Transfer of frozen-thawed embryos in artificially prepared cycles with and without prior gonadotrophin-releasing hormone agonist suppression: a prospective randomized study

Pituitary Suppression with Gonadotropin-Releasing Hormone Agonist Prior to Artificial Endometrial Preparation in Frozen-Thawed Embryo Transfer Cycles: A Systematic Review and Meta-Analysis of Different Protocols and Infertile Populations

This study investigates the effect of GnRHa pretreatment on pregnancy outcomes in artificial endometrial preparation for frozen-thawed embryo transfer (AC-FET) cycles. A systematic review of English language studies published before 1 September 2022, was conducted, excluding conference papers and preprints. Forty-one studies involving 43,021 participants were analyzed using meta-analysis, with a sensitivity analysis ensuring result robustness. The study found that GnRHa pretreatment generally improved the clinical pregnancy rate (CPR), implantation rate (IR), and live birth rate (LBR). However, discrepancies existed between randomized controlled trials (RCTs) and observational studies; RCTs showed no significant differences in outcomes for GnRHa-treated cycles. Depot GnRHa protocols outperformed daily regimens in LBR. Extended GnRHa pretreatment (two to five cycles) significantly improved CPR and IR compared to shorter treatment. Women with polycystic ovary syndrome (PCOS) saw substantial benefits from GnRHa pretreatment, including improved CPR and LBR and reduced miscarriage rates. In contrast, no significant benefits were observed in women with regular menstruation. More rigorous research is needed to solidify these findings.

Pretreatment with a long-acting GnRH agonist for frozen-thawed embryo transfer cycles: how to improve live birth?

BACKGROUND

Whether pretreatment with gonadotropin-releasing hormone agonist (GnRHa) can improve the pregnancy outcomes in frozen-thawed embryo transfer (FET) cycles is controversial. The inconsistencies in the results of different studies would be related to the characteristics of the included patients and the protocol of GnRHa use. In this study, we investigated the efficacy of pretreatment with a long-acting GnRH agonist in the early follicular phase of FET cycles and determined which population was suitable for the protocol.

RESULTS

We retrospectively included 630 and 1141 patients in the GnRHa FET and hormone replacement treatment (HRT) FET without GnRHa groups respectively, between October 2017 and March 2019 at a university-affiliated in vitro fertilization center. On the second or third day of menstruation, 3.75 mg of leuprorelin was administered. After 14 days, HRT was initiated for endometrial preparation. No significant differences were observed between the two groups in terms of patient characteristics. However, the GnRHa FET group showed a higher percentage of endometrium with a triple line pattern (94.8% vs 89.6%, p < 0.001) on the day of progesterone administration, with increased implantation (35.6% vs 29.8%, p = 0.005), clinical pregnancy (49.8% vs 43.3%, p = 0.008), and live birth rate (39.4% vs 33.7%, p = 0.016), than the HRT FET cycles with similar endometrial thickness, ectopic pregnancy and early miscarriage rates. Binary logistic regression analysis showed the GnRHa FET group to be associated with an increased chance of clinical pregnancy (P=0.028, odds ratio [OR] 1.32, 95% confidence interval [CI] 1.03-1.70) and live birth (P=0.013, odds ratio [OR] 1.34, 95% confidence interval [CI] 1.06-1.70) compared to the HRT FET without GnRHa group. After subgroup analysis, we found that the GnRHa FET group showed a significantly higher live birth rate in the subgroups of age < 40 years, primary infertility, with polycystic ovary syndrome (PCOS), and irregular menstruation.

CONCLUSIONS

Pretreatment with a long-acting GnRHa during the early follicular phase improved the live birth rate in FET cycles. Age < 40 years, primary infertility, PCOS, and irregular menstruation are effective indications for endometrial preparation with GnRHa pretreatment in FET cycles. However, further randomized controlled trials are required to verify these results.

Retrospective analysis of the endometrial preparation protocols for frozen-thawed embryo transfer cycles in women with endometriosis

BACKGROUND

There was inconsistency in optimal endometrial preparation protocol for frozen-thawed embryo transfer (FET) in patients with endometriosis. We conducted this study to investigate the effect of different endometrial preparation protocols on the pregnancy outcomes in patients with endometriosis undergoing FET cycles, and determine the optimal number of GnRHa injections in GnRHa-HRT protocols.

METHOD(S)

This was a retrospective cohort analysis of women with endometriosis who underwent FET cycles at a single university-based center. This study retrospectively analyzed 2048 FET cycles in our center from 2011 to 2020. According to the endometrial preparation protocols, patients were divided into 4 groups: gonadotropin releasing hormone agonist-hormone replacement therapy(GnRHa-HRT), hormone replacement therapy(HRT), ovulation induction(OI), and natural cycle(NC). In the GnRHa-HRT group, patients were further divided into 3 groups: one injection of GnRHa, two injections of GnRHa, and three or more injections of GnRHa. The primary outcome was the clinical pregnancy rate. Propensity score matching was used to adjust for potential non-similarities among the groups. Multivariate logistic regression analysis was performed to figure out the risk factors for pregnancy outcomes.

RESULT(S)

There were no statistical differences in pregnancy outcomes among the four endometrial preparation protocols in FET cycles with endometriosis patients, the results retained after propensity score matching(PSM). And in endometriosis patients complicated with adenomyosis, the results remained similar. In patients with GnRHa-HRT protocol, there were no differences in clinical pregnancy rate and live birth rate with different numbers of GnRHa injections, the early miscarriage rate were 18% in the two injections of GnRHa group and 6.5% in the one injection of GnRHa group(P = 0.017). Multifactorial logistic regression analysis showed that two injections of GnRHa before FET was associated with increased early miscarriage rate compared with one injection of GnRHa[adjusted OR (95% CI): 3.116(1.079-8.998),p = 0.036].

CONCLUSION(S)

The four kinds of endometrial preparation protocols for FET, GnRHa-HRT, HRT, OI and NC had similar pregnancy outcomes in patients with endometriosis. In endometriosis patients complicated with adenomyosis, the results remained similar. In patients with endometriosis undergoing GnRHa-HRT protocol for FET, more injections of GnRHa had no more advantages in pregnancy outcomes, on the contrary, it might increase the early miscarriage rate.

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.

STROBE-GnRHa pretreatment in frozen-embryo transfer cycles improves clinical outcomes for patients with persistent thin endometrium: A case-control study

The well-prepared endometrium with appropriate thickness plays a critical role in successful embryo implantation. The thin endometrium is the main factor of frozen-embryo transfer (FET), resulting in the failure of implantation undergoing FET. Hormone treatment is suggested to improve endometrium thickness; however, among the larger numbers of cases, it cannot reach the sufficient thickness, which leads to a high cancelation rate of embryo transfer as well as waste high-quality embryos. Thus, it increases the burden to patients in both economic and psychological perspectives. We performed a retrospective observational study, which was composed with 2 cohorts, either with the conventional hormone replacement therapy (HRT) protocol or HRT with gonadotrophin-releasing hormone agonist (GnRHa) pretreatment to prepare the endometrium before FET. The measurements of endometrium thickness, hormone level, transfer cycle cancelation rate, pregnancy rate, and implantation rate were retrieved from the medical records during the routine clinic visits until 1 month after embryo transfer. The comparisons between 2 cohorts were performed by t-test or Mann-Whitney U test depending on the different attributions of data. In total, 49 cycles were under HRT with GnRHa pretreatment and 84 cycles were under the conventional HRT protocol. HRT with GnRHa pretreatment group improved the endometrial thickness (8.13 ± 1.79 vs 7.51 ± 1.45, P = .031), decreased the transfer cancelation rate (P = .003), and increased clinical pregnancy rate and implantation rate significantly (both P = .001). Additionally, luteinizing hormone level in pretreatment group was consistently lower than conventional HRT group (P < .05). Our study revealed HRT with GnRHa pretreatment efficiently improved the endometrial thickness, therefore, decreased the FET cycle cancelation. It also elevated the embryo implantation rate and clinical pregnancy rate by improving endometrial receptivity.

Should any use of artificial cycle regimen for frozen-thawed embryo transfer in women capable of ovulation be abandoned: yes, but what's next for FET cycle practice and research?

Over the past decade, the use of frozen-thawed embryo transfer (FET) treatment cycles has increased substantially. The artificial ('programmed') cycle regimen, which suppresses ovulation, is widely used for that purpose, also in ovulatory women or women capable of ovulation, under the assumption of equivalent efficacy in terms of pregnancy achievement as compared to a natural cycle or modified natural cycle. The advantage of the artificial cycle is the easy alignment of the time point of thawing and transferring embryos with organizational necessities of the IVF laboratory, the treating doctors and the patient. However, recent data indicate that pregnancy establishment under absence of a corpus luteum as a consequence of anovulation may cause relevant maternal and fetal risks. Herein, we argue that randomized controlled trials (RCTs) are not needed to aid in the clinical decision for or against routine artificial cycle regimen use in ovulatory women. We also argue that RCTs are unlikely to answer the most burning questions of interest in that context, mostly because of lack of power and precision in detecting rare but decisive adverse outcomes (e.g. pre-eclampsia risk or long-term neonatal health outcomes). We pinpoint that, instead, large-scale observational data are better suited for that purpose. Eventually, we propose that the existing understanding and evidence is sufficient already to discourage the use of artificial cycle regimens for FET in ovulatory women or women capable of ovulation, as these may cause a strong deviation from physiology, thereby putting patient and fetus at avoidable health risk, without any apparent health benefit.

