. This sub-study was included in the primary project protocol and project plan for the RCT, as psychosocial wellbeing was considered a secondary outcome.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Women from eight public fertility clinics in Denmark and Sweden and one private clinic in Spain were randomized in a 1:1 ratio on the day of inclusion (menstrual cycle day 2 or 3) to either a freeze-all strategy with postponement of embryo transfer to a subsequent modified natural menstrual cycle or a fresh transfer strategy with embryo transfer in the hormone stimulated cycle. Treatment allocation was blinded until the day of the ovulation trigger. Women and their male partners were asked to complete a validated self-reported questionnaire 6 days after unblinding of treatment group allocation, corresponding to 4 days after oocyte retrieval, investigating their psychosocial wellbeing related to the treatment defined as emotional reactions to the treatment, quality-of-life, infertility-related stress, and marital benefit. The questionnaire included items from the Copenhagen Multi-Centre Psychosocial Infertility (COMPI) Fertility Problem Stress Scales and the COMPI Marital Benefit Measure.

MAIN RESULTS AND THE ROLE OF CHANCE

Baseline characteristics were comparable between the two groups for both women and men. In total, response rates were 90.7% for women and 90.2% for men. In the freeze-all group, 207 women and 179 men completed the questionnaire compared with 204 women and 178 men in the fresh transfer group. Men in the two treatment groups did not differ in any of the explored aspects of psychosocial wellbeing (i.e. emotional reactions to the treatment, quality-of-life, infertility-related stress, and marital benefit) 6 days after disclosure of treatment strategy. Women in the freeze-all group reported a slightly higher degree of depressive symptoms (P = 0.045) and mood swings (P = 0.001) (i.e. variables included in 'emotional reactions to treatment') compared to women in the fresh transfer group. When adjusted for multiple testing, depressive symptoms were no longer significantly different between the two groups. No additional differences in psychosocial wellbeing were found. Self-reported quality-of-life during treatment was also rated as similar between the two groups in both women and men, but was slightly lower than they would rate their quality-of-life when not in fertility treatment.

LIMITATIONS, REASONS FOR CAUTION

Although response rates were high, selection bias cannot be excluded. As this study was an RCT, we assume that psychosocial characteristics of the participants were equally distributed in the two groups, thus it is unlikely that the identified psychosocial differences between the freeze-all and fresh transfer group were present already at baseline. Furthermore, the questionnaire was completed as a one-time assessment 4 days after oocyte retrieval, thus not reflecting the whole treatment process, whereas an assessment after the full completed treatment cycle is needed to draw firm conclusions about the psychosocial consequences of the whole waiting period. However, a question posted that late would be highly biased on whether or not a pregnancy had been achieved.

WIDER IMPLICATIONS OF THE FINDINGS

The results indicate that individuals in the freeze-all group exhibited slightly higher levels of depressive symptoms and mood swings compared to those in the fresh transfer group. Nevertheless, it is important to note that any worries related to potential emotional strains stemming from delaying embryo transfer should not overshadow the adoption of a freeze-all approach in cases where it is clinically recommended. As long as patients are provided with comprehensive information about the treatment strategy before initiating the process, it is worth emphasising that other aspects of psychosocial wellbeing were comparable between the two groups.

STUDY FUNDING/COMPETING INTEREST(S)

The study is part of the Reprounion collaborative study, co-financed by the European Union, Interreg V Öresund-Kattegat-Skagerrak. L.P. reports financial support from Merck A/S. H.S.N. reports grants from Freya Biosciences ApS, Ferring Pharmaceuticals, BioInnovation Institute, Ministry of Education, Novo Nordic Foundation, Augustinus Fonden, Oda og Hans Svenningsens Fond, Demant Fonden, Ole Kirks Fond and Independent Research Fund Denmark and personal fees from Ferring Pharmaceuticals, Merck A/S, Astra Zeneca, Cook Medical, IBSA Nordic and Gedeon Richter. H.S.N is founder and chairman of the Maternity Foundation and co-developed the Safe Delivery App (non-profit). N.C.F. reports grants from Gedeon Richter, Merck A/S, Cryos International and financial support from Ferring Pharmaceuticals, Merck A/S and Gedeon Richter. N.C.F. is chairman in the steering committee for the guideline groups for The Danish Fertility Society (non-profit). P.H. reports honoraria from Merch A/S, IBSA Nordic and Gedeon Richter. A.L.M.E. reports grants and financial support from Merck A/S and Gedeon Richter. A.P. reports grants from Gedeon Richter, Ferring Pharmaceuticals, Merck A/S and personal fees from Preglem S.A., Novo Nordic Foundation, Ferring Pharmaceuticals, Gedeon Richter, Cryos International, Merch A/S, Theramex and Organon and the lend of embryoscope to the institution from Gedeon Richter. All other authors declare no conflict of interest.

