Impact of Serum Estradiol Levels Prior to Progesterone Administration in Artificially Prepared Frozen Embryo Transfer Cycles

Effect of estrogen exposure on pregnancy outcomes in artificial frozen-thawed embryo transfer cycles

In contemporary times, the employment of vitrification freezing technology has led to the widespread adoption of frozen-thawed embryo transfer (FET) worldwide. Meanwhile, hormone replacement therapy (HRT) is a crucial protocol for priming the endometrium during FET cycles. Estrogen is required in HRT cycles for the induction of progesterone receptors and to promote endometrial thickness. However, there is no universal consensus on the treatment duration, dosage regimen, administration route, and target serum estrogen levels. Therefore, this study aimed to offer a comprehensive review of these topics. A shorter duration of estrogen exposure may elevate the risk of early miscarriage, while prolonged exposure to estrogen does not seem to confer advantages to general population and may be attempted in individuals with thin endometrium. Moreover, excessive estrogen levels on the day of progesterone administration may be associated with higher miscarriage rates and lower live birth rates (LBR). To offer more comprehensive guidance for clinical practice, extensive and prospective studies involving a large sample size are warranted to determine the optimal concentration and duration of estrogen exposure.

Impact of elevated serum estradiol levels before progesterone administration on pregnancy outcomes in frozen-thawed embryo transfer for hormone replacement therapy

OBJECTIVE

The objective of this retrospective cohort study is to investigate the impact of monitoring serum estradiol (E2) levels before progesterone administration within hormone replacement therapy (HRT) on pregnancy outcomes in women undergoing frozen-thawed embryo transfer (FET).

METHODS

Analyzed HRT-FET cycles conducted at a reproductive center from 2017 to 2022. Serum E2 levels were measured prior to progesterone administration. Multivariate stratified and logistic regression analyses were performed on 26,194 patients grouped according to terciles of serum E2 levels before progesterone administration.

RESULTS

The clinical pregnancy rate (CPR) and live birth rate (LBR) exhibited a gradual decline with increasing serum E2 levels across the three E2 groups. Even after controlling for potential confounders, including female age, body mass index, infertility diagnosis, cycle category, number of embryos transferred, fertilization method, indication for infertility, and endometrial thickness, both CPR and LBR persistently showed a gradual decrease as serum E2 levels increased within the three E2 groups. The same results were obtained by multivariate logistic regression analysis.

CONCLUSIONS

This large retrospective study indicates that elevated serum E2 levels before progesterone administration during HRT-FET cycles are associated with reduced CPR and LBR post-embryo transfer. Therefore, it is advisable to monitor serum E2 levels and adjust treatment strategies accordingly to maximize patient outcomes.

Peri-implantation estradiol level has no effect on pregnancy outcome in vitro fertilization- embryo transfer

Background

The necessity of monitoring luteal endocrine functions in in vitro fertilization- embryo transfer (IVF-ET) remains uncertain. Specifically, the significance of luteal phase estradiol (E2) levels is a matter of debate in current literature.

Objective

To assess the impact of luteal phase (day 11 after HCG trigger) estradiol levels on IVF-ET outcomes.

Design

Twelve thousand five hundred and thirty-five (n = 12,535) IVF-ET cycles performed in our center between 2015 and 2021 were divided into 5 groups based on the middle and late luteal phase serum E2 (MllPSE2) level percentiles as follows: Group A < 50 pg/mL (N=500), group B 50 pg/mL≤E2<150 pg/mL (N=2545), group C 150 pg/mL≤E2<250 pg/mL (N=1327), group D 250 pg/mL≤E2<500 pg/mL (N=925), group E E2≥500 pg/mL (n=668). The clinical pregnancy rates, abortion rates, and live birth rates of each group were compared. Binary logistic regression analysis was carried out to assess the potential impact of MllPSE2 on the live birth rate (LBR).

Results

No significant differences were found in various parameters when comparing the five groups. The level of MllPSE2 showed no significant difference between the pregnant group and the non-pregnant group. The binary logistic regression analysis model demonstrated that MllPSE2 was not significantly related to LBR.