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.

GnRH-agonist pretreatment in hormone replacement therapy improves pregnancy outcomes in women with male-factor infertility

OBJECTIVE

This study aimed to examine the efficacy of HRT with gonadotropin-releasing hormone agonist (GnRH-a) pre-treatment in women with male-factor infertility who underwent a frozen embryo transfer (FET) programme.

DESIGN

Between January 2016 and October 2020, 2733 women with male-factor infertility who underwent the HRT protocol as the endometrial preparation method were enrolled at two Reproductive Medicine Centres. Patients were divided into two groups based on whether they had GnRH-a pre-treatment before HRTs: the GnRHa-HRT group and the HRT group. The inverse probability of treatment weighting (IPTW) method was conducted to balance patient baseline characteristics between treatment cohorts to reduce selection bias. The live birth rate was considered regarded as the primary pregnancy outcome.

RESULTS

Multivariate logistic regression adjusted for confounding factors, the GnRHa-HRT group showed a notably higher rate of live birth (OR 2.154, 95% CI 1.636~2.835, P<0.001) when compared to the HRT group. Additionally, the rate of miscarriage was significantly lower in the GnRHa-HRT group. The GnRHa-HRT group had significantly higher rates of biochemical pregnancy, clinical pregnancy, multiple pregnancy, and term birth.

CONCLUSION

The endometrial preparation protocol of HRT with GnRH-a pre-treatment could obviously increase the live birth rate for women with male-factor infertility undergoing the FET programme.

Hormonal Replacement Treatment for Frozen-Thawed Embryo Transfer With or Without GnRH Agonist Pretreatment: A Retrospective Cohort Study Stratified by Times of Embryo Implantation Failures

OBJECTIVE

To evaluate the efficacy of the long-acting gonadotropin-releasing hormone agonist (GnRH-a) administration before hormone replacement treatment for frozen-thawed embryo transfer in women with different times of embryo implantation failures.

METHODS

A retrospective cohort study was performed between January 2015 and December 2019. A total of 9263 women who underwent frozen-thawed embryo transfer were included in the study. The study is divided into three parts based on the times of embryo implantation failures. The sample sizes were 4611 for no implantation failure, 3565 for one failure and 1087 for multiple failures. Two endometrium preparation protocols, HRT and HRT with GnRH-a pretreatment (G-HRT), were compared. Confounding factors were treated by propensity score matching and generalized estimation equation.

RESULTS

For women with no failure of embryo implantation, the live birth rate was not statistically different when they underwent HRT and G-HRT (HRT: 42.75% [498/1165], G-HRT: 45.24% [527/1165], P=0.2261). Similar outcome also appeared in women with one failure of embryo implantation (HRT: 47.22% [535/1133], G-HRT: 50.31% [570/1131], P=0.1413). For women with multiple failures of embryo implantation, the live birth rate was significantly difference (HRT: 38.74% [117/302], G-HRT: 45.48% [357/785], P=0.0449). When stratified by age, the live birth rate is similar for women older than 37 years. Generalized estimation equation showed that GnRH agonist pretreatment was independently associated with the live birth rate for women with multiple failures (adjust OR: 1.5, 95%CI: [1.12-2.00]).

CONCLUSION

For women with no/one failure of embryo implantation, the live birth rate is similar between HRT and G-HRT protocols. For women with multiple failure of embryo implantation, GnRH agonist pretreatment is beneficial to raise the live birth rate.

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.

Association between endogenous LH level prior to progesterone administration and live birth rate in artificial frozen-thawed blastocyst transfer cycles of ovulatory women

STUDY QUESTION

Is there an association between serum LH levels prior to progesterone administration and live birth rate (LBR) in artificial frozen-thawed embryo transfer (FET) cycles?

SUMMARY ANSWER

: Low serum LH levels on the day before progesterone initiation in artificial frozen-thawed blastocyst transfer cycles of ovulatory women are associated with a lower LBR.

WHAT IS KNOWN ALREADY

In artificial FET cycles, exogenous oestrogen and progesterone are administered sequentially to mimic the serum hormone pattern similar to the natural cycle. In oestrogen-only phase, the supplemental oestrogen causes thickening of the endometrium and is sometimes accompanied by a rise in serum LH. However, whether the endogenous LH level in artificial FET cycles is related to clinical outcomes remains unclear.

STUDY DESIGN, SIZE, DURATION

A retrospective cohort study including 3469 artificial frozen-thawed blastocyst transfer cycles was conducted at a tertiary-care academic medical centre between February 2014 and January 2020.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 3469 frozen blastocyst transfer cycles were stratified into four groups based on the quartiles of serum LH level before progesterone initiation: <25th percentile (LH < 8.79 mIU/ml), 25-50th percentile (8.79 ≤ LH ≤ 13.91 mIU/ml), 51-75th percentile (13.91 < LH ≤ 20.75 mIU/ml) and >75th percentile (LH > 20.75 mIU/ml). The serum LH level >75th percentile group was considered as the reference group. Patients with polycystic ovarian syndrome or other ovulatory disorders were excluded from the study. We also excluded cycles with an endometrial thickness <7 mm before progesterone initiation and patients with intrauterine adhesions and uterine abnormalities. In order to avoid the interference of BMI, all patients were divided into two categories based on the overweight threshold: BMI <25 kg/m2 and ≥25 kg/m2, and the impacts of serum LH levels on LBR were investigated separately. Univariable and multivariable logistic regression analysis were performed to adjust for potential confounders. EmpowerStats software and R-project were used to build smooth curve fitting models.

MAIN RESULTS AND THE ROLE OF CHANCE

Compared with the reference group, the implantation rate significantly decreased with low LH levels (<25th percentile) on the day before progesterone initiation (odds ratio [OR] = 0.74; 95% CI, 0.64-0.86; P = 0.001). Accounting for major covariates, low LH levels were associated with a relatively lower LBR (adjusted OR = 0.649; 95% CI, 0.531-0.794; P < 0.001), mainly due to a lower implantation rate, lower clinical pregnancy rate and higher pregnancy loss rate. Moreover, in the patients with BMI <25 kg/m2, low LH was associated with a lower LBR (P < 0.001); while in the overweight subgroup, LBR and LH were not correlated (P = 0.823).

LIMITATIONS, REASONS FOR CAUTION

The main limitation of this study is its retrospective design. Owing to the relatively small number in the overweight group, the results of the overweight subgroup should be interpreted with caution.

WIDER IMPLICATIONS OF THE FINDINGS

The evidence provided in this study shows the importance of serum LH levels on the day before progesterone initiation in patients undergoing artificial FET cycles. Hypothalamic dysfunction may be one of the important causes of a relatively low LH, which is related to impaired pregnancy outcomes. Serum LH levels may be used as one of the clinical indicators to predict pregnancy outcomes.

STUDY FUNDING/COMPETING INTEREST(S)

No funding and no competing interest were involved in this study.

TRIAL REGISTRATION NUMBER

NA.

The effect of LH rise during artificial frozen-thawed embryo transfer (FET) cycles

PURPOSE

To evaluate the association between a rise in serum luteinizing hormone (LH) levels during artificial frozen-thawed embryo transfer (FET) cycles and clinical pregnancy rate.

METHODS

A retrospective cohort study of women undergoing artificial FET cycles. We compared cycles in which LH double itself from the early follicular phase and further (group A) to cycles without a rise in LH (group B). Endometrium preparation was achieved by administration of 2 mg three times per day estradiol valerate tablets. Embryo transfer (ET) was conducted after achieving endometrial thickness > 7 mm and vaginal progesterone was added according to the embryo's age. A beta-hCG was measured 13-14 days after ET. Clinical pregnancy was diagnosed on transvaginal ultrasound.

RESULTS

Data from 984-FET cycles were retrieved. LH, exogenous estradiol (E2), progesterone values, endometrial thickness, and pregnancy outcomes were available in all patients. From 984-FET cycles, 629 (63.9%) had a doubling, and 355 (36.07%) had no rise in LH. Patients mean age was 30 years, similar in both groups. A multivariable logistic regression analysis was calculated to assess the effect of LH rise and pregnancy outcomes, after adjusting for confounders including a rise in E2 level and endometrial thickness. In this model, there was no association between doubling LH values and pregnancy rates (adjusted odds ratio: 1.06, 95% CI: 0.75-1.5, P = 0.74).

CONCLUSION

LH rise during artificial FET cycles does not alter pregnancy rates. Apparently, hormonal monitoring of LH levels may not yield useful information in the artificial FET cycle and may be omitted.

LAY SUMMARY

Supplementation of estradiol, a hormone produced by the ovaries, starting at the beginning of the menstrual cycle of an artificially frozen embryo transfer (FET) can lead to a rise in luteinizing hormone (LH), the hormone that induces ovulation. Such a rise in LH may interfere with embryo implantation, the process where the embryo attaches to the inner lining of the uterus and, therefore, could affect the chances of pregnancy. The current study is the first to assess the effect of a dynamic rise in LH levels during FET cycles on pregnancy rates. This study found no difference in pregnancy rates between FET cycles where the LH doubled compared to cycles without such a rise in LH. Larger, prospective studies should be conducted to assess the impact of LH elevation on pregnancy outcomes.

