Impact of Endometrial Preparation Protocols for Frozen Embryo Transfer on Live Birth Rates

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.

Obstetric and neonatal outcomes after natural versus artificial cycle frozen embryo transfer and the role of luteal phase support: a systematic review and meta-analysis

BACKGROUND

The number of frozen embryo transfers (FET) has increased dramatically over the past decade. Based on current evidence, there is no difference in pregnancy rates when natural cycle FET (NC-FET) is compared to artificial cycle FET (AC-FET) in subfertile women. However, NC-FET seems to be associated with lower risk of adverse obstetric and neonatal outcomes compared with AC-FET cycles. Currently, there is no consensus about whether NC-FET needs to be combined with luteal phase support (LPS) or not. The question of how to prepare the endometrium for FET has now gained even more importance and taken the dimension of safety into account as it should not simply be reduced to the basic question of effectiveness.

OBJECTIVE AND RATIONALE

The objective of this project was to determine whether NC-FET, with or without LPS, decreases the risk of adverse obstetric and neonatal outcomes compared with AC-FET.

SEARCH METHODS

A systematic review and meta-analysis was carried out. A literature search was performed using the following databases: CINAHL, EMBASE, and MEDLINE from inception to 10 October 2022. Observational studies, including cohort studies, and registries comparing obstetric and neonatal outcomes between singleton pregnancies after NC-FET and those after AC-FET were sought. Risk of bias was assessed using the ROBINS-I tool. The quality of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation approach. We calculated pooled odds ratios (ORs), pooled risk differences (RDs), pooled adjusted ORs, and prevalence estimates with 95% CI using a random effect model, while heterogeneity was assessed by the I2.

OUTCOMES

The conducted search identified 2436 studies, 890 duplicates were removed and 1546 studies were screened. Thirty studies (NC-FET n = 56 445; AC-FET n = 57 231) were included, 19 of which used LPS in NC-FET. Birthweight was lower following NC-FET versus AC-FET (mean difference 26.35 g; 95% CI 11.61-41.08, I2 = 63%). Furthermore NC-FET compared to AC-FET resulted in a lower risk of large for gestational age (OR 0.88, 95% 0.83-0.94, I2 = 54%), macrosomia (OR 0.81; 95% CI 0.71-0.93, I2 = 68%), low birthweight (OR 0.81, 95% CI 0.77-0.85, I2 = 41%), early pregnancy loss (OR 0.73; 95% CI 0.61-0.86, I2 = 70%), preterm birth (OR 0.80; 95% CI 0.75-0.85, I2 = 20%), very preterm birth (OR 0.66, 95% CI 0.53-0.84, I2 = 0%), hypertensive disorders of pregnancy (OR 0.60, 95% CI 0.50-0.65, I2 = 61%), pre-eclampsia (OR 0.50; 95% CI 0.42-0.60, I2 = 44%), placenta previa (OR 0.84, 95% CI 0.73-0.97, I2 = 0%), and postpartum hemorrhage (OR 0.43; 95% CI 0.38-0.48, I2 = 53%). Stratified analyses on LPS use in NC-FET suggested that, compared to AC-FET, NC-FET with LPS decreased preterm birth risk, while NC-FET without LPS did not (OR 0.75, 95% CI 0.70-0.81). LPS use did not modify the other outcomes. Heterogeneity varied from low to high, while quality of the evidence was very low to moderate.

WIDER IMPLICATIONS

This study confirms that NC-FET decreases the risk of adverse obstetric and neonatal outcomes compared with AC-FET. We estimate that for each adverse outcome, use of NC-FET may prevent 4 to 22 cases per 1000 women. Consequently, NC-FET should be the preferred treatment in women with ovulatory cycles undergoing FET. Based on very low quality of evidence, the risk of preterm birth be decreased when LPS is used in NC-FET compared to AC-FET. However, because of many uncertainties-the major being the debate about efficacy of the use of LPS-future research is needed on efficacy and safety of LPS and no recommendation can be made about the use of LPS.

Young women were associated with higher risk of hypertensive disorders of pregnancy and cesarean section from hormone replaced cycles in frozen-thawed embryo transfer: a retrospective study of 5316 singleton deliveries

Background

The utilization of frozen-thawed embryo transfer (FET) cycles has been linked to heightened risks of adverse perinatal outcomes. However, the potential association between adverse perinatal outcomes and distinct endometrial preparation regimens remains unclear. Therefore, we aim to investigate the maternal and neonatal outcomes after hormone replacement treatment (HRT) cycles, natural cycles (NC) and HRT cycles with pretreatment using GnRHa (HRT + GnRHa) for ovulatory women undergoing FET cycles.

Methods

A large sample retrospective cohort study was carried out from 2016 to 2020. The data included a total of 5316 women who had singleton deliveries undergoing FET cycles and which were divided into three groups based on different endometrial preparation protocols: 4399 patients in HRT groups, 621 in GnRHa+HRT groups, 296 in NC groups. The outcomes consisted of maternal outcomes (cesarean section, hypertensive disorders of pregnancy (HDP), placenta previa, gestational diabetes mellitus (GDM));and neonatal outcomes (preterm birth, newborn birthweight, low birthweight, small for gestational age (SGA), macrosomia, large for gestational age (LGA), fetal malformation).

Results

After adjusting for a series of confounding variables, we found an increased risk of HDP (aOR=3.362; 95%CI, 1.059-10.675) and cesarean section (aOR=1.838; 95%CI, 1.333-2.535) in HRT cycles compared with NC, especially for ovulatory women under 35 years old. However, in all three groups, newborn birth weight was not significantly different. Meanwhile, perinatal outcomes did not differ significantly in terms of perinatal outcomes in HRT +GnRHa cycles compared with HRT cycles solely.

Conclusion

During FET cycles, singletons from HRT were related to higher risks of HDP and cesarean section, particularly for young women. GnRHa pretreatment didn't bring any benefit to perinatal outcomes compared with HRT cycles alone. Therefore, the natural cycle may be a more appropriate and safer option for young ovulatory women.

Reproductive and Obstetric Outcomes Following a Natural Cycle vs. Artificial Endometrial Preparation for Frozen-Thawed Embryo Transfer: A Retrospective Cohort Study

Background: The proportion of frozen embryo transfer cycles has consistently grown in recent decades. Some adverse obstetric outcomes after frozen embryo transfer could possibly be explained by different approaches in endometrial preparation. The aim of the present study was to investigate reproductive and obstetric outcomes after frozen embryo transfer, comparing different endometrial preparation strategies. Methods: This retrospective study included 317 frozen embryo transfer cycles, of which 239 had a natural or modified natural cycle and 78 underwent artificial endometrial preparation. After excluding late abortion and twin pregnancies, the outcomes of 103 pregnancies were analyzed, 75 of which were achieved after a natural cycle/modified natural cycle, and 28 were achieved after an artificial cycle. Results: The overall clinical pregnancy rate/embryo transfer was 39.7%, the miscarriage rate was 10.1%, and the live birth rate/embryo transfer was 32.8%, without significant differences in reproductive outcomes between natural/modified cycle and artificial cycle groups. The risks of pregnancy-induced hypertension and abnormal placental insertion were significantly increased in pregnancies achieved after the artificial preparation of the endometrium (p = 0.0327 and =0.0191, respectively). Conclusions: Our study encourages the use of a natural cycle or modified natural cycle for endometrial preparation for frozen embryo transfer in order to ensure the presence of a corpus luteum able to orchestrate maternal adaptation to pregnancy.

Clinical and laboratory parameters associated with pregnancy outcomes in patients undergoing frozen euploid blastocyst transfer

RESEARCH QUESTION

Which factors impact on clinical pregnancy rate (CPR) and live birth rates (LBR) in euploid frozen embryo transfer (eFET) cycles?

DESIGN

Retrospective observational study including 1660 eFET cycles with 2439 euploid blastocysts, from November 2016 to December 2020. The impact of clinical and laboratory parameters on CPR, biochemical miscarriage rate (BMR), clinical miscarriage rate (CMR) and LBR was evaluated.

