A randomized controlled trial of vaginal progesterone for luteal phase support in modified natural cycle - frozen embryo transfer

Progesterone concentrations on blastocyst transfer day in modified natural cycle frozen embryo transfer cycles

RESEARCH QUESTION

Are serum progesterone concentrations on the day of modified natural cycle (mNC) frozen blastocyst transfer (FET) without luteal phase support (LPS) associated with clinical pregnancy rate (CPR)?

DESIGN

Data were collected between January 2019 and October 2022 as a sub-study of an ongoing randomized controlled trial assessing pregnancy outcomes in mNC-FET. The sub-study included all women (n = 209) randomized to mNC-FET without LPS at the time of data extraction. Participants were aged 18-41 years, had regular menstrual cycles and underwent mNC-FET treatment with single-blastocyst transfer. Associations between the serum progesterone concentration on the day of blastocyst transfer and CPR, pregnancy rate and pregnancy loss rate (PLR) were examined between groups with low and higher progesterone concentrations using the 25th and 10th percentiles as cut-offs. Multivariate logistic regression analyses were performed to adjust for potential confounding factors.

RESULTS

Progesterone concentrations on the day of blastocyst transfer in mNC-FET without LPS ranged from 4.9 to 91.8 nmol/l, with the 25th and 10th percentiles at 29.0 nmol/l and 22.5 nmol/l, respectively. Serum progesterone concentrations did not differ between women with or without a clinical pregnancy (mean [SD] 38.5 [14.0] versus 36.8 [12.4] nmol/l; P = 0.350). Furthermore, the CPR, pregancy rate and PLR were similar in women with low or high progesterone concentrations when using the 25th or the 10th progesterone percentile as cut-off. Multivariate regression analyses showed no association between progesterone concentrations and CPR.

CONCLUSIONS

No association was found between progesterone concentration on the day of blastocyst transfer and pregnancy outcome in women undergoing mNC-FET without progesterone LPS.

Comparison of luteal support protocols in fresh IVF/ICSI cycles: a network meta-analysis

Despite the proven superiority of various luteal phase support protocols (LPS) over placebo in view of improved pregnancy rates in fresh cycles of IVF (in vitro fertilization) and ICSI (intracytoplasmic sperm injection) cycles, there is ongoing controversy over specific LPS protocol selection, dosage, and duration. The aim of the present study was to identify the optimal LPS under six core aspects of ART success, clinical pregnancy, live birth as primary outcomes and biochemical pregnancy, miscarriage, multiple pregnancy, ovarian hyperstimulation syndrome (OHSS) events as secondary outcomes. Twelve databases, namely Embase (OVID), MEDLINE (R) (OVID), GlobalHealth (Archive), GlobalHealth, Health and Psychosocial Instruments, Maternity & Infant Care Database (MIDIRS), APA PsycTests, ClinicalTrials.gov, HMIC Health Management Information Consortium, CENTRAL, Web of Science, Scopus and two prospective registers, MedRxiv, Research Square were searched from inception to Aug.1st, 2023, (PROSPERO Registration: CRD42022358986). Only Randomised Controlled Trials (RCTs) were included. Bayesian network meta-analysis (NMA) model was employed for outcome analysis, presenting fixed effects, odds ratios (ORs) with 95% credibility intervals (CrIs). Vaginal Progesterone (VP) was considered the reference LPS given its' clinical relevance. Seventy-six RCTs, comparing 22 interventions, and including 26,536 participants were included in the present NMA. Overall CiNeMa risk of bias was deemed moderate, and network inconsistency per outcome was deemed low (Multiple pregnancy χ2: 0.11, OHSS χ2: 0.26), moderate (Clinical Pregnancy: χ2: 7.02, Live birth χ2: 10.95, Biochemical pregnancy: χ2: 6.60, Miscarriage: χ2: 11.305). Combinatorial regimens, with subcutaneous GnRH-a (SCGnRH-a) on a vaginal progesterone base and oral oestrogen (OE) appeared to overall improve clinical pregnancy events; VP + OE + SCGnRH-a [OR 1.57 (95% CrI 1.11 to 2.22)], VP + SCGnRH-a [OR 1.28 (95% CrI 1.05 to 1.55)] as well as live pregnancy events, VP + OE + SCGnRH-a [OR 8.81 (95% CrI 2.35 to 39.1)], VP + SCGnRH-a [OR 1.76 (95% CrI 1.45 to 2.15)]. Equally, the progesterone free LPS, intramuscular human chorionic gonadotrophin, [OR 9.67 (95% CrI 2.34, 73.2)] was also found to increase live birth events, however was also associated with an increased probability of ovarian hyperstimulation, [OR 1.64 (95% CrI 0.75, 3.71)]. The combination of intramuscular and vaginal progesterone was associated with higher multiple pregnancy events, [OR 7.09 (95% CrI 2.49, 31.)]. Of all LPS protocols, VP + SC GnRH-a was found to significantly reduce miscarriage events, OR 0.54 (95% CrI 0.37 to 0.80). Subgroup analysis according to ovarian stimulation (OS) protocol revealed that the optimal LPS across both long and short OS, taking into account increase in live birth and reduction in miscarriage as well as OHSS events, was VP + SCGnRH-a, with an OR 2.89 [95% CrI 1.08, 2.96] and OR 2.84 [95% CrI 1.35, 6.26] respectively. Overall, NMA data suggest that combinatorial treatments, with the addition of SCGnRH-a on a VP base result in improved clinical pregnancy and live birth events in both GnRH-agonist and antagonist ovarian stimulation protocols.

