Frozen embryo transfer: a review on the optimal endometrial preparation and timing

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.

Livebirth rate after one frozen embryo transfer in ovulatory women starting with natural, modified natural, or artificial endometrial preparation in Viet Nam: an open-label randomised controlled trial

BACKGROUND

Use of frozen embryo transfer (FET) in in-vitro fertilisation (IVF) has increased. However, the best endometrial preparation protocol for FET cycles is unclear. We compared natural and modified natural cycle strategies with an artificial cycle strategy for endometrial preparation before FET.

METHODS

In this randomised, open-label study, we recruited ovulatory women aged 18-45 years at a hospital in Ho Chi Minh City, Viet Nam, who were randomly allocated (1:1:1) to natural, modified natural, or artificial cycle endometrial preparation using a computer-generated random list and block randomisation. The trial was not masked due to the nature of the study interventions. In natural cycles, no oestrogen, progesterone, or human chorionic gonadotropin (hCG) was used. In modified natural cycles, hCG was used to trigger ovulation. In artificial cycles, oral oestradiol valerate (8 mg/day from day 2-4 of menstruation) and vaginal progesterone (800 mg/day starting when endometrial thickness was ≥7 mm) were used. Embryos were vitrified, and then one or two day-3 embryos or one day-5 embryo were warmed and transferred under ultrasound guidance. If the first FET cycle was cancelled, subsequent cycles were performed with artificial endometrial preparation. The primary endpoint was livebirth after one FET. This trial is registered at ClinicalTrials.gov, NCT04804020.

FINDINGS

Between March 22, 2021, and March 14, 2023, 4779 women were screened and 1428 were randomly assigned (476 to each group). 99 first FET cycles were cancelled in each of the natural and modified cycle groups, versus none in the artificial cycle group. The livebirth rate after one FET was 174 (37%) of 476 in the natural cycle strategy group, 159 (33%) of 476 in the modified natural cycle strategy group, and 162 (34%) of 476 in the artificial cycle strategy group (relative risk 1·07 [95% CI 0·87-1·33] for natural vs artificial cycle strategy, and 0·98 [0·79-1·22] for modified natural vs artificial cycle strategy). Maternal and neonatal outcomes did not differ significantly between groups, as the power to detect small differences was low.

INTERPRETATION

Although the livebirth rate was similar after natural, modified natural, and artificial cycle endometrial preparation strategies in ovulatory women undergoing FET IVF, no definitive conclusions can be made regarding the comparative safety of the three approaches.

FUNDING

None.

Modified natural cycle allows a window of 7 days for frozen embryo transfer planning

RESEARCH QUESTION

Should ovulation be triggered in a modified natural cycle (mNC) with recombinant human chorionic gonadotrophin (rHCG) as soon as a mean follicle diameter of 17 mm is visible, or is more flexible planning possible?

DESIGN

This multicentre, retrospective, observational study of 3087 single frozen blastocyst transfers in mNC was carried out between January 2020 and September 2022. The inclusion criteria included endometrial thickness ≥7 mm and serum progesterone <1.5 ng/ml. The main outcome was ongoing pregnancy rate. Secondary end-points were pregnancy rate, implantation rate, clinical pregnancy rate and miscarriage rate. The mean follicle size at triggering was stratified into three groups (13.0-15.9, 16.0-18.9 and 19.0-22 mm).

RESULTS

The baseline characteristics between the groups did not vary significantly for age, body mass index and the donor's age for egg donation. No differences were found in pregnancy rate (64.5%, 60.2% and 57.4%; P = 0.19), clinical pregnancy rate (60.5%, 52.8% and 50.6%; P = 0.10), implantation rate (62.10%, 52.9% and 51.0%; P = 0.05) or miscarriage rate (15.0%, 22.2%; and 25.0%; P = 0.11). Although ongoing pregnancy rate (54.9%, 46.8% and 43.1%; P = 0.02) varied significantly in the univariable analysis, it was no longer significant after adjustment for the use of preimplantation genetic testing for aneuploidies and egg donation.

CONCLUSIONS

The findings showed rHCG could be flexibly administered with a mean follicle size between 13 and 22 mm as long as adequate endometrial characteristics are met, and serum progesterone is <1.5 ng/ml. Considering the follicular growth rate of 1-1.5 mm/day, this approach could allow a flexibility for FET scheduling of 6-7 days, simplifying mNC FET planning in clinical practice.

Individualized luteal phase support in frozen-thawed embryo transfer after intramuscular progesterone administration might rectify live birth rate

Background

The serum P concentrations are suggested to have an impact on pregnancy outcome. However there is no consensus about the optimal progesterone cut-off during the luteal phase. Few studies evaluated the effectiveness of a "rescue protocol" for low serum P concentrations and most of these studies used vaginal progesterone administration. There is paucity of data on the effectiveness of rescue protocol using intramuscular progesterone (IM-P) in frozen-thawed embryo transfer (FET).

Methods

This study is a retrospective cohort study included 637 single or double blastocyst FETs with artificially prepared endometrium receiving 100 mg IM progesterone (P) after incremental estrogen treatment. Serum P concentrations were evaluated using blood samples obtained 117-119 hours after the first IM-P administration and 21 ± 2 hours after the last IM-P administration. Patients with serum P concentrations <20.6 ng/ml on the ET day were administrated 400 mg vaginal progesterone for rescue.

Results

Demographic and cycle characteristics were similar between patients receiving rescue vaginal P (embryo transfer (ET)-day P concentration < 20.6 ng/ml) and patients who did not need rescue vaginal P (ET-day P concentration ≥ 20.6 ng/ml). Clinical pregnancy, miscarriage, and live birth rates were similar between two groups: 52.9%(45/85) vs 59.6%(326/552), p=0.287; 11.1%(5/45) vs 14.1%(46/326), p=0.583; and 47.1%(40/85) vs 50.7%(280/552), p=0.526, respectively. Logistic regression analysis revealed that the female age (p = 0.008, OR=0.942, 95% CI = 0.902-0.984) and embryo quality (ref: good quality for moderate: p=0.02, OR=0.469, 95% CI =0.269-0.760; for poor: p=0.013, OR= 0.269, 95% CI = 0.092-0.757) were independent variables for live birth. Following rescue protocol implementation, ET-day P concentration was not a significant predictor of live birth.

Conclusions

Rescue vaginal P administration for low ET day serum P concentrations following IM-P yields comparable live birth rates.

Ideal frozen embryo transfer regime

PURPOSE OF REVIEW

This review aims to compare evidence on four criteria (embryo implantation, obstetric outcomes, patient convenience, and IVF-unit efficiency) by analyzing published research on different endometrial preparation methods for frozen embryo transfer (FET).

RECENT FINDINGS

While the artificial-FET cycle provides advantages in scheduling and implantation, it falls short in ensuring optimal obstetric outcomes. In contrast, natural-FET ensures embryo implantation conditions if ovulation is correctly identified. Supplementing with exogenous progesterone shields against low corpus luteum progesterone secretion, crucial for positive obstetric outcomes. In mNC-FET, ovulation is hCG-triggered, closely resembling natural cycles and reducing monitoring visits for enhanced patient convenience.Letrozole is a recommended option for anovulatory patients, preserving endometrial thickness. It is cost-effective, less likely to induce multifollicular development than gonadotropins, and better tolerated.In a novel approach, the natural-proliferative-phase-FET initiates progesterone in an unmediated ovulatory cycle at 7 mm endometrial thickness, combining the benefits of a natural proliferative endometrium with the convenience of scheduled artificial cycles.

SUMMARY

The artificial cycle offers scheduling advantages, but may compromise obstetric outcomes. Natural FET relies on accurate ovulation timing for successful implantation. mNC-FET simplifies the process using hCG induction, minimizing clinic visits for improved convenience. Letrozole is highlighted as a cost-effective and well tolerated option in anovulatory patients. A recent innovative approach combines elements of natural and artificial cycles, showing promise for FET procedures.

Impact of Group vs Individual Embryo Culture Strategies on Blastocyst and Clinical Outcomes

Embryo culture is one of the most important steps in an assisted reproduction laboratory. Embryos can be cultured individually, one embryo per media drop, or in groups, culturing several embryos in the same media drop. Due to the controversy generated on this subject, we wondered which embryo culture method would have the best results in terms of quality and blastocyst formation rate. We designed a prospective randomized study comparing two different embryo culture strategies: group and individual embryo culture. The data were obtained from 830 embryos from 103 egg donation treatments. The zygotes were randomized into two groups: individual culture (group 1) or group culture (group 2). The embryos were cultured in 35-µl drops until day 5 when they were classified morphologically. We observed a significant increase in the blastocyst formation rate and in the usable embryo rate in individual culture on day 5 compared to group culture. However, good embryo quality (A/B blastocysts), implantation, and pregnancy rates were similar regardless of the type of embryo-culture. As a conclusion, individual culture may increase blastocyst formation rate and may benefit embryo quality on day 5. Our results support previous reports suggesting that individual culture could improve embryo development.

Effect of GnRH agonist down-regulation combined with hormone replacement treatment on reproductive outcomes of frozen blastocyst transfer cycles in women of different ages

Objective

To investigate the effect of GnRH agonist (GnRH-a) down-regulation prior to hormone replacement treatment (HRT) to prepare the endometrium in frozen embryo transfer (FET) cycles in women of different ages.