RESULTS

CPR per transfer was 63.4%, LBR per transfer 51.6%. CPR and LBR were significantly higher when double embryo transfer (DET) was performed (71.6% versus 57.7%, P < 0.001; 55.2% versus 49.1%, P = 0.016, respectively). However, pregnancy loss was significantly higher in the DET group (28.8% versus 22.8%, P = 0.02). When patients were classified by body mass index (BMI), no differences were observed for CPR, but CMR was lower (P < 0.001) and LBR higher (p = 0.031) for the normal BMI group. The natural cycle protocol revealed lower CMR (P < 0.001) and lower pregnancy loss (P < 0.001); subsequently, higher LBR (57.6%, 48.8%, 45.0%, P = 0.001) compared with hormonal replacement protocol and stimulated cycle. Day of trophectoderm biopsy affected CPR (P < 0.001) and LBR (P < 0.001), yet no differences were observed for BMR, CMR or pregnancy loss. The multivariate analysis showed that day 6/7 embryos had lower probabilities for pregnancy; overweight and obesity had a negative impact on LBR, and natural cycle improved LBR (adjusted odds ratio 1.445, 95% confidence interval 0.519-0.806).

CONCLUSIONS

Day of biopsy affected CPR, while BMI and endometrial preparation protocol were associated with LBR in eFET. DET should be discouraged as it will increase the risk of pregnancy loss. Women with higher BMI should be aware of the higher risk of pregnancy loss and lower LBR even though a euploid blastocyst is transferred.

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.

Comparison of two endometrial preparation methods for frozen-thawed embryo transfer in anovulatory PCOS patients: impact on miscarriage rate

OBJECTIVE

- Some studies have suggested that patients with polycystic ovary syndrome (PCOS) are at high risk of miscarriage. However, this still remains controversial. Several potential factors might explain this association: obesity, hyperinsulinemia and hyperandrogenism. Artificial and stimulated cycles appear to be comparable for endometrial preparation in frozen-thawed embryo transfer (FET) in PCOS patients. Only a few studies have assessed miscarriage rates specifically in PCOS. We have evaluated the impact of endometrial preparation on FET outcomes in anovulatory PCOS patients.

METHODS

- A retrospective cohort study was conducted at the Lille University Hospital, including 255 FET cycles in 134 PCOS patients between January 2011 and December 2017. PCOS was defined by the presence of at least two of the three Rotterdam's criteria. Patients were under 35 years old. Two endometrial preparation protocol were studied: stimulated cycle (gonadotropins on the second day of the cycle and luteal phase support including natural progesterone 600 mg/day) and artificial cycle (6 mg oral estradiol valerate and 800 mg micronized vaginal progesterone daily).

RESULTS

- 137 FET were performed under stimulated cycle and 118 FET under artificial cycle. Early pregnancy rates (30% versus 37.3%, p = NS), miscarriage rates (22% versus 25%, p = NS) and live birth rates (23.4% versus 26.3%, p = NS) were similar.

CONCLUSIONS

- In anovulatory PCOS women, the type of endometrial preparation does not influence FET outcomes, specifically regarding the miscarriage rate.

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.

Is duration of estrogen supplementation associated with clinical outcomes in frozen-thawed autologous single-blastocyst transfer cycles?

PURPOSE

To investigate the relationship between different duration of estrogen administration and live birth rate (LBR) after autologous single frozen blastocyst transfer with hormone replacement therapy.

METHODS

A total of 2026 frozen blastocyst transfer cycles in the assisted reproductive center of northwest women and children's hospital from January, 2017, to August, 2020, were retrospectively analyzed. All the cycles were allocated into 3 groups according to the duration of estrogen administration: group A, 11-14 days (n = 346); group B, 15-18 days (n = 1191), and group C, ≥ 19 days (n = 489). Baseline data, clinical, and perinatal outcomes of the three groups were compared. A multivariate regression model was constructed to analyze the association between duration of estradiol administration and clinical outcomes.

RESULTS

We did not observe a significant association between duration of estrogen supplementation and LBR in group B (adjusted odds ratio [aOR] 1.14; 95% confidence interval [CI], 0.89-1.45) or group C (aOR 1.16; 95% CI, 0.86-1.56) patients with group A as the reference group, through logistic regression analysis. No statistical differences were observed in perinatal outcomes among the three groups.

CONCLUSION

The duration of estrogen administration was not associated with the likelihood of live birth in women undergoing frozen-thawed autologous single-blastocyst transfer.

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.

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.

The impact of different cycle regimens on birthweight of singletons in frozen-thawed embryo transfer cycles of ovulatory women

OBJECTIVE

To investigate whether different endometrial preparation regimens affect neonatal outcomes after frozen-thawed embryo transfer (FET).

DESIGN

Retrospective cohort study.

SETTING

Tertiary care academic medical center.

PATIENTS

A total of 3,639 patients with live-born singletons were categorized into three groups on the basis of the type of endometrial preparation regimens. Of these, 1,225, 2,136, and 278 live-born singletons were conceived through natural cycle FET, artificial cycle FET, and stimulated cycle FET, respectively.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURES

The main outcomes were the measures of birthweight including the absolute mean birthweight, Z-score, low birthweight, high birthweight (HBW), small for gestational age, and large for gestational age (LGA).

RESULTS

After controlling for a variety of covariates, singletons from the artificial cycle FET group had a higher mean birthweight and Z-score than those from the natural cycle FET group and stimulated cycle FET group. The risk of LGA infants significantly increased in the artificial cycle group (14.0%) than that in the natural cycle group (10.3%) and stimulated cycle group (7.6%). The risk of hypertensive disorders of pregnancy in the artificial cycle group (4.4%) was significantly higher than that in the natural cycle group (2.5%). The stimulated cycle FET singletons had a higher risk of low birthweight than the natural cycle FET singletons. The other perinatal outcomes, including the incidence of preterm birth, small for gestational age, and gestational diabetes mellitus, were comparable between the groups before or after adjustment for confounders.

CONCLUSIONS

Singletons from artificial cycle FET were associated with a higher risk of LGA infants, and natural cycle FET may be a better regimen for ovulatory women. Our results indicate a link between the absence of the corpus luteum and adverse perinatal outcomes, and further studies are needed to detect the underlying mechanism.

Frozen Blastocyst Embryo Transfer: Comparison of Protocols and Factors Influencing Outcome

Background: Various factors, including treatment protocols, can influence the outcomes of frozen embryo transfers (FETs). The study objectives were to compare different endometrial preparation protocols of FET cycles and to evaluate the factors, including the endometrial thickness (ET), that affect outcomes. Methods: This observational cohort study involved 5037 women undergoing FETs at eight tertiary clinics in the UK between January 2016 and March 2019. The endometrial preparation protocols used were natural cycle (NC-FETs), artificial hormone support cycle with oestradiol valerate but without pituitary downregulation (AC-FETs) and artificial hormone support cycle with agonist downregulation (ACDR-FETs). Results: The mean (±SD) ages across NC-FET, AC-FET and ACDR-FET groups were 36.5 (±4.2), 35.9 (±5.0) and 36.4(±4.9) years, respectively. LBRs were comparable (40.7%, 175/430; 36.8%, 986/2658; and 36.7%, 716/1949, respectively) across the three groups. Clinical pregnancy, implantation, multiple pregnancies, miscarriage and ectopic pregnancy rates were also similar. In the regression analysis of variables including age, duration of infertility, number of embryos transferred, protocol type and endometrial thickness, age was the only significant predictor of LBRs, although its predictive ability was poor (AUC: 0.55). With the overall LBR of the study population being 37.1%, the post-test probability of a live birth at an ET of <5 mm was 0%, and at 5–5.9, 6–6.9, 7–7.9 and 8–8.9 mm, the probabilities were 16.7%, 33.8%, 36.7% and 37.7%, respectively. The LBR remained above 35% up to the 14–14.9 mm range and then declined gradually to 23% for the 17–25 mm range. Conclusions: The FET outcomes were similar for the three protocols used for endometrial preparation. The protocol type and endometrial thickness were not predictive of FET outcomes; age was the only predictive variable, despite its low predictive ability.

