Natural cycle frozen-thawed embryo transfer in young women with regular menstrual cycles increases the live-birth rates compared with hormone replacement treatment: a retrospective cohort study

Pregnancy and perinatal outcomes in pregnancies following frozen embryo transfer (FET) after transcervical resection of adhesions (TCRA): A retrospective cohort study with propensity score matching analysis

OBJECTIVE

To compare the pregnancy and perinatal outcomes of frozen-thawed embryo transfer (FET) in patients following transcervical resection of adhesions (TCRA) versus patients with normal uterine morphology, and to investigate the factors influencing pregnancy outcomes in patients undergoing FET after TCRA.

METHODS

We retrospectively analyzed FET cycles from September 2014 to September 2023, comparing patients with normal uterine morphology to those with intrauterine adhesions (IUAs) treated with TCRA. Propensity score matching (PSM) adjusted for confounding factors. LASSO regression and multivariate logistic regression identified predictors of outcomes, which were visually represented in nomograms. Model performance was assessed using calibration curves, ROC curves, and DCA, with bootstrap method for internal validation.

RESULTS

Post-PSM analysis showed higher live birth rates in patients with normal uterine morphology after clinical pregnancy (75.1% vs. 61.7%, P < 0.001). No significant differences were noted in clinical pregnancy rates and perinatal outcomes between the groups. Factors influencing clinical pregnancy in FET after TCRA included basal progesterone levels, endometrial thickness, parity, infertility cause, embryo stage at transfer, number and quality of embryos transferred, IUA severity, and TCRA surgical procedures. Body mass index, basal LH levels, and day 14 HCG levels post-embryo transfer were determinants of live birth outcome.

CONCLUSION

FET cycles following TCRA showed a lower rate of successful live births, but TCRA did not increase adverse perinatal outcome risks. Our study introduces an innovative predictive model for clinical pregnancy and live birth outcomes in patients undergoing FET following TCRA, addressing a significant void in existing research.

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.

Comparison of clinical outcomes and perinatal outcomes between natural cycle and hormone replacement therapy of frozen-thawed embryo transfer in patients with regular menstruation: a propensity score-matched analysis

Purpose

To investigate potential differences in pregnancy outcomes among patients with regular menstruation who underwent frozen-thawed embryo transfer using natural cycle (NC) or hormone replacement therapy (HRT).

Methods

This study retrospectively analyzed 2672 patients with regular menstruation who underwent FET from November 2015 to June 2021 at the single reproductive medical center. A one-to-one match was performed applying a 0.02 caliper with propensity score matching. Independent factors influencing the live birth and clinical pregnancy rates were screened and developed in the nomogram by logistic regression analysis. The efficacy of live birth rate and clinical pregnancy rate prediction models was assessed with the area under the ROC curve, and the live birth rate prediction model was internally validated within the bootstrap method.

Results

The NC protocol outperformed the HRT protocol in terms of clinical pregnancy and live birth rates. The stratified analysis revealed consistently higher live birth and clinical pregnancy rates with the NC protocol across different variable strata compared to the HRT protocol. However, compared to the HRT treatment, perinatal outcomes indicated that the NC protocol was related to a higher probability of gestational diabetes. Multifactorial logistic regression analysis demonstrated independent risk factors for live birth rate and clinical pregnancy rate. To predict the two rates, nomogram prediction models were constructed based on these influencing factors. The receiver operating characteristic curve demonstrated moderate predictive ability with an area under curve (AUC) of 0.646 and 0.656 respectively. The internal validation of the model for live birth rate yielded an average AUC of 0.646 implying the stability of the nomogram model.

Conclusion

This study highlighted that NC yielded higher live birth and clinical pregnancy rates in comparison to HRT in women with regular menstruation who achieved successful pregnancies through frozen-thawed embryo transfer. However, it might incur a higher risk of developing gestational diabetes.

Does growth hormone supplementation of in vitro fertilization/intracytoplasmic sperm injection improve cumulative live birth rates in women with poor embryonic development in the previous cycle?

BACKGROUND

Growth hormone (GH) has been proposed as an adjunct in in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) cycles, especially in women with poor ovarian response. However, it is unclear whether GH supplementation is effective in women with poor embryonic development in the previous IVF cycle. The aim of this study was to evaluate the effectiveness of GH supplementation in IVF/ICSI cycles in women with poor embryonic development in the previous cycle.

METHODS

This is a retrospective cohort study from a public fertility center in China, in which we performed propensity score-matching (PSM) for female age and AFC in a ratio of 1:1. We compared the cumulative live birth rate per started cycle, as well as a series of secondary outcomes. We included 3,043 women with poor embryonic development in the previous IVF/ICSI cycle, of which 1,326 had GH as adjuvant therapy and 1,717 had not. After PSM, there were 694 women in each group.

RESULTS

After PSM, multivariate analyses showed the cumulative live birth rate to be significantly higher in the GH group than the control group [N = 694, 34.7% vs. N = 694, 27.5%, risk ratio (RR): 1.4 (95%CI: 1.1-1.8)]. Endometrial thickness, number of oocytes retrieved, number of embryos available, and number of good-quality embryos were significantly higher in the GH group compared to controls. Pregnancy outcomes in terms of birth weight, gestational age, fetal sex, preterm birth rate, and type of delivery were comparable. When we evaluated the impact of GH on different categories of female age, the observed benefit in the GH group did not appear to be significant. When we assessed the effect of GH in different AFC categories, the effect of GH was strongest in women with an AFC5-6 (32.2% versus 19.5%; RR 2.0; 95% CI 1.2-3.3).

CONCLUSIONS

Women with poor embryonic quality in the previous IVF/ICSI cycles have higher rates of cumulative live birth with GH supplementation.

Clinical outcomes of frozen-thawed embryo transfer in natural cycles with luteinized unruptured follicles

OBJECTIVE

To assess the effect of luteinized unruptured follicles (LUF) on frozen-thawed embryo transfer cycles performed in natural cycles (FET-NC).

METHODS

Retrospective cohort study, held in a university hospital with 3415 cycles for frozen-thawed embryo transfer, performed between June 2019 and September 2022. Using propensity score matching, 242 patients with a diagnosis of LUF (LUF group) were matched with 484 ovulated patients (ovulation group). Stratified by the type of embryo transferred, the LUF group included 168 blastocyst transfer patients (blastocyst group) and 74 cleavage-stage embryo transfer patients (cleavage-embryo group). The ovulation group included 324 patients with blastocyst transfer (blastocyst group) and 160 patients with transferred cleavage-stage embryos. Clinical pregnancy rate was retrospectively analyzed between the LUF and ovulation groups, as well as between each subgroup.

RESULTS

After using propensity score matching, the general characteristics of the LUF and ovulation groups were similar. The implantation and clinical pregnancy rates in the LUF group were not significantly different from those in the ovulation group (44.98 % vs. 45.29 %, p = 0.93; 53.72 % vs. 52.48 %, p = 0.75). The implantation and pregnancy rates of transferred cleavage-stage embryos in the LUF group were also not significantly different from those in the ovulation group (32.39 % vs. 36.40 %, p = 0.42; 47.30 % vs. 47.50 %, p = 0.98). The implantation and pregnancy rates of transferred blastocysts in the LUF group were also not significantly different from those in the ovulation group (53.11 % vs. 52.03 %, p = 0.82; 56.55 % vs. 54.94 %, p = 0.73). There was also no significant difference in the miscarriage rate between the groups.

CONCLUSION

In the natural cycle, LUF does not affect the clinical pregnancy outcomes of FET. If adequate luteal support is given, the clinical pregnancy outcomes were similar between the LUF group and ovulation group.

What is the optimal means of preparing the endometrium in frozen-thawed embryo transfer cycles among anovulatory women? A retrospective cohort study

OBJECTIVE

Different endometrial preparation protocols are used prior to frozen-thawed embryo transfer (FET). It is not clear whether letrozole-stimulated cycles are beneficial for anovulatory women compared to artificial cycles (AC) in anovulatory women. Our objective was to investigate whether clinical outcomes following frozen-thawed embryo transfer in letrozole-stimulated cycles differ from artificial cycles in anovulatory women.

STUDY DESIGN

This is a retrospective cohort study conducted in a public fertility center in China comparing letrozole-stimulated and artificial cycles during FET. A total of 5,322 anovulatory women undergoing the first cycle of FET between January 2020 and December 2021. The primary outcome was the live birth rate. The secondary outcomes included biochemical pregnancy, clinical pregnancy, ongoing pregnancy, miscarriage, and ectopic pregnancy.

RESULTS

The live birth rates were significantly higher in the letrozole compared with AC (49.57 % vs. 45.22 %) both in the crude (odds ratio [OR] 1.19, 95 % confidence interval [CI] 1.01-1.40) and adjusted analysis (aOR 1.27, 95 %CI 1.08-1.50). After controlling for potential covariates, the adjusted probability of biochemical pregnancy (65.71 % vs. 63.25 %, aOR 1.20, 95 %CI: 1.01-1.43), clinical pregnancy (61.53 % vs. 58.79 %, aOR 1.20, 95 %CI: 1.02-1.43), and ongoing pregnancy (50.14 % vs. 45.66 %, aOR 1.28, 95 %CI: 1.08-1.51) were higher among those using letrozole-stimulated cycles than among those undergoing artificial cycles. The miscarriage rate was lower following letrozole compared with artificial cycles (aOR 0.59, 95 %CI: 0.43-0.80). The ectopic pregnancy in the letrozole group was similar to that in the artificial cycles.