Luteal phase support in assisted reproductive technology

Infertility affects one in six couples, with in vitro fertilization (IVF) offering many the chance of conception. Compared to the solitary oocyte produced during the natural menstrual cycle, the supraphysiological ovarian stimulation needed to produce multiple oocytes during IVF results in a dysfunctional luteal phase that can be insufficient to support implantation and maintain pregnancy. Consequently, hormonal supplementation with luteal phase support, principally exogenous progesterone, is used to optimize pregnancy rates; however, luteal phase support remains largely 'black-box' with insufficient clarity regarding the optimal timing, dosing, route and duration of treatment. Herein, we review the evidence on luteal phase support and highlight remaining uncertainties and future research directions. Specifically, we outline the physiological luteal phase, which is regulated by progesterone from the corpus luteum, and evaluate how it is altered by the supraphysiological ovarian stimulation used during IVF. Additionally, we describe the effects of the hormonal triggers used to mature oocytes on the degree of luteal phase support required. We explain the histological transformation of the endometrium during the luteal phase and evaluate markers of endometrial receptivity that attempt to identify the 'window of implantation'. We also cover progesterone receptor signalling, circulating progesterone levels associated with implantation, and the pharmacokinetics of available progesterone formulations to inform the design of luteal phase support regimens.

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.

Preparation of the endometrium for frozen embryo transfer: an update on clinical practices

Over the past decade, the application of frozen-thawed embryo transfer treatment cycles has increased substantially. Hormone replacement therapy and the natural cycle are two popular methods for preparing the endometrium. Hormone replacement therapy is now used at the discretion of the doctors because it is easy to coordinate the timing of embryo thawing and transfer with the schedules of the in-vitro fertilization lab, the treating doctors, and the patient. However, current results suggest that establishing a pregnancy in the absence of a corpus luteum as a result of anovulation may pose significant maternal and fetal risks. Therefore, a 'back to nature' approach that advocates an expanded use of natural cycle FET in ovulatory women has been suggested. Currently, there is increasing interest in how the method of endometrial preparation may influence frozen embryo transfer outcomes specifically, especially when it comes to details such as different types of ovulation monitoring and different luteal support in natural cycles, and the ideal exogenous hormone administration route as well as the endocrine monitoring in hormone replacement cycles. In addition to improving implantation rates and ensuring the safety of the fetus, addressing these points will allow for individualized endometrial preparation, also as few cycles as possible would be canceled.

Premature timing of progesterone luteal phase support initiation did not negatively impact live birth rates in modified natural frozen thawed embryo transfer cycles

Study question

In a modified natural cycle frozen-thawed embryo transfer (mNC-FET), does the premature timing of progesterone luteal phase support (LPS) initiation 24 h following human chorionic gonadotropin (hCG) trigger impact live birth?

Summary answer

Premature LPS initiation did not negatively affect the live birth rate (LBR) in mNC-FET cycles compared with conventional LPS initiation 48 h after hCG triggering.

What is known already

During natural cycle FET, human chorionic gonadotropin is routinely used to mimic endogenous luteinizing hormone (LH) surge to induce ovulation, which allows more flexibility in embryo transfer scheduling, thus relieving the burden of multiple visits by patients and laboratory workloads, which is also known as mNC-FET. Moreover, recent data demonstrates that ovulatory women undergoing natural cycle FETs have a lower risk of maternal and fetal complications due to the essential role of the corpus luteum in implantation, placentation and pregnancy maintenance. While several studies have confirmed the positive effects of LPS in mNC-FETs, the timing of progesterone LPS initiation is still unclear, as compared with fresh cycles where robust research has been conducted. To the best of our knowledge, no clinical studies comparing different beginning days in mNC-FET cycles have been published.