Pregnancy Outcomes of Different Endometrial Preparation in Patients With a History of Cesarean Section

OBJECTIVE

To investigate the efficacies of three cycle regimens in women receiving frozen embryo transfer with a history of cesarean section: natural cycle treatment, hormone replacement therapy and treatment with gonadotropin-releasing hormone agonist.

DESIGN

Retrospective cohort study.

METHODS

patients (N = 6,159) with a history of caesarean section who fulfilled the inclusion criteria were enrolled in the study from January 2014 to December 2019 at the CITIC-Xiangya Hospital of Reproduction and Genetics. Reproductive outcomes of patients in the natural cycle (n = 4,306) versus hormone replacement therapy (n = 1,007) versus gonadotropin-releasing hormone agonist + hormone replacement therapy groups (n = 846) were compared. Continuous data were analyzed using Student's t-test, and categorical variables were analyzed using the χ2 test. Multivariable logistic regression was used to evaluate the possible relationships between the types of endometrial preparation and pregnancy outcomes after adjusting for confounding factors.

RESULTS

The unadjusted odds of the miscarriage rate of singleton pregnancies were significantly higher in the hormone replacement therapy compared with the natural cycle (25.5% versus 20.4%, respectively). After adjusting for possible confounding factors, the early miscarriage rate and the miscarriage rate of singleton pregnancies remained significantly higher in the hormone replacement therapy than the natural cycle. The clinical pregnancy rates in the natural cycle, hormone replacement therapy and gonadotropin- releasing hormone agonist + hormone replacement therapy of women with a history of cesarean section was 48.8%, 48% and 47.1%, respectively, and the live birth rates were 37%, 34.1% and 35.7%, respectively.

CONCLUSIONS

In women undergoing frozen embryo transfer with a history of cesarean section, hormone replacement therapy for endometrial preparation was associated with a higher early miscarriage rate, albeit after statistical adjustment for confounding factors. However, the risk observed was little and did not influence the overall reproductive performances.

Ovulation induction regimens are associated with a higher rate of livebirth after frozen single-blastocyst transfer among women with polycystic ovary syndrome

BACKGROUND

Hormone replacement therapy (HRT) regimen was suggested to be associated with a decreased rate of livebirth and a higher risk of hypertensive disorders of pregnancy (HDP) after frozen cleavage stage embryo transfer in women with polycystic ovary syndrome (PCOS). With the dramatically increased use of elective single embryo transfer, there is great need to explore the impacts of different endometrial preparation regimens on frozen single-blastocyst transfer in women with PCOS.

METHODS

In this study, a total of 3941 women who diagnosed with PCOS and underwent single-blastocyst transfer during their first cycles of frozen embryo transfer (FET) between March 2012 and December 2020 were included. We retrospectively compared the pregnancy and neonatal outcomes after frozen single-blastocyst transfer with endometrial preparation by HRT regimen (n = 3540), ovulation induction by human menopausal gonadotropin (hMG) regimen (n = 226), and ovulation induction by letrozole regimen (n = 175).

RESULTS

After adjustment for confounders with multivariable logistic regression, the hMG regimen group [(58.4% vs. 49.6%; adjusted odds ratio (aOR): 1.43; 95% confidence interval (CI): 1.09-1.89)] and letrozole regimen group (58.9% vs. 49.6%; aOR: 1.42; 95% CI: 1.04-1.93) were associated with a higher rate of livebirth (primary outcome), compared with the group with HRT regimen. As to the secondary outcomes, the rate of pregnancy loss in the hMG regimen group (22.8% vs. 30.3%; aOR: 0.69; 95% CI: 0.48-1.00) and letrozole regimen group (16.9% vs. 30.3%; aOR: 0.48; 95% CI: 0.30-0.78) was also lower than that in the HRT regimen group. The pregnancy outcomes between the hMG regimen group and the letrozole regimen group were similar. We did not observe significant difference in the incidences of maternal and neonatal complications among these three groups.

CONCLUSION

Ovulation induction regimen with letrozole or hMG for endometrial preparation was associated with a higher livebirth rate and a lower pregnancy loss rate in frozen single-blastocyst transfer cycles among women with PCOS.

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.

Association between clinical and IVF laboratory parameters and miscarriage after single euploid embryo transfers

BACKGROUND

The goal of this study was to investigate which factors, excluding embryo aneuploidies, are associated with miscarriage in patients who have undergone a single euploid blastocyst transfer.

METHODS

Retrospective, observational and multicenter study with 2832 patients undergoing preimplantational genetic testing for aneuploidies (PGT-A) due to repeated implantation failure, recurrent pregnancy loss, advanced maternal age or severe male factor were transferred one single euploid embryo.

RESULTS

One of the main findings was a significant relationship between body mass index (BMI) and miscarriage rates (13.4% in underweight women, 12.1% in normal weight, 14.5% in overweight, and 19.2% in obese women, odds ratio [OD] 1.04; 95% confidence interval [CI], 1.01-1.07 p = 0.006). Endometrial thickness (OD 0.65; 95%, 0.52-0.77 p = 0.04) and type of endometrial preparation (natural cycle or hormone replacement cycle) (OD 0.77; 95%, 0.52-0.77, p = 0.04) were also associated with miscarriage rates.

CONCLUSIONS

BMI was strongly associated to miscarriage rates. We also observed a weaker association with endometrial thickness and with the type of endometrial preparation (natural cycle or hormone replacement cycle). None of the other studied variables (biopsy day, maternal and male age, duration of infertility, cycle length, previous miscarriages, previous live births, previous In Vitro Fertilization (IVF) cycles, endometrial pattern and/or diagnosis) were associated with miscarriage rates.

Effects of different frozen embryo transfer regimens on abnormalities of fetal weight: a systematic review and meta-analysis

BACKGROUND

Reported increases in maternal and perinatal morbidity (including macrosomia, large for gestational age (LGA), cesarean section, hemorrhage and hypertensive disorders of pregnancy) following frozen embryo transfer (FET) cycles may be associated with the lack of a corpus luteum seen in programmed FET. Given the growing number of studies comparing outcomes between natural FET and programmed FET cycles, a meta-analysis would prove useful to detect the presence of abnormalities in fetal birth weight in patients undergoing natural and programmed FET cycles.

OBJECTIVE AND RATIONALE

The aim of this study was to provide a systematic review and meta-analysis of the effects of natural versus programmed methods of endometrial preparation for FET cycles on fetal weight and the risks of LGA and macrosomia.

SEARCH METHODS

A literature search using MEDLINE, SCOPUS, EMBASE and clinicaltrials.gov was conducted for published research comparing neonatal outcomes in natural FET and programmed FET cycles. Primary outcomes of interest were fetal weight, macrosomia and LGA. Studies were included if the following criteria were met: study contained cohorts of NFET and programmed FET with outcome data of birth weight, large for gestational data and/or macrosomia. The data are presented as average weight and odds ratio (OR) with 95% confidence interval (CI) with fixed- or random-effects meta-analysis between cohorts of NFET and programmed FET cycles. Bias was assessed using Newcastle-Ottawa quality assessment scale for the 14 included studies. Multiple subgroup analyses were performed to assess for effect of the true natural cycle (defined as no ovulation trigger medication use) and the day of embryo transfer on fetal weight parameters compared with programmed cycle FET.