Conclusion

The influence of E2 during the peri-implantation period (day 11) on clinical outcome in IVF-ET is not affected, even if E2<50 pg/mL. It is speculated that ovarian-derived E2 in MllPSE2 is not deemed necessary for endometrial receptivity. Although caution is warranted due to the retrospective nature of the analysis and the potential for unmeasured confounding, it is argued that the need for luteal E2 monitoring in IVF-ET may be of questionable value.

The pathophysiological role of estrogens in the initial stages of pregnancy: molecular mechanisms and clinical implications for pregnancy outcome from the periconceptional period to end of the first trimester

BACKGROUND

Estrogens regulate disparate female physiological processes, thus ensuring reproduction. Altered estrogen levels and signaling have been associated with increased risks of pregnancy failure and complications, including hypertensive disorders and low birthweight babies. However, the role of estrogens in the periconceptional period and early pregnancy is still understudied.

OBJECTIVE AND RATIONALE

This review aims to summarize the current evidence on the role of maternal estrogens during the periconceptional period and the first trimester of pregnancies conceived naturally and following ART. Detailed molecular mechanisms and related clinical impacts are extensively described.

SEARCH METHODS

Data for this narrative review were independently identified by seven researchers on Pubmed and Embase databases. The following keywords were selected: 'estrogens' OR 'estrogen level(s)' OR 'serum estradiol' OR 'estradiol/estrogen concentration', AND 'early pregnancy' OR 'first trimester of pregnancy' OR 'preconceptional period' OR 'ART' OR 'In Vitro Fertilization (IVF)' OR 'Embryo Transfer' OR 'Frozen Embryo Transfer' OR 'oocyte donation' OR 'egg donation' OR 'miscarriage' OR 'pregnancy outcome' OR 'endometrium'.

OUTCOMES

During the periconceptional period (defined here as the critical time window starting 1 month before conception), estrogens play a crucial role in endometrial receptivity, through the activation of paracrine/autocrine signaling. A derailed estrogenic milieu within this period seems to be detrimental both in natural and ART-conceived pregnancies. Low estrogen levels are associated with non-conception cycles in natural pregnancies. On the other hand, excessive supraphysiologic estrogen concentrations at time of the LH peak correlate with lower live birth rates and higher risks of pregnancy complications. In early pregnancy, estrogen plays a massive role in placentation mainly by modulating angiogenic factor expression-and in the development of an immune-tolerant uterine micro-environment by remodeling the function of uterine natural killer and T-helper cells. Lower estrogen levels are thought to trigger abnormal placentation in naturally conceived pregnancies, whereas an estrogen excess seems to worsen pregnancy development and outcomes.

WIDER IMPLICATIONS

Most current evidence available endorses a relation between periconceptional and first trimester estrogen levels and pregnancy outcomes, further depicting an optimal concentration range to optimize pregnancy success. However, how estrogens co-operate with other factors in order to maintain a fine balance between local tolerance towards the developing fetus and immune responses to pathogens remains elusive. Further studies are highly warranted, also aiming to identify the determinants of estrogen response and biomarkers for personalized estrogen administration regimens in ART.

An integrative analysis of endometrial steroid metabolism and transcriptome in relation to endometrial receptivity in in vitro fertilization patients

OBJECTIVE

To study the relationship between the steroid concentration in the endometrium, in serum, and the gene expression level of steroid-metabolizing enzymes in the context of endometrial receptivity in in vitro fertilization (IVF) patients.

DESIGN

Case-control study of 40 IVF patients recruited in the SCRaTCH study (NTR5342), a randomized controlled trial investigating pregnancy outcome after "endometrial scratching." Endometrial biopsies and serum were obtained from patients with a first failed IVF cycle randomized to the endometrial scratch in the midluteal phase of the natural cycle before the next fresh embryo transfer during the second IVF cycle.

SETTING

University hopsital.

PATIENTS

Twenty women with clinical pregnancy were compared with 20 women who did not conceive after fresh embryo transfer. Cases and controls were matched for primary vs. secondary infertility, embryo quality, and age.