CONCLUSIONS

Letrozole-stimulated FET was significantly associated with higher rates of biochemical pregnancy, clinical pregnancy, ongoing pregnancy and live birth, and with a lower rate of miscarriage, compared with artificial cycles.

Bilateral versus unilateral orchidopexy: IVF/ICSI-ET outcomes

Introduction

Cryptorchidism is a common genital disorder. Approximately 20% of azoospermic or infertile men reported having histories of cryptorchidism. Bilateral cryptorchidism may have been more condemned than unilateral cryptorchidism. Early treatment by orchidopexy is the definitive procedure for cryptorchid patients with cryptorchidism. However, fertility potency after orchidopexy may be adversely affected and assisted reproduction techniques will be required for infertile patients.

Objective

To compare the reproductive outcomes between unilateral and bilateral orchidopexy groups.

Methods

A retrospective cohort study at a tertiary hospital, including a total of 99 infertile men who underwent orchidopexy to treat cryptorchidism and subsequently underwent their first IVF/ICSI-ET cycle. Men were grouped according to the laterality of their cryptorchidism and orchidopexy surgeries they received. Fertilization rate and live birth rate were chosen as parameters for evaluating outcomes.

Results

The sperm concentration and viability were significantly higher in unilateral orchidopexy group than in bilateral orchidopexy group (28.09 ± 27.99 vs 7.99 ± 14.68, P=0.001; 33.34 ± 22.52 vs 11.95 ± 17.85, P=0.001). Unilateral orchidopexy group showed lower demand for ICSI (66.07% vs 95.35%, P<0.001). Interestingly, both groups exhibited similar rates of fertilization, clinical pregnancy, live birth and birth defect. Boy birth ratio was lower in bilateral orchidopexy group as compared to unilateral orchidopexy group (27.27% vs 58.62%, P=0.026).

Conclusion

A history of bilateral orchidopexy surgery correlates with a worsened sperm parameter and a higher demand for ICSI as compared to patients with history of unilateral orchidopexy. However, this does not influence the final live birth rate.

Elective single versus double blastocyst-stage embryo transfer in women aged 36 years or older: a retrospective cohort study

We evaluated if elective single-blastocyst transfer (eSBT) could be adopted in women aged 36 or older. In this retrospective cohort, women aged ≥36 years received IVF ovarian stimulation cycles and had ≥ two blastocysts. A total of 240 women underwent eSBT and 189 double-blastocyst transfer (DBT) in the first transfer cycle. The subsequent frozen-thawed embryo transfer cycles were a combination of single- and double- blastocyst transfers. Analysis was stratified for patients in age groups 36-37, 38-39 and ≥40, considering the quality of the blastocyst transferred. The cumulative live birth rates (cLBR) were 74.2% (178/240) versus 63.0% (119/189) after eSBT versus DBT, respectively (aOR: 1.09 (0.68, 1.75)). Time to live birth did not vary significantly between the two groups (HR: 0.85 (0.68, 1.08)). The total number of children born was 194 after eSBT (162 singletons and 16 pairs of twins) versus 154 (84 singletons and 35 twins) after DBT. The odds ratios for preterm birth (0.37 (0.21-0.64)), and low birth weight (0.31 (0.16, 0.60)) were all lower in eSBT. In women aged ≥36 years, cLBR following single- versus double- blastocyst transfer was comparable while the odds of multiple live births and adverse perinatal outcomes were reduced.

Who may benefit from an increased gonadotropin dosing in predicted poor responders undergoing IVF/ICSI? A secondary analysis assessing treatment selection markers of a randomized trial

OBJECTIVE

To evaluate whether we can identify patient characteristics that serve as treatment selection markers to distinguish which women with expected poor response benefit from increased dosing of follicle-stimulating hormone (FSH) in terms of improving the cumulative live birth rate compared to standard FSH dosing and which women.

STUDY DESIGN

We performed a secondary analysis of an RCT performed between March 2019 and October 2021 comparing cumulative live birth after increased dosing (N = 328) who received 225 or 300 IU/day according to their antral follicle count (AFC) and standard dosing (N = 333) who received 150 IU/day of gonadotropin.

RESULTS

The MFPI analysis showed the benefit of the increased dosing of FSH on cumulative live birth starts to emerge when women were older than 30 years (women > 30 years: 46.5 % vs. 34.2 %; adjusted relative risk (aRR) 1.32, 95 % confidence interval (95 %CI) 1.05-1.66; women ≤ 30 years: 54.7 % vs. 58.6 %; aRR 0.91, 95 % CI 0.72-1.14; p for interaction 0.019). Only those who had AFC between 1 and 3 benefited from the increased FSH dose (AFC 1-3: 38.5 % vs. 6.5 %; aRR 5.88, 95 % CI 1.50-23.15; AFC 4-9: 50.3 % vs. 46.0 %; aRR 1.08, 95 % CI 0.92-1.27; p for interaction 0.023). Expected poor responders defined by the Bologna criteria and POSEIDON criteria did not significantly benefit from the increased dosing of FSH.

CONCLUSIONS

Women who are aged >30 years or have AFC 1-3 are likely to benefit from increased dosing of FSH by having a higher cumulative live birth rate.

The natural cycle protocol of endometrial preparation for frozen embryo transfer decreases the miscarriage rate in women with recurrent pregnancy loss

OBJECTIVE

To investigate whether different endometrial preparation methods lead to different results.

DESIGN

Retrospective cohort study.

PATIENTS

Women with recurrent pregnancy loss undergoing frozen embryo transfer (FET).

INTERVENTIONS

Natural cycle (NC) protocol (n = 111) with no drug or human chorionic gonadotropin (HCG) used for endometrial preparation, vs. the hormone replacement therapy (HRT) protocol (n = 797) with estrogen or gonadotropin releasing hormone agonist (GnRH-a) plus estrogen used for endometrial preparation.

MAIN OUTCOME MEASURES

Miscarriage rate and live birth rate (LBR).

RESULTS

Compared to women in the HRT protocol, women undergoing NCs had fewer previous FET cycles, lower antral follicle counts (AFCs), fewer oocytes retrieved and a thicker endometrium on the day of progesterone administration. Women in the HRT group had a higher miscarriage rate (29.4% vs. 17.2%) and a lower LBR (37% vs. 46.9%) than the rates of women in the NC group. Univariate analysis showed that female age also had a negative association with the miscarriage rate. Logistic regression indicated that endometrial preparation using the NC protocol was linked to a decreased likelihood of miscarriage.

CONCLUSIONS

The NC protocol decreased the miscarriage rate and increased the LBR for patients with recurrent pregnancy loss compared with the HRT protocol.

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.

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

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

The time interval between laparoscopic tubal ligation and frozen-thawed embryo transfer does not affect the reproductive outcomes

BACKGROUND

Hydrosalpinx may decrease implantation and pregnancy rates after embryo transfer. Laparoscopic tubal ligation after embryo freeze and before frozen-thawed embryo transfer (FET) is effective at improving reproductive outcomes for hydrosalpinx patients. This study is to find out the optimal interval between laparoscopic tubal ligation and FET.

METHODS

We retrospectively analyzed 259 infertile women who performed laparoscopic tubal ligation for embryo freeze and FET. Participants were divided into three groups, based on the interval between laparoscopic tubal ligation and FET. Group I: <30 days; Group II: 31- 60 days; Group III: >60 days. Outcomes of cleavage-stage and blastocyst-stage embryo FET were analyzed respectively.

RESULTS

There was no significant difference in clinical pregnancy rate, live birth rate, implantation rate, biochemical pregnancy rate, ectopic pregnancy rate, miscarriage rate and preterm birth rate among the three groups, in both cleavage-stage and blastocyst-stage embryo FET cycles. In cleavage-stage embryo FET cycle, singleton gestational age was significantly younger in group III (38.11 ± 2.28 weeks) compared with group I (39.29 ± 1.06 weeks, P = 0.001) and group II (38.96 ± 1.05, P = 0.026). Singleton birth weight was significantly heavier in group II (3.65 ± 0.32 Kg) compared with group I (3.38 ± 0.29 Kg, P = 0.001) and group III (3.35 ± 0.60 Kg, P = 0.004). Twin birth weight was significantly heavier in group III (2.72 ± 0.43 Kg) compared to group I (2.23 ± 0.67 Kg, P = 0.002). In blastocyst-stage embryo FET cycles, twin gestational age was significantly younger in group II (34.07 ± 3.18 weeks) compared with group I (35.56 ± 2.27 weeks, P = 0.049) and group III (36.50 ± 1.47 weeks, P = 0.005). Twin birth weight was significantly heavier in group III (2.71 ± 0.39 Kg) compared to group II (2.39 ± 0.67 Kg, P = 0.009).

CONCLUSIONS

The duration of the interval between laparoscopic tubal ligation and FET does not affect the reproductive outcomes; however, it may affect the neonate outcomes to some extent.

The likelihood of a healthy live birth after frozen embryo transfer with endometrium prepared by natural ovulation regimen vs programmed regimen: a propensity-score matching study

BACKGROUND

The number of frozen embryo transfer cycles is increasing, but the optimal method of endometrial preparation for frozen embryo transfer remains controversial. Few studies have investigated the healthy live birth outcome after the natural ovulation regimen vs the programmed regimen.

OBJECTIVE

This study aimed to explore whether the likelihood of a healthy live birth after frozen embryo transfer differs between the natural ovulation regimen and the programmed regimen.