OUTCOMES

A total of 879 studies were identified, with 15 meeting inclusion the criteria. The studies varied with respect to country of origin, definition of natural cycle FET and type of progesterone supplementation used. The included studies had similar gestational ages at the time of birth. Programmed FET cycles resulted in a higher fetal weight compared with natural FET cycles (mean difference 47.38 gp = 0.04). Programmed FET cycles were also at higher risk for macrosomia (OR 1.15, 95% CI 1.06-1.26) and LGA (OR 1.10, 95% CI 1.02-1.19) compared with natural FET cycles. Subgroup analyses demonstrated that programmed FET cycles resulted in a higher fetal weight compared with true natural FET (mean difference 62.18 gp = 0.0001) cycles. Cleavage stage embryo transfers had an increased risk of LGA (OR 1.27, 95% CI 1.00-1.62) and an increased risk of macrosomia (OR 1.25, 95% CI 1.08-1.44) in programmed FET cycles compared with natural FET cycles. Blastocyst transfer in programmed FET cycles resulted in no difference in risk of macrosomia but an increased risk of LGA (OR 1.13, 95% CI 1.06-1.21) compared with natural FET cycles.

WIDER IMPLICATIONS

Programmed endometrial preparation for FET cycles had a significant effect, causing increased fetal birth weight and increased risks of LGA and macrosomia. The numbers of studies in the subgroup analyses were too low to determine reliable results. Further prospective randomized trials are needed to determine whether the changes seen in the observational trials are indeed accurate.

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.

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.

Frozen embryo transfer and preeclampsia: where is the link?

PURPOSE OF REVIEW

Preeclampsia is the leading cause of maternal death and has a higher incidence in patients undergoing assisted reproduction treatments. New studies about the mechanisms by which it is more frequent in this population have emerged. The purpose of this review is to gather current information about the available results on this correlation and its possible physiopathology.

RECENT FINDINGS

Recent publications on the physiopathology of preeclampsia indicate that the corpus luteum is the main source of hormonal production until placental formation and that apart from the secretion of estrogen and progesterone, corpus luteum also produces important substances involved in maternal circulatory adaptation, such as relaxin.With the recent increasing number of frozen embryos transfer in natural cycles or under hormonal replacement, this adaptive circulatory process may be unbalanced and predispose this population to preeclampsia.

SUMMARY

This article provides a review of frozen embryo transfer and available protocols, the highest incidence of gestational hypertensive disorders presented by the infertile population and an overview of the possible impact of the absence of corpus luteum on the genesis of this disease.

Comparison of the Method of Endometrial Preparation Prior to Frozen-Thawed Embryo Transfer: a Retrospective Cohort Study from 9733 Cycles

Our objective was to compare the effectiveness of natural cycles (NC), modified natural cycle (mNC), and artificial cycles (AC) in women undergoing frozen-thawed embryo transfer (FET) after in vitro fertilization (IVF). This is a retrospective cohort study analyzing 9733 women undergoing the first cycle of FET over a 3-year period (June 2014-December 2017) at Northwest Women's and Children's Hospital after IVF-ICSI cycles. The type of endometrial preparation was determined by the treating physician's preference, based on patients' characteristics. Women with regular ovulation were allocated to natural cycles (n = 1480) or modified natural cycles (n = 196) when the leading follicle was triggered with hCG, while patients who were reluctant to frequently monitoring or living far from the hospital were allocated to artificial cycles (n = 8057). A logistic regression model was used to assess the association between endometrial preparation and clinical outcomes while adjusting for potential confounders. Live birth rate was primary outcome while miscarriage rate, clinical pregnancy rate, preterm birth rate, and ectopic pregnancy rate were secondary outcomes. In the adjusted model, type of endometrial preparation did not affect live birth (OR, 0.89; 95% CI, 0.74-0.96), clinical pregnancy (OR, 0.93; 95% CI, 0.81-1.06), preterm birth (OR, 1.03; 95% CI, 0.84-1.26), and ectopic pregnancy (OR, 0.73; 95% CI, 0.33-1.59), while AC significantly increased the miscarriage rate (OR, 1.49; 95% CI, 1.17-1.89, P=0.001). In conclusions, in women undergoing FET, natural cycles and artificial cycles resulted in comparable live birth rate while miscarriage rate was higher in artificial cycles.

Effects of different cycle regimens for frozen embryo transfer on perinatal outcomes of singletons

STUDY QUESTION

Does the endometrial preparation protocol for frozen embryo transfer (FET) have an impact on perinatal outcomes?

SUMMARY ANSWER

Singleton newborns from conceptions after an artificial FET cycle had a higher risk of being large for gestational age (LGA).

WHAT IS KNOWN ALREADY

Most previous studies have concentrated on the clinical pregnancy, miscarriage and live birth rates of different endometrial preparation protocols for FET. However, the impacts of these cycle regimens on perinatal outcomes including birthweight, gestational age (GA) and related outcomes require more investigation.

STUDY DESIGN, SIZE, DURATION

We retrospectively analysed all singletons conceived by women who underwent non-donor FET cycles between July 2014 and July 2017. The propensity score matching (PSM) method using nearest neighbour matching at a proportion of 1:1 was established to adjust for factors that influence the probability of receiving different FET cycle regimens. The main outcomes of the study included birthweight and its related outcomes, Z-score, low birthweight (LBW, <2500 g), small for gestational age (SGA, ≤10th percentile of referential birthweight), LGA (≥90th percentile of referential birthweight) and macrosomia (birthweight >4000 g). The study outcomes also included GA at birth, preterm delivery (<37 weeks), very preterm delivery (<32 weeks), very low birthweight (VLBW, <1500 g), term LBW (at 37 weeks of gestation or greater) and preterm LBW (at <37 weeks of gestation).

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 9267 cycles with live-born singletons were included in the analysis in our centre between July 2014 and July 2017. Of these, 2224, 4299 and 2744 live-born singletons were conceived by natural cycle FET, stimulated cycle FET and artificial cycle FET, respectively. After PSM, 1947 cycles of natural cycle FET versus stimulated cycle FET, 1682 cycles of stimulated cycle FET versus artificial cycle FET and 2333 cycles of natural cycle FET versus artificial cycle FET were included in the analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

A higher mean birthweight and Z-score were observed in the artificial cycle FET group than in the stimulated cycle FET group (P = 0.005; P = 0.004, respectively). Singleton newborns conceived after artificial cycle FET were more likely to be LGA than those born after natural cycle FET or stimulated cycle FET (19.92% versus 16.94% and 19.29% versus 16.12%, respectively). The adjusted ORs (95% CIs) were 1.25 (1.05, 1.49) for artificial cycle FET compared with natural cycle FET (P = 0.014) and 1.26 (1.08, 1.46) for artificial cycle FET compared with stimulated cycle FET (P = 0.003). Newborns conceived after stimulated cycle FET had a lower mean GA at birth and a lower mean birthweight than those born after natural cycle FET or artificial cycle FET. The stimulated cycle FET group had lower adjusted odds of being macrosomia than the natural cycle FET group. No significant differences between natural cycle FET and stimulated cycle FET were found for any of the other outcomes.

LIMITATIONS, REASONS FOR CAUTION

This study had the disadvantage of being retrospective, and some cases were excluded due to missing data. The original allocation process was not randomized, which may have introduced bias. We have chosen not to account for multiple comparisons in our statistical analysis.

WIDER IMPLICATIONS OF THE FINDINGS

LGA can have long-term consequences in terms of risk for disease, which means that the influences of artificial cycle FET are of clinical significance and deserve more attention. Furthermore, these findings are critical for clinicians to be able to make an informed decision when choosing an endometrial preparation method.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by grants from the National Natural Science Foundation of China (NSFC) (31770989 to Y.W.) and the Shanghai Ninth People's Hospital Foundation of China (JYLJ030 to Y.W.). None of the authors have any conflicts of interest to declare.

The impact of timing modified natural cycle frozen embryo transfer based on spontaneous luteinizing hormone surge

PURPOSE

To evaluate whether adjusting timing of modified natural cycle frozen embryo transfer (mNC-FET) 1 day earlier in the setting of a spontaneous LH surge has an impact on pregnancy outcomes.

METHODS

This retrospective cohort study evaluated all mNC-FET with euploid blastocysts from May 1, 2016 to March 30, 2019, at a single academic institution. Standard protocol for mNC-FET included ultrasound monitoring and hCG trigger when the dominant follicle and endometrial lining were appropriately developed. Patients had serum LH, estradiol, and progesterone checked on day of trigger. If LH was ≥ 20 mIU/mL, trigger was given that day and FET was performed 6 days after surge (LH/HCG+6), with the intent of transferring 5 days after ovulation. If LH was < 20 mIU/mL, FET was performed 7 days after trigger (hCG+7). Primary outcomes included clinical pregnancy and live birth rates. To account for correlation between cycles, a generalized estimating equation (GEE) method for multivariable logistic regression was used.