Effect of unplanned spontaneous follicular growth and ovulation on pregnancy outcomes in planned artificial frozen embryo transfer cycles: a propensity score matching study

STUDY QUESTION

Does unplanned spontaneous follicular growth and ovulation affect clinical outcomes after planned artificial frozen-thawed embryo transfer (AC-FET) cycles?

SUMMARY ANSWER

AC-FET and spontaneous follicular growth and ovulation events resulted in notably better pregnancy outcomes with a significantly higher implantation rate (IR), clinical pregnancy rate (CPR), ongoing pregnancy rate (OPR) and live birth rate (LBR) and a significantly lower miscarriage rate.

WHAT IS KNOWN ALREADY

The AC-FET protocol without GnRH agonist administration is associated with a low incidence of follicular growth and ovulation. In the literature, authors often refer to these types of cycles with concern due to possibly impaired FET outcomes. However, the real impact of such cycles has yet to be elucidated due to the lack of existing data.

STUDY DESIGN, SIZE, DURATION

This was a retrospective clinical study involving 2256 AC-FET cycles conducted between January 2017 and August 2019. Propensity score (PS) matching was used to control for confounding variables.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Subjects were divided into two groups: a study group: cycles with spontaneous follicular growth and ovulation (the maximum diameter of follicles in any ovary was ≥14 mm and ovulation was confirmed by consecutive ultrasound examinations) and a control group featuring cycles without growing follicles (the maximum diameter of follicles in both ovaries were <10 mm). The study group was matched by PS with the control group at a ratio of 1:2. The study group consisted of 195 patients before PS matching and 176 patients after matching. The numbers of participants in the control group before and after PS matching were 2061 and 329, respectively.

MAIN RESULTS AND THE ROLE OF CHANCE

This analysis showed that patient age (adjusted odds ratio [aOR] 1.05; 95% CI 1.01-1.09; P=0.010) and basal FSH level (aOR 1.06; 95% CI 1.01-1.11; P=0.012) were significantly and positively related with the spontaneous follicular growth and ovulation event. In addition, this event was negatively correlated with BMI (aOR 0.92; 95% CI 0.87-0.97; P=0.002), AMH level (aOR 0.66; 95% CI 0.59-0.74; P<0.001) and a high starting oestrogen dose (aOR 0.53; 95% CI 0.38-0.76 for 6 mg vs. 4 mg; P<0.001). Baseline characteristics were similar between groups after PS matching. Patients in the study group had a significantly higher IR (28.8% vs. 21.8%, P=0.016), CPR (44.9% vs. 33.4%, P=0.011), OPR (39.2% vs. 26.1%, P=0.002) and LBR (39.2% vs. 24.9%, P=0.001) and a lower miscarriage rate (12.7% vs. 25.5%, P=0.030), compared with those in the control group.

LIMITATIONS, REASONS FOR CAUTION

This was a retrospective study carried out in a single centre and was therefore susceptible to bias. In addition, we only analysed patients with normal ovulation patterns and excluded those with follicular growth but without ovulation. Further studies remain necessary to confirm our results.

WIDER IMPLICATIONS OF THE FINDINGS

It is not necessary to cancel cycles that experience spontaneous follicular growth and ovulation. Our data support promising clinical outcomes after this event. Our findings are important as they can better inform clinicians and patients.

STUDY FUNDING/COMPETING INTEREST(S)

This research was supported by National Natural Science Foundation of China (grant no. 81701507, 81801404, 81871210, 82071648), Natural Science Foundation of Jiangsu Province (grant no. BK20171126, BK20201123) and Jiangsu Province '333' project. The authors declare that they have no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

When Should We Freeze Embryos? Current Data for Fresh and Frozen Embryo Replacement IVF Cycles

Recent years have seen a dramatic rise in the number of frozen-thawed embryo replacement (FER) cycles. Along with the advances in embryo cryopreservation techniques, the optimization of endometrial receptivity has resulted in outcomes for FER that are similar to fresh embryo transfer. However, the question of whether the Freeze all strategy is for all is nowadays a hot topic. This review addresses this issue and describes current evidence based on randomized controlled trials and observational studies. To date, it is reasonable to perform FER in cases with a clear indication for the benefits of such strategy including impending ovarian hyperstimulation syndrome (OHSS) or preimplantation genetic testing for aneuploidy (PGT-A); however, this strategy does not fit for all. This review analyses the pros and cons of the freeze all strategy highlighting the need to follow a personalized plan in embryo transfer, avoiding a freeze all methodology for all patients in an unselected manner.

Investigating the impact of different strategies for endometrial preparation in frozen cycles considering normal responders undergoing IVF/ICSI cycles: a multicenter retrospective cohort study

Uncertainty exists concerning the type, adjunct, or dose of regimen to offer in frozen cycles in infertile women undergoing IVF/ICSI. Current systematic reviews have failed to identify one method of endometrial preparation as being more effective than another, whereas many IVF Units use variable and mixed protocols mainly based on their experience and convenience of use. Thus, we performed a four-center two-arm retrospective cohort study, encompassing 439 cycles in 311 women. The modalities analyzed were: Modified natural cycle without and with luteal support (Groups 1,2) and Hormone Replacement cycle (HRC) with and without GnRHa suppression (Groups 3,4). Various schemes of progesterone and estradiol were used and compared. χ² tests for categorical data and t-tests for continuous data were employed, stratifying by exposure, along with univariate and multivariable Logistic Regression models and subgroup analyses, according to the number of embryos transferred (1 vs. ≥2) and day of transfer (d2 vs. d5). Group 3 presented with statistically significant higher live birth and miscarriage rates in comparison to Group 4 (RR = 5.87, 95%CI: 2.44-14.14 and RR = 0.19, 95%CI: 0.06-0.60, respectively), findings that persisted in subgroup analyses according to the day of transfer and the number of embryos transferred. Progesterone administration through the combination of vaginal tabs and gel was associated with lower clinical pregnancy rates when compared to tabs (RR = 0.19, 95%CI: 0.05-0.71). The stable estrogen protocol compared to increasing estrogen at day 5 was associated with a higher positive hCG test and clinical pregnancy rate, while the progesterone through vaginal tabs was linked with lower miscarriages compared either with gel or combinations. In conclusion, HRC with GnRHa appears to be superior to HRC without GnRHa, concerning live birth and miscarriage, especially when the number of embryos transferred are ≥2 and irrespective of day of transfer. The use of progesterone vaginal tabs compared to gel or combinations is associated with better outcomes. Age is a significant predictor of a negative hCG test and clinical pregnancy rates. A properly conducted RCT is needed to evaluate the optimal frozen embryo transfer preparation strategy.Abbreviations: SD: standard deviation; BMI: body mass index; PCOS: polycystic ovarian syndrome; IQR: interquartile range; FSH: follicle-stimulating hormone; LH: luteinizing hormone; TSH: thyroid-stimulating hormone.

Endometrial Preparation for Frozen-Thawed Embryo Transfer With or Without Pretreatment With GnRH Agonist: A Randomized Controlled Trial at Two Centers

OBJECTIVE

This prospective randomized controlled trial compared the reproductive outcomes of frozen embryo transfer (FET) with hormone replacement treatment (HRT) with or without gonadotropin-releasing hormone agonist (GnRHa) pretreatment.

METHODS

A total of 133 patients scheduled for HRT-FET mainly because of tubal and/or male factors who received two high-quality cleavage-stage embryos were enrolled at two participating centers. The GnRHa group (n = 65) received GnRHa pretreatment, while the control group (n = 68) did not. Analysis was based on the intention-to-treat (ITT) principle.

RESULTS

Among the 133 participants, 130 (97.7%) underwent embryo transfer and 127 (95.5%) completed the protocol. The clinical pregnancy rate according to ITT did not differ between the GnRHa and control groups [39/65 (60.0%) vs. 41/68 (60.3%), p = 0.887]. The implantation rate (47.6% vs. 45.3%, p = 0.713), early pregnancy loss rate (5.1% vs. 19.5%, p = 0.09), and live birth rate (49.2% vs. 50.0%, p = 0.920) were also comparable between groups.

CONCLUSION

Pretreatment with GnRHa does not improve the reproductive outcomes for women receiving HRT-FET.

CLINICAL TRIAL REGISTRATION

The study was registered with the Chinese Clinical Trial Registry (ChiCTR-IOR-17014170; http://www.chictr.org.cn).

Endometrial preparation for women undergoing embryo transfer with frozen embryos or embryos derived from donor oocytes

BACKGROUND

A frozen embryo transfer (FET) cycle is when one or more embryos (frozen during a previous treatment cycle) are thawed and transferred to the uterus. Some women undergo fresh embryo transfer (ET) cycles with embryos derived from donated oocytes. In both situations, the endometrium is primed with oestrogen and progestogen in different doses and routes of administration.

OBJECTIVES

To evaluate the most effective endometrial preparation for women undergoing transfer with frozen embryos or embryos from donor oocytes with regard to the subsequent live birth rate (LBR).