Methods

This was a retrospective study, and after excluding patients with adenomyosis, endometriosis, severe endometrial adhesions, polycystic ovary syndrome (PCOS), and repeated embryo implantation failures, a total of 4,091 HRT cycles were collected. Patients were divided into group A (<35 years old) and group B (≥35 years old), and each group was further divided into HRT and GnRHa-HRT groups. The clinical outcomes were compared between groups.

Results

There was no statistically significant difference in clinical outcomes between the HRT and GnRHa-HRT groups among women aged <35 years. In women of advanced age, higher rates of clinical pregnancy and live birth were seen in the GnRHa-HRT group. Logistic regression analysis showed that female age and number of embryos transferred influenced the live birth rate in FET cycles, and in women aged ≥ 35 years, the use of GnRH-a down-regulation prior to HRT improved pregnancy outcomes.

Conclusions

In elderly woman without adenomyosis, endometriosis, PCOS, severe uterine adhesions, and RIF, hormone replacement treatment with GnRH agonist for pituitary suppression can improve the live birth rate of FET cycles.

Comparable ongoing pregnancy and pregnancy loss rates in natural cycle and artificial cycle frozen embryo transfers with intensive method-specific luteal phase support; a retrospective cohort study

STUDY OBJECTIVE

The absence of corpus lutea in artificial cycle (AC) frozen embryo transfers (FET) may increase the chances of pregnancy loss. In this retrospective cohort study, the efficacy of AC endometrial preparation was compared natural cycle (NC) endometrial preparation in terms of ongoing pregnancy.

METHODS

One thousand six hundred and eighteen consecutive vitrified-warmed blastocyst FET performed between December 2021 and November 2022 were included, with 1023 compared after exclusions according to the endometrial preparation method; 293 NC-FET, 143 modified NC-FET, 204 unprogrammed AC-FET, and 383 oral contraceptive pill (OCP) programmed AC-FET. Intensive method-specific luteal phase support (LPS) was administered in NC- (human chorionic gonadotropin and micronized vaginal progesterone), mNC- (micronized vaginal progesterone), and in AC-FET (micronized vaginal progesterone, intramuscular progesterone, and oral dydrogesterone).

RESULTS

Clinician choice of endometrial preparation method resulted in the NC- or AC-FET groups having distinct differences, with female age, antral follicle count and body mass index as well as the percentage of DOR or PCOS diagnosed patients significantly different. The unadjusted ongoing pregnancy and total pregnancy loss rates for NC-, mNC-, AC-, and ocp-AC-FET were 61.8 %, 55.2 %, 57.4 %, and 58.5 %, and 19.2 %, 24.0 %, 23.5 % and 23.8 %, respectively. In multivariate logistic regressions to predict the dependent outcomes of ongoing pregnancy and total pregnancy loss, none of the FET methods were selected as independent predictors.

CONCLUSION

Patients undergoing NC- and AC-FET with method-specific progesterone LPS had comparable ongoing pregnancy rates as well as total pregnancy loss rates, with NC-FET ranked first in the regression analysis.

Intrauterine Infusion and Hysteroscopic Injection of Autologous Platelet-Rich Plasma for Patients with a Persistent Thin Endometrium: A Prospective Case-Control Study

Objectives: To evaluate the effect of intrauterine infusion and hysteroscopic injection of autologous platelet-rich plasma (PRP) in patients with a persistent thin endometrium (EM) undergoing euploid frozen embryo transfer (EFET) cycles. Methods: This prospective case-control study enrolled 116 infertile women with thin EM (<7 mm) who underwent hormone replacement therapy (HRT) for EFET. These women had experienced at least one previous unsuccessful EFET cycle, which either resulted in the cancellation of the cycle or failure of pregnancy. A total of 55 women received an intrauterine infusion of PRP before FET, 38 received a hysteroscopic injection of PRP, and 23 received standard HRT treatment without PRP (control group). Only euploid embryos were transferred in these cycles. The primary outcomes were the implantation rate (IR) and clinical pregnancy rate (CPR) after EFET. Results: After receiving intrauterine infusion and hysteroscopic injection of PRP, 78.2% and 55.3% of patients, respectively, showed an EM thickness exceeding 7 mm, followed by embryo transfer. The hysteroscopic injection group demonstrated significantly higher IR (52%), a higher trend of CPR (52%), and a higher live birth rate (38%) than the control group (18%, 22%, and 4%). Conclusions: Intrauterine infusion and hysteroscopic injection of autologous PRP may be effective methods to increase EM thickness in HRT cycles. According to our results, both methods could increase EM thickness, while hysteroscopic injection appeared to provide more significant assistance in increasing IR, CPR, and live birth rate after EFET in patients with persistent thin EM.

Comparison between oral dydrogesterone versus micronized vaginal progesterone gel in clinical outcome within the first HRT-FET cycle: a retrospective analysis

OBJECTIVE

The purpose of this study is to compare the clinical efficacy of oral dydrogesterone and micronized vaginal progesterone (MVP) gel during the first HRT-FET cycle.

METHODS

A retrospective cohort study based on a total of 344 women undergoing their first HRT-FET cycles without Gonadotropin-Releasing Hormone agonist (GnRH-a) pretreatment was conducted. All the cycles were allocated to two groups in the reproductive medical center at the University of Hong Kong-Shenzhen Hospital. One group (n = 193) received oral dydrogesterone 30 mg/d before embryo transfer, while the other group (n = 151) received MVP gel 180 mg/d.

RESULTS

The demographics and baseline characteristics of two groups were comparable. We found no statistically significant difference in live birth rate (24.35% vs. 31.13%, P = 0.16), clinical pregnancy rate (34.72% vs. 36.42%, P = 0.74), embryo implantation rate (25.09% vs. 28.36%, P = 0.43), positive pregnancy rate (42.49% vs 38.41%, P = 0.45), miscarriage rate (9.33% vs 3.97%, P = 0.05), or ectopic pregnancy rate (0.52% vs. 0.66%, P = 0.86) between the oral dydrogesterone group and MVP gel group. In the multivariate logistic regression analysis for covariates, medication used for luteal support was not associated with live birth rate (OR = 0.73, 95% CI: 0.32-1.57, P = 0.45). And the different luteal support medication did not have a significant positive association with the live birth rate in the cycles with day 2 embryo transferred (OR = 1.39, 95% CI:0.66-2.39, P = 0.39) and blastocyst transferred (OR = 1.31 95% CI:0.64-2.69, P = 0.46).

CONCLUSION

30 mg/d oral dydrogesterone and 180 mg/d MVP gel revealed similar reproductive outcomes in HRT-FET cycles in the study.

Is large for gestational age in singletons born after frozen embryo transfer associated with freezing technique or endometrial preparation protocol? A longitudinal national French study

STUDY QUESTION

Is large for gestational age (LGA) observed in babies born after frozen embryo transfer (FET) associated with either the freezing technique or the endometrial preparation protocol?

SUMMARY ANSWER

Artificial cycles are associated with a higher risk of LGA, with no difference in rate between the two freezing techniques (vitrification versus slow freezing) or embryo stage (cleaved embryo versus blastocyst).

WHAT IS KNOWN ALREADY

Several studies have compared neonatal outcomes after fresh embryo transfer (ET) and FET and shown that FET is associated with improved neonatal outcomes, including reduced risks of preterm birth, low birthweight, and small for gestational age (SGA), when compared with fresh ET. However, these studies also revealed an increased risk of LGA after FET. The underlying pathophysiology of this increased risk remains unclear; parental infertility, laboratory procedures (including embryo culture conditions and freezing-thawing processes), and endometrial preparation treatments might be involved.

STUDY DESIGN, SIZE, DURATION

A multicentre epidemiological data study was performed through a retrospective analysis of the standardized individual clinical records of the French national register of IVF from 2014 to 2018, including single deliveries resulting from fresh ET or FET that were prospectively collected in fertility centres. Complementary data were collected from the participating fertility centres and included the vitrification media and devices, and the endometrial preparation protocols.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Data were collected from 35 French ART centres, leading to the inclusion of a total of 72 789 fresh ET, 10 602 slow-freezing FET, and 39 062 vitrification FET. Main clinical outcomes were presented according to origin of the transferred embryos (fresh, slow frozen, or vitrified embryos) and endometrial preparations for FET (ovulatory or artificial cycles), comparing five different groups (fresh, slow freezing-ovulatory cycle, slow freezing-artificial cycle, vitrification-ovulatory cycle, and vitrification-artificial cycle). Foetal growth disorders were defined in live-born singletons according to gestational age and sex-specific weight percentile distribution: SGA and LGA if <10th and ≥90th percentiles, respectively. Analyses were performed using linear mixed models with the ART centres as random effect.