RESULTS

Four hundred fifty-three mNC-FET cycles met inclusion criteria, of which 205 were in the LH/HCG+6 group and 248 were in the HCG+7 group. The overall clinical pregnancy rate was 64% and clinical miscarriage rate was 4.8%, with similar rates between the two groups. The overall live birth rate was 60.9% (61.0% in LH/HCG+6 group and 60.9% in HCG+7 group). After implementing GEE, the odds of CP (aOR 0.97, 95% CI [0.65-1.45], p = 0.88) and LB (aOR 0.98, 95% CI [0.67-1.45], p = 0.93) were similar in both groups.

CONCLUSIONS

In our study cohort, mNC-FET based on LH/HCG+6 versus HCG+7 had similar pregnancy outcomes.

An artificial intelligence model based on the proteomic profile of euploid embryos and blastocyst morphology: a preliminary study

RESEARCH QUESTION

The study aimed to develop an artificial intelligence model based on artificial neural networks (ANNs) to predict the likelihood of achieving a live birth using the proteomic profile of spent culture media and blastocyst morphology.

DESIGN

This retrospective cohort study included 212 patients who underwent single blastocyst transfer at IVI Valencia. A single image of each of 186 embryos was studied, and the protein profile was analysed in 81 samples of spent embryo culture medium from patients included in the preimplantation genetic testing programme. The information extracted from the analyses was used as input data for the ANN. The multilayer perceptron and the back-propagation learning method were used to train the ANN. Finally, predictive power was measured using the area under the curve (AUC) of the receiver operating characteristic curve.

RESULTS

Three ANN architectures classified most of the embryos correctly as leading (LB+) or not leading (LB-) to a live birth: 100.0% for ANN1 (morphological variables and two proteins), 85.7% for ANN2 (morphological variables and seven proteins), and 83.3% for ANN3 (morphological variables and 25 proteins). The artificial intelligence model using information extracted from blastocyst image analysis and concentrations of interleukin-6 and matrix metalloproteinase-1 was able to predict live birth with an AUC of 1.0.

CONCLUSIONS

The model proposed in this preliminary report may provide a promising tool to select the embryo most likely to lead to a live birth in a euploid cohort. The accuracy of prediction demonstrated by this software may improve the efficacy of an assisted reproduction treatment by reducing the number of transfers per patient. Prospective studies are, however, needed.

Should we still perform fresh embryo transfers in ART?

An increasing number of researchers have alluded to the potential benefit of deferring the transfer of embryos produced during assisted reproductive technologies (ARTs) away from ovarian stimulation, using cryopreservation to enable this. The scientific evidence that may justify this recent trend in the use of the so-called 'freeze-all strategy' includes early, mostly small randomised controlled trials that have demonstrated an increase in live birth rates after elective embryo cryopreservation in certain patient populations, as well as evidence from cohort studies and retrospective analyses. What are the risks and benefits of freeze-all strategies in ART, who are the patients in whom it is likely to be advantageous, and does the current evidence allow us to identify situations when deciding that a fresh embryo transfer would be counter-productive? ART professionals are often faced with challenging clinical decisions regarding the best course of treatment for their patient. The purpose of this opinion paper is to provide a clinical guide for whether to perform a fresh embryo transfer or to opt for freezing all embryos in specific situations.

Novel and conventional embryo parameters as input data for artificial neural networks: an artificial intelligence model applied for prediction of the implantation potential

OBJECTIVE

To describe novel embryo features capable of predicting implantation potential as input data for an artificial neural network (ANN) model.

DESIGN

Retrospective cohort study.

SETTING

University-affiliated private IVF center.

PATIENT(S)

This study included 637 patients from the oocyte donation program who underwent single-blastocyst transfer during two consecutive years.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The research was divided into two phases. Phase 1 consisted of the description and analysis of the following embryo features in implanted and nonimplanted embryos: distance and speed of pronuclear migration, blastocyst expanded diameter, inner cell mass area, and trophectoderm cell cycle length. Phase 2 consisted of the development of an ANN algorithm for implantation prediction. Results were obtained for four models fed with different input data. The predictive power was measured with the use of the area under the receiver operating characteristic curve (AUC).

RESULT(S)

Out of the five novel described parameters, blastocyst expanded diameter and trophectoderm cell cycle length had statistically different values in implanted and nonimplanted embryos. After the ANN models were trained and validated using fivefold cross-validation, they were capable of predicting implantation on testing data with AUCs of 0.64 for ANN1 (conventional morphokinetics), 0.73 for ANN2 (novel morphodynamics), 0.77 for ANN3 (conventional morphokinetics + novel morphodynamics), and 0.68 for ANN4 (discriminatory variables from statistical test).

CONCLUSION(S)

The novel proposed embryo features affect the implantation potential, and their combination with conventional morphokinetic parameters is effective as input data for a predictive model based on artificial intelligence.

D6 blastocyst transfer on day 6 in frozen-thawed cycles should be avoided: a retrospective cohort study

Background

There is no definitive evidence about the suitable timing to transfer blastocysts formed and cryopreserved on day 6 (D6 blastocysts) in frozen-thawed embryo transfer (FET) cycles. This study aimed to investigate the suitable timing to transfer D6 blastocysts in FET cycles and to identify factors affecting clinical pregnancy rate (CPR) and early miscarriage rate (EMR) in FET cycles with blastocysts.

Methods

This retrospective cohort study included 1788 FET cycles with blastocysts. There were 518 cycles with D6 blastocysts, and 1270 cycles with blastocysts formed and cryopreserved on day 5 (D5 blastocysts) (D5 group). According to the blastocyst transfer timing, the cycles with D6 blastocysts were divided into cycles with D6 blastocysts transferred on day 5 (D6-on-D5 group, 103 cycles) and cycles with D6 blastocysts transferred on day 6 (D6-on-D6 group, 415 cycles). The chi-square test, independent t-test or Mann-Whitney test, and logistic regression analysis were used for data analysis.

Results

The CPR and implantation rate (IR) were significantly higher in the D6-on-D5 group than in the D6-on-D6 group (55.3% vs. 37.3%, 44.8% vs. 32.6%, P < 0.01). The CPR and IR were significantly higher in the D5 group than in the D6-on-D5 group (66.0% vs. 55.3%, 62.1% vs. 44.8%, P < 0.05), and the EMR was significantly lower in the D5 group than in the D6-on-D5 group (11.2% vs. 21.1%, P < 0.05). Logistic regression analysis demonstrated that transfer D6 blastocysts on day 5, instead of day 6, could significantly increase the CPR (odds ratio[OR]: 2.031, 95% confidence interval (CI): 1.296–3.182, P = 0.002). FET cycles with D6 blastocysts transferred on day 5 had a higher EMR than those with D5 blastocysts (OR: 2.165, 95% CI: 1.040–4.506, P = 0.039). Hormone replacement therapy (HRT) cycles exhibited a higher EMR than natural cycles (OR: 1.953, 95% CI: 1.254–3.043, P = 0.003), while no difference was observed in the CPR (P > 0.05).

Conclusions

These results indicate that the suitable timing to transfer D6 blastocysts in FET cycles may be day 5, and D6 blastocyst transfer on day 6 in FET cycles should be avoided. D6 blastocysts transfer and HRT cycles may be associated with a higher EMR.

Maternal and Neonatal Complications After Natural vs. Hormone Replacement Therapy Cycle Regimen for Frozen Single Blastocyst Transfer

Objective: To evaluate the maternal and neonatal complications after frozen-thawed blastocyst transfer cycles utilizing different endometrial preparation regimens.