STUDY DESIGN

We conducted a retrospective cohort study including 7824 ovulatory women who underwent the first frozen embryo transfer cycle of single-blastocyst transfer with endometrial preparation by natural ovulation regimen vs programmed regimen, between June 2017 and June 2021. Propensity score matching was used to control for confounding variables in a 1:1 ratio. The primary outcome was healthy live birth, defined as birth of a live, singleton infant born at term, with an appropriate birthweight for gestational age.

RESULTS

The natural ovulation regimen resulted in a higher probability of achieving healthy live birth compared with the programmed regimen (35.8% vs 30.6%; P<.0001). In addition, a higher rate of singleton live birth was observed after the natural ovulation regimen relative to the programmed regimen (49.6% vs 45.7%; P=.003). Women with the natural ovulation regimen were also less likely to experience clinical pregnancy loss (16.0% vs 19.7%; P=.005) and hypertensive disorders of pregnancy (3.9% vs 6.0%; P=.004) compared with women with the programmed regimen. Singletons born after the programmed regimen had greater mean birthweight (3441.50±539.97 vs 3394.96±503.87; P=.020) and higher risk of being large for gestational age (23.3% vs 18.7%; P=.003) than those conceived after the natural ovulation regimen.

CONCLUSION

The natural ovulation regimen may be superior to the programmed regimen with regard to higher likelihood of healthy live birth and lower risk of pregnancy loss and maternal hypertensive disorders of pregnancy.

Gonadotropin-Releasing Hormone agonist (GnRH-a) Pretreatment before Hormone Replacement Therapy Does Not Improve Reproductive Outcomes of Frozen-Thawed Embryo Transfer Cycle in Older Patients with Intrauterine Fibroid: A Retrospective Cohort Study

BACKGROUND

Surgery in elder patients with intermural fibroids delays pregnancy, and GnRH-a can shrink uterine fibroids to a certain extent; therefore, for geriatric patients with fibroids, determining whether GnRH-a pretreatment before frozen-thawed embryo transfer (FET) can improve its success rate remains to be studied. We conducted this study to research whether GnRH-a pretreatment before hormone replacement treatment (HRT) could optimize the reproductive outcomes compared with others preparations in geriatric patients with intramural fibroids.

METHODS

According to the endometrial preparation, patients were divided into a GnRH-a-HRT group, a HRT group and a natural cycle (NC) group. The live birth rate (LBR) was the first outcome, and the clinical pregnancy outcome (CPR), the miscarriage rate, the first trimester abortion rate and the ectopic pregnancy rate were the secondary outcomes.

RESULTS

A total of 769 patients (aged 35 years or older) were included in this study. No significant difference was observed in the live birth rate (25.3% vs. 17.4% vs. 23.5%, p = 0.200) and the clinical pregnancy rate (46.3% vs. 46.1% vs. 55.4%, p = 0.052) among the three endometrial preparation regimens.

CONCLUSION

In this study, for the geriatric patient with the intramural myoma, the pretreatment with GnRH-a did not show any advantage over the NC and HRT preparation groups before the FET, and the LBR was not significantly increased.

Overweight and obesity affect the efficacy of vaginal vs. intramuscular progesterone for luteal-phase support in vitrified-warmed blastocyst transfer

OBJECTIVE

To compare the difference in the live birth rates (LBRs) between vaginal progesterone and intramuscular progesterone as luteal-phase support in programmed vitrified-warmed blastocyst transfer cycles and determine whether the association was moderated by overweight/obesity.

DESIGN

Retrospective cohort study.

SETTING

Tertiary reproductive medicine center.

PATIENT(S)

Patients who underwent transfer of single vitrified-warmed blastocyst in a programmed cycle between January 2018 and June 2021.

INTERVENTION(S)

Vaginal or intramuscular progesterone as luteal-phase support. Analysis was performed using the generalized estimating equation framework and multivariate regression models. Interaction testing was used to determine whether overweight/obesity (body mass index of ≥25 kg/m²) moderated the association between progesterone replacement and LBRs.

MAIN OUTCOME MEASURE(S)

The primary outcome was live birth. The secondary outcomes were biochemical pregnancy, clinical pregnancy, miscarriage, and total pregnancy loss.

RESULT(S)

A total of 6,905 programmed cycles (4,616 with vaginal progesterone and 2,289 with intramuscular progesterone) were included in the analysis. In the general cohort who underwent cryopreserved blastocyst transfer, the LBRs were 46.23% and 48.62% in the vaginal and intramuscular progesterone groups, respectively (odds ratio [OR], 0.91; 95% confidence interval [CI], 0.82-1.01; adjusted OR [aOR], 0.89; 95% CI, 0.81-0.98), with a significantly increased rate of pregnancy losses in the vaginal progesterone group compared with that in the intramuscular progesterone group (22.22% vs. 18.90%; OR, 1.23; 95% CI, 1.08-1.39; aOR, 1.23; 95% CI, 1.08-1.40). Among normal-weight women, the LBR in the vaginal progesterone group was lower than that in the intramuscular progesterone group (aOR, 0.84; 95% CI, 0.75-0.95). On the other hand, among women with overweight/obesity, the LBRs were similar between the 2 groups of progesterone replacement (aOR, 1.06; 95% CI, 0.86-1.33). Interaction testing of the routes of progesterone administration and overweight/obesity was significant.

CONCLUSION(S)

Luteal-phase support with vaginal progesterone was associated with reduced LBRs compared with intramuscular progesterone for vitrified-warmed blastocyst transfer, and the association was modified by maternal overweight/obesity. Further research is needed to better understand the mechanisms behind the association.

Comparison of endometrial preparation protocols (natural cycle versus hormone replacement cycle) for frozen embryo transfer (COMPETE): a study protocol for a randomised controlled trial

INTRODUCTION

Natural cycle (NC) and hormone replacement treatment (HT) are frequently used endometrial preparation protocols prior to frozen-thawed embryo transfer in ovulatory women. It is not clear which protocol results in a higher live birth rate. It has been suggested that there is an increased risk in maternal and perinatal morbidity following HT protocol due to the lack of corpus luteum. The objective of this trial is to compare the clinical outcomes of NC and HT protocols in frozen embryo transfer.

METHODS AND ANALYSIS

COMPETE is an open-label, single-centre, randomised controlled trial targeting to recruit 888 women, with 444 women each in two arms (1:1 treatment ratio). Women undergoing in vitro fertilisation scheduled for a frozen embryo transfer and have a regular menstrual cycle are eligible. Exclusion criteria include ovulation disorders and intrauterine adhesions. The primary outcome is live birth resulting from the first frozen embryo transfer after randomisation. Secondary outcomes include biochemical pregnancy, clinical pregnancy, multiple pregnancy, ongoing pregnancy, miscarriage, endometrial thickness, cycle cancellation, gestational diabetes mellitus, hypertensive disorders of pregnancy, antepartum haemorrhage, preterm birth, birth weight, large for gestational age, congenital anomaly and perinatal mortality. The data analysis will be following the intention-to-treat principle.

ETHICS AND DISSEMINATION

This study has been approved by the Institutional Review Board of Northwest women's and children's hospital (2020008). Written informed consent will be obtained from each participant before randomisation. The results of the trial will be presented via publications.

TRIAL REGISTRATION NUMBER

ChiCTR2000040640.

Increased risk of abortion after frozen-thawed embryo transfer in women with polycystic ovary syndrome phenotypes A and D

Polycystic ovary syndrome (PCOS) is associated with adverse pregnancy outcomes, including an increased risk of abortion, premature delivery, and even neonatal outcomes. After removing the effect of COH on patients, studying the pregnancy outcomes of patients with different PCOS phenotypes after FET may better reflect the impact of different PCOS phenotypes on ART outcomes. Data of 8903 patients who underwent FET between January 2017 and October 2019 were retrospectively collected and evaluated. All patients were divided into a control group and four phenotype groups based on Rotterdam criteria. The main outcomes were pregnancy outcomes after FET. We found significantly higher abortion (P = 0.010) and lower ongoing pregnancy (P = 0.023) rates for women with PCOS phenotypes A and D compared to those in the control group. After adjusting for potential confounders, PCOS phenotypes A and D were associated with an elevated risk of abortion (adjusted OR, 1.476, P = 0.016; adjusted OR, 1.348, P = 0.008, respectively). The results of this study suggest that when performing FET, clinicians should individually manage women with PCOS phenotypes A and D to reduce the rate of abortion and increase the rate of LB, and achieve better pregnancy outcomes.

A comparison of frozen-thawed embryo transfer protocols in 2920 single-blastocyst transfers

OBJECTIVE

To assess the effect of frozen-thawed embryo transfer (FET) protocol on live-birth rate (LBR) and clinical pregnancy rate (CPR), in single-vitrified-blastocyst transfer MATERIALS AND METHODS: Retrospective cohort study with FET of a single-blastocyst embryos (n = 2920 cycles) thawed 2013-2018. FET protocols were natural cycles (NC-FET) (n = 147), artificial hormone replacement treatment cycles (HRT-FET) (n = 2645), and modified NC (mNC) with hCG triggering (n = 128). Primary outcome was LBR. Adjustment for age, embryo grade, year of freezing\thawing, infertility cause, and endometrial thickness was performed.