INTERVENTION

None.

MAIN OUTCOME MEASURE(S)

Steroid concentrations in endometrial tissue homogenates and serum were measured with liquid chromatography-mass spectrometry. The endometrial transcriptome was profiled by RNA-sequencing, followed by principal component analysis and differential expression analysis. False discovery rate-adjusted and log-fold change >|0.5| were selected as the threshold for differentially expressed genes.

RESULT(S)

Estrogen levels were comparable in both serum (n = 16) and endometrium (n = 40). Androgens and 17-hydroxyprogesterone were higher in serum than that in endometrium. Although steroid levels did not vary between pregnant and nonpregnant groups, subgroup analysis of primary women with infertility showed a significantly lower estrone concentration and estrone:androstenedione ratio in serum of the pregnant group (n = 5) compared with the nonpregnant group (n = 2). Expression of 34 out of 46 genes encoding the enzymes controlling the local steroid metabolism was detected, and estrogen receptor β gene was differentially expressed between pregnant and nonpregnant women. When only the primary infertile group was considered, 28 genes were differentially expressed between pregnant and nonpregnant women, including HSD11B2, that catalyzes the conversion of cortisol into cortisone.

CONCLUSION(S)

Steroidomic and transcriptomic analyses show that steroid concentrations are regulated by the local metabolism in the endometrium. Although no differences were found in endometrial steroid concentration in the pregnant and nonpregnant IVF patients, primary women with infertility showed deviations in steroid levels and gene expression, indicating that a more homogeneous patient group is required to uncover the exact role of steroid metabolism in endometrial receptivity.

CLINICAL TRIAL REGISTRATION NUMBER

The study was registered in the Dutch trial registry (www.trialregister.nl), registration number NL5193/NTR5342, available at https://trialsearch.who.int/Trial2.aspx?TrialID=NTR6687. The date of registration is July 31, 2015. The first enrollment is on January 1, 2016.

Clinical pregnancy rate for frozen embryo transfer with HRT: a randomized controlled pilot study comparing 1 week versus 2 weeks of oestradiol priming

RESEARCH QUESTION

Does a frozen-embryo transfer in an artificially-prepared endometrium (FET-HRT) cycle yield similar clinical pregnancy rate with 7 days of oestrogen priming compared to 14 days?

DESIGN

This is a single-centre, randomized, controlled, open-label pilot study. All FET-HRT cycles were performed in a tertiary centre between October 2018 and January 2021. Overall, 160 patients were randomized, with a 1:1 allocation, into two groups of 80 patients each: group A (7 days of E2 prior to P4 supplementation) and group B (14 days of E2 prior to P4 supplementation). Both groups received single blastocyst stage embryos on the 6th day of vaginal P4 administration. The primary outcome was the feasibility of such strategy assessed as clinical pregnancy rate, secondary outcomes were biochemical pregnancy rate, miscarriage rate, live birth rate and serum hormone levels on the day of FET. Chemical pregnancy was assessed by an hCG blood test 12 days after FET and clinical pregnancy was confirmed by transvaginal ultrasound at 7 weeks.

RESULTS

The analysis included 160 patients who were randomly assigned to either group A or group B on the seventh day of their FET-HRT cycle if the measured endometrial thickness was above 6.5 mm. Following screening failures and of drop-outs, 144 patients were finally included both in group A (75 patients) or group B (69 patients). Demographic characteristics for both groups were comparable. The biochemical pregnancy rate was 42.5% and 48.8% for group A and group B, respectively (p 0.526). Regarding the clinical pregnancy rate at 7 weeks, no statistical difference was observed (36.3% vs 46.3% for group A and group B, respectively, p = 0.261). The secondary outcomes of the study (biochemical pregnancy, miscarriage, and live birth rate) were comparable between the two groups for IIT analysis, as well as the P4 values on the day of FET.