Design: This is a retrospective cohort study and a secondary analysis of a multicenter, randomized, controlled trial comparing live birth rate after fresh vs. frozen single blastocyst transfer (Frefro-blastocyst).

Setting: Reproductive medicine centers.

Patient(s): A total of 800 women with regular menstrual cycles undergoing their first cycle of in-vitro fertilization after frozen-thawed single blastocyst transfer.

Intervention(s): Endometrium preparation was performed with a natural cycle regimen or hormone replacement therapy (HRT) cycle regimen, at the discretion of local investigators. All pregnancies were followed up until delivery.

Main Outcome Measure(s): Maternal and neonatal complications.

Result(s): 513 infertile patients who underwent natural cycles regimen and 287 who underwent HRT cycles regimen were analyzed. The incidences of maternal and neonatal complications were comparable between the natural cycle and HRT cycle regimen. Regarding the risk of gestational diabetes, gestational hypertension, pre-eclampsia, preterm delivery, small for gestational age and large for gestational age, the HRT cycle was still not a significant risk factor after adjusting for potential confounders. The natural cycle regimen yielded an insignificant higher total live birth rate [59.45 vs. 50.17%, P = 0.001, adjusted odds ratio (AOR) 1.366, 95% confidence interval (CI) 0.975–1.913], clinical pregnancy rate (68.23 vs. 58.89%, P = 0.008, AOR 1.406, 95% CI 0.992–1.991) and ongoing pregnancy rate (62.18 vs. 52.61%, P = 0.008, AOR 1.387, 95% CI 0.988–1.948) than did the HRT cycle regimen. However, compared to natural cycles, HRT cycles were associated with a significantly higher risk of biochemical miscarriage (6.86 vs. 18.18%, P < 0.001, AOR 0.328, 95% CI, 0.176–0.611).

Conclusion(s): The incidence of maternal and neonatal complications in natural cycle and HRT cycle regimens after frozen single blastocyst transfer were comparable. Frozen-thawed single blastocyst transfer in a natural cycle was associated with lower biomedical miscarriage than the use of the HRT cycle.

Clinical Trial Registration Number: Frefro-blastocyst was registered at Chinese Clinical Trial Registry, ChiCTR-IOR-14005405.

Pregnancy Outcomes After Different Cycle Regimens for Frozen-Thawed Embryo Transfer: A Retrospective Study Using Propensity Score Matching

Background: Nowadays, the choice of frozen embryo transfer (FET) regimens is mainly guided by personal convenience. Clinicians prefer the predictability and reliability of artificial cycle (AC) FET and have extended its usage to general in vitro fertilization population. More recent primary studies are beginning to challenge the comparability of AC-FET and suggest reduced clinical pregnancy rate and live birth rate (LBR) compared with those in modified natural cycle (mNC) FET (ovulation triggered by human chorionic gonadotrophin) and stimulated cycle (SC) FET.

Objective: To assess the pregnancy outcomes within matched mNC-FET, SC-FET, and AC-FET cycles by using propensity score matching (PSM) in a larger cohort.

Methods: A total of 16,946 women who underwent their first autologous FET cycle between July 2014 and July 2017 were evaluated. PSM, using the nearest neighbor matching, were established to adjust the baseline features within the three protocols in proportion of 1:1 (mNC-FET vs. SC-FET, mNC-FET vs. AC-FET, SC-FET vs. AC-FET). Furthermore, there were 3,567, 2,917, and 3,964 cycles compared between matched mNC-FET and SC-FET, mNC-FET and AC-FET, and SC-FET and AC-FET after the PSM, respectively.

Results: LBR was significant lower in the AC-FET group than that in the mNC-FET (40.0 vs. 43.3%) and SC-FET groups (40.9 vs. 46.5%). The adjusted odds ratios (95% CIs) were 1.11 (1.00, 1.24) for mNC/AC (P = 0.044) and 0.84 (0.76, 0.92) for AC/SC (P < 0.001), which indicated that the AC-FET group was associated with lowest LBR. The LBR was comparable between matched mNC-FET and SC-FET after adjusting for endometrial thickness. Moreover, a lower clinical pregnancy rate and a higher risk of early pregnancy loss were discovered in AC-FET cycles compared with those in SC-FET.

Conclusion: In view of our data, AC used for scheduling FET was associated with lower LBR compared with SC and modified natural cycle. This interpretation requires future verification from well-designed prospective multicenter randomized clinical trials, although the comparisons in our study were conducted in the homogenous population after the PSM.

Comparing pregnancy outcomes between natural cycles and artificial cycles following frozen-thaw embryo transfers

BACKGROUND

Frozen embryo transfer (FET) is increasing in prevalence. In contrast to the amount of research performed on the actual cryopreservation procedure, there are limited data with respect to optimal endometrial preparation in FET cycles. Increasingly artificial cycle (AC) preparation is being adopted over the natural cycle (NC) to facilitate greater access to FET. However, there remains a paucity of data comparing pregnancy outcomes between these two commonly used cycle types.

AIMS

To examine the efficacy of AC vs NC following FET, by comparing pregnancy outcomes including biochemical, clinical and live birth rates, along with miscarriage rates.

MATERIALS AND METHOD

This is a large single-centre retrospective analysis, examining a standardised data set from January 2015 to July 2018. It included 3030 cycles (NC = 2033, AC = 997). Main outcomes were biochemical pregnancy (beta-human chorionic gonadotropin > 5 IU), ultrasound-diagnosed clinical pregnancy, and live births. Using the χ² test, the above pregnancy outcomes were compared between AC and NC. A multivariate logistic regression, controlling for factors such as age, embryo quality, and day of blastocyst freeze was further utilised to assess for confounding variables.

RESULTS

No difference was observed between biochemical pregnancy rates (NC = 39.45% vs AC = 37.71%, P = 0.357); statistically significant differences were observed between clinical pregnancy (30.84% vs 26.08%, P = 0.007), and live birth rates (24.40% vs 18.86% P = 0.001). Multivariate analysis confirmed that NC produces superior pregnancy outcomes when controlling for confounding variables.

CONCLUSION

This analysis demonstrates the non-inferiority of NC thaw compared to AC, on continuing pregnancy rates. Taken together with patient acceptability and possibly increased obstetric risks with AC, these findings support the use of NC when medically possible.

Live birth after frozen-thawed embryo transfer: which endometrial preparation protocol is better?

OBJECTIVE

To compare the clinical outcomes of modified natural cycle (mNC) and artificial cycle (AC) protocols for frozen embryo transfers.

MATERIAL AND METHODS

A total of 490 frozen-thawed autologous embryo transfer cycles, performed in a single tertiary IVF center, between January 2015 and September 2017, were retrospectively analyzed. Of these, 214 cycles were performed after mNC and 276 cycles were performed after gonadotrophin-releasing hormone (GnRH) agonist plus sequential estrogen and progestin priming protocol. The primary outcome was live birth and secondary outcomes were clinical pregnancy, implantation and miscarriage rates. Multivariate regression analysis was used to adjust covariates on clinical outcome.

RESULTS

The rates of live birth (33.6 % vs. 29.3 %, respectively), clinical pregnancy (40.2 % vs. 36.6 %, respectively), implantation (32.3 % vs. 28.5 %, respectively), and miscarriage (5.1 % vs. 6.9 %, respectively) were not different between the mNC and AC groups. Multivariate analysis also showed that the method for endometrial preparation had no significant effect on clinical pregnancy and live birth. The adjusted odds ratios (OR) of live births and clinical pregnancies were 0.97 (95 % CI 0.64-1.48) and 0.98 (95 % CI 0.65-1.46) for the AC compared to mNC group. However, there was a significant difference between mNC and AC in cycles in which double embryo transfer was performed. The live birth (48 % vs. 31.4 %P= 0.01) and clinical pregnancy rates (53.9 % vs. 38.8 %, P= 0.02) were significantly higher in the mNC group than the AC group for double embryo transfers.

CONCLUSION

The live birth and clinical pregnancy rates are comparable between mNC and AC with GnRH agonists in frozen thawed embryo transfer cycles. In ovulatory patients with planned double embryo transfer, mNC can be considered. Further well-designed prospective studies are needed to confirm our results.

