Deferred Frozen Embryo Transfer: What Benefits can be Expected from this Strategy in Patients with and without Endometriosis?

IVF/ICSI Outcomes After a Freeze-All Strategy: an Observational Cohort Study

In order to inform patients undergoing ART regarding their chances for motherhood, it seems useful to describe "freeze all" outcomes according to the different potential indications. The goal of this study was to examine the impact of a "freeze-all approach" on the cumulative live birth rate (cLBR) according to the indication. It is a cohort study including women who had undergone ovarian stimulation (OS) using an antagonist protocol with GnRH agonist triggering between 09.2016 and 09.2018 followed by a freeze-all cycle of blastocyst embryos. The ART outcomes were compared between the two main indications of the freeze-all strategy which were in our cohort: risk of ovarian hyperstimulation syndrome (OHSS) and endometriosis. The ART outcomes were also described for the others indications (inadequate endometrium and/or premature progesterone elevation at trigger day, two or more previous ART failures, and autoimmune disease and/or a high risk of thromboembolic disease (AI and/or TE risk)). In total, 658 women were included. The cLBR in the total population was 37.7% (248/658). The cLBR was significantly higher in the "OHSS risk" group (133/281, 47.3%) than in the "endometriosis" group (69/190, 36.3%) (p = 0.017). No significant differences were noted regarding perinatal outcomes, except a significantly higher risk of placenta praevia (PP) observed in the "endometriosis" group (10.1%) (p = 0.002). The "freeze-all approach" yielded good results in terms of the cLBR and especially in case of OHSS risk. These data should be taken into account when informing patients about the ART strategy and their chances of motherhood.

The freeze-all strategy after IVF: which indications?

The freeze-all strategy is gaining popularity worldwide as an alternative to the conventional fresh embryo transfer. It consists of cryopreservation of the entire embryo cohort and the embryo transfer in a subsequent cycle that takes place separately from ovarian stimulation. The freeze-all strategy was initially a 'rescue' strategy for women at high risk of ovarian hyperstimulation syndrome; however, this approach has been extended to other indications as a scheduled strategy to improve implantation rates. This assumes that ovarian stimulation can alter endometrial receptivity in fresh cycles owing to the effect of supraphysiological levels of steroids on endometrial maturation. The procedure, however, has not been associated with increased live birth rates in all infertile couples, and concerns have been raised about the occurrence of several adverse perinatal outcomes. It is, therefore, crucial to identify in which subgroups of patients a freeze-all strategy could be beneficial. The aim of this review is to summarize current scientific research in this field to highlight potential indications for this strategy and to guide clinicians in their daily practice.

Prolonged estrogen (E2) treatment prior to frozen-blastocyst transfer decreases the live birth rate

STUDY QUESTION

How does the duration of estrogen (E2) treatment prior to frozen-blastocyst transfers affect the live birth rate (LBR)?

SUMMARY ANSWER

Prolonged E2 exposure as part of artificial endometrial preparation (AEP) significantly decreases the LBR after autologous frozen-thawed blastocyst transfer.

WHAT IS KNOWN ALREADY

One effective method for endometrial preparation prior to frozen embryo transfer is AEP, a sequential regimen with E2 and progesterone, which aims to mimic the endocrine exposure of the endometrium in a normal cycle. Nevertheless, the optimal duration of E2 administration prior to transfer remains unknown.

STUDY DESIGN, SIZE, DURATION

An observational cohort study was conducted in a tertiary care university hospital between 01/07/2012 and 31/12/2015. The main inclusion criteria was having a single frozen-thawed blastocyst transfer with an AEP using exogenous E2.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 1377 frozen-thawed blastocyst transfers were assigned to four groups according to the duration of the E2 administration prior to the embryo transfers. These comprised a '≤21 days' group (n = 330), a '22-28 days' group (n = 665), a '29-35 days' group (n = 289) and a '36-48 days' group (n = 93). The '≤21 days' group' was taken as the reference group. The main measured outcome was the LBR following frozen-thawed blastocyst transfers. Statistical analysis was conducted using univariate and multivariate logistic regression models.

MAIN RESULTS AND THE ROLE OF CHANCE

LBR significantly decreased when the E2 exposure prior to the frozen-thawed blastocyst transfer exceeded 28 days: OR = 0.66; 95% CI [0.46-0.95]; P = 0.026 and OR = 0.49 [0.27-0.89]; P = 0.018, respectively, for the '29 to 35 days' group and for the '36 to 48 days' group compared to the reference group. Early pregnancy loss rates significantly increased when the E2 exposure lasted more than 35 days prior to the frozen-thawed blastocyst transfer (OR = 2.37 [1.12-5.05]; P = 0.025 vs. the reference group). After multivariate logistic regression, E2 exposure lasting more than 28 days prior to the frozen-thawed blastocyst transfer was associated with a decrease in the LBR, for the '29-35 days' group (OR = 0.65; [0.45-0.95]; P = 0.044) as for the '36-48 days' group (OR = 0.49; [0.26-0.92]; P = 0.035), vs. the reference group.

LIMITATIONS, REASONS FOR CAUTION

One limitation is linked to the observational design of this study.

WIDER IMPLICATIONS OF THE FINDINGS

In order to give patients the best chance to obtain a live birth after frozen-thawed blastocyst transfer, the length of E2 exposure prior to the frozen-blastocyst transfer should not exceed 28 days. This study provides new insight in regard to endometrial preparation using AEP prior to frozen-blastocyst transfer.

STUDY FUNDING/COMPETING INTEREST(S)

No funding and no competing interest.

The Deferred Embryo Transfer Strategy Seems Not to be a Good Option After Repeated IVF/ICSI Cycle Failures

Objective:

The aim of this study was to assess whether a deferred frozen–thawed embryo transfer (Def-ET) offers any benefits compared to a fresh ET strategy in women who have had 2 or more consecutive in vitro fertilization (IVF)/intracytoplasmic injection (ICSI) cycle failures.

Design:

An observational cohort study in a tertiary referral care center including 416 cycles from women with a previous history of 2 or more consecutive IVF/ICSI failures cycles. Both Def-ET and fresh ET strategies were compared using univariate and multivariate logistic regression models. The main outcome measured was the cumulative live birth rate (CLBR).

Results:

A total of 416 cycles were included in the analysis: 197 in the fresh ET group and 219 in the Def-ET group. The CLBR was not significantly different between the fresh and Def-ET groups (58/197 [29.4%] and 57/219 [26.0%], respectively, P = .437). In addition, after the first ET, there was no significant difference in the live birth rate between the fresh ET and Def-ET groups (50/197 [25.4%] vs 44/219 [20.1%], respectively). Multivariate logistic regression analysis indicated that compared to the fresh strategy, the Def-ET strategy was not associated with a higher probability of live birth.

Conclusions:

In cases with 2 or more consecutive prior IVF/ICSI cycle failures, a Def-ET strategy did not result in better ART outcomes than a fresh ET strategy.