SEARCH METHODS

The Cochrane Gynaecology and Fertility Group trials register, CENTRAL, MEDLINE, Embase, PsycINFO, LILACS, trials registers and abstracts of reproductive societies' meetings were searched in June 2020 together with reference checking and contact with study authors and experts in the field to identify additional studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) evaluating endometrial preparation in women undergoing fresh donor cycles and frozen embryo transfers.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures recommended by Cochrane. We analysed all available interventions versus placebo, no treatment, or between each other. The primary review outcome was live birth rate. Secondary outcomes were clinical and multiple pregnancy, miscarriage, cycle cancellation, endometrial thickness and adverse effects.

MAIN RESULTS

Thirty-one RCTs (5426 women) were included. Evidence was moderate to very low-quality: the main limitations were serious risk of bias due to poor reporting of methods, and serious imprecision. Stimulated versus programmed cycle We are uncertain whether a letrozole-stimulated cycle compared to a programmed cycle, for endometrial preparation, improves LBR (odds ratio (OR) 1.26, 95% confidence interval (CI) 0.49 to 3.26; 100 participants; one study; very low-quality evidence). Stimulating with follicle stimulating hormone (FSH), letrozole or clomiphene citrate may improve clinical pregnancy rate (CPR) (OR 1.63, 95% CI 1.12 to 2.38; 656 participants; five studies; I² = 11%; low-quality evidence). We are uncertain if they reduce miscarriage rate (MR) (OR 0.79, 95% CI 0.36 to 1.71; 355 participants; three studies; I² = 0%; very low-quality evidence). Endometrial thickness (ET) may be reduced with clomiphene citrate (mean difference(MD) -1.04, 95% CI -1.59 to -0.49; 92 participants; one study; low-quality evidence). Other outcomes were not reported. Natural versus programmed cycle We are uncertain of the effect from a natural versus programmed cycle for LBR (OR 0.97, 95% CI 0.74 to 1.28; 1285 participants; four studies; I² = 0%; very low-quality evidence) and CPR (OR 0.79, 95% CI 0.62 to 1.01; 1249 participants; five studies; I² = 60%; very low-quality evidence), while a natural cycle probably reduces the cycle cancellation rate (CCR) (OR 0.60, 95% CI 0.44 to 0.82; 734 participants; one study; moderate-quality evidence). We are uncertain of the effect on MR and ET. No study reported other outcomes. Transdermal versus oral oestrogens From low-quality evidence we are uncertain of the effect transdermal compared to oral oestrogens has on CPR (OR 0.86, 95% CI 0.59 to 1.25; 504 participants; three studies; I² = 58%) or MR (OR 0.55, 95% CI 0.27 to 1.09; 414 participants; two studies; I² = 0%). Other outcomes were not reported. Day of starting administration of progestogen When doing a fresh ET using donated oocytes in a synchronised cycle starting progestogen on the day of oocyte pick-up (OPU) or the day after OPU, in comparison with recipients that start progestogen the day prior to OPU, probably increases the CPR (OR 1.87, 95% CI 1.13 to 3.08; 282 participants; one study, moderate-quality evidence). We are uncertain of the effect on multiple pregnancy rate (MPR) or MR. It probably reduces the CCR (OR 0.28, 95% CI 0.11 to 0.74; 282 participants; one study; moderate-quality evidence). No study reported other outcomes. Gonadotropin-releasing hormone (GnRH) agonist versus control A cycle with GnRH agonist compared to without may improve LBR (OR 2.62, 95% CI 1.19 to 5.78; 234 participants; one study; low-quality evidence). From low-quality evidence we are uncertain of the effect on CPR (OR 1.08, 95% CI 0.82 to 1.43; 1289 participants; eight studies; I² = 20%), MR (OR 0.85, 95% CI 0.36 to 2.00; 828 participants; four studies; I² = 0%), CCR (OR 0.49, 95% CI 0.21 to 1.17; 530 participants; two studies; I² = 0%) and ET (MD -0.08, 95% CI -0.33 to 0.16; 697 participants; four studies; I² = 4%). No study reported other outcomes. Among different GnRH agonists From very low-quality evidence we are uncertain if cycles among different GnRH agonists improves CPR or MR. No study reported other outcomes. GnRH agonists versus GnRH antagonists GnRH antagonists compared to agonists probably improves CPR (OR 0.62, 95% CI 0.42 to 0.90; 473 participants; one study; moderate-quality evidence). We are uncertain of the effect on MR and MPR. No study reported other outcomes. Aspirin versus control From very low-quality evidence we are uncertain whether a cycle with aspirin versus without improves LBR, CPR, or ET. Steroids versus control From very low-quality evidence we are uncertain whether a cycle with steroids compared to without improves LBR, CPR or MR. No study reported other outcomes.

AUTHORS' CONCLUSIONS

There is insufficient evidence on the use of any particular intervention for endometrial preparation in women undergoing fresh donor cycles and frozen embryo transfers. In frozen embryo transfers, low-quality evidence showed that clinical pregnancy rates may be improved in a stimulated cycle compared to a programmed one, and we are uncertain of the effect when comparing a programmed cycle to a natural cycle. Cycle cancellation rates are probably reduced in a natural cycle. Although administering a GnRH agonist, compared to without, may improve live birth rates, clinical pregnancy rates will probably be improved in a GnRH antagonist cycle over an agonist cycle. In fresh synchronised oocyte donor cycles, the clinical pregnancy rate is probably improved and cycle cancellation rates are probably reduced when starting progestogen the day of or day after donor oocyte retrieval. Adequately powered studies are needed to evaluate each treatment more accurately.

A clinical and basic study of optimal endometrial preparation protocols for patients with infertility undergoing frozen-thawed embryo transfer

The optimal protocol for endometrial preparation in patients with infertility remains unclear. Due to this, the current study retrospectively analyzed 1,589 patients with infertility and regular menstrual cycles to assess reproductive outcomes per embryo transferred and per embryo transfer (ET) cycle following the transfer of frozen-thawed embryos (FET) in a modified natural cycle (mNC) or hormone therapy cycle (HT) with or without gonadotropin-releasing hormone agonist (GnRHa)-induced pituitary suppression. The molecular mechanisms involved were also studied using tissues from endometrial biopsies. Patients who underwent FET were assigned to 5 groups as follows: Group A underwent a mNC (n=276); group B (n=338) received estradiol (E2) and progesterone (P4); group C received 1 cycle of GnRHa, E2 and P4 (n=323); group D received 2 cycles of GnRHa, E2 and P4 (n=329); and group E received 3 cycles of GnRHa, E2 and P4 (n=323). Tissues from endometrial biopsies of 91 patients performed on the day of ET were tested for endometrial receptivity marker mRNA expression and microRNA (miR)-223-3p mRNA. Furthermore, endometrial stromal cells (ESCs) were used for an in-depth study of the molecular mechanisms involved. Among the 5 groups of patients, implantation rates, clinical pregnancy rates and live birth rates were not significantly different. However, endometrial receptivity was enhanced in group E when compared with groups A-D, which was associated with endometrial leukemia inhibitory factor (LIF), osteopontin, vascular endothelial growth factor, integrin β3 and homeobox gene 10 and 11 mRNA upregulation, and miR-223-3p miRNA downregulation. Transfection of ESCs with an miR-223-3p mimic significantly reduced levels of LIF mRNA and protein. In addition, pre-treating ESCs with GnRHa upregulated mRNA and protein expression of the decidualization markers prolactin and insulin-like growth factor binding protein-1 in a time-dependent manner. In conclusion, these results indicated that HT with GnRHa may be a potential endometrial preparation protocol for FET.

A UK-wide cross-sectional survey of practice exploring current trends in endometrial preparation for frozen-thawed embryo replacement

In the United Kingdom, between 2012 and 2017 the annual number of frozen-thawed embryo replacement (FER) cycles doubled, while fresh cycles declined. With FER now accounting for 34% of IVF cycles, the aim of this UK-wide survey of IVF clinics was to determine current trends in the management of FER. A senior clinician in each of the 84 UK IVF clinics was asked to complete an online survey between September 2018 and February 2019 focussing on their clinic's first-line protocols for FER. Sixty-five clinics (77%) responded, accounting for approximately 24,419 FER cycles annually. In ovulatory women, 69% of clinics favour medicated, 26% natural cycle and 5% modified natural cycle FER. In medicated FER, 61% of clinics undertake blastocyst transfer on the sixth day of progesterone administration, 21% on the fifth, 13% on the seventh, 3% on the fourth and 2% on the third. The preferred route of progesterone in medicated FER is vaginal, favoured by 82% of clinics. For pituitary suppression, 55% of clinics favour GnRH-agonist, 11% GnRH-antagonist and 34% oestrogen-only. In natural cycle FER, 31% always, 44% sometimes and 25% never give supplementary luteal support. In summary, the results illustrate wide variation in practice and highlight key research priorities.

Does high estrogen level negatively affect pregnancy success in frozen embryo transfer?

Introduction

High estrogen levels could reduce pregnancy rates by disrupting the implantation of the embryo into the endometrium in patients treated with fresh cycles of in vitro fertilization. The aim of the present study was to investigate the effect of estrogen levels on the pregnancy and abortion rate in autologous frozen embryo transfer with hormone replacement therapy (HRT).

Material and methods

A historical cohort study was conducted in an academic setting to investigate the effect of estrogen levels on the pregnancy and abortion rates for all autologous artificial frozen embryo transfer cycles performed from January 2016 to January 2018. Serum estradiol levels recorded on day 2 or 3 of the cycle were stated as e1, and levels recorded on the day of progesterone were indicated as e2. Human chorionic gonadotropin (β-hCG) positivity, which was examined 14 days after the transfer, was used to evaluate biochemical pregnancy. Abortion was defined as the termination of pregnancy before the 20th gestational week.