Study design size duration

This retrospective cohort study involved 756 mNC-FET cycles performed at a university-affiliated reproductive center between January 2019 and August 2021. The primary outcome measured was the LBR.

Participants/materials setting methods

Ovulatory women ≤42 years of age who were referred for their autologous mNC-FET cycles were included in the study. According to the timing of progesterone LPS initiation following the hCG trigger, patients were assigned into two categories: premature LPS group (progesterone initiation 24 h after hCG trigger, n = 182) versus conventional LPS group (progesterone initiation 48 h after hCG trigger, n = 574). Multivariate logistic regression analysis was used to control for confounding variables.

Main results and the role of chance

There were no differences in background characteristics between the two study groups, except for the proportion of assisted hatching (53.8% in premature LPS group versus 42.3% in conventional LPS group, p = 0.007). In the premature LPS group, 56 of 182 patients (30.8%) had a live birth, compared to 179 of 574 patients (31.2%) in the conventional LPS group, with no significant difference observed between groups (adjusted odds ratio [aOR] 0.98, 95% confidence interval [CI] 0.67-1.43, p = 0.913). In addition, there was no significant difference between the two groups in other secondary outcomes. A sensitivity analysis for LBR according to the serum LH and progesterone levels on hCG trigger day also confirmed the aforementioned findings.

Limitations reasons for caution

In this study, retrospective analysis was conducted in a single center and was therefore prone to bias. Additionally, we did not anticipate monitoring the patient's follicle rupture and ovulation after hCG triggering. Future prospective clinical trials remain necessary to confirm our results.

Wider implications of the findings

While exogenous progesterone LPS was added 24 h after hCG triggering, embryo-endometrium synchrony would not be adversely affected so long as sufficient time was allowed for endometrial exposure to exogenous progesterone. Our data support promising clinical outcomes following this event. As a result of our findings, clinicians and patients will be able to make better informed decisions.

Study funding/competing interests

No specific funding was available for this study. The authors have no personal conflicting interests to declare.

Trial registration number

N/A.

The effect of progesterone supplementation for luteal phase support in natural cycle frozen embryo transfer: a systematic review and meta-analysis based on randomized controlled trials

IMPORTANCE

The necessity of progesterone supplementation for luteal phase support (LPS) in natural cycle frozen embryo transfer (NC-FET) cycles warrants further confirmation.

OBJECTIVE

To investigate the effect of progesterone supplementation for LPS on the reproductive outcomes of patients undergoing NC-FET cycles.

DATA SOURCES

The PubMed, Ovid-Embase, Cochrane Library, Web of Science, CNKI, Wanfang, VIP, and CBM were electronically searched. The search time frame was from inception up to September 2022.

STUDY SELECTION AND SYNTHESIS

Randomized controlled trials (RCTs) that used progesterone for LPS in NC-FET cycles, including true NC-FET cycles (tNC-FET) and modified NC-FET cycles (mNC-FET), were included. The counted data were analyzed using relative risk (RR) as the effect-size statistic, and each effect size was assigned its 95% confidence interval (CI).

MAIN OUTCOME MEASURES

The primary outcomes were the live birth rate (LBR) and the clinical pregnancy rate (CPR), and the secondary outcome was the miscarriage rate.

RESULTS

Four RCTs were included, which involved 1116 participants. The results of the meta-analysis showed that progesterone supplementation was associated with increased LBR (RR, 1.42; 95% CI, 1.15-1.75; I² = 0%, moderate-quality evidence) and CPR (RR, 1.30, 95% CI, 1.07-1.57; I² = 0%, moderate-quality evidence) in patients undergoing NC-FET cycles. Subgroup analysis showed that progesterone supplementation was associated with higher LBR and CPR in tNC-FET cycles. However, no association was found between increased LBR and CPR in mNC-FET cycles. In addition, only one RCT reported that oral dydrogesterone had similar CPR and miscarriage rate compared with vaginal progesterone in mNC-FET cycles.

CONCLUSION(S)

Overall, moderate-quality evidence suggested that progesterone supplementation for LPS was associated with increased LBR and CPR in NC-FET cycles. Progesterone supplementation was associated with a higher LBR and CPR in tNC-FET cycles. However, the effectiveness of progesterone supplementation in mNC-FET cycles should be further verified by larger RCTs. Low to very low-quality evidence indicated that oral dydrogesterone and vaginal progesterone have similar reproductive outcomes in mNC-FET cycles, which requires further study, especially in tNC-FET cycles.

REGISTRATION NUMBER

PROSPERO CRD42022355550 (https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=355550) was registered on September 3, 2022.