Comparison of perinatal outcomes between spontaneous vs. commissioned cycles in gestational carriers for single and same-sex male intended parents

PURPOSE

To determine whether gestational carrier (GC) in vitro fertilization (IVF) cycles (commissioned cycles) for same-sex or single male intended parents have an increased incidence of adverse perinatal outcomes compared with spontaneous cycles in the same GCs.

DESIGN

GC singleton pregnancies were identified from a database of 895 commissioned cycles from a large fertility center. Of these, 78 commissioned cycles met inclusion and exclusion criteria and were compared with 71 spontaneous cycles by the same GCs. The primary outcome was the composite score for adverse perinatal outcomes. Secondary outcomes included mode of delivery, birthweight, and gestational age. Chi-square test of association and Mann-Whitney U tests were used to compare categorical and continuous variables between the cohorts, respectively. Logistic and linear regressions controlling for GC age were constructed to determine the influence of GC cycle type on adverse perinatal outcomes.

RESULTS

Commissioned cycles were significantly associated with adverse perinatal outcomes (25.6% vs. 9.9%; p = 0.02) and lower average gestational age (38.7 ± 1.5 vs. 39.4 ± 0.9; p < 0.001) compared with spontaneous cycles. Commissioned cycle increased the likelihood of adverse perinatal outcomes (OR 3.3; p = 0.03) and was a significant independent predictor of a lower average gestational age (β = 0.897; p < 0.001). There were no significant differences in the incidence of vaginal deliveries or cesarean sections between commissioned and spontaneous cycles.

CONCLUSIONS

Commissioned cycles confer a greater incidence of composite perinatal complications and were independently associated with a lower average gestational age when compared with spontaneous pregnancies carried by the same GC despite a confirmed healthy uterine environment, sperm samples, and donor oocytes.

Comparison of letrozole with gonadotropin-releasing hormone agonist in frozen embryo transfer after recurrent implantation failure: An RCT

Background

The use of frozen embryo transfer (FET) is increasing worldwide in the treatment of infertility by in vitro fertilization. Different methods of endometrial preparation for FET have been suggested.

Objective

The aim of this study was to compare the pregnancy outcomes after treatment with letrozole and those after treatment with the combination of gonadotropin-releasing hormone (GnRH) agonist and estradiol in FET.

Materials and Methods

This randomized controlled trial study was conducted on 142 infertile women with a history of previous FET failure. Participants were randomly assigned to two groups (n = 71 each). The GnRH group received 500 µg of buserelin plus 4mg estradiol (which increased to 8 mg if endometrial thickness was less than 5 mm), and the letrozole group received 5 mg of letrozole plus 75 IU of recombinant human follicle-stimulating hormone). At least two high-quality embryos were transferred to each subject in both groups. The outcome measures were clinical pregnancy rate and fetal heart rate detection.

Results

Subjects in the study groups had similar demographic characteristics and baseline clinical condition. Mean endometrial thickness in the letrozole and GnRH agonist groups were 8.90 ± 0.88 mm and 8.99 ± 0.85 mm, respectively (p = 0.57). The number of positive results of the beta human chorionic gonadotropin test and detection of fetal heartbeat were not significantly different between the groups (p > 0.05).

Conclusion

The administration of letrozole and GnRH may produce similar pregnancy outcomes in FET.

Comparison of stimulated versus modified natural cycles for endometrial preparation prior to frozen embryo transfer: a randomized controlled trial

RESEARCH QUESTION

To compare stimulated cycle (STC) versus modified natural cycle (MNC) for endometrial preparation prior to frozen embryo transfer (FET) in terms of convenience and efficacy.

DESIGN

Prospective, open-label, randomized controlled study including 119 patients aged 20-38 years, undergoing intra-conjugal IVF/intracytoplasmic sperm injection, having regular cycles, at least two day 2 or day 3 frozen embryos, for whom it was the first or second FET performed, randomized to either MNC (n = 59) or STC (n = 60). Monitoring consisted of ultrasound and hormonal measurements. The number of monitoring visits required was compared between the two groups.

RESULTS

STC required a significantly lower number of monitoring visits compared with MNC (3.6 ± 0.9 versus 4.4 ± 1.1, respectively, P < 0.0001), a lower number of blood tests (2.7 ± 0.8 versus 3.5 ± 1.0, respectively, P < 0.0001) and of ultrasounds (1.2 ± 0.4 versus 1.5 ± 0.6, respectively, P = 0.0039). FET during 'non-opening' hours (22.6% versus 27.5%, respectively, P = 0.32) and cancellation rates (11.7% versus 11.9%, respectively, P = 0.97) were comparable between the STC and MNC groups. No difference concerning HCG-positive rates (34.0% versus 23.1%, respectively, P = 0.22) nor live birth rates (24.5% for STC versus 23.1% for MNC, respectively, P = 0.86) was observed. Quality of life as defined by the FertiQol score was not different (P > 0.05 for each item).

CONCLUSION

Altogether, these findings can be used for everyday clinical practice to better inform patients when deciding on the protocol to use for FET. These results suggest that MNC is a good option for patients reluctant to have injections, but requires increased monitoring. STC may offer more flexibility for patients and IVF centres.

Effect of endometrial thickness on ectopic pregnancy in frozen embryo transfer cycles: an analysis including 17,244 pregnancy cycles

OBJECTIVE

To investigate whether endometrial thickness (EMT) influences the incidence of ectopic pregnancy (EP) in frozen embryo transfer (FET) cycles.

DESIGN

Retrospective cohort study.

SETTING

Academic tertiary-care medical center.

PATIENT(S)

A total of 16,556 patients were enrolled between January 2010 and December 2017, comprising 16,701 intrauterine, 488 ectopic, and 45 heterotopic pregnancy cycles after FET.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

EP was the primary outcome. EMT was the main measured variable. Data were analyzed with the binary logistic general estimating equations model to calculate the adjusted odds ratio (aOR) for EP.

RESULT(S)

After adjusting for confounders, EMT remained statistically significant as an independent risk factor for EP. Compared with women with an EMT of ≥14 mm, the aORs for women with EMT in the ranges 7-7.9, 8-9.9, and 10-11.9 mm were 2.70 (95% confidence interval [CI], 1.65-4.40), 2.06 (95% CI, 1.33-3.20), and 1.66 (95% CI, 1.07-2.58), respectively. Hormone replacement treatment for endometrial preparation during FET increased the risk of EP after adjustment for confounding variables.

CONCLUSION(S)

EMT is inversely proportional to EP rate in FET cycles and is therefore a potential quantitative marker of endometrial receptivity and uterine contractibility in an FET cycle. The predictive validity of EMT value must be evaluated in further studies.

Higher live birth rate with stimulated rather than artificial cycle for frozen-thawed embryo transfer

OBJECTIVE

To study which endometrial preparation allows a better ongoing pregnancy rates (OPR) and live birth rate (LBR) after frozen-thawed embryo transfer (FET) between mild gonadotropin ovarian stimulation (OS) and artificial cycles (AC).

STUDY DESIGN

Retrospective follow-up study including all FET performed in one fertility center from 2013 to 2016. In the OS group, gonadotropins were followed by r-hCG triggering. Vaginal micronized progesterone (200 mg/day) was given systematically. In the AC group, estradiol (E2) was started on Day 1. Vaginal micronized progesterone (600 mg/d) was added to E2 for 12 weeks. Data were analyzed using a multiple regression model.

RESULTS

Among 1021 FETs, 35% underwent OS preparation, 65% had an AC. As expected, patients in the AC group suffered more from endometriosis (18.5% vs. 12.9%; p = .021) and polycystic ovarian syndrome (21.7% vs. 10.9%; p < .0001) than patients in the OS group. There was no difference between groups with respect to endometrial thickness, number of embryos transferred, development stage at FET, cryopreservation technique. Despite a similar clinical pregnancy rate (CPR) (24.4% vs. 20.8%; p = .189), the OPR was significantly higher in the OS than in the AC group (17.9% vs. 11%; p = .002), leading to an increased LBR (17.1% vs. 9.8%; p < .001). After adjusting for parameters usually linked to early pregnancy losses or potential bias (patient age at freezing, smoking status, PCOS, endometriosis, rank of transfer and previous miscarriages), the results remained significant.