RESULTS

There were no significant differences between the groups with regard to female age, embryo grade, and endometrial thickness. LBR was higher in the mNC compared to HRT-FET cycles (38.3% vs. 20.9% P < 0.0001), and in the NC compared to HRT-FET cycles (34.7% vs. 20.9%, P = 0.0002). CPR was higher in the mNC compared to HRT-FET cycles (46.1% vs. 33.3% P = 0.0003), and in the NC compared to HRT-FET cycles (45.9% vs. 33.3%, P = 0.002). There was no significant difference in LBR or CPR between NC-FET and mNC-FET. Higher LBR with NC-FET and mNC-FET remained significant after adjusting for confounders (aOR 2.42, 95%CI 1.53-3.66, P < 0.0001).

CONCLUSION

The use of the convenient artificial HRT-FET cycles must be cautiously reconsidered in light of the potential negative effect on LBR when compared with natural cycle FET.

Treatment outcomes of blastocysts thaw cycles, comparing the presence and absence of a corpus luteum: a systematic review and meta-analysis

PURPOSE

This study aims to review the literature and perform a meta-analysis to determine if the presence of a corpus luteum has an impact on treatment outcomes in thaw cycles, where blastocyst embryos are transferred.

METHOD

PUBMED, EMBASE, CENTRAL and CINAHL were searched for papers published between January 2017 and 27 July 2020. Additional articles were selected from the reference list of the results and previous reviews. Three reviewers independently reviewed and extracted data. The meta-analysis was conducted though RevMan V.5.4.1. Studies were quality assessed with the Cochrane risk of bias tool and the Newcastle-Ottawa Scale.

RESULTS

Nine publications were included for data extraction and subsequent meta-analysis. Two studies were randomised controlled trials, and seven were cohort studies. Subgroup analysis of the different study designs was performed. While the rates of positive human chorionic gonadotropin results (relative risk, RR 1.0, 95% CI 0.95 to 1.05) and clinical pregnancies (RR 1.06, 95% CI 0.96 to 1.18) were comparable between the two groups, the rates of live births were higher in thaw cycles with a corpus luteum (RR 1.14, 95% CI 1.06 to 1.22). Analysis of pregnancy losses demonstrated that both biochemical pregnancy (early miscarriage) (RR 0.71, 95% CI 0.62 to 0.82) and miscarriages (RR 0.72, 95% CI 0.62 to 0.83) were increased in cycles without a corpus luteum.

CONCLUSION

Where clinically appropriate, the use of cycle types that have a functional corpus luteum should be favoured. There were several limitations to this study, including the quality of studies and the inherent bias of retrospective cohort studies. Further, high-quality research, particularly randomised controlled trials with blastocysts embryos, is required to further explore these findings.

PROSPERO REGISTRATION NUMBER

CRD42020209583.

Natural cycles achieve better pregnancy outcomes than artificial cycles in non-PCOS women undergoing vitrified single-blastocyst transfer: a retrospective cohort study of 6840 cycles

PURPOSE

To identify the optimal method for endometrial preparation in vitrified single-blastocyst transfer (VSBT) cycles.

METHODS

This was a retrospective cohort study for non-PCOS patients who underwent VSBT cycles from March 2015 to November 2019 in an academic reproductive medical center. A total of 6840 VSBT cycles were enrolled and classified into two groups according to different endometrial preparation methods.

RESULTS

The non-PCOS patients who underwent VSBT showed a significantly higher clinical pregnancy rate (61.96% vs 56.85%, p < 0.001) and live birth rate (49.09% vs 39.86%, p < 0.001), as well as a statistically lower early miscarriage rate (12.02% vs 18.08%, p < 0.001) in the natural cycle (NC) group compared with the artificial cycle (AC) group. Multivariable analysis further confirmed that NC was associated with an increased likelihood of clinical pregnancy (adjusted odds ratio (aOR) 0.852, 95% confidence interval (CI) 0.765-0.949, p = 0.004) and live birth (aOR 0.746, 95% CI 0.669-0.832, p < 0 .001), but decreased early miscarriage occurrence (aOR 1.447, 95% CI 1.215-1.724, p < 0.001) compared to AC.

CONCLUSIONS

Our study demonstrated that non-PCOS patients could benefit from NC in vitrified blastocyst transfer. Increased clinical pregnancy rate and decreased early miscarriage rate led to a significantly higher live birth rate in NC patients compared with AC with our present protocol.

The impact of euploid blastocyst morphology and maternal age on pregnancy and neonatal outcomes in natural cycle frozen embryo transfers

PURPOSE

To evaluate whether morphology impacts the pregnancy and neonatal outcomes of euploid blastocysts, and whether maternal age still affects outcomes when top-graded, euploid blastocysts are used.

METHODS

This retrospective cohort study included all natural-cycle frozen embryo transfers (NC-FET) using an autologous, euploid blastocyst from June 2016 to June 2020 (n = 610). There were five groups based on embryo grade: AA, AB, BA, BB, and "any C". For analysis of only AA-graded embryos, there were three maternal age groups: < 35, 35-39, and 40 + years. The main outcomes measured were clinical pregnancy and live birth rates, while the secondary outcomes included neonatal outcomes such as gestational age at delivery and birthweight. Multivariable logistic regression models were performed to adjust for confounders.

RESULTS

Euploid blastocysts with poorer morphology had lower odds of pregnancy and live birth; specifically, embryos with inner cell mass (ICM) graded as "C" had statistically significant decreased odds of pregnancy (aOR 0.33, p = 0.04) and live birth (aOR 0.32, p = 0.03) compared with ICM grade "A". The differences in pregnancy rate between trophectoderm grades were not statistically significant. Even in cycles that transferred a top-graded (AA) euploid embryo, maternal age at transfer was independently associated with outcomes. Embryo grade and maternal age, however, did not significantly impact neonatal outcomes such as prematurity and birthweight.

CONCLUSION

The morphology of euploid blastocysts and maternal age at NC-FET both independently impact pregnancy outcomes. Neonatal outcomes were similar across embryo morphology and maternal age groups, suggesting that lower morphology euploid embryos not be discounted as viable options for transfer.

Impact of endometrial preparation on early pregnancy loss and live birth rate after frozen embryo transfer: a large multicenter cohort study (14,421 frozen cycles)

STUDY QUESTION

Does the endometrial preparation protocol (artificial cycle (AC) vs natural cycle (NC) vs stimulated cycle (SC)) impact the risk of early pregnancy loss and live birth rate after frozen/thawed embryo transfer (FET)?

SUMMARY ANSWER

In FET, ACs were significantly associated with a higher pregnancy loss rate and a lower live birth rate compared with SC or NC.

WHAT IS KNOWN ALREADY

To date, there is no consensus on the optimal endometrial preparation in terms of outcomes. Although some studies have reported a higher pregnancy loss rate using AC compared with NC or SC, no significant difference was found concerning the pregnancy rate or live birth rate. Furthermore, no study has compared the three protocols in a large population.

STUDY DESIGN, SIZE, DURATION

A multicenter retrospective cohort study was conducted in nine reproductive health units in France using the same software to record medical files between 1 January 2012 and 31 December 2016. FET using endometrial preparation by AC, modified NC or SC were included. The primary outcome was the pregnancy loss rate at 10 weeks of gestation. The sample size required was calculated to detect an increase of 5% in the pregnancy loss rate (21–26%), with an alpha risk of 0.5 and a power of 0.8. We calculated that 1126 pregnancies were needed in each group, i.e. 3378 in total.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Data were collected by automatic extraction using the same protocol. All consecutive autologous FET cycles were included: 14 421 cycles (AC: n = 8139; NC: n = 3126; SC: n = 3156) corresponding to 3844 pregnancies (hCG > 100 IU/l) (AC: n = 2214; NC: n = 812; SC: n = 818). Each center completed an online questionnaire describing its routine practice for FET, particularly the reason for choosing one protocol over another.

MAIN RESULTS AND THE ROLE OF CHANCE

AC represented 56.5% of FET cycles. Mean age of women was 33.5 (SD ± 4.3) years. The mean number of embryos transferred was 1.5 (±0.5). Groups were comparable, except for history of ovulation disorders (P = 0.01) and prior delivery (P = 0.03), which were significantly higher with AC. Overall, the early pregnancy loss rate was 31.5% (AC: 36.5%; NC: 25.6%; SC: 23.6%). Univariable analysis showed a significant association between early pregnancy loss rate and age >38 years, history of early pregnancy loss, ovulation disorders and duration of cryopreservation >6 months. After adjustment (multivariable regression), the early pregnancy loss rate remained significantly higher in AC vs NC (odds ratio (OR) 1.63 (95% CI) [1.35–1.97]; P < 0.0001) and in AC vs SC (OR 1.87 [1.55–2.26]; P < 0.0001). The biochemical pregnancy rate (hCG > 10 and lower than 100 IU/l) was comparable between the three protocols: 10.7% per transfer.

LIMITATIONS, REASONS FOR CAUTION

This study is limited by its retrospective design that generates missing data. Routine practice within centers was heterogeneous. However, luteal phase support and timing of embryo transfer were similar in AC. Univariable analysis showed no difference between centers. Moreover, a large number of parameters were included in the analysis.

WIDER IMPLICATIONS OF THE FINDINGS

Our study shows a significant increase in early pregnancy loss when using AC for endometrial preparation before FET. These results suggest either a larger use of NC or SC, or an improvement of AC by individualizing hormone replacement therapy for patients in order to avoid an excess of pregnancy losses.