Comparing the success rate of natural cycle and modified natural cycle protocols for frozen-thawed embryo transfer

Objective: The aim of the present study is to compare the effects of Natural Cycle and modified Natural Cycle protocols for frozen-thawed embryo transfer on clinical pregnancy rate and live birth rate. Methods: This prospective randomized controlled trial comprised 145 patients scheduled for frozen-thawed embryo transfer and was conducted at a university hospital between 2019 and 2021. The Natural Cycle protocol was administered to 73 patients and the modified Natural Cycle protocol to 72 patients and the clinical outcome was compared between the groups. The main outcome measure was live birth rate. Results: Baseline characteristics and cycle parameters were similar in both groups. There was no difference in clinical pregnancy rate (58.9% and 54.2%, respectively; p = .565) and live birth rate between the Natural Cycle and modified Natural Cycle groups (49.3% and 48.6% respectively; p = .932). Conclusion: This study established that clinical pregnancy and live birth rates were not affected by natural cycle ovulation being spontaneous or hCG-triggered among patients undergoing frozen-thawed embryo transfer. Thus, the protocol for natural cycle frozen-thawed embryo transfers should be chosen according to the priorities of the patient and the physician.

Luteal phase support in fresh and frozen embryo transfers

Context

Luteal phase support (LPS) has become an essential component of IVF protocols following both fresh and frozen embryo transfers, yet there is still controversy with regards to the optimal protocol of LPS to enhance treatment outcome.

Search strategy

A search via PubMed for all the selected topics was limited to publications from the past 10 years and to English language. We subsequently searched the reference lists of retrieved articles. Where available, RCTs were chosen over non-randomized studies. Here we provide an updated review of the current literature on various issues relating to LPS, in both fresh and frozen embryo transfers. The timing of LPS initiation as well as the route of administration and dosing are discussed for both fresh and frozen transfers. A separate discussion for frozen thawed embryo transfer in natural cycles and non-ovulatory cycles is presented.

Conclusions

We present data that supports the use of Progesterone LPS in fresh and frozen embryo transfers. No benefits were found to the addition of hCG or estradiol to progesterone LPS in fresh transfers, however GnRH agonist may have a role. IM Progesterone was not advantageous over vaginal progesterone in fresh transfers but was superior in frozen transfers. The timing of LPS introduction, the interval to embryo transfer, as well as the serum concentration of progesterone, have significant effects on the success of the treatment.

Vaginal progesterone as luteal phase support in natural cycle frozen-thawed embryo transfer (ProFET): protocol for a multicentre, open-label, randomised controlled trial

INTRODUCTION

Vaginal progesterone supplementation is frequently given to patients receiving frozen embryo transfer (FET) in the natural cycle aiming to increase the chance of pregnancy and live birth. To date, only a few studies have investigated if progesterone supplementation is beneficial in these cycles and the level of evidence for progesterone supplementation is very low.

METHODS AND ANALYSIS

The ProFET trial is a multicentre, open-label, randomised controlled trial powered for this investigation, including 1800 women with regular menstrual cycles (24-35 days), aged 18-43 years planned for natural cycle-FET receiving a single blastocyst for transfer. Participants are randomised (1:1:1) to either luteal phase progesterone for 3 weeks, luteal phase progesterone for 7 weeks or no luteal phase progesterone. The participating study centres consist of 12 in vitro fertilisation-clinics in Sweden and 1 in Iceland. The primary outcome is to investigate if luteal phase support (LPS) by vaginal progesterone increases the chance of a live birth per randomised patient in a natural FET cycle compared with no LPS.

ETHICS AND DISSEMINATION

The trial was approved by the Swedish Ethical Review Authority (ID 2020-06774, 2021-02822 and 2022-01502-02) and the Swedish Medical Products Agency (ID nr 5.1-2020-102613). All participants are required to provide written informed consent. The outcome of this study will be disseminated to the public through broadcasts, newspapers and presentations at scientific congresses as well as publications in international scientific journals.

TRIAL REGISTRATION NUMBER

NCT04725864.