MAIN RESULTS AND THE ROLE OF CHANCE

Transfers led to, respectively, 19 006, 1798, and 9195 deliveries corresponding to delivery rates per transfer of 26.1%, 17.0%, and 23.5% after fresh ET, slow-freezing FET, and vitrification FET, respectively. FET cycles were performed in either ovulatory cycles (n = 21 704) or artificial cycles (n = 34 237), leading to 5910 and 10 322 pregnancies, respectively, and corresponding to pregnancy rates per transfer of 31.6% and 33.3%. A significantly higher rate of spontaneous miscarriage was observed in artificial cycles when compared with ovulatory cycles (33.3% versus 21.4%, P < 0.001, in slow freezing groups and 31.6% versus 21.8%, P < 0.001 in vitrification groups). Consequently, a lower delivery rate per transfer was observed in artificial cycles compared with ovulatory cycles both in slow freezing and vitrification groups (15.5% versus 18.9%, P < 0.001 and 22.8% versus 24.9%, P < 0.001, respectively). Among a total of 26 585 live-born singletons, 16 413 babies were born from fresh ET, 1644 from slow-freezing FET, and 8528 from vitrification FET. Birthweight was significantly higher in the FET groups than in the fresh ET group, with no difference between the two freezing techniques. Likewise, LGA rates were higher and SGA rates were lower in the FET groups compared with the fresh ET group whatever the method used for embryo freezing. In a multivariable analysis, the risk of LGA following FET was significantly increased in artificial compared with ovulatory cycles. In contrast, the risk of LGA was not associated with either the freezing procedure (vitrification versus slow freezing) or the embryo stage (cleaved embryo versus blastocyst) at freezing. Regarding the vitrification method, the risk of LGA was not associated with either the vitrification medium used or the embryo stage.

LIMITATIONS, REASONS FOR CAUTION

No data were available on maternal context, such as parity, BMI, infertility cause, or maternal comorbidities, in the French national database. In particular, we cannot exclude that the increased risk of LGA observed following FET with artificial cycles may, at least partially, be associated with a confounding effect of some maternal factors. No information about embryo culture and incubation conditions was available. Most of the vitrification techniques were performed using the same device and with two main vitrification media, limiting the validity of a comparison of risk for LGA according to the device or vitrification media used.

WIDER IMPLICATIONS OF THE FINDINGS

Our results seem reassuring, since no potential foetal growth disorders following embryo vitrification in comparison with slow freezing were observed. Even if other factors are involved, the endometrial preparation treatment seems to have the greatest impact on LGA risk following FET. FET during ovulatory cycles could minimize the risk for foetal growth disorders.

STUDY FUNDING/COMPETING INTEREST(S)

This work has received funding from the French Biomedicine Agency (Grant number: 19AMP002). None of the authors has any conflict of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

Does surgery for colorectal endometriosis prior to IVF±ICSI have an impact on cumulative live birth rates?

RESEARCH QUESTION

Does colorectal endometriosis surgery prior to IVF ± intracytoplasmic sperm injection (ICSI) impact cumulative live birth rates?

DESIGN

This retrospective, monocentric study (Lille University Hospital) was conducted between 1 January 2007 and 31 December 2018. Two groups of patients from the JFIV database were included: a group undergoing IVF±ICSI alone (120 patients, 215 oocyte retrievals), and a group undergoing surgery and then IVF±ICSI (69 patients, 109 oocyte retrievals). The mode of management was decided after a multidisciplinary team meeting. Different criteria such as age (cut-off 35 years), anti-Müllerian hormone concentration (cut off 2 ng/ml), imaging results and the patient's symptomatology were considered: the most symptomatic patients underwent surgery prior to IVF±ICSI. The cumulative clinical pregnancy and live birth rates obtained after four IVF attempts were estimated and compared between the two groups using competing risk survival methods.

RESULTS

The cumulative live birth rates after four IVF attempts in the two groups were not statistically significantly different (50.8% in the IVF±ICSI group versus 52.2% in the surgery followed by IVF±ICSI group, P = 0.43). The results for the cumulative clinical pregnancy rates were the same (56.7% in the IVF±ICSI group versus 58% in the surgery followed by IVF±ICSI group, P = 0.47).

CONCLUSION

The study shows that cumulative live birth and pregnancy rates were similar in infertile patients with colorectal endometriosis who underwent IVF±ICSI either with or without prior colorectal endometriosis surgery.

The combination of dydrogesterone and micronized vaginal progesterone can render serum progesterone level measurements on the day of embryo transfer and rescue attempts unnecessary in an HRT FET cycle

PURPOSE

To evaluate the role of serum progesterone (P4) on the day of embryo transfer (ET) when dydrogesterone (DYD) and micronized vaginal progesterone (MVP) are combined as luteal phase support (LPS) in a hormone replacement therapy (HRT) frozen ET (FET) cycles.

METHODS

Retrospective study, including single euploid HRT FET cycles with DYD and MVP as LPS and P4 measurement on ET day. Initially, patients with P4 levels < 10 ng/ml increased MVP to 400 mg/day; this "rescue" was abandoned later.

RESULTS

560 cycles of 507 couples were included. In 275 women, serum P4 level was < 10 ng/ml on the ET day. Among those with low P4 levels, MVP dose remained unchanged in 65 women (11.6%) and was increased in 210 women (37.5%). Women with P4 levels ≥ 10 ng/ml continued LPS without modification. Overall pregnancy rates in these groups were 61.5% (40/65), 54.8% (115/210), and 48.4% (138/285), respectively (p = n.s.). Association of serum P4 levels with ongoing pregnancy rates was analyzed in women without any additional MVP regardless of serum P4 levels (n = 350); multivariable analysis (adjusted for age, BMI, embryo quality (EQ)) did not show a significant association of serum P4 levels with OPR (OR 0.96, 95% CI 0.90-1.02; p = 0.185). Using inverse probability treatment weights, regression analysis in the weighted sample showed no significant association between P4 treatment groups and OP. Compared to fair EQ, the transfer of good EQ increased (OR 1.61, 95% CI 1.22-2.15; p = 0.001) and the transfer of a poor EQ decreased the odds of OP (OR 0.73, 95% CI 0.55-0.97; p = 0.029).

CONCLUSION

In HRT FET cycle, using LPS with 300 mg/day MVP and 30 mg/day DYD, it appears that serum P4 measurement and increase of MVP in patients with P4 < 10 ng/ml are not necessary.

Effect of repeated vitrification of human embryos on pregnancy and neonatal outcomes

BACKGROUND

Repeated cryopreservation of embryos should occasionally be considered when embryos were not suitable for transfer. The effect of re-cryopreservation on embryos remains contentious.

METHODS

This retrospective cohort study aimed to evaluate the pregnancy and neonatal outcomes of twice vitrificated blastocyst derived from once vitrified embryos. Total 410 vitrified-warmed blastocyst transfer cycles were divided into two groups according to the times of embryo vitrification: (1) vitrified blastocysts derived from fresh blastocysts (control group, n = 337); (2) twice vitrified blastocysts derived from once vitrified embryos (n = 73). The primary outcome was live birth rate. Multivariable logistic or linear regression analysis model was performed to describe the association between embryo cryopreservation times and clinical outcomes.

RESULTS

No difference was observed in female age at retrieval and transfer, infertility period, body mass index (BMI), infertility type, endometrial thickness, and embryo transfer numbers between the two groups. The pregnancy outcomes of embryos in repeated cryopreservation group were comparable to those of embryos in control group, including implantation rate, clinical pregnancy rate, and live birth rate. In multivariate logistic regression analysis, the cryopreservation times did not affect the outcomes of biochemical pregnancy, clinical pregnancy, and live birth. Moreover, there was no difference in gestational age, birthweight and sex ratio of singleton newborns between groups. After correcting several possible confounding variables, no significant association was observed between cryopreservation times and neonatal birthweight.

CONCLUSION

In conclusion, pregnancy and neonatal outcomes achieved with twice vitrified blastocyst transfer were comparable to those achieved with vitrified blastocyst transfer in control group.

Endometrial receptivity in women with endometriosis

As endometriosis is recognized as a contributing factor to infertility, prompting couples to embark on Assisted Reproductive Technology (ART) treatments, it becomes crucial to comprehend the extent and way this condition can affect success rates. Natural conception data reveal lower success rates for women with endometriosis, yet the same cannot be extrapolated to the outcomes of in vitro fertilization (IVF). In recent years, advancements in the ART process, particularly the distinct stages of the IVF pathway and investigations into embryo quality have shown a comparable rate of embryonic quality and chromosomal normalcy (euploidy) between embryos obtained from individuals with or without endometriosis. Thus, the primary question that lingers relates to the functionality of the endometrium. This review addresses whether endometriosis can influence endometrial receptivity and implantation rates.

Clinical Outcomes in Hormone Replacement Therapy (HRT)-Frozen Embryo Transfer (FET) Protocol Increased by Administering Gonadotropin-Releasing Hormone Agonist (GnRH) in the Initial Stage of the Luteal Phase: A Retrospective Analysis

OBJECTIVE

The objective of this study was to determine if gonadotropin-releasing hormone agonist (GnRH) administration supporting the luteal phase in frozen embryo transfer (FET) improves clinical outcomes Methods and materials This is a retrospective cohort study and we analyzed 3515 cycles of FET at the Department of Reproductive Medicine in our hospital from February 2018 through December 2021. Patients were divided into the GnRH (triptorelin+progesterone and human chorionic gonadotropin (hCG)) group and the non-GnRHa (existing treatment without triptorelin) group. There were 1033 and 2485 cases in the above groups, respectively. Live birth rates (LBR) and clinical pregnancy rates (CPR) were contrasted in the two groups.

RESULTS

We found greater CPR (58.00% versus 48.40%, P-value = 0.003) and LBR (52.70% versus 45.60%, P-value = 0.001) for HRT-FET cycles, and found no clinical significance for natural cycle FET (NC-FET) (58.20% versus 52.90%, P-value = 0.364 and 54.40% versus 47.00%, P-value=0.211), GnRH+HRT-FET (53.00% versus 53.00%, P-value=0.176 and 46.20% versus 47.30%, P-value=0.794), and stimulation-FET (59.30% versus 52.90%, P-value=.00.566 and 59.30% versus 47.10%, P-value=.00.247) in terms of CPR and LBR in the two groups. There was a 47% increase in CPR in the GnRH group, and there was a 33% increase in LBR in the same group.