CONCLUSIONS

In a frozen embryo transfer cycle, performed with artificial preparation of the endometrium, 7 versus 14 days of oestrogen priming are comparable, in terms of clinical pregnancy rate; the advantages of a seven-day protocol include the shorter time to pregnancy, reduced exposure to oestrogens, and more flexibility of scheduling and programming, and less probability to recruit a follicle and have a spontaneous LH surge. It is important to keep in mind that this study was designed as a pilot trial with a limited study population as such it was underpowered to determine the superiority of an intervention over another; larger-scale RCTs are warranted to confirm our preliminary results.

TRIAL REGISTRATION

Clinical trial number: NCT03930706.

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.

Treatment options for endometrial hypoproliferation

PURPOSE OF REVIEW

Endometrial hypoproliferation refers to the failure of the endometrium to reach optimal thickness during fresh or frozen embryo transfer cycles in women undergoing infertility treatment with in-vitro fertilization (IVF). This review discusses the treatment options for endometrial hypoproliferation.

RECENT FINDINGS

Apart from factors related to the embryo quality, ultrasonographic findings associated with the endometrium, such as endometrial thickness, endometrial pattern and subendometrial blood flow, are considered key factors associated with the outcome of assisted reproductive treatment. To date, a consensus has not been reached regarding the definition of thin endometrium, while thresholds of 6, 7 or 8 mm have been used in the literature. Strategies to increase endometrial thickness can be reviewed in three groups: endocrine approaches, vitamins & supplements, and new experimental therapeutic interventions. Some of the recently introduced experimental therapeutic interventions such as platelet-rich plasma injection, stem cell treatment and tissue bioengineering are exciting potential therapies that need to be further studied.

SUMMARY

Despite a large number of publications on the topic, diagnosing and treating endometrial hypoproliferation remains a challenge. Well designed studies are needed to establish a widely accepted endometrial thickness cut-off value below which endometrial hypoproliferation is diagnosed and to generate meaningful data that would allow an evidence-based discussion of available therapeutic options with patients.

Endometrial receptivity in adenomyosis and/or endometriosis

A narrative review of endometrial receptivity in adenomyosis and/or endometriosis revealed that this parameter is difficult to assess in natural conception because both disorders alter natural fertility. Recent data emanating from assisted reproductive technology have allowed the study of endometrial receptivity in women affected by adenomyosis and endometriosis. This has upended our views on the effects of these 2 disorders on embryo implantation. Today, the very existence of altered receptivity in assisted reproductive technology is questioned. In this context, we now know that frozen euploid blastocyst transfers in estradiol and progesterone cycles have unaltered outcomes in both adenomyosis and endometriosis.

Impact of an estrogen replacement regimen on live birth rate in frozen-thawed good-quality embryo transfer

OBJECTIVE

To assess the impact of an estrogen replacement regimen on frozen embryo transfer (FET) cycle outcome.

METHODS

In the present retrospective cohort study, data of infertile women undergoing FET with good-quality embryos were reviewed. The first group received 2 mg of estradiol hemihydrate (EH) once daily for 6 to 7 days, then twice daily for 4 to 5 days, and then three times a day until embryo transfer. The second group received EH twice daily for 7 to 8 days, then three times a day. The third group received EH three times a day constantly. The main outcome measure was live birth rate.

RESULTS

In total, 394 FET cycles were included. The fixed 6-mg group required the highest estradiol hemihydrate dose. The duration of estrogen treatment was significantly longer in the first group. Maximal endometrial thickness was highest in the second group (10.2 ± 1.3 mm vs. 9.6 ± 1.4 mm vs. 8.6 ± 0.9 mm, respectively; P < 0.001). The clinical pregnancy rates in the groups were 41.1%, 55.2%, and 42.2%, respectively (P = 0.035). Live birth rates were 40.8%, 50.9%, and 48.1%, respectively (P = 0.320).

CONCLUSION

In FET cycles with hormone replacement therapy, a step-up 4-mg regimen provides thicker endometrium with optimal-dose estrogen in an adequate time frame. The tendency for increased clinical pregnancy and live birth rates is remarkable.