STUDY FUNDING/COMPETING INTEREST(S)

The authors declare no conflicts of interest in relation to this work. G.P.-B. declares consulting fees from Ferring, Gedeon-Richter, Merck KGaA, Theramex, Teva; Speaker’s fees or equivalent from Merck KGaA, Ferring, Gedeon-Richter, Theramex, Teva. N.C. declares consulting fees from Ferring, Merck KGaA, Theramex, Teva; Speaker’s fees or equivalent from Merck KGaA, Ferring. C.R. declares a research grant from Ferring, Gedeon-Richter; consulting fees from Gedeon-Richter, Merck KGaA; Speaker’s fees or equivalent from Merck KGaA, Ferring, Gedeon-Richter; E.M.d’A. declares Speaker’s fees or equivalent from Merck KGaA, MSD, Ferring, Gedeon-Richter, Theramex, Teva. I.C-D. declares Speaker’s fees or equivalent from Merck KGaA, MSD, Ferring, Gedeon-Richter, IBSA. N.M. declares a research grant from Merck KGaA, MSD, IBSA; consulting fees from MSD, Ferring, Gedeon-Richter, Merck KGaA; Speaker’s fees or equivalent from Merck KGaA, MSD, Ferring, Gedeon-Richter, Teva, Goodlife, General Electrics.

TRIAL REGISTRATION NUMBER

N/A.

Placenta Accreta Spectrum Disorder Complicated with Endometriosis: Systematic Review and Meta-Analysis

This study aimed to assess the relationship between placenta accreta spectrum disorder (PASD) and endometriosis. The relationships among pregnancy, assisted reproductive technology (ART), placenta previa, ART-conceived pregnancy and PASD were also determined. A systematic literature review was conducted using multiple computerized databases. Forty-eight studies (1990–2021) met the inclusion criteria. According to the adjusted pooled analysis (n = 3), endometriosis was associated with an increased prevalence of PASD (adjusted odds ratio [OR] 3.39, 95% confidence interval [CI] 1.96–5.87). In the included studies, the ART rate ranged from 18.2% to 37.2% for women with endometriosis. According to the adjusted pooled analysis, women who used ART were more likely to have placenta previa (n = 13: adjusted OR 2.96, 95%CI, 2.43–3.60) and PASD (n = 4: adjusted OR 3.54, 95%CI 1.86–6.76) than those who did not use ART. According to the sensitivity analysis using an unadjusted analysis accounting for the type of ART, frozen embryo transfer (ET) was associated with an increased risk of PASD (n = 4: OR 2.79, 95%CI, 1.22−6.37) compared to fresh ET. Endometriosis may be associated with an increased rate of PASD. Women with placenta previa complicated with endometriosis who conceived using frozen ET may be a high risk for PASD.

Endometrial preparation methods prior to frozen embryo transfer: A retrospective cohort study comparing true natural cycle, modified natural cycle and artificial cycle

Purpose

The aim of this study was to compare the outcomes of three endometrial preparation methods prior to frozen embryo transfer (FET): Natural cycle (NC), modified natural cycle (mNC), and programmed/artificial cycle (AC) protocols. Primary outcomes investigated were clinical pregnancy rate (CPR) and live birth rate (LBR).

Methods

A retrospective study on 2080 FET cycles including patients ≤ 35 years with a BMI ≤ 30 who underwent FET with a single autologous blastocyst stage embryo at Aarhus University Hospital or Horsens Regional Hospital in the period 2013–2019. Only blastocysts frozen by vitrification were included. No luteal phase support (LPS) was used in natural cycles.

Results

In NC, mNC and AC, CPRs were 34.9%, 40.6% and 32.0%, while LBRs were 32.3%, 36.3% and 26.6%, respectively. There were no significant differences in main outcomes when comparing AC with NC [LBR: OR = 0.9 (0.6; 1.2), p = 0.4]. Compared to NC, mNC-FET displayed significantly higher positive hCG, implantation rate, CPR and LBR [LBR: OR = 1.4 (1.0; 1.9), p = 0.03]. An analysis with mNC as reference group demonstrated significantly better outcomes in the mNC group compared to AC [LBR: OR 0.6 (0.5; 0.8), p =  < 0.01].

Conclusion

The present study overall demonstrated better outcomes including LBR with mNC protocol as compared to NC and AC protocol, while comparison of AC and NC showed both protocols to be equally effective. A programmed cycle may be necessary for women with anovulatory cycles; however, normo-ovulating women may be offered a natural cycle protocol.

Trial registration number

3-3013-3047/1 and 31-1522-44. Date of registration: June 24, 2019 and April 23, 2020.

Natural cycle increases the live-birth rate compared with hormone replacement treatment for frozen-thawed single euploid blastocyst transfer

BACKGROUND

A number of studies have compared the clinical outcomes between the two endometrial preparation methods: natural cycles (NCs) and hormone replacement treatment (HRT) before frozen embryo transfer, but the results were conflicting. In order to mitigate the potential effect of embryos per se, several researchers have worked on this subject for euploid blastocyst transfer, but the results were still inconsistent. Therefore, the present study was aimed to investigate the clinical outcomes between HRT and NC for autologous single vitrified-warmed euploid blastocyst transfer based on our data.

METHODS

A total of 598 frozen-thawed single euploid blastocyst transfer cycles in the assisted reproductive center of Northwest Women's and Children's Hospital from January 2014 to May 2021 were retrospectively analyzed. Women were stratified into the NC (n = 125) or HRT (n = 473) group according to the patient's preference and the physician's guidance. Multivariate regression models and subgroup analysis were constructed to analyze the association between endometrial preparation and live birth.

RESULTS

Women in the NC group had a higher live birth rate (68.80% versus 58.35%, P = 0.034) and a lower risk of total pregnancy loss (8.51% versus 21.14%, P = 0.005) when compared with women in the HRT group. The biochemical pregnancy rate (75.20% versus 74.00%, P = 0.784) and clinical pregnancy rate (74.40% versus 69.98%, P = 0.334) were similar between the two groups (NC versus HRT). NC was associated with an increased odds of live birth compared with HRT by different multivariable analysis models (Model 1: adjusted odds ratio [aOR], 95% confidence interval [CI]: 0.57, 0.36 - 0.90; Model 2: aOR, 95%CI: 0.57, 0.35 - 0.92). In addition, the increased chance of live birth in the NC group was found in all subgroups. No major obstetrical complications and two malformation livebirths were reported.

CONCLUSIONS

In women undergoing single euploid frozen blastocyst transfers, the NC group was associated with a lower pregnancy loss rate and an ultimately higher live birth rate than the HRT group. Although HRT is convenient for both clinicians and patients, the lower live birth rate should be taken into account and NC might be the first choice of endometrial preparation method.

Pretreatment with a GnRH agonist and hormone replacement treatment protocol could not improve live birth rate for PCOS women undergoing frozen-thawed embryo transfer cycles

BACKGROUND

The ideal protocols of endometrial preparation for polycystic ovary syndrome (PCOS) patients are lacking and need further declaration. Our objective was to compare the clinical outcomes of frozen-thawed embryo transfer (FET) with and without pretreatment gonadotropin-releasing hormone agonist (GnRHa) in PCOS patients.

METHODS

In this retrospective cohort study, we used propensity score matching (PSM) to compare the live birth rate between patients who underwent FET with hormone replacement treatment (HRT) and patients with GnRHa pretreatment (GnRHa + HRT). Patients using GnRHa + HRT (n = 514) were matched with 514 patients using HRT.

RESULTS

The live birth rate was higher in the GnRHa + HRT group compared with the HRT group with no significant difference (60.12% vs 56.03%, p = 0.073). The clinical pregnancy rate (75.29% vs 70.62%), miscarriage rate (14.20% vs 13.81%) and ectopic pregnancy rate (0.39% vs 0.19%) were similar between the two groups. The preterm birth rate in GnRHa + HRT was higher than HRT (20.23% vs 13.04%). No difference was found in live birth between GnRHa +HRT and HRT before adjusting for covariates (crude OR 1.22, 95%CI, 0.99-1.51, p = 0.062) and after PSM (OR 1.47, 95%CI, 0.99-2.83, p = 0.068). In addition, there is a marginally difference after adjusting for covariates (aOR 1.56, 95%CI, 1.001-2.41, p = 0.048), this finding with p-value close to 0.05 represent insufficient empirical evidence. Similar results were obtained after propensity score matching in the entire cohort.

CONCLUSIONS

GnRHa pretreatment could not improve the live birth rate in women with PCOS.

Cumulative live birth rate after ovarian stimulation with freeze-all in women with polycystic ovaries: does the polycystic ovary syndrome phenotype have an impact?

RESEARCH QUESTION

Do cumulative live birth rates (CLBR) differ between polycystic ovary syndrome (PCOS) phenotypes when a freeze-all strategy is used to prevent OHSS after ovarian stimulation?

DESIGN

A single-centre, retrospective cohort study of 422 women with PCOS or polycystic ovarian morphology (PCOM), in whom a freeze-all strategy was applied after GnRH agonist triggering because of hyper-response in their first or second IVF/ICSI. Primary outcome was CLBR; multivariate logistic regression analysis was used.

RESULTS

Phenotype A (hyperandrogenism + ovulation disorder + PCOM [HOP]) (n = 91/422 [21.6%]); phenotype C (hyperandrogenism + PCOM [HP]) (33/422 [7.8%]; phenotype D (ovulation disorder + PCOM [OP]) (n = 161/422 [38.2%]); and PCOM (n = 137/422 [32.5%]. Unadjusted CLBR was similar among the groups (69.2%, 69.7%, 79.5% and 67.9%, respectively; P = 0.11). According to multivariate logistic regression analysis, the phenotype did not affect CLBR (OR 0.72, CI 0.24 to 2.14 [phenotype C]; OR 1.55, CI 0.71 to 3.36 [phenotype D]; OR 0.84, CI 0.39 to 1.83 [PCOM]; P = 0.2, with phenotype A as reference).