CONCLUSION

During HRT-FET cycles, administering triptorelin three to four times in the existing luteal support can improve CPR and LBR, and administering triptorelin during the initial stage of the luteal phase can prove a new option for luteal support.

Role of Dydrogesterone for Luteal Phase Support in Assisted Reproduction

Clinical outcomes of in vitro fertilization (IVF) have significantly improved over the years with the advent of the frozen-thawed embryo transfer (FET) technique. Ovarian hyperstimulation during IVF cycles causes luteal phase deficiency, a condition of insufficient progesterone. Intramuscular or vaginal progesterone and dydrogesterone are commonly used for luteal phase support in FET. Oral dydrogesterone has a higher bioavailability than progesterone and has high specificity for progesterone receptors. Though micronized vaginal progesterone has been the preferred option, recent data suggest that oral dydrogesterone might be an alternative therapeutic option for luteal phase support to improve clinical outcomes of IVF cycles. Dydrogesterone has a good safety profile and is well tolerated. Its efficacy has been evaluated in several clinical studies and demonstrated to be non-inferior to micronized vaginal progesterone in large-scale clinical trials. Oral dydrogesterone may potentially become a preferred drug for luteal phase support in millions of women undergoing IVF.

Preliminary application of real-time shear wave elastography to evaluate endometrial receptivity and predict pregnancy outcome

BACKGROUND

Endometrial receptivity is crucial for the establishment of a healthy pregnancy outcome. Previous research on endometrial receptivity primarily examined endometrial thickness, endometrial echo types, and endometrial blood supply.

OBJECTIVE

To explore the differences in the elastic modulus of the endometrium in women with various pregnancy outcomes by real-time shear wave elastography (SWE) and to investigate its application value in evaluation of endometrial receptivity.

METHODS

A total of 205 pregnant women who were admitted at Wenzhou People's Hospital between January 2021 and December 2022 were selected. Three-dimensional transvaginal sonography and real-time shear wave elastography were performed in the proliferative phase and receptive phase of the endometrium, and the average elastic modulus of the endometrium in the two phases was obtained and compared. According to whether the pregnancy was successful or not, the participants were divided into the pregnancy group (n= 72) and non-pregnancy group (n= 133), and the differences in intimal thickness, 3D blood flow parameters, and average elastic modulus of intima were compared between the two groups.

RESULTS

The average elastic modulus of the endometrium in the proliferative phase and receptive phase was (23.92 ± 2.31) kPa and (11.82 ± 2.24) kPa, respectively, and the difference was statistically significant P< 0.05. The average elastic modulus of the endometrium in the pregnancy group and non-pregnancy group was (9.97 ± 1.08) kPa and (12.82 ± 2.06) kPa, respectively, and the difference was statistically significant P< 0.05. The area under the curve of predicting pregnancy by the average elastic modulus of the endometrium in the receptive phase was 0.888 (0.841∼0.934), with corresponding P value < 0.05. The critical value was 11.15, with a corresponding sensitivity of 81.7% and specificity of 78.2%.

CONCLUSION

Real-time shear wave elastography can quantitatively evaluate endometrial elasticity, indirectly reflect the endometrial phase, and provide a new diagnostic concept for evaluating endometrial receptivity and predicting pregnancy outcome in infertile patients.

Thick endometrium is associated with hypertensive disorders of pregnancy in programmed frozen-thawed embryo transfers: a retrospective analysis of 2,275 singleton deliveries

OBJECTIVE

To investigate whether endometrial thickness (EMT) acts as a contributing factor to adverse perinatal outcomes in programmed frozen-thawed embryo transfer (FET) cycles.

DESIGN

Retrospective cohort study.

SETTING

University-based reproductive medical center.

SUBJECT

The study included singleton live births resulting from programmed FET cycles that took place between January 2017 and April 2022 (N = 2,275 cycles).

EXPOSURE

The EMT measurement conducted on the day of progesterone initiation was utilized. Programmed FET cycles with EMT <7 mm were excluded from consideration. All included subjects were divided into 4 groups on the basis of the 10th, 50th, and 90th percentiles of EMT: group Ⅰ (EMT ≤8 mm, n = 193), group Ⅱ (EMT = 8.1-10 mm, n = 1,261), group Ⅲ (EMT = 10.1-12 mm, n = 615), and group Ⅳ (EMT >12 mm, n = 206). After adjusting for patient demographics and FET parameters, logistic regression analysis and restricted cubic spline were used to investigate the relationship between EMT and perinatal outcomes. The group Ⅱ (EMT = 8.1-10 mm) served as a reference.

MAIN OUTCOME MEASURE(S)

The primary outcome measure was the hypertensive disorders of pregnancy (HDP). Secondary outcomes included gestational diabetes mellitus, cesarean delivery, placenta previa, premature rupture of membrane, birthweight, preterm birth, low birthweight, macrosomia, small for gestational age, large for gestational age and neonatal morbidity.

RESULTS(S)

The incidence of HDP was substantially elevated in group Ⅳ when compared with the other groups (5.7% vs. 4.1% vs. 5.7% vs. 9.7% for groups Ⅰ-Ⅳ, respectively). In addition, group I displayed a higher incidence of cesarean deliveries, whereas both group I and group IV exhibited an elevated prevalence of placenta previa. After adjusting for confounding factors, patients in group IV exhibited a significantly increased risk of HDP (adjusted odds ratio [OR] = 2.03, 95% confidence interval [CI] 1.13-3.67) as compared with patients in the reference group. The restricted cubic spline model revealed a nonlinear association between EMT and the odds of HDP on continuous scales. In comparison to women with an EMT of 9.5 mm, there was no significant change in the risk of HDP in women with EMT between 7 and 11 mm, as indicated by adjusted ORs of 1.37 (95% CI 0.41-4.52), 1.34 (95% CI 0.73-2.47), 1.13 (95% CI 0.79-1.62), 1.04 (95% CI 0.87-1.25), and 1.46 (95% CI 0.81-2.65), respectively. However, the risk of HDP was significantly higher in women with EMT ranging from 12 to 15 mm, with adjusted ORs of 1.86 (95% CI 1.03-3.35), 2.33 (95% CI 1.32-4.12), 2.92 (95% CI 1.52-5.60), and 3.62 (95% CI 1.63-8.04), respectively.

CONCLUSION(S)

This study demonstrated a noteworthy association between EMT and adverse perinatal outcomes during the programmed FET cycles. Specifically, a thick endometrium (EMT >12 mm) was independently associated with an increased risk of developing HDP, whereas the optimal EMT for reducing the risk of HDP was at around 9-10 mm.

Circadian serum progesterone variations on the day of frozen embryo transfer in artificially prepared cycles

RESEARCH QUESTION

What is the intra-day variation of serum progesterone related to vaginal progesterone administration on the day of frozen embryo transfer (FET) in an artificial cycle?

DESIGN

A prospective cohort study was conducted including 22 patients undergoing a single blastocyst artificial cycle (AC)-FET from August to December 2022. Endometrial preparation was achieved by administering oestradiol valerate (2 mg three times daily) and consecutively micronized vaginal progesterone (MVP; 400 mg twice daily). A blastocyst FET was performed on the 6th day of MVP administration. Serum progesterone concentrations were measured on the day of transfer at 08:00, 12:00, 16:00 and 20:00 hours. The first and last blood samples were collected just before MVP was administered.

RESULTS

The mean age and body mass index of the study population were 33.95 ± 3.98 years and 23.10 ± 1.95 kg/m2. The mean P-values at 08:00, 12:00, 16:00 and 20:00 hours were 11.72 ± 4.99, 13.59 ± 6.33, 10.23 ± 3.81 and 9.28 ± 3.09 ng/ml, respectively. A significant decline, of 2.41 ng/ml (95% confidence interval 0.81-4.00), was found between the first and last progesterone measurements.

CONCLUSION

A statistically significant intra-day variation of serum progesterone concentrations on the day of FET in artificially prepared cycles was observed. This highlights the importance of a standardized procedure for the timing of progesterone measurement on the day of AC-FET. Of note, the study results are applicable only to women using MVP for luteal phase support; therefore it is necessary to confirm its validity in comparison with the different existing administration routes of progesterone.

IVF with reception of oocytes from partner in lesbian couples: a systematic review and SWOT analysis

The growing utilization of assisted reproductive technology (ART) by the LGBTQ+ community, especially among lesbian couples, challenges societal norms and promotes inclusivity. The reception of oocytes from partner (ROPA) technique enables both female partners to have a biological connection to their child. A systematic review was conducted of the literature on ROPA IVF to provide the latest data and a SWOT analysis was subsequently performed to understand the strengths, weaknesses, opportunities and threats associated with ROPA IVF. Publications from 2000 to 2023 with relevant keywords were reviewed and 16 records were included. Five studies provided clinical information on couples who used ROPA IVF. ROPA IVF provides a unique opportunity for a biological connection between the child and both female partners and addresses concerns related to oocyte donation and anonymity. Weaknesses include limited cost-effectiveness data and unresolved practical implications. Opportunities lie in involving both partners in parenthood, advancing ART success rates and mitigating risks. Threats encompass increased pregnancy complications, ethical concerns, insufficient safety data, legal or cultural barriers, and emotional stress. In conclusion, ROPA IVF offers a promising solution for lesbian couples seeking to create a family in which both partners want to establish a biological connection with their child.