Effectiveness of progesterone rescue in women presenting low circulating progesterone levels around the day of embryo transfer: a systematic review and meta-analysis

IMPORTANCE

Over the last decade, frozen embryo transfer (FET) has been increasingly used in contemporary fertility units. Despite the rapid increase in FET, there is still insufficient evidence to recommend an optimized protocol for endometrial preparation especially in patients with lower progesterone (P4) levels. Previous studies have concluded that P4 levels <10 ng/mL are associated with poorer pregnancy outcomes than those reported with high levels of circulating P4.

OBJECTIVE

To identify whether rescue P4 dosing in patients with low P4 can salvage adverse outcomes associated with low P4 levels, resulting in outcomes comparable to patients with adequate progesterone.

DATA SOURCES

The study was conducted according to the Preferred Reporting Items for Systematic reviews and Meta-analyses guidelines and prospectively registered under the PROSPERO database (CRD42022357125). Six databases (Embase, MEDLINE, APA PsycInfo, Global Health, HMIC Health Management Information Consortium, and Google Scholar) and 2 additional sources were searched from inception to August 29, 2022.

STUDY SELECTION AND SYNTHESIS

Prospective and retrospective cohort studies, reporting the association between rescue progesterone and one or more pregnancy outcomes, were included. The quality of the included studies was assessed using the Newcastle-Ottawa Scale (NOS), while the quality of evidence by the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) framework. Summative and subgroup data as well as heterogeneity were generated by the Cochrane platform RevMan (V. 5.4).

MAIN OUTCOME MEASURE(S)

To compare ongoing pregnancy rate as primary outcome and clinical pregnancy rate, miscarriage rate, and live birth rate as secondary outcomes between patients with low (<10 ng/mL) receiving rescue progesterone vs. those with adequate levels of P4 (≥10 ng/mL).

RESULT(S)

Overall, 7 observational studies were included in the analysis, with a total of 5927 patients of median age 34 (interquartile range [IQR]: 31.55, 37.13). Overall, patient group comparison, namely those with low P4 that received a rescue dose and those with adequate P4 levels, did not yield significant differences for either the primary or secondary outcomes. For ongoing clinical pregnancy, patients with low P4 receiving the rescue dose vs. those with adequate P4 levels was odds ratio (OR) 0.98 (95% CI: 0.78, 1.24; P = .86, I²: 41%), whereas for miscarriage events, OR was 0.98 (95% CI: 0.81, 1.17; P = .80, I²: 0). Equally, for clinical pregnancy, OR was 0.91 (95% CI: 0.78, 1.06; P = .24; I²: 33%), and for live birth, OR was 0.92 (95% CI: 0.77, 1.09; P = .33; I²: 43%). Subgroup analysis on the basis or rescue administration route successfully explained summative heterogeneity.

CONCLUSION(S)

Rescue P4 dosing in patients with low P4 results in ongoing pregnancy rate, clinical pregnancy and live birth rates were comparable to those of patients with adequate P4 levels. However, robust randomized controlled trials assessing rescue treatment in women with low P4 are needed to confirm these findings. Rescue P4 in patients with low circulating P4 around embryo transfer day may result in reproductive outcomes comparable to those with adequate P4 levels.

STUDY REGISTRATION

CRD42022357125 (PROSPERO).

Effects of serum estrogen levels before frozen-thawed blastocyst transfer on pregnancy outcomes in hormone replacement cycles