TRIAL REGISTRATION NUMBER

Clinicaltrials.gov NCT02746562.

The HERA (Hyper-response Risk Assessment) Delphi consensus for the management of hyper-responders in in vitro fertilization

PURPOSE

To provide agreed-upon guidelines on the management of a hyper-responsive patient undergoing ovarian stimulation (OS) METHODS: A literature search was performed regarding the management of hyper-response to OS for assisted reproductive technology. A scientific committee consisting of 4 experts discussed, amended, and selected the final statements. A priori, it was decided that consensus would be reached when ≥66% of the participants agreed, and ≤3 rounds would be used to obtain this consensus. A total of 28/31 experts responded (selected for global coverage), anonymous to each other.

RESULTS

A total of 26/28 statements reached consensus. The most relevant are summarized here. The target number of oocytes to be collected in a stimulation cycle for IVF in an anticipated hyper-responder is 15-19 (89.3% consensus). For a potential hyper-responder, it is preferable to achieve a hyper-response and freeze all than aim for a fresh transfer (71.4% consensus). GnRH agonists should be avoided for pituitary suppression in anticipated hyper-responders performing IVF (96.4% consensus). The preferred starting dose in the first IVF stimulation cycle of an anticipated hyper-responder of average weight is 150 IU/day (82.1% consensus). ICoasting in order to decrease the risk of OHSS should not be used (89.7% consensus). Metformin should be added before/during ovarian stimulation to anticipated hyper-responders only if the patient has PCOS and is insulin resistant (82.1% consensus). In the case of a hyper-response, a dopaminergic agent should be used only if hCG will be used as a trigger (including dual/double trigger) with or without a fresh transfer (67.9% consensus). After using a GnRH agonist trigger due to a perceived risk of OHSS, luteal phase rescue with hCG and an attempt of a fresh transfer is discouraged regardless of the number of oocytes collected (72.4% consensus). The choice of the FET protocol is not influenced by the fact that the patient is a hyper-responder (82.8% consensus). In the cases of freeze all due to OHSS risk, a FET cycle can be performed in the immediate first menstrual cycle (92.9% consensus).

CONCLUSION

These guidelines for the management of hyper-response can be useful for tailoring patient care and for harmonizing future research.

Letrozole During Frozen Embryo Transfer in Women With Polycystic Ovarian Syndrome: A Randomized Controlled Trial

OBJECTIVE

To compare live-birth rates between letrozole application and artificial cycle for endometrium preparation during frozen embryo transfer (FET) cycle among women with polycystic ovarian syndrome (PCOS).

METHODS

A randomized controlled trial was conducted. Women with PCOS were randomized to letrozole application for ovulation induction compared with artificial cycle for endometrial preparation during FET. The primary outcome was live-birth rate per embryo transfer. Secondary outcomes included pregnancy-related outcomes, perinatal outcomes, and maternal complication rates. Assuming α=0.05 and 80% power, 186 patients per group were required to demonstrate a difference of 15% in live-birth rate: 205 patients (at least) per group were randomized to allow for a 10% dropout rate.

RESULTS

Four hundred twenty patients were enrolled from 2018 to 2021. Two hundred ten patients were assigned to the letrozole application group, and 210 were assigned to the artificial cycle group. There was no difference in the live-birth rate (42.4% vs 42.9%, P =>.99). There was no difference in secondary outcomes, including clinical pregnancy rate (51.4% vs 56.2%, P =.378), implantation rate (51.8% vs 55.8%, P =.401), and miscarriage rate (8.6% vs 11.0%, P =.511). For perinatal outcomes, singleton birth weight was significantly higher in the artificial cycle group (3,108±56 g vs 3,301±58, P =.018), and the incidence of gestational diabetes mellitus (GDM) was significantly higher in letrozole application group (14.6% vs 5.6%, P =.050). The other outcome was no difference in maternal complications.

CONCLUSION

There was no difference in pregnancy outcomes between letrozole application compared with artificial cycle for endometrial preparation in women with PCOS who underwent FET. The risk of GDM was higher in the letrozole application group, and the singleton birth weight was lower in the artificial cycle group.

CLINICAL TRIAL REGISTRATION

Chinese Clinical Trial Registry, ChiCTR1800014746.