Development of a Predictive Model for Optimization of Embryo Transfer Timing Using Blood-Based microRNA Expression Profile

MicroRNAs (miRNAs) can regulate the expression of genes involved in the establishment of the window of implantation (WOI) in the endometrium. Recent studies indicated that cell-free miRNAs in uterine fluid and blood samples could act as alternative and non-invasive sample types for endometrial receptivity analysis. In this study, we attempt to systematically evaluate whether the expression levels of cell-free microRNAs in blood samples could be used as non-invasive biomarkers for assessing endometrial receptivity status. We profiled the miRNA expression levels of 111 blood samples using next-generation sequencing to establish a predictive model for the assessment of endometrial receptivity status. This model was validated with an independent dataset (n = 73). The overall accuracy is 95.9%. Specifically, we achieved accuracies of 95.9%, 95.9%, and 100.0% for the pre-receptive group, the receptive group, and the post-respective group, respectively. Additionally, we identified a set of differentially expressed miRNAs between different endometrial receptivity statuses using the following criteria: p-value < 0.05 and fold change greater than 1.5 or less than -1.5. In conclusion, the expression levels of cell-free miRNAs in blood samples can be utilized in a non-invasive manner to distinguish different endometrial receptivity statuses.

Expression of vascular endothelial growth factor A (VEGFA), placental growth factor (PlGF) and insulin-like growth factor 1 (IGF-1) in serum from women undergoing frozen embryo transfer

VEGFA, PlGF and IGF-1 are three main angiogenic factors which play significant roles in embryo implantation. However, the relationship between serum expressions of VEGFA, PlGF and IGF-1 and pregnancy outcomes has not been fully illustrated. In this study, serum specimens were collected precisely on day 7 after the LH surge in a natural non-conception cycle from 38 infertile patients who underwent frozen embryo transfer (FET) treatment. ELISA was used to determine the concentrations of VEGFA, PlGF and IGF-1. Serum levels of VEGFA, PlGF and IGF-1 were compared between patients who conceived (n=25) and who did not (n=13). Correlation and linear regression analyses were used to investigate the correlations of serum angiogenic factors and β-hCG MoM levels in the pregnant group. The results demonstrated that no significant difference was found in serum VEGFA, PlGF or IGF-1 concentration between pregnant and non-pregnant women. Spearman correlation analysis revealed a positive correlation between IGF-1 concentration and β-hCG level in pregnant participants (rs = 0.490, p = 0.013). In conclusion, serum IGF-1 level correlated positively with β-hCG level in pregnant women, which may provide information on the prognostic value of IGF-1 in this group of women.

The effects of different endometrial preparation regimens on pregnancy outcomes in frozen-thawed embryo transfer cycles: a prospective randomized controlled study

OBJECTIVE

An increasing number of research have emerged to compare the pregnancy outcomes between the natural cycle and the hormone replacement therapy (HRT) cycle in preparing the endometrium for frozen-thawed embryo transfer (FET), but the results are controversial. This prospective randomized controlled study was hence designed to obtain more solid evidence.

MATERIALS AND METHODS

In this study, patients with regular menstrual cycle length (21-35 days) who underwent FET between January 2010 to December 2017 were recruited for this study. Upon further filtering with the selection criteria of patients being, a total of 405 patients were recruited and randomized. Finally, analysis was performed on 384 patients: 178 belonged to the natural cycle group whereas the remaining 206 were in the HRT group. The primary outcome was live birth rate, while the secondary outcomes were implantation rate, clinical pregnancy rate, early miscarriage rate, late miscarriage rate, multiple birth rate and low birth weight rate.

RESULTS

The live birth rate (37.6% vs 30.1%, p = 0.119) of natural cycle group were higher than those of the hormone replacement therapy group, although the difference was not significant. The secondary outcomes were not found to differ significantly between the two groups. Nonetheless, the endometrium was found to be thicker in the natural cycle group (10.75 mm) than the HRT group (9.00 mm) (p < 0.001).

CONCLUSION

No significant differences were observed between the pregnancy outcomes of the natural cycle group and the HRT group which comprised of patients with regular menstrual cycle length.

Impact of Assisted Reproduction Techniques on Adverse Maternal Outcomes and on the Rate of Hospitalization in Maternal Intensive Care

Background and Objective: The aim of this retrospective cohort study is to evaluate the impact of assisted reproductive treatment (ART) on adverse maternal outcomes and the rate of hospitalization in maternal intensive care (MIC) in a tertiary university center in Liege, Belgium. Materials and Methods: This is a retrospective cohort study comparing two groups, 6557 patients who achieved pregnancy spontaneously and 330 patients who achieved pregnancy after ART, between January 2020 and December 2022. These patients were followed in the academic obstetrics department of Citadelle Hospital, Liège. The database of the ART center was compared with the database of the delivery unit to determine the cohort of patients who conceived after ART. Adverse maternal outcomes and MIC hospitalization rates were compared with between spontaneous pregnancies and ART groups. ART groups were also compared with each other. Results: The rate of hospitalization in maternal intensive care for patients who achieved pregnancy spontaneously was 12.1%, compared to 17.3% after ART. Comparing the rate of pre-eclampsia, 3.5% of spontaneous pregnancies were complicated by pre-eclampsia, while after ART, 10.9% of patients developed this complication during pregnancy. This rate was higher after IVF (12%) compared to intrauterine insemination and particularly after frozen embryo transfer (FET) in artificial cycle (17.9%). The birthweight of newborns after ART was also analyzed. A significant difference was obtained when comparing fresh embryo transfer with FET. Conclusions: Our study confirmed that FET in artificial cycle is a risk factor for pre-eclampsia and that fresh embryo transfer is associated with a higher rate of newborns with a lower percentile of birthweight. Our data showed that the rate of MIC hospitalization was significantly higher after ART but did not differ between groups.

Prediction of ovulation: new insight into an old challenge

Ultrasound monitoring and hormonal blood testing are considered by many as an accurate method to predict ovulation time. However, uniform and validated algorithms for predicting ovulation have yet to be defined. Daily hormonal tests and transvaginal ultrasounds were recorded to develop an algorithm for ovulation prediction. The rupture of the leading ovarian follicle was a marker for ovulation day. The model was validated retrospectively on natural cycles frozen embryo transfer cycles with documented ovulation. Circulating levels of LH or its relative variation failed, by themselves, to reliably predict ovulation. Any decrease in estrogen was 100% associated with ovulation emergence the same day or the next day. Progesterone levels > 2 nmol/L had low specificity to predict ovulation the next day (62.7%), yet its sensitivity was high (91.5%). A model for ovulation prediction, combining the three hormone levels and ultrasound was created with an accuracy of 95% to 100% depending on the combination of the hormone levels. Model validation showed correct ovulation prediction in 97% of these cycles. We present an accurate ovulation prediction algorithm. The algorithm is simple and user-friendly so both reproductive endocrinologists and general practitioners can use it to benefit their patients.

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.

Association of serum progesterone levels on the transfer day with pregnancy outcomes in hormone replacement frozen-thawed cycles with oral dydrogesterone for strengthened luteal phase support

OBJECTIVE

To investigate the relationship between serum progesterone (P) levels on the day of blastocyst transfer and pregnancy outcomes in frozen-thawed embryo transfer (FET) cycles using hormone replacement therapy (HRT) with oral dydrogesterone for strengthened luteal phase support (LPS).

MATERIALS AND METHODS

This was a retrospective study including 1176 FET cycles. All patients received 40 mg of intramuscular (IM) P daily for endometrium transformation plus oral dydrogesterone 10 mg BID from transfer day for strengthened LPS. Pregnancy outcomes were compared between serum P levels on the transfer day ≥10 ng/ml and <10 ng/ml. Furthermore, cycles were divided into 10 groups by deciles of P and ongoing pregnancy rate (OPR) was calculated in each group. Analyses using deciles of serum P were completed to see if these could create further prognostic power.

RESULTS

No differences were observed in clinical pregnancy rates (CPRs), OPRs and live birth rates (LBRs) between serum P levels ≥10 ng/ml and <10 ng/ml. Patients with serum P levels <5.65 ng/ml (10th percentile) had a significantly lower OPR (48.31% vs. 58.98%, p = 0.03) and LBR (43.22% vs. 57.75%, p = 0.003) than the rest of the patients. Multivariate logistic regression analysis showed serum P levels on the transfer day were not associated with pregnancy outcomes.

CONCLUSION

Measuring serum P levels on the day of HRT-FET is of clinical importance. Lower serum P levels impact the success of HRT-FET cycles, suggesting that there may be a threshold below which it is difficult to improve pregnancy outcomes via oral dydrogesterone to strengthen LPS.