We investigated the effects of serum estrogen levels before frozen-thawed blastocyst transfer on pregnancy outcomes in hormone replacement cycles. Clinical data of 708 hormone replacement cycles with frozen-thawed blastocyst were retrospectively analyzed. According to quartile (P25) of serum estrogen levels on the endometrium transformation day, the 708 cycles were divided into group A1 (E2 < 157.5 pg/ml), group A2 (157.5 pg/ml ≤ E2 < 206.4 pg/ml), group A3 (206.4 pg/ml ≤ E2 < 302.3 pg/ml) and group A4 (E2 ≥ 302.3 pg/ml). According to quartile (P25) of serum estrogen levels on the frozen-thawed blastocyst transfer day, the 708 cycles were divided into group B1 (E2 < 147 pg/ml), group B2 (147 pg/ml ≤ E2 < 200.4 pg/ml), group B3 (200.4 pg/ml ≤ E2 < 323 pg/ml) and group B4 (E2 ≥ 323 pg/ml). According to different clinical outcomes, the 708 cycles were divided into clinical pregnant group and non-clinical pregnant group. The group A4 (E2 ≥ 302.3 pg/ml on the endometrium transformation day) was significantly lower than other groups in blastocyst implantation rate and multiple-pregnancy rate (P < 0.05). The days of taking progynova was significantly different among groups on both endometrium transformation day and frozen-thawed blastocyst transfer day (P < 0.05), but there were no statistical differences in the mean age, endometrial thickness and number of high-quality blastocysts transferred among groups (P > 0.05). The mean age was significantly younger and the number of high-quality blastocysts transferred was significantly higher in the clinical pregnant group than in the non-clinical pregnant group (P < 0.05), but endometrial thickness, days of taking progynova, progesterone level on the blastocyst transfer day, and E2 level were not significantly different between both groups (P > 0.05). Multivariate regression analysis indicated that age was an independent factor affecting clinical pregnancy (P < 0.05). Correlation analysis displayed that the serum estrogen levels did not affect clinical pregnancy (P > 0.05). The days of taking progynova and serum estrogen levels before frozen-thawed blastocyst transfer do not affect pregnancy outcomes in hormone replacement cycles.

Assessment of progesterone levels on the day of pregnancy test determination: A novel concept toward individualized luteal phase support

RESEARCH QUESTION

The main objective of the study is to define the optimal trade-off progesterone (P4) values on the day of embryo transfer (ET), to identify low P4-human chorionic gonadotropin (hCG), and to establish whether P4 supplementation started on the hCG day can increase the success rate of the frozen embryo transfer (FET) cycle.

DESIGN

A single-center, cohort, retrospective study with 664 hormone replacement therapy (HRT)-FET cycles analyzed female patients who received vaginal 600 mg/day of P4 starting from 6 days before the FET, had normal P4 values on the day before ET, and whose P4 on the day of the pregnancy test was assessed.

RESULTS

Of the 664 cycles, 69.6% of cycles showed P4 ≥ 10.6 ng/ml, while 30.4% showed P4 < 10.6 ng/ml on the day of the hCG. Of the 411 chemical pregnancies detected, 71.8% had P4-hCG ≥ 10.6 ng/ml (group A), while 28.2% had P4-hCG < 10.6 ng/ml. Of the cycles with P4-hCG < 10.6 ng/ml, 64.7% (group B) were supplemented with a higher dose of vaginal P4 (1,000 mg/day), while 35.3% (group C) were maintained on the same dose of vaginal micronized P4. The live birth rate was 71.9%, 96%, and 7.3% for groups A, B, and C, respectively.

CONCLUSION

The likelihood to detect P4-hCG < 10.6 ng/ml decreased as the level of serum P4 the day before ET increased. The live birth rate (LBR) was shown to be significantly lower when P4 was low and not supplemented.

Impact of different endometrial preparation protocols before frozen embryo transfer on pregnancy outcomes: a review

The use of frozen embryo transfer cycles has exponentially increased in the last few years. Optimization of endometrial preparation protocols before frozen embryo transfer is mandatory to further improve pregnancy outcomes. This review will focus on the existing literature with regard to the different available endometrial preparation protocols and their impact on pregnancy outcomes. More specifically, we will focus on programmed, natural, and stimulated frozen embryo transfer cycles. The studies performed on this topic are generally of low quality, and only a few well-performed randomized controlled trials have been published. To date, no strong evidence is available to support the use of 1 preparation method over another in terms of pregnancy outcomes. However, robust data have shown a clearly protective effect of natural frozen embryo transfer cycles against long-term obstetric complications, mainly hypertensive disorders of pregnancy and large for gestational age infants. The introduction of individualized luteal phase support in different endometrial preparation protocols is actually gaining a lot of attention and requires further investigation.