Results

There were 130 patients with unexplained infertility, 20 patients with poor ovarian reserve, and 54 patients with male factor. Of the patients with unexplained infertility, poor ovarian reserve, and male factor, 58, 4, and 27 of them were pregnant, respectively. No statistically significant difference was found between the e1 and e2 levels of the pregnant and non-pregnant groups (p = 0.273, p = 0.219). In addition, there was no statistically significant difference between e2 levels in terms of the abortion rate (p = 0.722).

Conclusions

In autologous frozen embryo transfer with HRT, estrogen levels did not have a significant effect on the pregnancy or abortion rate. Therefore, estrogen levels do not need to be monitored in frozen embryo transfer with HRT.

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

Background: The need for endocrine monitoring in artificial cycles for frozen embryo transfer (FET) remains unclear and, more specifically, the value of the late-proliferative phase serum estradiol (E2) levels is with conflicting evidence in current literature. Objective: To investigate whether artificial FET cycles require endocrine monitoring for the serum E2 level prior to initiation of exogenous progesterone administration after an endometrial thickness of 6.5 mm has been reached. Design: One thousand two hundred and twenty-two (n = 1,222) artificial FETs performed in a tertiary center between 2010 and 2015 were subdivided into 3 groups according to the following late-proliferative serum E2 level percentiles: ≤p10 (E2 ≤144 pg/ml; n = 124), p11-p90 (E2 from 145 to 438 pg/ml; n = 977) and >p90 (E2 >439 pg/ml; n = 121). A mixed-effects multilevel multivariable regression analysis was performed to assess the potential effect of the late-proliferative E2 level on the live birth rate (LBR). Results: The level of late-proliferative circulating E2 showed no significant difference in terms of LBR after FET. Specifically, the multivariable regression model demonstrated a LBR of 19.5% for the p11-p90 reference group, compared to 24.4% for the ≤p10 (p = 0.251) and 19.5% for the >p90 group (p = 0.989). Conclusion: In this large retrospective dataset, no association was observed between late-proliferative phase serum E2 levels and LBR following FET in artificially prepared cycles. Although, caution is warranted due to the retrospective nature of the analysis and the potential for unmeasured confounding, we argue that monitoring of the late-proliferative serum E2 levels and using them to guide clinical decision-making (e.g., medication step-up, cycle prolongation or cancelation) may be of questionable value.

Oral versus transdermal oestrogen delivery for endometrial preparation before embryo transfer: a prospective, comparative, randomized clinical trial

RESEARCH QUESTION

To determine whether the transdermal route is equal or superior to the oral route, when preparing the endometrium with oestrogens for embryo transfer.

DESIGN

Prospective, randomized controlled trial; 140 patients randomized; the pills group followed a protocol with oestradiol valerate pills and the patches group followed a protocol with oestradiol hemihydrate patches. The primary variable was endometrial thickness on day 10 ± 1 of treatment. Secondary variables were endometrial thickness on day 15 ± 1 of treatment, patient satisfaction, plasma levels of oestradiol, rates of pregnancy, miscarriage and delivery. Endometrial thickness was measured on day 10 ± 1 of the cycle, if the lining was 7 mm or less in thickness, another measurement was made on day 15 ± 1. Blood oestradiol levels were analysed on the day the endometrial lining was greater than 7 mm (day 10 ± 1 or day 15 ± 1). Patients completed a survey to evaluate comfort and side-effects.

RESULTS

The patches group achieved significantly thicker endometrium by the first check-up on day 10 ± 1 (7.6 mm versus 7.0 mm; P = 0.026), with lower blood levels of oestradiol (159.2 pg/ml versus 237.1 pg/ml; P < 0.001) when the endometrial thickness was over 7mm. The pills group considered the treatment more comfortable, with less side-effects. No significant differences in the rates of pregnancy, miscarriage or live birth were found.

CONCLUSIONS

Transdermal oestrogen treatment allows patients to reach a higher endometrial thickness after 10 days of treatment, with lower plasma levels of oestradiol, although it is not tolerated as well.

GnRH antagonist for endometrial priming in an oocyte donation programme: a prospective, randomized controlled trial

RESEARCH QUESTION

Can gonadotrophin releasing hormone (GnRH) antagonist be used in egg donation recipients with ovulatory cycles for the purpose of achieving synchronization between the donor´s and recipient´s cycle?

DESIGN

Prospective randomized controlled trial to compare 7-day dosage of GnRH antagonist for endometrial priming in an oocyte donation programme with a single dose of long-acting GnRH agonist. A total of 563 women were randomized in a private single centre, and 473 women underwent embryo transfer. Ongoing pregnancy rate was the primary end point. Analysis was adjusted for embryonic stage at the time of embryo transfer; data collected included days on the waiting list; number of fresh-vitrified oocytes collected; and oocyte donor´s age at the time of retrieval.

RESULTS

No statistically significant differences were found between groups in per intention-to-treat analysis: adjusted OR 1.42 (CI 0.97 to 2.09); per treatment received: adjusted OR 1.43 (CI 0.97 to 2.09); per embryo transfer: adjusted OR for ongoing pregnancy rate 1.47 (CI 1.01 to 2.13), P = 0.047.

CONCLUSIONS

For women with ovulatory cycles undergoing oocyte donation, the outcomes are similar between GnRH antagonist and down-regulated hormone replacement protocols.

Comparison of the clinical outcome of frozen-thawed embryo transfer with and without pretreatment with a gonadotropin-releasing hormone agonist

Objective

To describe the clinical outcomes of frozen-thawed embryo transfer (FET) with artificial preparation of the endometrium, using a combination of estrogen (E2) and progesterone (P4) with or without a gonadotropin-releasing hormone agonist (GnRHa), and the modified natural cycle (MNC) with human chorionic gonadotropin (hCG) trigger.

Methods

In this retrospective study, we evaluated 187 patients during 3 years (February 2012–April 2015). The patients were allocated to the following treatment groups: group A, comprising 113 patients (181 cycles) who received GnRHa+E2+P4; group B, comprising 49 patients (88 cycles) who received E2+P4; and group C, comprising 25 patients (42 cycles) who received hCG+P4. The inclusion criteria were regular menstrual cycles (length 24–35 days) and age 21–45 years.

Results

The primary outcome of the study — implantation rate (IR) per embryo transferred — was not statistically different among the 3 groups. Similar results were found for the IRs with fetal heartbeat per embryo transferred (68/181 [37.6%] in group A vs. 22/88 [25.0%] in group B vs. 14/42 [33.3%] in group C) and for the live birth rates (LBRs) per embryo transferred (56/181 [30.9%] in group A vs. 18/88 [20.5%] in group B vs. 11/42 [26.2%] in group C).

Conclusion

Although the pregnancy outcomes were better in the hormone therapy with GnRHa group, hormone therapy FET with GnRHa for pituitary suppression did not result in significantly improved IRs and LBRs when compared with hormone therapy FET without GnRHa or MNC FET.

Cycle regimens for frozen-thawed embryo transfer

BACKGROUND

Among subfertile couples undergoing assisted reproductive technology (ART), pregnancy rates following frozen-thawed embryo transfer (FET) treatment cycles have historically been found to be lower than following embryo transfer undertaken two to five days following oocyte retrieval. Nevertheless, FET increases the cumulative pregnancy rate, reduces cost, is relatively simple to undertake and can be accomplished in a shorter time period than repeated in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI) cycles with fresh embryo transfer. FET is performed using different cycle regimens: spontaneous ovulatory (natural) cycles; cycles in which the endometrium is artificially prepared by oestrogen and progesterone hormones, commonly known as hormone therapy (HT) FET cycles; and cycles in which ovulation is induced by drugs (ovulation induction FET cycles). HT can be used with or without a gonadotrophin releasing hormone agonist (GnRHa). This is an update of a Cochrane review; the first version was published in 2008.

OBJECTIVES

To compare the effectiveness and safety of natural cycle FET, HT cycle FET and ovulation induction cycle FET, and compare subtypes of these regimens.

SEARCH METHODS

On 13 December 2016 we searched databases including Cochrane Gynaecology and Fertility's Specialised Register, CENTRAL, MEDLINE, Embase, PsycINFO and CINAHL. Other search sources were trials registers and reference lists of included studies.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) comparing the various cycle regimens and different methods used to prepare the endometrium during FET.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures recommended by Cochrane. Our primary outcomes were live birth rates and miscarriage.