Impact of Endometrial Preparation on the Maternal and Fetal Cardiovascular Variables of the First Trimester Combined Screening Test

The modality of endometrial preparation for the transfer of frozen-thawed embryos may influence maternal and fetal adaptation to pregnancy and could thus impact the results of the first trimester combined screening test. We conducted a retrospective cross-sectional study on singleton pregnancies achieved by embryo transfer of a single frozen-thawed blastocyst, comparing two different endometrial preparation protocols: natural cycle (n = 174) and hormone replacement therapy (HRT) (n = 122). The primary outcome was the risk of preeclampsia at the first trimester combined screening test. Secondary endpoints included variable reflecting fetal cardiac function (nuchal translucency and fetal heart rate), maternal adaptation (median arterial blood pressure-MAP and uterine arteries pulsatility index-UtA-PI), and placentation (pregnancy associated plasma protein A and placental growth factor). The risk of early preeclampsia was comparable in the two groups (38% vs. a 28%, p = 0.12). However, women in the natural cycle group showed lower fetal heart rate (159 [155-164] vs. 164 [158-168], p = 0.002) and higher UtA-PI (0.96 [0.74-1.18] vs. 0.72 [0.58-0.90], p < 0.001). The frequency of a screening test at high risk for aneuploidies was similar. The modality of transfer of frozen-thawed embryos is associated with changes in the variables reflecting maternal and fetal cardiovascular function.

Live birth rates after resolution of endometrial cavity fluid in frozen embryo transfer cycles

RESEARCH QUESTION

Are live birth rates affected in frozen embryo transfer cycles that develop transient endometrial cavity fluid that resolves by day of embryo transfer?

DESIGN

The first frozen blastocyst transfer cycle between January 1st, 2016 and December 31st, 2019 were included in this retrospective cohort study at an academic fertility center. The presence or absence of endometrial cavity fluid (ECF) detected on initial ultrasound and at time of transfer was recorded. Patients who had persistent ECF at time of transfer were excluded from the study. The primary outcome was live birth rate in the group with resolved ECF relative to the group without ECF.

RESULTS

A total of 1034 frozen blastocyst transfer cycles were included, 54 with resolved ECF and 980 without ECF. Adjusted analyses were performed using a log-binomial regression model. Live birth rates were 35.2% and 34.2%, adjusted risk ratio 1.00 [95% CI 0.70-1.50] in the two groups, respectively.

CONCLUSION

Live birth rates in frozen embryo transfer cycles are equivalent between patients with resolved endometrial cavity fluid compared to those who never had endometrial cavity fluid. Our findings suggest that the presence of endometrial cavity fluid is likely not detrimental to live birth rates if the fluid spontaneously resolves by the time of embryo transfer.

Natural Cycle Frozen Embryo Transfer: Evaluating Optimal Protocols for Preparation and Timing

Background

While natural cycle frozen embryo transfer (NC-FET) is becoming increasingly common, significant practice variation exists in the use of ovulation induction medications, administration of ovulation trigger, and timing of embryo transfer without consensus as to the optimal protocol.

Aims

The objective of this study is to evaluate the association of key aspects of the NC-FET protocol with implantation, pregnancy and live birth.

Settings and Design

This was a retrospective cohort study of blastocyst stage NC-FET cycles from October 2019 to July 2021 at a single academic fertility centre.

Materials and Methods

Protocols varied between cycles across three key parameters which were evaluated as primary predictors of cycle outcomes: (1) use of letrozole for mild ovarian stimulation/ovulation induction, (2) administration of exogenous ovulation trigger versus spontaneous luteinising hormone surge and (3) transfer timing based on ovulation trigger versus sequential progesterone monitoring. Primary outcomes included implantation rate, clinical pregnancy and ongoing pregnancy.

Statistical Analysis Used

Generalised estimating equations were fitted to obtain adjusted odds ratios or rate ratios as appropriate with 95% confidence intervals for each outcome across the three primary predictors.

Results

A total of 183 cycles from 170 unique patients were eligible for inclusion. The average implantation rate was 0.58, resulting in an overall clinical pregnancy and ongoing pregnancy rate of 59.0% and 51.4%, respectively. After adjusting for age at embryo freeze and history of a failed embryo transfer, there were no significant associations between any predictor and implantation rate, clinical pregnancy, ongoing pregnancy, or live birth.

Conclusion

In NC-FET, a variety of preparation and timing protocols may lead to comparable cycle outcomes, potentially allowing for flexibility on the basis of patient and physician preference. These findings warrant validation in a larger, randomised trial.

Live birth after letrozole-stimulated cycles versus hormone replacement treatment cycles for the first frozen embryo transfer in women with polycystic ovary syndrome: protocol for a multicentre randomised controlled trial

INTRODUCTION

Hormone replacement treatment (HRT) is the most commonly used endometrial preparation protocol for frozen embryo transfer (FET) in patients with polycystic ovary syndrome (PCOS). However, studies have found that HRT may increase the risk of hypertensive disorders of pregnancy and some obstetric complications. Letrozole is a new first-line ovulation induction drug for PCOS and can effectively induce spontaneous ovulation by reducing oestrogen levels. However, letrozole is still rarely used in FET and has only been reported in a few studies in Asian populations. High-quality, well-powered randomised controlled trials (RCTs) comparing HRT and letrozole-stimulated protocols are lacking. The aim of this study is to compare the efficacy and safety of two protocols in patients with PCOS.

METHODS AND ANALYSIS

This is a multicentre, open-label RCT in four reproductive medical centres in China. In total, 1078 women with PCOS will be randomised (1:1) to the letrozole-stimulated or HRT group in their first FET cycle and their pregnancy and perinatal outcomes during this cycle will be followed up and analysed. The primary outcome is live birth. Secondary outcomes are cycle cancellation rate, biochemical pregnancy, clinical pregnancy, miscarriage, ectopic pregnancy, obstetric and perinatal complications, neonatal complications and birth weight.

ETHICS AND DISSEMINATION

Ethical approval was obtained from the Institutional Review Board of Reproductive and Genetic Hospital of CITIC-XIANGYA (LL-SC-2022-001). Written informed consent will be obtained from each participant. The findings will be disseminated through conference presentations and publication in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT05227391.

An ultrasound-based deep learning radiomic model combined with clinical data to predict clinical pregnancy after frozen embryo transfer: a pilot cohort study

RESEARCH QUESTION

Can a multi-modal fusion model based on ultrasound-based deep learning radiomics combined with clinical parameters provide personalized evaluation of endometrial receptivity and predict the occurrence of clinical pregnancy after frozen embryo transfer (FET)?

DESIGN

Prospective cohort study of women (n = 326) who underwent FET between August 2019 and December 2021. Input quantitative variables and input image data for radiomic feature extraction were collected to establish a multi-modal fusion prediction model. An additional independent dataset of 453 ultrasound endometrial images was used to establish the segmentation model to determine the endometrial region on ultrasound images for analysis. The performance of different algorithms and different input data for prediction of FET outcome were compared.

RESULTS

A total of 240 patients with complete data were included in the final cohort. The proposed multi-modal fusion model performed significantly better than the use of either image or quantitative variables alone to predict the occurrence of clinical pregnancy after FET (P ≤ 0.034). Its area under the curve, accuracy, sensitivity, specificity, positive predictive value and negative predictive value of the proposed model were 0.825, 72.5%, 96.2%, 58.3%, 72.3% and 89.5%, respectively. The Dice coefficient of the multi-task endometrial ultrasound segmentation model was 0.89. Use of endometrial segmentation features significantly improved the prediction performance of the model (P = 0.041).

CONCLUSIONS

The multi-modal fusion model based on ultrasound-based deep learning radiomics combined with clinical quantitative variables offers a favourable and rapid non-invasive approach for personalized prediction of FET outcome.

Oocyte donation outcomes in endometriosis patients with multiple IVF failures

RESEARCH QUESTION

What are the reproductive outcomes and the prognostic factors of live birth rates in patients with endometriosis referred to oocyte donation after multiple IVF failures?

DESIGN

Observational cohort study including all women with endometriosis-related infertility and two or more failed IVF/intracytoplasmic sperm injection (ICSI) cycles referred to oocyte donation between January 2013 and June 2022. Endometriosis was diagnosed based on published imaging criteria, and was confirmed histologically in women who had a history of surgery for endometriosis. The main outcome measured was the cumulative live birth rate (CLBR). The characteristics of women who had a live birth were compared with those who did not using univariate and multivariate analysis to identify determinant factors of fertility outcome.

RESULTS

Fifty-seven patients underwent 90 oocyte donation cycles after 244 failed autologous IVF cycles. The mean ± SD age of the population was 36.8 ± 3.3 years, with a mean duration of infertility of 3.6 ± 2.2 years, and a mean number of autologous IVF/ICSI cycles of 4.4 ± 2.3 cycles per patient. Three patients (5.3%) had superficial peritoneal endometriosis, two patients (3.5%) had ovarian endometriomas, and 52 patients (91.2%) had deep infiltrating endometriosis, among which 30 patients (57.7%) had bowel lesions. Thirty patients (52.6%) had associated adenomyosis. Overall, CLBR per patient was 36/57 (63.2%). After multivariate analysis, only being nulligravida (P=0.002) remained an independent negative predictive factor of the live birth rate. Previous surgery did not impact reproductive outcomes.

CONCLUSION

This study suggests that oocyte donation appears to be a viable option to optimize the live birth rate in women with endometriosis-related infertility and recurrent IVF failures.

Association between duration of progesterone supplementation and clinical outcomes in artificial frozen-thawed embryo transfer cycles

Objective

The administration of progesterone before transfer in hormone replacement treatment (HRT) is crucial for the clinical outcomes of frozen-thawed embryo transfer (FET), but the optimal duration of progesterone remains controversial. This study aimed to investigate the effect of the duration of progesterone administration on the clinical outcomes of FET cycles.