CONCLUSION

Despite a similar CPR, LBR was significantly higher with mild OS than with the AC preparation, even after adjusting for potential confounders. In light of these results, the first-line endometrial preparation could be OS instead of an AC. In an AC, a potential defect of the luteal phase may exist, treatment could be optimized to avoid pregnancy losses. A randomized controlled trial should be undertaken to assess the role of OS and ACs in FET.

Elective and Onco-fertility preservation: factors related to IVF outcomes

STUDY QUESTION

Is the indication for fertility preservation (FP) related to success in IVF cycles after elective-FP (EFP) for age-related fertility decline and FP before cancer treatment (Onco-FP)?

SUMMARY ANSWER

Although success rates were lower in cancer patients, there was no statistically significant association between malignant disease and reproductive outcome after correction for age and controlled-ovarian stimulation (COS) regime.

WHAT IS KNOWN ALREADY

FP is increasingly applied in assisted reproduction, but little is known about the outcome of IVF cycles with vitrified oocytes in FP patients.

STUDY DESIGN, SIZE, DURATION

Retrospective, observational multicenter study of vitrification cycles for FP and of the warming cycles of women who returned to attempt pregnancy from January 2007 to May 2018.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In all, 6362 women (EFP = 5289 patients; 7044 cycles + Onco-FP = 1073 patients; 1172 cycles) had their oocytes vitrified for FP. A logistic regression analysis was performed to examine the impact of indication for FP corrected for age at vitrification. The protocol used for COS was also included as a possible confounder. The main outcome measures were oocyte survival and live birth. A detailed description of the baseline and clinical data is provided, with comparisons between EFP and Onco-FP. The cumulative live birth rate (CLBR) per utilized oocyte according to age at vitrification was analyzed in those patients returning to use their oocytes.

MAIN RESULTS AND ROLE OF CHANCE

Age at vitrification was significantly older in EFP patients (37.2 ± 4.9 vs. 32.3 ± 3.5 year; P < 0.0001). Fewer oocytes were retrieved and vitrified per cycle in EFP (9.6 ± 8.4 vs. 11.4 ± 3.5 and 7.3 ± 11.3 vs. 8.7 ± 2.1, respectively; P < 0.05), but numbers became comparable when analyzed per patient (12.8 ± 7.4 vs. 12.5 ± 3.2 and 9.8 ± 6.4 vs. 9.5 ± 2.6). Storage time was shorter in EFP (2.1 ± 1.6 vs. 4.1 ± 0.9 years; P < 0.0001). In all, 641 (12.1%) EFP and 80 (7.4%) Onco-FP patients returned to attempt pregnancy (P < 0.05). Overall oocyte survival was comparable (83.9% vs. 81.8%; NS), but lower for onco-FP patients among younger (≤35 year) subjects (81.2% vs. 91.4%; P > 0.05). Fewer EFP cycles finished in embryo transfer (50.2% vs. 72.5%) (P < 0.05). The implantation rate was 42.6% and 32.5% in EFP versus Onco-FP (P < 0.05). Ongoing pregnancy (57.7% vs. 35.7%) and live birth rates (68.8% vs. 41.1%) were higher in EFP patients aged ≤35 than the Onco-FP matching age patients (P < 0.05). The reason for FP per se had no effect on oocyte survival (OR = 1.484 [95%CI = 0.876-2.252]; P = 0.202) or the CLBR (OR = 1.275 [95%CI = 0.711-2.284]; P = 0.414). Conversely, age (<36 vs. ≥36 y) impacted oocyte survival (adj.OR = 1.922 [95%CI = 1.274-2.900]; P = 0.025) and the CLBR (adj.OR= 3.106 [95%CI = 2.039-4.733]; P < 0.0001). The Kaplan-Meier analysis showed a significantly higher cumulative probability of live birth in patients <36 versus >36 in EFP (P < 0.0001), with improved outcomes when more oocytes were available for IVF.

LIMITATIONS, REASONS FOR CAUTION

Statistical power to compare IVF outcomes is limited by the few women who came to use their oocytes in the Onco-FP group. The patients' ages and the COS protocols used were significantly different between the EFP and ONCO-PP groups.

WIDER IMPLICATIONS OF THE FINDINGS

Although the implantation rate was significantly lower in the Onco-FP patients the impact of cancer disease per se was not proven'. EFP patients should be counseled according to their age and number of available oocytes.

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was used for this study. The authors have no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

A Comparison of the Miscarriage and Live Birth Rate for Frozen Embryo Transfer According to Two Endometrial Preparations: Natural or Primed with Estrogens

Objective The primary objective is to compare miscarriage rates in frozen-thawed embryo transfer (FET) cycles, according to the endometrial preparation used either artificial through the administration of exogenous estrogen and progesterone or natural without any treatment, during a spontaneous ovulatory cycle. The secondary objective is to compare the live birth rates between the two endometrial preparations.

Study design This is a retrospective study done at KK Women’s and Children’s Hospital Singapore. We included women who underwent FET cycles either with hormone replacement treatment (HRT) or no treatment (natural) for the endometrial preparation, regardless of their cycle number, from 1 January 2011 till 31 December 2015.

Results A total of 2,752 FET cycles were included in our analysis. The natural cycle followed by vaginal progesterone support was used in 1,221 cycles and the HRT cycle with estrogen and vaginal progesterone was used in 1,531 cycles. There is a significantly higher miscarriage rate in the HRT group (38.4%) compared with the natural group (22.3%). The live birth rate is significantly higher in the natural group (22.8%) compared with the HRT group (17.3%). The multivariate analysis further shows that the HRT therapy is independently associated with an increased risk of miscarriage (adjusted odds ratio 2.05; 95% confidence interval 1.45–2.90; [Formula: see text] <0.001) and hence lower odds of live birth (adjusted odds ratio 0.69; 95% confidence interval 0.56–0.84; [Formula: see text] <0.001) after adjusting for the patient’s age at which the embryo was cryopreserved, race, body mass index, main indications for in vitro fertilization, number of embryos transferred and type of embryo transferred.

Conclusion We have shown in this study that the miscarriage rate is higher in the HRT FET group and that this increased miscarriage rate translates into a lower live birth rate in the HRT group. Thus, we conclude that patients with regular menstrual cycles should be offered a natural FET cycle to achieve better outcomes in terms of live birth rate and reducing the miscarriage rate.

Impact of method of endometrial preparation for frozen blastocyst transfer on pregnancy outcome: a retrospective cohort study

OBJECTIVE

To determine whether live birth rates differ by type of endometrial preparation in frozen embryo transfer (FET) cycles.

DESIGN

Retrospective cohort study.

SETTING

Academic fertility center.

PATIENT(S)

Reproductive-aged women undergoing autologous vitrified-warmed blastocyst FETs.

INTERVENTION(S)

Comparison of two methods of endometrial preparation: programmed FET (known as group A: luteal phase GnRH agonist suppression, oral E2, and IM P starting 5 days before ET) versus unstimulated FET (known as group B: hormone and ultrasound monitoring for follicle collapse to time transfer).

MAIN OUTCOME MEASURE(S)

Live birth rates in group A and group B.

RESULT(S)

Group A consisted of 923 cycles, and group B consisted of 105. When stratified by age at transfer, there was no difference in any of the measured outcomes, including live birth rates in adjusted models (adjusted odds ratio 1.0, 95% confidence interval 0.6-1.5), except in patients older than 40 years. These patients in group B had a 100% failure rate (n = 6).

CONCLUSION(S)

In most women, unstimulated endometrial preparation with luteal support before FET has similar success compared with exogenous hormone preparation. Women older than 40 years may benefit from programmed FETs owing to the challenges of increased cycle variability expected in that age group.