Association between serum estradiol level on day of progesterone start and outcomes from frozen blastocyst transfer cycles utilizing oral estradiol

PURPOSE

Supraphysiologic serum estradiol levels may negatively impact the likelihood of conception and live birth following IVF. The purpose of this study is to determine if there is an association between serum estradiol level on the day of progesterone start and clinical outcomes following programmed frozen blastocyst transfer cycles utilizing oral estradiol.

METHODS

This is a retrospective cohort study at an academic fertility center analyzing 363 patients who underwent their first autologous single (SET) or double frozen embryo transfer (DET) utilizing oral estradiol and resulting in blastocyst transfer from June 1, 2012, to June 30, 2018. Main outcome measures included implantation, clinical pregnancy, live birth, and miscarriage rates. Cycles were stratified by quartile of serum estradiol on the day of progesterone start and separately analyzed for SET cycles only. Poisson and Log binomial regression were used to calculate relative risks (RR) with 95% confidence intervals (CI) for implantation, clinical pregnancy, live birth, and miscarriage with adjustments made for age and BMI.

RESULTS

Cycles with the highest quartile of estradiol (mean 528 pg/mL) were associated with lower risks of implantation (RR 0.66, CI 0.50-0.86), ongoing pregnancy (RR 0.66, CI 0.49-0.88), and live birth (RR 0.70, CI 0.52-0.94) compared with those with the lowest estradiol quartile (mean 212 pg/mL). Similar findings were seen for analyses limited to SETs. There was no significant difference in miscarriage rate or endometrial thickness between groups.

CONCLUSION

High levels of serum estradiol on the day of progesterone start may be detrimental to implantation, pregnancy, and live birth following frozen blastocyst transfer.

Elevated estradiol levels in frozen embryo transfer have different effects on pregnancy outcomes depending on the stage of transferred embryos

Supplementation with estradiol (E2) is routinely used in frozen embryo transfer (FET) cycles and embryo age plays an important role in conceiving. This study was to compare the effects of serum E2 levels on pregnancy outcomes between cleavage- and blastocyst-stage FET cycles using hormone replacement therapy. A total of 776 FET cycles (669 couples) performed from January 2016 to December 2019 were included in the present retrospective cohort study. Regarding cleavage-stage embryo transfers, E2 levels on progesterone initiation day were significantly lower in the ongoing pregnancy/live birth (OP/LB) group than in the non-OP/LB group (214.75 ± 173.47 vs. 253.20 ± 203.30 pg/ml; P = 0.023). In addition, there were downward trends in implantation, clinical pregnancy and OP/LB rates with increasing E2 levels. However, in blastocyst-stage embryo transfers, such trends were not observed, and E2 levels were not significant difference between the OP/LB group and the non-OP/LB group (201.66 ± 182.14 vs. 197.89 ± 212.83 pg/ml; P = 0.884). The results suggests that elevated progesterone-initiation-day E2 levels may negatively affect pregnancy outcomes during artificial cleavage-stage embryo transfers. However, it is not necessary to monitor E2 levels when transferring blastocysts in artificial FET cycles.

Progesterone and estrogen levels are associated with live birth rates following artificial cycle frozen embryo transfers

PURPOSE

Does an association exist between serum progesterone and estradiol levels and live birth rates in artificial cycle frozen embryo transfer (AC-FET)?

METHODS

Retrospective cohort study was based on prospectively collected data at a university-affiliated fertility center. Included were all cycles using an artificial endometrial preparation with estradiol hemihydrate (Estrofem, 2 mg/8 h) and vaginal progesterone (Endometrin 100 mg/8 h), autologous oocytes, and cleavage stage embryo transfers. Serum progesterone and estradiol levels were measured 14 days after FET. A total of 921 cycles in 568 patients from to December 2010 to June 2019 were investigated. Live birth was the primary outcome measure.

RESULTS

Significant association was found between live birth and progesterone as well as estradiol levels (progesterone 14.65 vs 11.62 ng/ml, p = 0.001; estradiol 355.12 vs 287.67 pg/ml, p = 0.001). A significant difference in live birth rate was found below and above the median progesterone level (10.9 ng/ml, p = 0.007). Lower estradiol level was significantly associated with lower live birth rate (< 188.2 pg/ml 8.3%, > 263.1 pg/ml 16%, p = 0.02).