Methods

This prospective cohort study included 353 artificial FET cycles conducted at a reproductive medicine center between April and October 2021. The FET cycles were stratified into four groups based on the duration of progesterone supplementation before the procedure and the embryonic development stage: group P3 (73 patients) received intramuscular progesterone for 3 days and group P4 (87 patients) for 4 days before Day 3 frozen embryo transfer, group P5 (70 patients) for 5 days and group P6 (123 patients) for 6 days before frozen blastocyst transfer. This trial was performed using one or two vitrified embryo(s) when the endometrial thickness reached 7 mm after estrogen supplementation in an artificial cycle. The primary outcome was clinical pregnancy, and secondary outcomes included biochemical pregnancy, implantation, early pregnancy loss, and live births.

Results

There were no significant differences in the demographic and clinical characteristics between the groups. No significant difference was observed in the clinical pregnancy rates between groups: 23/73 (31.5%) in group P3 vs 28/87 (32.2%) in group P4 (P = 0.927). Compared to group P5 (41/70, 58.6%), the clinical pregnancy rate was not significantly different in group P6 (77/123, 62.6%, P = 0.753). There was no significant difference in the implantation rates between groups: 33/136 (24.3%) in group P3 vs 34/166 (20.5%) in group P4 (P = 0.431), and 62/133 (46.6%) in group P5 vs 107/231 (46.3%) in group P6 (P = 0.956). The duration of progesterone supplementation (mean: 3.5 ± 0.5 days; range:3-4 days) before Day 3 frozen embryo transfer did not impact clinical pregnancy (odds ratio [OR] 1.048; 95% confidence interval [CI], 0.518-2.119). The duration of progesterone administration (mean: 5.6 ± 0.5 days; range:5-6 days) before frozen blastocyst transfer may not affect clinical pregnancy (OR 1.339; 95% CI, 0.717-2.497).

Conclusion

There may be no significant correlation between the duration of progesterone supplementation and pregnancy outcomes in artificial FET cycles, although the clinical pregnancy rate was higher when progesterone supplementation was extended for one day before FET.

The Effect of Different Luteal Phase Support Applications on Clinical Pregnancy Outcomes in Frozen-Thawed Embryo Transfer

Purpose

During the frozen-thawed embryo transfer (FET) method, controlled ovarian hyperstimulation is used. At the same time, progesterone support is given for luteal phase support. In this study, we investigated the effects of various luteal phase support agents administered orally, intramuscularly (IM), and vaginally during FET on pregnancy rates.

Methods

The files of 166 patients between the ages of 21 and 44 in the Assisted Reproductive Techniques Center of Acıbadem Mehmet Ali Aydınlar University Atakent Hospital were analyzed retrospectively between 2016 and 2022. The patients' FSH, LH, E2, P4, AMH, and TSH levels were measured. The GnRH antagonist protocol was initiated on the 2nd or 3rd day of menstruation. Three types of progesterone agents were used in females with PCOS. Three different methods were applied: 50 mg/ml of IM progesterone daily, 90 mg of progesterone gel 2∗1 vaginally, and dydrogesterone acetate tb. orally 3∗1. FET was performed on women who received 21 days of treatment by thawing 5th-day embryos. B-hCG was performed on the 12th day after the transfer, and evaluations were made. The study results were evaluated as follows: for the whole study group, for those <30 years of age, for those 30-35 years of age, and for those >35 years of age.

Results

A total of 164 patients, 57 females using vaginal progesterone gel, 30 females using oral progesterone tablet, and 77 females using IM progesterone, who met the inclusion criteria, were included in the study. The pregnancy outcomes of IM progesterone application were statistically significantly higher in the entire study group and the >35 age group when compared to the vaginal progesterone gel application. It was found that the pregnancy outcomes of IM progesterone application increased statistically significantly in the <30 age group when compared to outcomes in the other groups, using vaginal progesterone gel and oral progesterone tb.

Conclusions

We found that IM progesterone application was more effective than vaginal progesterone gel application for luteal phase support. Many randomized controlled, especially live birth rate studies, are required before results can more closely approximate those for the general population.

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.

Maternal Hepatitis B Virus Infection and Pregnancy Outcomes of Freeze-Thaw Embryo Transfer

This cohort study assesses the association of maternal hepatitis B virus (HBV) serostatus with pregnancy outcomes in women undergoing freeze-thaw embryo transfer (FET).

The relationship between dominant follicle development and clinical outcomes of hormone replacement therapy-frozen embryo transfer: a retrospective clinical study

Research question

Hormone replacement therapy (HRT) is one of the most used endometrial preparation protocols for frozen embryo transfer (FET) due to the convenience of its administration and stability of pregnancy outcomes. There are several HRT cycles accompanied by the development of dominant follicles. However, the relationship between dominant follicle development and clinical outcomes in HRT-FET cycles remains unclear.

Design

We carried out a retrospective cohort study of 13251 cycles at our reproductive medicine center from 2012 to 2019. Total cycles were divided into two groups according to whether there was dominant follicular development. In addition, we conducted a secondary analysis that used propensity-score matching to reduce confounding variables. A univariate and multivariable logistic regression model was further employed to analyze the effect of dominant follicle development in HRT cycles on clinical pregnancy outcomes.

Results

There was no significant correlation between dominant follicle development in HRT-FET cycles and the clinical pregnancy rate (adjusted OR = 1.162, 95% CI: 0.737-1.832, P = 0.52). In addition, there was a positive correlation between the basic follicle-stimulating hormone (FSH) level and the development of dominant follicles, while there was a negative correlation between antral follicle count (AFC), menstrual cycle length and the development of dominant follicles in HRT cycles.

Conclusions

The development of dominant follicles in HRT-FET cycles does not affect the clinical pregnancy rate, early miscarriage rate and live birth rate. Therefore, it is not necessary to immediately cancel the FET cycle immediately when dominant follicle development is monitored in the HRT-FET cycle.

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.

PGT-A improved singleton live birth rate among all age groups of women who underwent elective single blastocyst transfer: a single-centre retrospective study

PURPOSE

This study assessed the difference in singleton live birth rate (SLBR) between preimplantation genetic testing for aneuploidy (PGT-A) and non-PGT in patients undergoing elective single frozen blastocyst transfer (eSFBT).

METHODS

This retrospective cohort study evaluated 10,701 cycles of eSFBT, including PGT-A (n = 3125) and non-PGT (n = 7576). Cycles were further stratified according to age at retrieval. The main outcome was SLBR; secondary outcomes were clinical pregnancy, conception rates, and multiple live birth rate. Confounders were adjusted using multivariable logistic regression models, and the trend test was performed using the general linear model.

RESULTS

SLBR was negatively correlated with age in the non-PGT group (p-trend < 0.001) but not in PGT-A group (p-trend = 0.974). Stratified by the age, SLBR were significantly different between two groups except for the 20-24-year-old group: PGT-A vs non-PGT group in 20-24, 25-29, 30-34, 35-39 and ≥ 40-year-old subgroups were, 53.5% vs 53.2%, 53.5% vs 48.0%, 53.5% vs 43.1%, 53.3% vs 32.5%, and 42.9% vs 17.6%, respectively. In addition, after adjusting for potential confounders, SLBR still remained significantly different in all age groups except in the youngest quartile (PGT-A vs non-PGT group, 20-24: adjusted odds ratio (aOR), 1.33, 95% CI, 0.92-1.92, p = 0.129; 25-29: aOR, 1.32, 95% CI, 1.14-1.52, p < 0.001; 30-34: aOR, 1.91, 95% CI, 1.65-2.20, p < 0.001; 35-39: aOR, 2.50, 95% CI, 1.97-3.17, p < 0.001; ≥ 40: aOR, 3.54, 95% CI, 1.66-7.55, p = 0.001).

CONCLUSION

PGT-A might improve SLBR among all age groups and play an increasingly important role in SLBR in older patients who underwent eSFBT.

Association between serum progesterone levels on the day of frozen-thawed embryo transfer and pregnancy outcomes after artificial endometrial preparation

BACKGROUND

Previous studies have examined that a range of optimal serum P level during the implantation period was associated with optimal live birth rates. However, those results obtained with vaginal or intramuscular route of progesterone administration for luteal phase support (LPS) alone. Is there a relationship between the serum progesterone (P) on the day of frozen-thawed embryo transfer (FET) with the likelihood of a live birth (LB) in artificial cycles (AC) when using a combination of oral dydrogesterone and vaginal progesterone for LPS?

METHODS

This was a retrospective study of 3659 FET cycles with artificial endometrial preparation in a Chinese tertiary-care academic medical centre from January 2015 to February 2017. Endometrial preparation was performed using estradiol (E₂) valerate (Fematon-red tablets) 8 mg/d beginning on day 3 of the cycle, followed by administration of P both orally (8 mg/d Fematon-yellow tablets) and vaginally (400 mg/d; Utrogestan). The primary endpoint was live birth rate (LBR). The association between the serum P level on the embryo transfer day and pregnancy outcomes was evaluated by univariable and multivariable logistic regression analysis.