MAIN RESULTS

We included 18 RCTs comparing different cycle regimens for FET in 3815 women. The quality of the evidence was low or very low. The main limitations were failure to report important clinical outcomes, poor reporting of study methods and imprecision due to low event rates. We found no data specific to non-ovulatory women. 1. Natural cycle FET comparisons Natural cycle FET versus HT FETNo study reported live birth rates, miscarriage or ongoing pregnancy.There was no evidence of a difference in multiple pregnancy rates between women in natural cycles and those in HT FET cycle (odds ratio (OR) 2.48, 95% confidence interval (CI) 0.09 to 68.14, 1 RCT, n = 21, very low-quality evidence). Natural cycle FET versus HT plus GnRHa suppressionThere was no evidence of a difference in rates of live birth (OR 0.77, 95% CI 0.39 to 1.53, 1 RCT, n = 159, low-quality evidence) or multiple pregnancy (OR 0.58, 95% CI 0.13 to 2.50, 1 RCT, n = 159, low-quality evidence) between women who had natural cycle FET and those who had HT FET cycles with GnRHa suppression. No study reported miscarriage or ongoing pregnancy. Natural cycle FET versus modified natural cycle FET (human chorionic gonadotrophin (HCG) trigger)There was no evidence of a difference in rates of live birth (OR 0.55, 95% CI 0.16 to 1.93, 1 RCT, n = 60, very low-quality evidence) or miscarriage (OR 0.20, 95% CI 0.01 to 4.13, 1 RCT, n = 168, very low-quality evidence) between women in natural cycles and women in natural cycles with HCG trigger. However, very low-quality evidence suggested that women in natural cycles (without HCG trigger) may have higher ongoing pregnancy rates (OR 2.44, 95% CI 1.03 to 5.76, 1 RCT, n = 168). There were no data on multiple pregnancy. 2. Modified natural cycle FET comparisons Modified natural cycle FET (HCG trigger) versus HT FETThere was no evidence of a difference in rates of live birth (OR 1.34, 95% CI 0.88 to 2.05, 1 RCT, n = 959, low-quality evidence) or ongoing pregnancy (OR 1.21, 95% CI 0.80 to 1.83, 1 RCT, n = 959, low-quality evidence) between women in modified natural cycles and those who received HT. There were no data on miscarriage or multiple pregnancy. Modified natural cycle FET (HCG trigger) versus HT plus GnRHa suppressionThere was no evidence of a difference between the two groups in rates of live birth (OR 1.11, 95% CI 0.66 to 1.87, 1 RCT, n = 236, low-quality evidence) or miscarriage (OR 0.74, 95% CI 0.25 to 2.19, 1 RCT, n = 236, low-quality evidence) rates. There were no data on ongoing pregnancy or multiple pregnancy. 3. HT FET comparisons HT FET versus HT plus GnRHa suppressionHT alone was associated with a lower live birth rate than HT with GnRHa suppression (OR 0.10, 95% CI 0.04 to 0.30, 1 RCT, n = 75, low-quality evidence). There was no evidence of a difference between the groups in either miscarriage (OR 0.64, 95% CI 0.37 to 1.12, 6 RCTs, n = 991, I² = 0%, low-quality evidence) or ongoing pregnancy (OR 1.72, 95% CI 0.61 to 4.85, 1 RCT, n = 106, very low-quality evidence).There were no data on multiple pregnancy. 4. Comparison of subtypes of ovulation induction FET Human menopausal gonadotrophin(HMG) versus clomiphene plus HMG HMG alone was associated with a higher live birth rate than clomiphene combined with HMG (OR 2.49, 95% CI 1.07 to 5.80, 1 RCT, n = 209, very low-quality evidence). There was no evidence of a difference between the groups in either miscarriage (OR 1.33, 95% CI 0.35 to 5.09,1 RCT, n = 209, very low-quality evidence) or multiple pregnancy (OR 1.41, 95% CI 0.31 to 6.48, 1 RCT, n = 209, very low-quality evidence).There were no data on ongoing pregnancy.

AUTHORS' CONCLUSIONS

This review did not find sufficient evidence to support the use of one cycle regimen in preference to another in preparation for FET in subfertile women with regular ovulatory cycles. The most common modalities for FET are natural cycle with or without HCG trigger or endometrial preparation with HT, with or without GnRHa suppression. We identified only four direct comparisons of these two modalities and there was insufficient evidence to support the use of either one in preference to the other.

Determining the Optimal Duration of Progesterone Supplementation prior to Transfer of Cryopreserved Embryos and Its Impact on Implantation and Pregnancy Rates: A Pilot Study

Objective. To determine the optimal duration of progesterone supplementation prior to transfer of cryopreserved embryos and its impact on implantation and pregnancy rates. Study Design. Prospective randomised study. Materials and Methods. In an IVF unit of a tertiary centre, sixty-six patients undergoing cryopreserved embryo transfer cycles were included. Endometrial preparation was done with estradiol valerate. Once it reached a minimum of 7 mm, patients were allocated randomly into group I (n = 39) and group II (n = 27). Injectable progesterone 100 mg daily was then started for 3 and 4 days, respectively. This was followed by transfer of at least one thawed cleavage stage day 2 embryo of good quality. Groups I and II were compared in terms of clinical pregnancy and implantation rates. Results. In group I (3-day progesterone) and group II (4-day progesterone) the pregnancy rates were 41.02% (16/39) and 18.51% (5/27), respectively. On the other hand, the implantation rates were 16.82% (18/107) and 7.69% (6/78), respectively. The difference was statistically significant (p values 0.0172 and 0.0386, resp.). Conclusion. Progesterone supplementation for three days before the transfer of cleavage stage (day 2) cryopreserved embryos has significantly higher pregnancy and implantation rates, as compared to four-day supplementation.

Methods for endometrial preparation in frozen-thawed embryo transfer cycles

Frozen-thawed (FT) embryo transfer is a procedure used for the storage and transfer of excess embryos obtained during in vitro fertilization- intracytoplasmic sperm injection cycles. In recent years, improvements in laboratory conditions and limitations on the number of embryos to be transferred have led to a progressive increase in FT embryo transfer cycles. However, the best solution for endometrial preparation in these cycles is still a matter of debate. In this study, we aimed to review the current methods of endometrial preparation in FT embryo transfer cycles. In light of the current literature, it is hard to determine which method is the best for endometrial preparation. It is therefore necessary to conduct randomized controlled studies in a prospective design, which will also evaluate the above-mentioned factors.

Preparation of endometrium for frozen embryo replacement cycles: a systematic review and meta-analysis

PURPOSE

The purpose of this study was to evaluate the best protocol to prepare endometrium for frozen embryo replacement (FER) cycles.

METHODS

This study is a systematic review and meta-analysis. Following PubMed and OvidSP search, a total of 1166 studies published after 1990 were identified following removal of duplicates. Following exclusion of studies not matching our inclusion criteria, a total of 33 studies were analyzed. Primary outcome measure was live birth. The following protocols, including true natural cycle (tNC), modified natural cycle (mNC), artificial cycle (AC) with or without suppression, and mild ovarian stimulation (OS) with gonadotropin (Gn) or aromatase inhibitor (AI), were compared.

RESULTS

No statistically significant difference for both clinical pregnancy and live birth was noted between tNC and mNC groups. When tNC and AC without suppression groups are compared, there was a statistically significant difference in clinical pregnancy rate in favor of tNC, whereas it failed to reach statistical significance for live birth. When tNC and AC with suppression groups are compared, there was a statistically significant difference in live birth rate favoring the latter. Similar pregnancy outcome was noted among mNC versus AC with or without suppression groups. Similarly, no difference in clinical pregnancy and live birth was noted when ACs with or without suppression groups are compared.

CONCLUSIONS

There is no consistent superiority of any endometrial preparation for FER. However, mNC has several advantages (being patient-friendly; yielding at least equivalent or better pregnancy rates when compared with tNC and AC with or without suppression; may not require LPS). Mild OS with Gn or AI may be promising.

A randomized controlled, non-inferiority trial of modified natural versus artificial cycle for cryo-thawed embryo transfer

STUDY QUESTION

Are live birth rates (LBRs) after artificial cycle frozen-thawed embryo transfer (AC-FET) non-inferior to LBRs after modified natural cycle frozen-thawed embryo transfer (mNC-FET)?

SUMMARY ANSWER

AC-FET is non-inferior to mNC-FET with regard to LBRs, clinical and ongoing pregnancy rates (OPRs) but AC-FET does result in higher cancellation rates.

WHAT IS ALREADY KNOWN

Pooling prior retrospective studies of AC-FET and mNC-FET results in comparable pregnancy and LBRs. However, these results have not yet been confirmed by a prospective randomized trial.

STUDY DESIGN, SIZE AND DURATION

In this non-inferiority prospective randomized controlled trial (acronym 'ANTARCTICA' trial), conducted from February 2009 to April 2014, 1032 patients were included of which 959 were available for analysis. The primary outcome of the study was live birth. Secondary outcomes were clinical and ongoing pregnancy, cycle cancellation and endometrium thickness. A cost-efficiency analysis was performed.

PARTICIPANT/MATERIALS, SETTING, METHODS

This study was conducted in both secondary and tertiary fertility centres in the Netherlands. Patients included in this study had to be 18-40 years old, had to have a regular menstruation cycle between 26 and 35 days and frozen-thawed embryos to be transferred had to derive from one of the first three IVF or IVF-ICSI treatment cycles. Patients with a uterine anomaly, a contraindication for one of the prescribed medications in this study or patients undergoing a donor gamete procedure were excluded from participation. Patients were randomized based on a 1:1 allocation to either one cycle of mNC-FET or AC-FET. All embryos were cryopreserved using a slow-freeze technique.