CONCLUSIONS

Serum progesterone and estradiol levels impact live birth rate in AC-FET.

The impact of estradiol on pregnancy outcomes in letrozole-stimulated frozen embryo transfer cycles

OBJECTIVE

To assess the impact of low estradiol (E2) levels in letrozole-stimulated frozen embryo transfer (FET) cycles on pregnancy and neonatal outcomes.

DESIGN

Retrospective cohort.

SETTING

University-affiliated fertility center.

PATIENTS

All patients who underwent letrozole-stimulated FET cycles from January 2017 to April 2020 (n = 217). The "Low E2" group was defined as those with E2 serum levels on the day of trigger <10th percentile level (E2 <91.16 pg/mL, n = 22) and the "Normal E2" group was defined as those with E2 serum levels ≥10th percentile level (E2 ≥91.16 pg/mL, n = 195).

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Pregnancy outcomes including rates of clinical pregnancy, clinical miscarriage, and live birth. Neonatal outcomes including gestational age at delivery, birth weight, and Apgar score.

RESULTS

The mean ± SD estradiol level was 66.8 ± 14.8 pg/mL for the "Low E2" group compared with 366.3 ± 322.1 pg/mL for the "Normal E2" group. There were otherwise no substantial differences in cycle characteristics such as endometrial thickness on the day of ovulation trigger and progesterone levels in early pregnancy. The "Low E2" group had a significantly higher clinical miscarriage rate (36.4% vs. 8.8%, adjusted odds ratio 8.06) and lower live birth rate (31.8% vs. 57.9%, adjusted odds ratio 0.28). Neonatal outcomes such as gestational age at delivery, mean birth weight, Apgar scores, and incidence of newborn complications were not clinically different between the groups.

CONCLUSION

Low E2 levels were associated with a significantly higher miscarriage rate and lower live birth rate, suggesting that E2 levels in the follicular phase may have an effect on cycle outcomes. Given the rise in use of FET, further studies are needed to confirm our findings and understand the mechanisms.

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.

Association between serum estradiol levels prior to progesterone administration in artificial frozen-thawed blastocyst transfer cycles and live birth rate: a retrospective study

OBJECTIVE

To study whether serum estradiol (E2) levels prior to progesterone administration in the artificial endometrial preparation (AEP) of frozen-thawed blastocyst transfer affect the live birth rate.

DESIGN

Retrospective cohort study.

SETTING

Tertiary-care academic medical centre.

POPULATION

A total of 3857 frozen-thawed blastocyst transfer cycles were divided into three groups: <200 pg/ml (n = 1676); 200-399 pg/ml (n = 1296); and ≥400 pg/ml (n = 885), based on the 25th (182.3 pg/ml) and 75th percentile (390.2 pg/ml) of serum E2 level prior to progesterone administration.

METHODS

Univariable and multivariable logistic regression analysis was performed.

MAIN OUTCOME MEASURES

The primary outcome of the study was the live birth rate and the secondary outcomes included clinical pregnancy rate, pregnancy loss rate, neonatal birthweight, Z-score, and small for gestational age (SGA).

RESULTS

Compared with the reference group, accounting for major covariates, the live birth rate significantly decreased in the '≥400 pg/ml' group (adjusted OR 0.71, 95% CI 0.59-0.85). Compared with the reference group, there was an association between the E2 level in the '≥400 pg/ml' group and a decrease in the clinical pregnancy rate (adjusted OR 0.74, 95% CI 0.61-0.89). Compared with the reference group, the pregnancy loss rate significantly increased in the '≥400 pg/ml' group (adjusted OR 1.45, 95% CI 1.08-1.93). The E2 levels did not affect neonatal birthweight, Z-score, and SGA among singletons.

CONCLUSIONS

High serum E2 levels prior to progesterone administration in AEP are associated with a decreased live birth rate after frozen-thawed blastocyst transfer.

TWEETABLE ABSTRACT

High serum E2 levels prior to progesterone administration in artificial FET are associated with a decreased live birth rate after frozen-thawed blastocyst transfer.