RESULTS

The LBRs according to the serum P quartiles were as follows: Q1: 35.7%; Q2: 37.4%; Q3: 39.1% and Q4: 38.9%. Logistic regression analysis showed that the odds of a LB were not significantly different between the low (P < 7.9 ng/mL) and high (P ≥ 7.9 ng/mL) progesterone groups before or after adjustment (crude OR = 0.89, 95% CI: 0.76-1.04; adjusted OR = 0.89, 95% CI: 0.75-1.04).

CONCLUSION

The present study suggests that the serum P levels on the day of embryo transfer (ET) do not correlate with the likelihood of a LB in artificial cycles when using a combination of oral dydrogesterone and vaginal progesterone for luteal phase support.

Interindividual variation of progesterone elevation post LH rise: implications for natural cycle frozen embryo transfers in the individualized medicine era

BACKGROUND

The key to optimal timing of frozen embryo transfer (FET ) is to synchronize the embryo with the receptive phase of the endometrium. Secretory transformation of the endometrium is induced by progesterone. In contrast, detection of the luteinizing hormone (LH) surge is the most common surrogate used to determine the start of secretory transformation and to schedule FET in a natural cycle. The accuracy of LH monitoring to schedule FET in a natural cycle relies heavily on the assumption that the period between the LH surge and ovulation is acceptably constant. This study will determine the period between LH rise and progesterone rise in ovulatory natural menstrual cycles.

METHODS

Retrospective observational study including 102 women who underwent ultrasound and endocrine monitoring for a frozen embryo transfer in a natural cycle. All women had serum LH, estradiol and progesterone levels measured on three consecutive days until (including) the day of ovulation defined with serum progesterone level exceeding 1ng/ml.

RESULTS

Twenty-one (20.6%) women had the LH rise 2 days prior to progesterone rise, 71 (69.6%) had on the day immediately preceding progesterone rise and 10 (9.8%) on the same day of progesterone rise. Women who had LH rise 2 days prior to progesterone rise had significantly higher body mass index and significantly lower serum AMH levels than women who had LH rise on the same day with progesterone rise.

CONCLUSION

This study provides an unbiased account of the temporal relationship between LH and progesterone increase in a natural menstrual cycle. Variation in the period between LH rise and progesterone rise in ovulatory cycles likely has implications for the choice of marker for the start of secretory transformation in frozen embryo transfer cycles. The study participants are representative of the relevant population of women undergoing frozen embryo transfer in a natural cycle.

Ovulatory-cycle frozen embryo transfer: spontaneous or triggered ovulation and the impact of LH elevation at hCG triggering

The effect of the luteinizing hormone (LH) elevation before the human chorionic gonadotropin (hCG) trigger in ovulatory frozen-thawed embryo transfer (Ovu-FET) cycles has not been determined. We aimed to investigate whether triggering ovulation in Ovu-FET cycles affects the live birth rate (LBR), and the contribution of elevated LH at the time of hCG trigger. This retrospective study included Ovu-FET cycles performed in our center from August 2016 to April 2021. Modified Ovu-FET (hCG trigger) and true Ovu-FET (without hCG trigger) were compared. The modified group was divided according to whether hCG was administered, before or after LH increased to > 15 IU/L and was twice the baseline value. The modified (n = 100) and true (n = 246) Ovu-FET groups and both subgroups of the modified Ovu-FET, those who were triggered before (n = 67) or after (n = 33) LH elevation, had comparable characteristics at baseline. Comparison of true vs. modified Ovu-FET outcomes revealed similar LBR (35.4% vs. 32.0%; P = 0.62), respectively. LBR were similar between the modified Ovu-FET subgroups regardless of the hCG trigger timing (31.3% before vs. 33.3% after LH elevation; P = 0.84). In conclusion, LBR of Ovu-FET were not affected by hCG trigger or whether LH was elevated at the time of hCG trigger. These results add reassurance regarding hCG triggering even after LH elevation.

Fetal cardiac function at midgestation and conception by in-vitro fertilization

OBJECTIVE

To assess differences in cardiac morphology and function at midgestation in fetuses conceived by in-vitro fertilization (IVF), using fresh or frozen embryo transfer, compared with those conceived naturally.

METHODS

This was a prospective study of 5801 women with a singleton pregnancy attending for a routine ultrasound examination at 19 + 0 to 23 + 6 weeks' gestation, including 343 that conceived by IVF. Conventional and more advanced echocardiographic modalities, including speckle-tracking analysis, were used to assess fetal cardiac function in the right and left ventricles. The morphology of the fetal heart was assessed by calculating the right and left sphericity index. Placental perfusion and function were assessed by measurement of uterine artery pulsatility index (UtA-PI) and serum placental growth factor (PlGF), respectively.

RESULTS

Fetuses that were conceived by IVF, compared with those conceived spontaneously, had significantly lower right and left ventricular sphericity index, higher left ventricular global longitudinal strain and lower left ventricular ejection fraction. There were no significant differences in any of the cardiac indices within the IVF group between the fresh and frozen embryo transfers. In the IVF group, compared with spontaneously conceived pregnancies, UtA-PI was lower and PlGF was higher, suggesting better placental perfusion and function.

CONCLUSIONS

Our study demonstrates that, in IVF pregnancies, compared with those conceived spontaneously, there is evidence of fetal cardiac remodeling at midgestation, which is not related to the use of fresh or frozen embryo transfer. In the IVF group, compared with naturally conceived pregnancies, fetal heart was globular and left ventricular systolic function was mildly reduced. Whether these cardiac changes are accentuated later in pregnancy and remain in the postnatal period remains to be established. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Natural cycle frozen embryo transfer: a survey of current assisted reproductive technology practices in the U.S

PURPOSE

Emerging data suggests improved obstetric outcomes with frozen embryo transfer (FET) in an ovulatory or natural cycle (NC-FETs), as compared to programmed endometrial preparation. The objective of this study is to better understand practice patterns and provider attitudes regarding the use of NC-FETs in the United States (U.S.).

METHODS

In this cross-sectional study, an anonymous 22-question survey was emailed to 441 U.S. Assisted Reproductive Technology (ART) clinics to assess the utilization of NC endometrial preparation for FET, protocols used, restrictions to offering NC-FET, and providers' perspectives on advantages and disadvantages of NC-FET. Descriptive statistics were used to analyze survey responses.

RESULT(S)

The survey response rate was 49% (216/441). Seventeen percent of responding clinics did not offer NC-FET. Of the clinics that did not offer NC-FET, 65% had only 1-2 physicians in their practice. Common reasons for not offering NC-FET included "lack of timing predictability for transfer" (81%) and "increased burden on staff/laboratory personnel on holidays and weekends" (54%). Of clinics offering NC-FET, 76% reported < 25% of cycles used the NC for endometrial preparation. Over half (52%) of clinics that offered NC-FET reported having eligibility restrictions for NC-FET. Reported benefits of NC-FET were "patient satisfaction" (18%), "decreased cost of medications" (18%), and "avoidance of intramuscular progesterone" (17%). The attitude towards NC-FET in their clinics was reported as positive by 65% of respondents.

CONCLUSION

NC-FETs are offered by most U.S. ART clinics but are used only in the minority of FET cycles for endometrial preparation, and use is often restricted.

Comparing endometrial preparation methods in frozen embryo transfers - Does a previous live birth make a difference?

RESEARCH QUESTION

Does the outcome of a medicated or natural endometrial preparation for a frozen cycle differ if a patient has previously experienced a failed fresh cycle?

DESIGN

Retrospective matched case-controlled study to investigate frozen embryo transfer (FET) outcomes in women undergone medicated or natural endometrial preparation, with adjustment to the history of previous live birth. 878 frozen cycles were included for analysis, over a period of 2 years.

RESULTS

After adjusting for the number of embryos transferred, endometrial thickness and the number of previous embryo transfers, there was no difference in live birth rate (LBR) between medicated-FET and natural-FET groups regardless of the previous fertility outcome (p = 0.08).

CONCLUSIONS

A previous live birth does not affect the outcome of a subsequent frozen cycle, regardless of whether medicated- or natural endometrial preparation is used.

Influencing factors and predictive model of live birth involving low-grade blastocyst frozen-thawed transfer: a retrospective study

BACKGROUND

Whether only low-grade blastocysts should undergo freeze-thaw transfer during the in vitro fertilization/intracytoplasmic sperm injection cycle remains controversial; however, high-quality embryos cannot be obtained from some patients. Therefore, we aimed to identify factors that may affect the live birth.

METHODS

A total of 662 couples with only low-grade blastocysts who voluntarily accepted freeze-thaw blastocyst transfer at a single reproductive center over a 7-year period were followed-up. According to the outcome after transfer, they were divided into live birth group and failed pregnancy group. A nomogram was constructed for predicting live births.

RESULTS

Baseline information and clinical treatment characteristics of patients in the two groups were comparable. Fifty-two of the 662 cycles (7.9%) resulted in live birth. Paternal age, maternal basal luteinizing hormone level, endometrial preparation scheme, and blastocyst development days were independent factors that affected low-grade blastocyst freeze-thaw transfer outcomes. The predictive model constructed based on these four factors presented favorable calibration and discriminatory abilities (area under the curve, 0.734; 95% confidence interval, 0.781-0.813).

CONCLUSIONS

For patients who exclusively underwent low-grade blastocyst freeze-thaw transfer, advanced paternal age and a high level of maternal basal luteinizing hormone adversely affected low-grade blastocyst freeze-thaw transfer outcomes. Artificial cycle preparation of the endometrium and day 5 blastocyst selection may improve the probability of live birth.