MAIN RESULTS AND THE ROLE OF CHANCE

LBR after mNC-FET was 11.5% (57/495) versus 8.8% in AC-FET (41/464) resulting in an absolute difference in LBR of -0.027 in favour of mNC-FET (95% confidence interval (CI) -0.065-0.012; P = 0.171). Clinical pregnancy occurred in 94/495 (19.0%) patients in mNC-FET versus 75/464 (16.0%) patients in AC-FET (odds ratio (OR) 0.8, 95% CI 0.6-1.1, P = 0.25). 57/495 (11.5%) mNC-FET resulted in ongoing pregnancy versus 45/464 (9.6%) AC-FET (OR 0.7, 95% CI 0.5-1.1, P = 0.15). χ(2) test confirmed the lack of superiority. Significantly more cycles were cancelled in AC-FET (124/464 versus 101/495, OR 1.4, 95% CI 1.1-1.9, P = 0.02). The costs of each of the endometrial preparation methods were comparable (€617.50 per cycle in NC-FET versus €625.73 per cycle in AC-FET, P = 0.54).

LIMITATIONS, REASONS FOR CAUTION

The minimum of 1150 patients required for adequate statistical power was not achieved. Moreover, LBRs were lower than anticipated in the sample size calculation.

WIDER IMPLICATIONS OF THE FINDINGS

LBRs after AC-FET were not inferior to those achieved by mNC-FET. No significant differences in clinical and OPR were observed. The costs of both treatment approaches were comparable.

STUDY FUNDING/COMPETING INTERESTS

An educational grant was received during the conduct of this study. Merck Sharpe Dohme had no influence on the design, execution and analyses of this study. E.R.G. received an education grant by Merck Sharpe Dohme (MSD) during the conduct of the present study. B.J.C. reports grants from MSD during the conduct of the study. A.H. reports grants from MSD and Ferring BV the Netherlands and personal fees from MSD. Grants from ZonMW, the Dutch Organization for Health Research and Development. J.S.E.L. reports grants from Ferring, MSD, Organon, Merck Serono and Schering-Plough during the conduct of the study. F.J.M.B. receives monetary compensation as member of the external advisory board for Merck Serono, consultancy work for Gedeon Richter, educational activities for Ferring BV, research cooperation with Ansh Labs and a strategic cooperation with Roche on automated anti Mullerian hormone assay development. N.S.M. reports receiving monetary compensations for external advisory and speaking work for Ferring BV, MSD, Anecova and Merck Serono during the conduct of the study. All reported competing interests are outside the submitted work. No other relationships or activities that could appear to have influenced the submitted work.

TRIAL REGISTRATION NUMBER

Netherlands trial register, number NTR 1586.

TRIAL REGISTRATION DATE

13 January 2009.

FIRST PATIENT INCLUDED

20 April 2009.

The endometrial preparation for frozen-thawed euploid blastocyst transfer: a prospective randomized trial comparing clinical results from natural modified cycle and exogenous hormone stimulation with GnRH agonist

PURPOSE

The aim of the study was to evaluate two methods of endometrial preparation for frozen-thawed single euploid blastocyst transfer: modified natural and artificial cycle with GnRH-agonist pituitary suppression.

METHODS

In this prospective, controlled randomized trial, a total of 236 patients undergoing infertility treatment were randomized in 1:1 ratio; 118 received a frozen-thawed single euploid blastocyst transfer in a modified natural cycle and 118 in an artificial cycle with GnRH-agonist pituitary suppression. In the artificial protocol, GnRH-agonist combined with estradiol valerate was administered. In the natural protocol, only final oocyte maturation was induced using human chorionic gonadotropin administration. The primary end-points were the clinical pregnancy and implantation rates; the secondary end-points were the cost-benefit in terms of drug cost and the number of visits and the woman psychological distress caused by the treatment.

RESULTS

No significant differences were found in clinical pregnancy, implantation, and miscarriage rates between protocols. The number of clinical and ultrasound controls and the number of laboratory dosages and venous samplings were similar in both study groups. No significant differences were found between the groups in the anxiety and depression values before the start of treatment, on the days of progesterone administration, the blastocyst transfer, and pregnancy test.

CONCLUSIONS

The findings of this study evidence that in case of frozen-thawed single euploid blastocyst transfer, both protocols are equally effective in terms of clinical outcomes, cost-benefit, and patient compliance. The choice of endometrial preparation protocol should be based on women menstrual and ovulatory characteristics or otherwise on patient need for cycle planning.

TRIAL REGISTRATION

www.clinicaltrials.gov with number NCT02378584.

A randomized trial comparing the endometrial effects of daily subcutaneous administration of 25 mg and 50 mg progesterone in aqueous preparation

OBJECTIVE

To study the efficacy of a new P preparation in aqueous solution for subcutaneous injection for inducing the predecidual transformation of the endometrium.

DESIGN

Prospective, single-blinded, randomized, parallel pilot trial.

SETTING

University-affiliated clinical research center.

PATIENT(S)

Twenty-five regularly cycling female volunteers.

INTERVENTION(S)

Volunteers, aged 18-45 years, body mass index 19-25 kg/m(2), whose ovaries were suppressed with a GnRH agonist were estrogenized for 14 or 21 days with the use of transdermal systems delivering 0.1 mg/d E₂. After confirming that the endometrial thickness was >7 mm, the women were randomized to 25 mg or 50 mg of subcutaneous P injections daily for 11 days, after which the endometrium was sampled with the use of a Pipelle device. The endometrial biopsies were evaluated by two independent pathologists. Adverse events and subjective tolerance were checked every day by the study investigator.

MAIN OUTCOME MEASURE(S)

Predecidual changes in endometrial biopsies obtained after 11 days of subcutaneous administration of P.

RESULT(S)

Of 24 biopsies performed (one dropout), 22 provided tissue for histologic analysis. Evidence of predecidual changes in the endometrial stroma was found in 100% of the cases, with no differences between the two studied doses.

CONCLUSION(S)

Both doses of the new aqueous P preparation available for subcutaneous administration demonstrated predecidual changes in 100% of the interpretable endometrial biopsies in total absence of endogenous P. This offers good prospect of efficacy in luteal phase support for the lowest dose tested, 25 mg/d, the physiologic amount produced daily by the ovary during the midluteal phase.

CLINICAL TRIAL REGISTRATION NUMBER

NCT00377923.

Does a vitrified blastocyst stage embryo transfer program need hormonal priming for endometrial preparation?

AIM

To compare the clinical outcomes of a vitrified blastocyst stage embryo transfer (ET) program among natural, ovulation induced and artificial cycles.

MATERIAL & METHODS

The clinical outcomes were retrospectively analyzed in three groups according to endometrial preparation (natural cycle group [n = 34], ovulation induced [n = 21], and artificial cycles [n = 70]) among women that underwent vitrified blastocyst stage ET.

RESULTS

The overall pregnancy rate was 48.8%. There were no significant differences in the duration of endometrial preparation, endometrial thickness on the day of progesterone or human chorionic gonadotropin administration, implantation and clinical pregnancy rates among the three groups. Triple-line endometrial patterns were more frequently observed in the natural and ovulation induced groups than in the artificial cycle group (85.3% vs 64.3%, P = 0.021; 90.5% vs 64.3%, P = 0.016).

CONCLUSION

Our findings suggest that the types of endometrial preparation may have no significant effect on the clinical outcomes of vitrified blastocyst ET. Hormonal priming does not appear to be a prerequisite for endometrial preparation for vitrified blastocyst ET.

Endometrial preparation for women undergoing embryo transfer with frozen embryos or embryos derived from donor oocytes

BACKGROUND

If a fresh embryo, assisted reproductive technology procedure cycle is unsuccessful and there are frozen embryos available, a frozen-thawed embryo transfer is performed. In some specific cases women may undergo oocyte donation treatment. In both situations the endometrium is primed by the administration of estrogen and progesterone. To prevent the possibility of spontaneous ovulation, gonadotropin-releasing hormone (GnRH) agonists are frequently used.

OBJECTIVES

To evaluate the most effective endometrial preparation for women undergoing transfer with frozen embryos or embryos from donor oocytes with regard to the subsequent live birth rate.

SEARCH STRATEGY

We searched the Cochrane Menstrual Disorders and Subfertility Group Trials Register, Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library), MEDLINE, EMBASE, LILACS, and abstracts of reproductive societies' meetings (from inception). No language restrictions were applied. Experts in the field were contacted.

SELECTION CRITERIA

Randomised controlled trials evaluating endometrial preparation in women undergoing fresh donor cycles and frozen embryo transfers.

DATA COLLECTION AND ANALYSIS

Two review authors independently applied the inclusion criteria, assessed trial risk of bias, and extracted data.

MAIN RESULTS

Twenty two randomised controlled trials were included. Five studies analysed the use of a GnRH agonist versus control. No significant benefit was demonstrated when using GnRH agonists. No evidence of statistically significant benefit was found for one GnRH agonist over another, or vaginal over intramuscular progesterone administration. No difference in pregnancy rate was demonstrated when no treatment was compared to aspirin, steroids, ovarian stimulation, or human chorionic gonadotropin (hCG) prior to embryo transfer, although using hCG several times before the oocyte retrieval decreases the pregnancy rate. Finally, when oocyte recipients were studied further, starting progesterone on the day of oocyte pick-up (OPU) or the day after OPU produced a significantly higher pregnancy rate (OR 1.87, 95% CI 1.13 to 3.08) than when recipients started progesterone the day prior to OPU.