CONCLUSIONS

In women with PCOS, hyper-response after ovarian stimulation confers CLBR of around 70%, irrespective of phenotype, when a freeze-all strategy is used. This contrasts with unfavourable clinical outcomes in women with hyperandrogenism and women with PCOS who underwent mild ovarian stimulation targeting normal ovarian response and fresh embryo transfer. The results should be interpreted with caution because the study is retrospective and cannot be generalized to all cycles as they pertain to those in which hyper-response is observed.

Nomogram to predict an endometrial thickness above 7.5 mm in the frozen embryo transfer cycle of women with a thin endometrium

RESEARCH QUESTION

Which characteristics of patients with a thin endometrium (endometrial thickness [EMT] ≤7.5 mm on human chorionic gonadotrophin [HCG] trigger day) suggest the possibility of an EMT >7.5 mm in the subsequent frozen cycle?

DESIGN

Data were collected from the university-affiliated Centre for Reproductive Medicine between January 2013 and September 2019. Multivariable logistic regression was used to generate the final prediction model and construct the nomogram. Model performances were quantified by discrimination and calibration.

RESULTS

The predictive variables that entered the final model were: hysteroscopic adhesiolysis history, polycystic ovary syndrome status, application of clomiphene in the ovarian stimulation process, the ovarian stimulation protocol and the endometrial preparation protocol. The receiver operating characteristic (ROC) curve for the final model and validation cohort was 0.760 (95% confidence interval [CI] 0.722-0.797) and 0.713 (95% CI 0.664-0.759), respectively. Discrimination performed well in both the modelling and validation cohorts.

CONCLUSIONS

In women with a thin endometrium (EMT ≤7.5 mm on HCG trigger day), the absence of a hysteroscopic adhesiolysis history, the presence of polycystic ovary syndrome, the application of clomiphene in the ovarian stimulation process, the application of a gonadotrophin-releasing hormone agonist short protocol, mild stimulation protocol, natural cycle protocol, and natural cycle for endometrial preparation are prognostic for an increased possibility of an EMT >7.5 mm in the subsequent frozen cycle.

Is Human Chorionic Gonadotropin Trigger Beneficial for Natural Cycle Frozen-Thawed Embryo Transfer?

Objective: The aim of this study is to investigate, in ovulatory patients, whether there is a difference in reproductive outcomes following frozen-thawed embryo transfer (FET) in natural cycles (NC) compared to modified natural cycles (mNC).

Methods: This retrospective cohort study, performed at the public tertiary fertility clinic, involved all infertile patients undergoing endometrial preparation prior to FET in NC and mNC from January, 2017 to November, 2020. One thousand hundred and sixty-two patients were divided into two groups: mNC group (n = 248) had FET in a NC after ovulation triggering with human chorionic gonadotropin (hCG); NC group (n = 914) had FET in a NC after spontaneous ovulation were observed. The primary outcome was live birth rate. All pregnancy outcomes were analyzed by propensity score matching (PSM) and multivariable logistic regression analyses.

Results: The NC group showed a higher live birth rate [344/914 (37.6%) vs. 68/248 (27.4%), P = 0.003; 87/240 (36.3%) vs. 66/240 (27.5%), P = 0.040] than the mNC group before and after PSM analysis. Multivariable analysis also showed mNC to be associated with a decreased likelihood of live birth compared with NC [odds ratio (OR) 95% confidence interval (CI) 0.71 (0.51–0.98), P = 0.039].

Conclusion: For women with regular menstrual cycles, NC-FET may have a higher chance of live birth than that in the mNC-FET cycles. As a consequence, it's critical to avoid hCG triggering as much as possible when FETs utilize a natural cycle strategy for endometrial preparation. Nevertheless, further more well-designed randomized clinical trials are still needed to determine this finding.

Impact of maternal education level on live birth rate after in vitro fertilization in China: a retrospective cohort study

PURPOSE

To assess the association between maternal education level and live birth after in vitro fertilization (IVF).

METHODS

We studied women who underwent the first cycle of fresh or frozen-thawed embryo transfer between 2014 and 2019. Women were divided into four educational categories according to the level of education received (elementary school graduate or less, middle school graduate, high school graduate, college graduate or higher). The live birth rate was compared between different education level groups. We used logistic regression to analyze the association between maternal education level and live birth after IVF.

RESULTS

We studied 41,546 women, who were grouped by maternal educational level: elementary school graduate or less (n = 1590), middle school graduate (n = 10,996), high school graduate (n = 8354), and college graduate or higher (n = 20,606). In multivariable logistic regression analysis, we did not demonstrate a statistically significant relationship between educational level and live birth in middle school graduate (adjusted odds ratio [AOR] 0.96; 95% confidence interval [CI], 0.84-1.09), high school graduate (AOR 1.01; 95% CI, 0.87-1.14) or college graduate or higher (AOR 1.01; 95% CI, 0.88-1.14) patients, with elementary school graduate or less as the reference group.

CONCLUSIONS

Maternal educational level was not associated with the likelihood of live birth in patients undergoing fresh or frozen embryo transfer.

Pregnancy Outcomes After Frozen-Thawed Embryo Transfer in the Absence of a Corpus Luteum

Background: Nowadays, frozen-thawed embryo transfer (FET) cycles represent a high proportion of fertility treatments worldwide. Recent studies suggest differences in pregnancy outcomes depending on the FET treatment protocol used. The reason for this is still unclear, but the number of corpora lutea (CL) at conception is discussed as a possible factor. This study aims to investigate whether maternal and neonatal outcomes for pregnancies following FET lacking a CL differ from FET with one or more CL in order to explore a potential link between CL absence and adverse pregnancy outcomes.

Methods: The study was designed as a retrospective, multi-center observational study with two cohorts after singleton live birth [0 CL cohort (FET in a programmed cycle, n = 114) and ≥ 1 CL cohort (FET in a natural or stimulated cycle, n = 68)]. Participants completed a questionnaire on the outcome of pregnancy and birth records were analyzed in a descriptive way. Multivariable logistic and linear regressions were performed in order to explore associations between CL absence and pregnancy outcomes. The strength of the agreement between the information in the survey and the diagnoses extracted from the files was assessed by Cohen's Kappa.

Results: The risk of hypertensive disorders of pregnancy was higher after FET in the absence of a CL compared to FET with CL presence (aOR 5.56, 95% CI 1.12 – 27.72). Birthweights and birthweight percentiles were significantly higher in the 0 CL group. CL absence was a predictor of higher birthweight (adjusted coefficient B 179.74, 95% CI 13.03 – 346.44) and higher birthweight percentiles (adjusted coefficient B 10.23, 95%, 95% CI 2.28 – 18.40) particularly in female newborns of the 0 CL cohort. While the strength of the agreement between the reported information in the survey and the actual diagnoses extracted from the files was good for the majority of outcomes of interest it was fair in terms of hypertension (κ = 0.38).

Conclusion: This study supports observations suggesting a potential link between a lack of CL at conception and adverse maternal and neonatal outcomes. Further investigations on causes and pathophysiological relationships are yet to be conducted.

Comparison of two mainstream endometrial preparation regimens in vitrified-warmed embryo transfers after PGT

RESEARCH QUESTION

Which of the two mainstream endometrial preparation regimens, assisted natural cycle (NC) or hormone replacement treatment cycle (HRT), help frozen-thawed embryo transfer (FET) cycles after preimplantation genetic testing (PGT) achieve better clinical outcomes?

DESIGN

This retrospective analysis included 3400 vitrified-warmed single blastocyst transfer cycles after PGT from January 2011 to November 2020, and involved 2332 patients with regular menstrual cycles. The decision to proceed with an assisted NC (n = 827) or HRT (n = 2573) before FET was reached based on a combination of patient preference and physician guidance. Clinical pregnancy rate, live birth rate, early miscarriage rate and obstetric outcomes were compared.

RESULTS

No significant difference was observed between the assisted NC and HRT groups in terms of clinical pregnancy rate (51.6% versus 50.7%, P = 0.634), live birth rate (44.0% versus 43.4%, P = 0.746) or early miscarriage rate (12.6% versus 12.0%, P = 0.707). Multivariate analysis indicated that the endometrial preparation protocol was not an independent factor for a clinical pregnancy or live birth. In the HRT group, the Caesarean section rate (64.7% versus 51.9%, P < 0.001) and pregnancy complication rate (20.2% versus 13.8%, P = 0.003) were significantly higher. The two groups were not statistically different with respect to gestational age, early preterm birth rate, fetal weight or fetal birth defect rate.

CONCLUSIONS

For patients undergoing a PGT-FET cycle involving a single blastocyst transfer, using assisted NC and HRT for the endometrial preparation could lead to comparable rates of clinical pregnancy and live birth. Additionally, NC is safer than HRT in terms of avoiding pregnancy complications and adverse obstetric outcomes.

Live birth rates after natural cycle versus hormone replacement therapy for single euploid blastocyst transfers: a retrospective cohort study

RESEARCH QUESTION

Is there any difference in live birth rate between the natural cycle and hormone replacement therapy (HRT) endometrial preparation protocols for women with regular menstrual cycles undergoing their first single vitrified-warmed euploid blastocyst transfer?