Finding of the optimal preparation and timing of endometrium in frozen-thawed embryo transfer: a literature review of clinical evidence

Frozen-thawed embryo transfer (FET) has been a viable alternative to fresh embryo transfer in recent years because of the improvement in vitrification methods. Laboratory-based studies indicate that complex molecular and morphological changes in endometrium during the window of implantation after exogenous hormones with controlled ovarian stimulation may alter the interaction between the embryo and endometrium, leading to a decreased implantation potential. Based on the results obtained from randomized controlled studies, increased pregnancy rates and better perinatal outcomes have been reported following FET. Compared to fresh embryo transfer, fewer preterm deliveries, and reduced incidence of ovarian hyperstimulation syndrome were found after FETs, yet there is a trend of increased pregnancy-related hypertensive diseases in women receiving FET. Despite the increased application of FET, the search for the most optimal priming protocol for the endometrium is still undergoing. Three available FET protocols have been proposed to prepare the endometrium: i) natural cycle (true natural cycle and modified natural cycle) ii) artificial cycle (AC) or hormone replacement treatment cycle iii) mild ovarian stimulation (mild-OS) cycle. Emerging evidence suggests that the optimal timing for FET using warmed blastocyst transfer is the LH surge+6 day, hCG administration+7 day, and the progesterone administration+6 day in the true natural cycle, modified natural cycle, and AC protocol, respectively. Although still controversial, better clinical pregnancy rates and live birth rates have been reported using the natural cycle (true natural cycle/modified natural cycle) compared with the AC protocol. Additionally, a higher early pregnancy loss rate and an increased incidence of gestational hypertension have been found in FETs using the AC protocol because of the lack of a corpus luteum. Although the common clinical practice is to employ luteal phase support (LPS) in natural cycles and mild-OS cycles for FET, the requirement for LPS in these protocols remains equivocal. Recent findings obtained from RCTs do not support the routine application of endometrial receptivity testing to optimize the timing of FET. More RCTs with rigorous methodology are needed to compare different protocols to prime the endometrium for FET, focusing not only on live birth rate, but also on maternal, obstetrical, and neonatal outcomes.

The time interval between oocyte retrieval and frozen embryo transfer does not impact reproductive outcomes

RESEARCH QUESTION

Does the time interval between oocyte retrieval and frozen embryo transfer (FET) affect pregnancy outcomes after a freeze-all strategy?

DESIGN

Retrospective study including a total of 5995 patients who underwent their first FET following a freeze-all cycle between 1 January 2017 and 31 December 2020. Patients were divided into immediate (the interval between oocyte retrieval and the day of first FET ≤40 days), delayed (>40 days but ≤180 days) and overdue groups (>180 days). Pregnancy and neonatal outcomes were analysed, and multivariable regression analysis was used to study the effect of FET timing on the live birth rate (LBR) in the entire cohort and the different subgroups.

RESULTS

The LBR was significantly lower in the overdue group than in the delayed group (34.9% versus 42.8%, P = 0.002); however, after adjusting for confounding factors, the difference was not statistically significant. The immediate group had a comparable LBR (36.9%) to the other two groups in both the crude and adjusted analyses. Multivariable regression analysis showed no impact of FET timing on LBR in the whole cohort or in the subgroups according to ovarian stimulation protocol, trigger type, insemination method, reason for freezing all, FET protocol or transferred embryo stage.

CONCLUSIONS

The time interval between oocyte retrieval and FET does not impact reproductive outcomes. Unnecessary delays in FET should be avoided to shorten the time to live birth.

It is not worth postponing frozen embryo transfers after oocyte pickup: A retrospective cohort study based on propensity score matching

This study was to explore whether postponing frozen embryo transfers (FET) after oocyte pickup (OPU) improves clinical and neonatal outcomes. From May 2018 to Dec 2020, a total of 1109 patients underwent their first OPU cycles adopting a non-selective freeze-all policy were included in this retrospective cohort study. In the immediate group (n=219), patients underwent FET in the first menstrual cycle after OPU, and patients in the postponed group (n=890) waited for more than 1 menstrual cycle after OPU to perform FET. A propensity score matching (PSM) model was used to evaluate the clinical outcomes and neonatal outcomes between the two groups. There were 209 patients in the immediate group and 499 patients in the postponed one after PSM. Patients waited for a significantly shorter period for FET in the immediate group (30.74 ± 3.85 days) compared with the postponed group (80.39 ± 26.25 days, P<0.01). The clinical pregnancy rate (CPR) and live birth rate (LBR) in the immediate group were 58.4% and 48.3%, respectively, which were comparable to those of the postponed one (58.1%, 49.7%, P > 0.05). No statistical significance was found in the average birth weight (3088.82 ± 565.35 g vs 3038.64 ± 625.78 g, P > 0.05) and height (49.08 ± 1.87 cm vs 49.30 ± 2.52 cm) of neonates between the two groups. The gender ratio, the incidence of macrosomia and low birth weight did not differ significantly between the two groups. In conclusion, postponing FET does not improve clinical and neonatal outcomes. If patients have no contraindications, FETs should be carried out immediately after OPU.