AUTHORS' CONCLUSIONS

There is insufficient evidence to recommend any one particular protocol for endometrial preparation over another with regard to pregnancy rates after embryo transfers. These were either frozen embryos or embryos derived from donor oocytes. However, there is evidence of a lower pregnancy rate and a higher cycle cancellation rate when the progesterone supplementation is commenced prior to oocyte retrieval in oocyte donation cycles. Adequately powered studies are needed to evaluate each treatment more accurately.

A GnRH agonist and exogenous hormone stimulation protocol has a higher live-birth rate than a natural endogenous hormone protocol for frozen-thawed blastocyst-stage embryo transfer cycles: an analysis of 1391 cycles

OBJECTIVE

To compare embryo and birth data in cryopreserved-thawed blastocyst-stage ET cycles between natural endogenous hormone cycles and exogenous hormone stimulation cycles.

DESIGN

Retrospective cohort analysis.

SETTING

Large academic assisted reproductive technology center.

PATIENT(S)

One thousand three hundred ninety-one patient cycles undergoing frozen-thawed blastocyst-stage ET cycles.

MAIN OUTCOME MEASURE(S)

Live-birth rate.

INTERVENTION(S)

The synthetic protocol used GnRH agonist followed by estrogen and P. The natural protocol used monitoring and post-transfer P.

RESULT(S)

The patients in the two protocols had similar baseline characteristics. Multiple linear regression showed the synthetic protocol to have a higher live-birth rate (odds ratio [OR], 1.46; 95% confidence interval [CI], 1.02-2.09). In patients having two embryos transferred, the synthetic stimulation protocol resulted in a higher live-birth rate per cycle start (32.3% vs. 20.4%; relative risk [RR], 1.58; 95% CI, 1.22-2.06). Similarly, patients with one or two embryos transferred who had additional cryopreserved blastocysts available also had a higher live-birth rate per cycle start (36.1% vs. 12.1; RR, 2.98; 95% CI, 1.16-7.63).

CONCLUSION(S)

The synthetic hormone protocol was associated with a higher live-birth rate when compared with a natural cycle protocol for frozen-thawed blastocyst-stage ET cycles. This improvement persisted when analysis was controlled for cycle cancellation. The synthetic stimulation protocol for frozen-thawed embryo cycles offers improved outcome results for patients.

Estrogen level monitoring in artificial frozen-thawed embryo transfer cycles using step-up regime without pituitary suppression: is it necessary?

Background

To discuss the meaning of serum oestradiol monitoring in frozen embryo transfer cycle using hormone replacement without pretreatment with gonadotropin hormone (GnRH) agonist.

Methods

The data from two hundred twelve women undergoing two hundred seventy-four frozen-thawed embryo transfer (FET) cycles was included in this retrospective cohort study. They were detected of serum oestradiol levels and endometrium thicknesses during hormone supplement FET cycles and compared their pregnancy outcomes according to their oestradiol level on progesterone initiation day.

Results

Patients with different levels of serum oestradiol (percentile 0–25^th, 25^th–75^th and 75^th–100^th) on progesterone initiation day yielded the endometrium thickness of 9.3 ± 0.12, 8.9 ± 0.07 and 9.1 ± 0.11 mm(P > 0.05) and the pregnancy rate of 32.2%, 38.4% and 36.3% (P > 0.05) respectively.

Conclusion

The serum estradiol level did not predict pregnancy success in hormone replacement FET cycles, suggesting that oestradiol monitoring in this method of endometrial preparation is unnecessary.

Cycle regimens for frozen-thawed embryo transfer

BACKGROUND

Pregnancy rates following frozen-thawed embryo transfer (FET) treatment have always been found to be lower than following embryo transfer using fresh embryos. Nevertheless, FET increases the (cumulative) pregnancy rate, reduces cost, is relatively simple to undertake and can be accomplished in a shorter time period compared to repeated 'fresh' cycles. FET is performed using different cycle regimens: spontaneous ovulatory cycles, cycles in which ovulation is induced by drugs and cycles in which the endometrium is artificially prepared by oestrogen (O) and progesterone (P) hormones, with or without a gonadotrophin releasing hormone agonist (GnRHa).

OBJECTIVES

To determine whether there is a difference in outcome between natural cycle FET, artificial cycle FET and ovulation induction cycle FET.

SEARCH STRATEGY

Our search included CENTRAL,DARE, MEDLINE (1950 to 2007), EMBASE (1980 to 2007) and CINAHL (1982 to 2007).

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing the various cycle regimens and different methods used to prepare the endometrium during FET in assisted reproductive technology (ART).

DATA COLLECTION AND ANALYSIS

The two authors independently extracted data. Dichotomous outcomes results (e.g. clinical pregnancy rate) were expressed as an odds ratio (OR) with 95% confidence intervals (CI) for each study. Continuous outcome results (endometrial thickness) were expressed as weighted mean difference (WMD). Where suitable, results were combined for meta-analysis with RevMan software using the Peto-modified Mantel-Haenszel method.

MAIN RESULTS

Seven randomised controlled studies assessing six comparisons and including 1120 women in total were included in this review.1) O + P FET versus natural cycle FET: this comparison demonstrated no significant differences in outcomes but confidence intervals remain wide, and therefore moderate differences in either direction remain possible (OR 1.06, 95% CI 0.40 to 2.80, P 0.91).2) GnRHa + O + P FET versus O + P FET: this comparison showed that the live birth rate per woman was significantly higher in the former group (OR 0.38, 95% CI 0.17 to 0.84, P 0.02). The clinical pregnancy rate was also higher but not significantly so (OR 0.76, 95% CI 0.52 to 1.10, P 0.14).3) O + P FET versus follicle stimulating hormone (FSH) FET, 4) O + P FET versus clomiphene FET and 5) GnRHa + O + P FET versus clomiphene FET: there were no differences in the outcomes in the comparison of these cycle regimens.6) Clomiphene + human menopausal gonadotrophin (HMG) FET versus HMG FET: in a comparison of two ovulation induction regimes the pregnancy rate was found to be significantly higher in the HMG group (OR 0.46, 95% CI 0.23 to 0.92). There were also fewer cycle cancellations and a lower multiple pregnancy rate when HMG was used without clomiphene but these did not reach statistical significance.

AUTHORS' CONCLUSIONS

At the present time there is insufficient evidence to support the use of one intervention in preference to another.

Facteurs cliniques et résultats du don d'ovocytes

This article aims at reviewing the literature in order to provide a summary of the actual knowledge about the clinical factors of the oocyte recipient (other than those affecting the morphology of the uterine cavity) influencing the outcome of oocyte donation cycles. Recipient age, from 45 years onwards, is clearly associated with a poorer outcome in oocyte donation cycles as well as the presence of a hydrosalpinx. The negative impact of smoking has recently been confirmed. The exact influence of a high body mass index is under examination but it is likely that it is associated with a lower ongoing pregnancy rate. Endometriosis does not have a negative impact when standard endometrial priming protocols are used in oocyte donation. During endometrial priming, serum estradiol levels and endometrial thickness, if >5 mm, does not influence negatively the outcome; however duration of estrogen treatment of more than 7 weeks is associated with a diminished pregnancy and implantation rate.

Intramuscular route of progesterone administration increases pregnancy rates during non-downregulated frozen embryo transfer cycles

OBJECTIVE

The optimal route of progesterone (P4) administration in embryo transfer (FET) cycles remains to be determined. The objective of this study is to compare the pregnancy outcomes between intramuscular (IM) and vaginal progesterone (PV) administration for endometrial preparation in non-donor FET cycles.

STUDY DESIGN

A retrospective clinical study in a private practice infertility setting.

RESULTS

No significant differences in patient demographics and embryo characteristics were noted between the two groups. The clinical pregnancy rate as well as the live birth rate were significantly higher in the IM arm compared to the PV arm (38.2% vs 28%, 34.5 % vs 22.8%, respectively).

CONCLUSION

Although both routes of progesterone administration had similar rates of initial positive pregnancy tests, the IM route had a significantly higher live birth rate. The exact reason for this difference remains to be determined.

Artificial versus stimulated cycles for endometrial preparation prior to frozen-thawed embryo transfer

The objective of this study was to compare the implantation rate, pregnancy rate and endometrial thickness of frozen-thawed embryo transfers using endometrial preparation with either an artificial cycle or stimulated cycle. This was a prospective randomized trial at a single academic IVF centre. Seventy-seven patients undergoing artificial cycles received oral oestradiol; patients with endometrium < 7 mm on day 9-10 were switched to vaginal oestradiol. Eighty-six patients undergoing stimulated cycles received recombinant FSH followed by human gonadotrophin hormone injection. Vaginal progesterone was begun 2 or 3 days prior to embryo transfer. There was no difference in implantation rate (8.5% versus 7.3%), pregnancy rate (16% versus 13%), cancellation rate (both 23%) or endometrium thickness (8.7 +/- 1.1 mm versus 8.7 +/- 1.0 mm) between artificial and stimulated cycles. Stimulated cycles had a higher incidence of thin endometrium (27% versus 5%, P < 0.01). In artificial cycles, patients switched to vaginal oestradiol had improved pregnancy rate (31%) versus patients who received oral oestradiol alone (13%) (P = 0.05). It is concluded that artificial and stimulated cycles produce comparable pregnancy rates, implantation rates, cancellation rates and endometrial thickness, although stimulated cycles have a higher incidence of thin endometrium. Vaginal oestradiol supplementation improved implantation rates.