DESIGN

This was a retrospective cohort study that enrolled 722 women who underwent vitrified-warmed euploid blastocyst transfer at assisted reproductive technology (ART) centre of The First Affiliated Hospital of Zhengzhou University, from January 2013 to December 2019. Univariate and multivariate logistic regression models were used to analyse the relationship between the endometrial preparation protocols and live birth rates. Stratified analyses and sensitivity analyses were performed to ensure the reliability and stability of the results.

RESULTS

A total of 722 single vitrified-warmed euploid blastocyst transfer cycles were included. Overall, the live birth rates were 50.00% (110/220) in the natural cycle group and 47.61% (239/502) in the HRT group. Multiple logistic regression analyses showed that there was no significant association (adjusted odds ratio 0.82; 95% confidence interval 0.56-1.20; P = 0.313) between natural cycle and HRT protocols and the live birth rate. Interaction analysis showed that there was no significant difference in live birth rates between the two groups for any subgroup after adjusting for confounding factors.

CONCLUSIONS

For single vitrified-warmed euploid blastocyst transfer, natural cycle and HRT endometrial preparation protocols result in similar live birth rates among women with regular menstrual cycles. Further studies are needed into the effects of endometrial preparation protocols on pregnancy outcomes.

Clinical Observation on the Improvement of Serum Sex Hormone and Ovarian Function in Premature Ovarian Failure Patients with Deficiency-Cold Syndrome by Combining Wenjing Decoction with Tiaobu Chongren Acupuncture and Moxibustion

OBJECTIVE

To explore the effect of Wenjing Decoction and Tiaobu Chongren acupuncture and moxibustion therapy on serum sex hormones and ovarian function recovery in premature ovarian failure (POF) patients with deficiency-cold syndrome.

METHODS

From February 2018 to October 2019, 119 POI patients with deficiency-cold syndrome who met the selection criteria were randomly divided into the control group (n = 59) and the observation group (n = 60). The control group was treated with hormone replacement therapy, and the observation group was treated with Wenjing Decoction and Tiaobu Chongren acupuncture and moxibustion therapy on the basis of the control group. Both groups were treated continuously for 3 months. After treatment, the clinical efficacy of the two groups was compared, the Chinese medicine syndrome score, serum estradiol (E 2), follicle-stimulating hormone (FSH), luteinizing hormone (LH), anti-mullerian hormone (AMH) and bilateral antral follicle count (AFC), mean ovarian volume, and endometrial thickness of the two groups before and after treatment were compared.

RESULT

The effective rate of the observation group (93.10%) was higher than that of the control group (77.59%) (P < 0.05). After treatment, the index scores of traditional Chinese medicine syndromes in two groups were lower than before (P < 0.05), and the observation group was lower than the control group (P < 0.05). The serum E 2 and AMH levels in the two groups increased, while FSH and LH levels decreased compared with before treatment, and the observation group improved significantly compared with the control group (P < 0.05). The bilateral AFC, mean ovarian volume, and endometrial thickness of the two groups increased compared with before treatment, and the observation group was higher than the control group (P < 0.05).

CONCLUSION

On the basis of hormone replacement therapy, the combination of Wenjing Decoction and Tiaobu Chongren acupuncture and moxibustion therapy is effective in treating POF patients with deficiency-cold syndrome, which can effectively regulate their serum sex hormone levels and promote the recovery of ovarian function.

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

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

Natural cycle versus hormone replacement cycle for transferring vitrified-warmed embryos in eumenorrhoeic women. A retrospective cohort study

OBJECTIVE

To compare pregnancy, miscarriage and live birth rates and cycle monitoring parameters between Natural Cycle (NC-FET) and Hormone replacement cycle (HRC-FET) in eumenorrhoeic women undergoing vitrified-warmed autologous embryo transfer.

STUDY DESIGN

Single-centre retrospective cohort study analyzed 173 NC-FET and 507 HRC-FET cycles with transfer of day2/3/5/6 embryos. Natural cycle monitoring occurred with serial ultrasound with the first day of the scan determined by the shortest cycle frequency. Serum progesterone was ordered when ultrasound was ambiguous in ascertaining ovulation. For HRC-FET oral estradiol valerate was used in fixed or escalating doses with maximum daily dose of 12 mg. Transdermal estradiol gel was added when desired endometrial thickness was not achieved. Vaginal progesterone was introduced with Endometrial thickness(ET)> = 7 mm. Embryos were transferred after stage-appropriate progesterone exposure. Luteal support was given with vaginal progesterone in NC-FET and vaginal and oral progesterone in HRC-FET. Primary outcome was live-birth-rate. Secondary outcomes were ET, length-of-estrogenic-phase, numbers-of-ultrasounds&hormone-monitoring, pregnancy&miscarriage rate. The odds ratio for live-birth was adjusted for age, embryo number, previous-live-births, previous-losses, past-negative-ET-cycles, IVF-indication and embryo-developmental-stage. Quantitative variables were compared using unpaired-t-test and qualitative variables with chi-square test. Two tailed p-value < 0.05 was considered significant. Binary logistic regression was used to calculate adjusted odds for live-births.

RESULTS

The two cohorts were comparable in age, infertility-duration, previous-live-births, previous-losses, past-negative-ET-cycles, IVF-indication and embryo-developmental-stage. Length-of-estrogenic-phase was significantly shorter for NC-FET than HRC-FET 14.32 ± 2.83vs.18.18 ± 4.48; p = 0.0001) as was mean ultrasound-monitoring-scans (2.73 ± 0.95vs. 3.3 ± 1.04; p = 0.0001). Mean-endometrial-thickness (8.75 ± 1.83vs. 8.5 ± 1.25; p = 0.25) and mean-hormonal-tests (1.75 ± 1.28 vs. 1.88 ± 0.69; p = 0.09) did not differ significantly between NC-FET vs HRC-FET. Significantly higher live births took place in NC-FET vs. HRC-FET (87/173 = 50.3%vs.204/507 = 40.2%;p = 0.026). No significant difference was found in pregnancy rate (66.5% vs. 58%; p = 0.058) or in the pregnancy loss rate (24.3%vs30.6%; p = 0.23). The odds ratio for live-births adjusted for relevant variables was 1.48 (1.03-2.13) in NC-FET compared to HRC-FET.

CONCLUSIONS

NC-FET is a superior method of endometrial preparation compared to HRC-FET in eumenorrhoeic women since it has a shorter estrogenic phase, reduces patient visits to the hospital and improves live birth rates. Future adequately powered studies should look at antenatal and perinatal outcomes, patient satisfaction rates and cost-effectiveness in the two endometrial preparation regimes.

Early pregnancy loss in patients with polycystic ovary syndrome after IVM versus standard ovarian stimulation for IVF/ICSI

STUDY QUESTION

Is the incidence of early pregnancy loss (EPL) in patients with polycystic ovary syndrome (PCOS) higher after IVM of oocytes than after ovarian stimulation (OS) for IVF/ICSI?

SUMMARY ANSWER

Women with PCOS who are pregnant after fresh embryo transfer have a higher probability of EPL following IVM, but after frozen embryo transfer (FET), no significant difference in the incidence of EPL was observed following IVM compared to OS.

WHAT IS KNOWN ALREADY

There is conflicting evidence in the current literature with regard to the risk of EPL after IVM of oocytes when compared with OS. Because of the limited sample size in previous studies, the use of different IVM systems and the possible bias introduced by patient characteristics and treatment type, firm conclusions cannot be drawn.

STUDY DESIGN, SIZE, DURATION

This was a retrospective cohort study evaluating 800 women, with a diagnosis of infertility and PCOS as defined by Rotterdam criteria, who had a first positive pregnancy test after fresh or FET following IVM or OS between January 2010 and December 2017 in a tertiary care academic medical centre.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Pregnancies after non-hCG triggered IVM following a short course of highly purified human menopausal gonadotropin were compared with those after conventional OS. The primary outcome was EPL, defined as a spontaneous pregnancy loss before 10 weeks of gestation.

MAIN RESULTS AND THE ROLE OF CHANCE

In total, 329 patients with a positive pregnancy test after IVM and 471 patients with a positive pregnancy test after OS were included. Women who were pregnant after IVM were younger (28.6 ± 3.4 years vs 29.3 ± 3.6 years, P = 0.005) and had higher serum anti-Mullerian hormone levels (11.5 ± 8.1 ng/ml vs 7.2 ± 4.1 ng/ml, P < 0.001) compared to those who were pregnant after OS. The distribution of PCOS phenotypes was significantly different among women in the IVM group compared to those in the OS group and women who were pregnant after OS had previously suffered EPL more often (28% vs 17.6%, P = 0.003). EPL was significantly higher after fresh embryo transfer following IVM compared to OS (57/122 (46.7%) vs 53/305 (17.4%), P < 0.001), while the results were comparable after FET (63/207 (30.4%) vs 60/166 (36.1%), respectively, P = 0.24). In the multivariate logistic regression analysis evaluating fresh embryo transfer cycles, IVM was the only independent factor (adjusted odds ratio (aOR) 4.24, 95% CI 2.44-7.37, P < 0.001)) significantly associated with increased odds of EPL. On the other hand, when the same model was applied to FET cycles, the type of treatment (IVM vs OS) was not significantly associated with EPL (aOR 0.73, 95% CI 0.43-1.25, P = 0.25).

LIMITATIONS, REASONS FOR CAUTION

The current data are limited by the retrospective nature of the study and the potential of bias due to unmeasured confounders.

WIDER IMPLICATIONS OF THE FINDINGS

The increased risk of EPL after fresh embryo transfer following IVM may point towards inadequate endometrial development in IVM cycles. Adopting a freeze-all strategy after IVM seems more appropriate. Future studies are needed to ascertain the underlying cause of this observation.