Preparation of the Endometrium for Frozen Embryo Transfer: A Systematic Review

Despite the worldwide increase in frozen embryo transfer, the search for the best protocol to prime endometrium continues. Well-designed trials comparing various frozen embryo transfer protocols in terms of live birth rates, maternal, obstetric and neonatal outcome are urgently required. Currently, low-quality evidence indicates that, natural cycle, either true natural cycle or modified natural cycle, is superior to hormone replacement treatment protocol. Regarding warmed blastocyst transfer and frozen embryo transfer timing, the evidence suggests the 6th day of progesterone start, LH surge+6 day and hCG+7 day in hormone replacement treatment, true natural cycle and modified natural cycle protocols, respectively. Time corrections, due to inter-personal differences in the window of implantation or day of vitrification (day 5 or 6), should be explored further. Recently available evidence clearly indicates that, in hormone replacement treatment and natural cycles, there might be marked inter-personal variation in serum progesterone levels with an impact on reproductive outcomes, despite the use of the same dose and route of progesterone administration. The place of progesterone rescue protocols in patients with low serum progesterone levels one day prior to warmed blastocyst transfer in hormone replacement treatment and natural cycles is likely to be intensively explored in near future.

Thicker endometrium on hCG trigger day improves the live birth rate of fresh cleavage embryo transfer in GnRH-agonist regimen of normogonadotrophic women

Background

Luteinizing hormone (LH) and progesterone (PROG) on human chorionic gonadotropin (hCG) trigger day are significantly correlated with assisted reproductive technology (ART) outcome. Moreover, LH and PROG are also involved in the functional preparation of the endometrium during the implantation window; however, whether they are related to endometrial thickness (EMT) is still unknown. The aim of the present study was to assess whether EMT has a positive correlation on the live birth rate following fresh embryo transfer (ET), and whether LH and PROG have an impact on EMT.

Methods

A total of 2,260 normogonadotrophic women were treated with a GnRH agonist for in vitro fertilization (IVF)/intracytoplasmic sperm injection. Patients with advanced age and poor ovarian reserve were excluded. The levels of LH, PROG, and EMT on the hCG trigger day were divided into binary variables, respectively, by the cutoff values, and which were obtained based on receiver operating characteristic curve analysis of live birth among LH, PROG and EMT levels on the hCG trigger day, respectively. Multivariate binary logistic regression was used to confirm the role of LH, PROG, and EMT on the live birth, and stratified analysis was used to determine whether LH and PROG have an impact on EMT.

Results

EMT and LH were protective factors for live births, with odds ratios (OR) of 1.11 [95% confidence interval (CI): 1.066–1.157] and 1.696 (95% CI: 1.345–2.139), respectively. However, PROG was a risk factor for live birth, with an OR of 0.635 (95% CI: 0.526–0.766). The hierarchical cross-table analysis indicated that EMT had no significant difference for live birth in the combination of low LH and high PROG group. In the other subgroups, thick EMT was associated with a higher live birth rate (P<0.05).

Conclusions

On hCG trigger day, EMT, LH, and PROG all were independent factors that affected the live birth of fresh ETs. Thick EMT can significantly increase the live birth rate. However, multivariate logistic regression analysis showed that EMT does not affect the live birth rate in combination of low LH and high PROG environment.

Should women receive luteal support following natural cycle frozen embryo transfer? A systematic review and meta-analysis

BACKGROUND

Spontaneous ovulation during a natural menstrual cycle is frequently used for timing frozen embryo transfer (FET). Nevertheless, it remains unclear whether or not women should receive luteal phase support (LPS) following natural cycle frozen embryo transfer (NC-FET).

OBJECTIVE AND RATIONALE

The aim of this systematic review and meta-analysis was to study whether the administration of LPS improves the reproductive outcome following NC-FET.

SEARCH METHODS

We conducted a systematic search of the literature published in Medline/PubMed, Embase and the Cochrane Library, from January 2000 until December 2020. We included all original English, peer-reviewed articles, irrespective of the study design. The search strategy included keywords related to NC-FET and luteal phase support. Studies reporting the results of artificial or stimulated FET cycles were excluded.

OUTCOMES

Our systematic search generated 416 records. After screening, eight studies were included in the review and seven studies were included in the meta-analysis. Two studies (n = 858) used hCG and six studies (n = 1507) used progesterone for luteal support. Four studies were randomised controlled trials (RCTs), whereas the other four were historic cohort studies. In a meta-analysis using a random effects model, hCG administration for LPS did not increase the clinical pregnancy rate (CPR) (two studies, odds ratio (OR) 0.85, 95% CI 0.64-1.14). On the other hand, progesterone LPS was associated with a higher CPR (five studies, OR 1.48, 95% CI 1.14-1.94), and a higher live birth rate (LBR) (three studies, OR 1.67, 95% CI 1.19-2.36). The association between progesterone LPS and the LBR remained significant after excluding non-randomised studies.

WIDER IMPLICATIONS

The available evidence indicates that progesterone administration for LPS is beneficial following NC-FET. There is no evidence to support the administration of hCG for LPS in these cases. Additional large RCTs are necessary to improve the quality of evidence and validate our findings.