STUDY FUNDING/COMPETING INTEREST(S)

The Clinical IVM research has been supported by research grants from Cook Medical and Besins Healthcare. All authors declared no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

Antenatal diagnosis of placenta accreta spectrum after in vitro fertilization-embryo transfer: a systematic review and meta-analysis

Increasing evidence suggests a relationship between in vitro fertilization-embryo transfer (IVF-ET) and placenta accreta spectrum (PAS). Some studies have reported a lower rate of antenatal diagnosis of PAS after IVF-ET compared to PAS with spontaneous conception. This study aimed to review the diagnostic accuracy of PAS after IVF-ET and to explore the relationship between IVF-ET pregnancy and PAS. According to the PRISMA guidelines, a comprehensive systematic review of the literature was conducted through August 31, 2020 to determine the effects of IVF-ET on PAS. In addition, a meta-analysis was conducted to explore the relationship between IVF-ET pregnancy and PAS. Twelve original studies (2011-2020) met the inclusion criteria. Among these, 190,139 IVF-ET pregnancies and 248,534 spontaneous conceptions met the inclusion criteria. In the comparator analysis between PAS after IVF-ET and PAS with spontaneous conception (n = 2), the antenatal diagnosis of PAS after IVF-ET was significantly lower than that of PAS with spontaneous conception (22.2% versus 94.7%, P < 0.01; < 12.9% versus 46.9%, P < 0.01). The risk of PAS was significantly higher in women who conceived with IVF-ET than in those with spontaneous conception (odds ratio [OR]: 5.03, 95% confidence interval [CI]: 3.34-7.56, P < 0.01). In the sensitivity analysis accounting for the type of IVF-ET, frozen ET was associated with an increased risk of PAS (OR: 4.60, 95%CI: 3.42-6.18, P < 0.01) compared to fresh ET. Notably, frozen ET with hormone replacement cycle was significantly associated with the prevalence of PAS compared to frozen ET with normal ovulatory cycle (OR: 5.76, 95%CI 3.12-10.64, P < 0.01). IVF-ET is associated with PAS, and PAS after IVF-ET was associated with a lower rate of antenatal diagnosis. Therefore, clinicians can pay more attention to the presence of PAS during antenatal evaluation in women with IVF-ET, especially in frozen ET with hormone replacement cycle.

Ovulatory-Based FET Cycles May Achieve Higher Pregnancy Rates in the General Population and among Anovulatory Women

This study evaluated which endometrial preparation protocol in frozen embryo transfer (FET) cycles provides the best results for polycystic ovarian syndrome (PCOS) patients and the general population. This retrospective study of 634 FET cycles was conducted 2016-2018. Cycles were divided into Group A: Artificial endometrial preparations for FET (aFET; n = 348), Group B: Ovulatory cycle (n = 286) to compare two methods of endometrial preparation for FET. Artificial endometrial preparation with exogenous estrogen and progesterone versus natural ovulation cycles, modified natural cycles using hCG for the final triggering and letrozole-induced ovulation with hCG. Anovulatory patients were analyzed separately. Anovulatory PCOS patients had significantly higher pregnancy rates with letrozole treatment compared with aFET cycles (44% vs. 22.5%; p = 0.044). For the entire cohort, ovulatory cycles and aFET were similar in terms of patient characteristics, demographics, infertility causes, treatment protocols and number of embryos transferred. Although the mean ESHRE score of the transferred embryos was higher in the aFET group, we found higher clinical pregnancy rate in the ovulatory cycle FET (41.3% vs. 27.3%, p < 0.0001). A better pregnancy rate was found after ovulatory cycle FET. In the ovulatory cycles, the outcome of letrozole-induced and non-induced cycles were comparable. PCOS patients, as well as the general population, may benefit from ovulation induced FET cycles, with significantly better outcomes in FET in ovulatory cycles.

Endometrial receptivity and embryo implantation in carnivores-commonalities and differences with other mammalian species

Endometrial receptivity and embryo implantation processes are a major point of pregnancy failure in many mammalian species, including humans. Although reproductive biology in many carnivore species remains enigmatic, the few that have been studied so far are invaluable comparative models. The goals of this review are to (1) summarize current data on the mechanisms involved in uterine receptivity and embryo implantation in carnivores, including commonalities and differences with other mammalian species and (2) identify research priorities to better understand a key phenomenon in a critical group of mammals. Besides unique reproductive traits in some carnivores (induced vs. spontaneous ovulation in cats, ovulation at the germinal vesicle stage in dogs), preimplantation embryo development is comparable with other orders. However, the timing of implantation varies, especially in species having an embryonic diapause. Mechanisms involved in endometrial receptivity and decidualization still remain to be fully understood, but specific markers have already been identified. Importantly, the use of endogenous hormones to control the ovarian activity may impact endometrial receptivity and subsequent embryo implantation. Next, research efforts should take advantage of advanced technologies to further study embryo implantation in carnivores and to provide more relevant models to reproductive medicine or for the conservation of rare and endangered species.

Frozen Embryo Transfer in Mildly Stimulated Cycle With Letrozole Compared to Natural Cycle in Ovulatory Women: A Large Retrospective Study

OBJECTIVE

To evaluate the clinical effect of mild stimulation with letrozole on pregnancy outcomes in ovulatory women undergoing frozen embryo transfer (FET) compared to natural cycle.

DESIGN

Retrospective observational study.

SETTING

Tertiary care academic medical center.

POPULATION

A total of 6,874 infertile women with regular menstrual cycles (21-35 days) met the criteria for this study in the period from 2013 to 2020.

METHODS

All patients who were prepared for and underwent FET were divided into two groups: a modified natural cycle (NC) group (n=3,958) and a letrozole cycle group (n=2,916).

MAIN OUTCOME MEASURES

The primary outcome of the study was clinical pregnancy rate. Secondary outcome measures were endometrial thickness, rates of implantation, positive HCG test, live birth, early miscarriage and ectopic pregnancy.

RESULTS

The clinical pregnancy rate was not statistically different between the modified NC-FET group and the letrozole-FFT group before (crude OR 0.99, 95% CI 0.90-1.09, P=0.902>0.05) and after propensity score matching (PSM) (crude OR 1.01, 95% CI 0.91-1.12, P=0.870>0.05). After multivariable logistic regression analysis, the clinical pregnancy rate remained insignificant before (adjusted OR 1.00, 95% CI 0.91-1.10, P=0.979>0.05) and after matching (adjusted OR 1.00, 95% CI 0.89-1.11, P=0.936>0.05), respectively. Similarly, in the crude and adjusted analysis, the positive HCG test, implantation, live birth and early miscarriage rates were also comparable in the letrozole-FFT group and modified NC-FET group before and after matching. Furthermore, the endometrial thickness of letrozole-FFT group was similar to that of modified NC-FET group with adjusted analysis.

CONCLUSION

Our observation suggests that mild stimulation with letrozole could produce similar pregnancy outcomes in ovulatory patients who undergo FET when compared with a natural cycle.

Seven Years of Vitrified Blastocyst Transfers: Comparison of 3 Preparation Protocols at a Single ART Center

Introduction: Frozen-thawed embryo transfers (FET) have become a standard practice to increase cumulative pregnancy rates, however, the choice of the best preparation protocol remains a matter of debate. Design: Retrospective analysis of clinical pregnancy (CPR) and live birth rate (LBR) of FET in natural cycles (NC-FET), modified natural cycles with hCG-triggered ovulation (mNC-FET), and hormonal artificial replacement (AR-FET). Materials and Methods: For natural cycles, patients were monitored by ultrasound to evaluate the dominant follicle and by urinary LH kits (NC-FET). When the endometrial thickness reached at least 7 mm and the dominant follicle 16-20 mm, hCG was administered in absence of urinary LH surge (mNC-FET). Embryo thawing and transfer was planned 7 days after LH surge or hCG administration. For the AR-FET, oral estradiol valerate was administered from day 2 of menstrual cycle until endometrial thickness reached at least 7 mm and transfer was planned after 5 days of vaginal progesterone start. Only single vitrified blastocyst transfers were included. Results: In total 2,895 transfers were performed of which 561 (19.4%) carried out with NC-FET, 1,749 (60.4%) with mNC-FET and 585 (20.2%) with AR-FET. CPRs were 32.62, 43.05, and 37.26%, respectively. LBR were 24.06, 33.56, and 25.81%, respectively. A statistically significant (p < 0.001) higher LBR for mNC-FET vs. NC-FET (OR 0.49-0.78) and AR-FET (OR 0.47-0.74) was observed. A higher ectopic pregnancy rate (p = 0.002) was observed in NC-FET (3.28%) than in AR-FET (1.83%) and mNC-FET (0.40%). A higher abortion rate (p = 0.031) in pregnancies <12 weeks was observed in AR-FET (27.52%) than in NC-FET (19.67%) and in mNC-FET (19.39%). At Post hoc analysis only female age (OR 0.91-0.95), antimullerian hormone (AMH) (OR 1.01-1.07) and mNC-FET (OR 1.39-1.98) were statically significant prognostic factors for LBRs. Conclusions: These results demonstrate a superior CPR and LBR following FET in hCG-triggered ovulation cycles compared to NC and AR-FET, a higher ectopic pregnancy rate in NC-FET and a higher abortion rate in pregnancies <12 weeks in AR-FET. However, these data need to be confirmed in randomized and prospective studies before definitive conclusions can be drawn. Clinicaltrials.gov ID: NCT03581422.