Letrozole Versus Clomiphene Citrate and Natural Cycle: Endometrial Receptivity During Implantation Window in Women With Polycystic Ovary Syndrome

Letrozole ovulation regimen for frozen-thawed embryo transfer in women with polycystic ovary syndrome: study protocol for a randomized controlled trial

BACKGROUND

Women with polycystic ovary syndrome (PCOS) are usually selected to undergo an ovulation induction regimen or a programmed regimen for endometrial preparation in the frozen-thawed embryo transfer (FET) during their IVF/ICSI treatment. The programmed regimen permits flexible scheduling of embryo transfer but requires long-term usage of exogenous estrogen and higher dosages of luteal support while the letrozole ovulation regimen needs lower dosages of luteal support only. Recently, multiple studies have shown that the letrozole ovulation regimen can improve pregnancy outcomes of FET in women with PCOS compared with the programmed regimen. However, most of these studies are retrospective, and prospective studies are urgently needed the evidence from the perspective study is insufficient.

METHODS/DESIGN

We are undertaking a multicentre, randomized, controlled clinical trial of an endometrial preparation regimen for FET in women with PCOS. The eligible women are randomly assigned to either the letrozole ovulation regimen or the programmed regimen for endometrial preparation. The primary outcome is the clinical pregnancy rate.

DISCUSSION

The results of this study will provide evidence for whether the letrozole ovulation regimen for endometrial preparation could improve pregnancy outcomes in PCOS women undergoing FET.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2200062244. Registered on 31 July 2022.

Immediate Effect of Electro-acupuncture on Endometrial Blood Flow in Patients with Recurrent Implantation Failure: A Randomized Controlled Trial

OBJECTIVE

To investigate the immediate effects of electro-acupuncture (EA) on endometrial blood flow among recurrent implantation failure (RIF) patients.

METHODS

Eighty RIF patients, enrolled from March 2022 to December 2022, were randomly allocated into either the EA group (40 cases) or the waiting-list (WL) group (40 cases) by using a random number table. The EA group underwent acupuncture at points of Shenting (GV 24), Baihui (GV 4), Benshen (GB 13), bilateral Zigong (EX-CA 1), Huangshu (KI 16), Sanyinjiao (SP 6) and Xuehai (SP10), and electric acupuncture apparatus was connected to EX-CA 1, KI 16, SP 6, and SP 10 with disperse-dense waves at 4/20 Hz frequencies for 30 min after transvaginal ultrasound, while the WL group received no intervention. The primary outcome measured was the endometrial volume blood flow. The secondary outcomes included the bilateral uterine artery index, endometrial volume, endometrial blood flow type, vascular distribution index (VIMV) for endometrial and ovary, clinical pregnancy rate, and embryo implantation rate.

RESULTS

In the EA group, there was a notable decrease in the bilateral pulsatility index and a significant improvement in the endometrial blood flow type post-EA (P<0.05). Both the endometrial blood flow type and VIMV for the endometrium and right ovary were markedly higher in the EA group compared to the WL group post-treatment (P<0.05). Conversely, no significant disparities were observed in vascular index, flow index, vascular blood flow index, uterine arterial blood flow indices, endometrial volume, clinical pregnancy rate and embryo implantation rate between the two groups after treatment (P>0.05). Besides, no adverse events related to EA were observed.

CONCLUSIONS

EA can promptly ameliorate VIMV for the endometrial and right ovary, and endometrial blood flow type. Future randomized controlled trials are warranted to investigate the long-term effects of EA on blood flow of RIF patients and its implications for pregnancy outcomes. (Trial registration No. ChiCTR2200057377).

Successful live birth of thin endometrium: A case report

RATIONALE

The success of pregnancy depends on various factors, with the endometrial receptivity being a crucial component. Endometrial thickness (EMT) serves as a direct indicator for assessing endometrial receptivity. Previous studies have suggested that a thin endometrium is associated with lower pregnancy rates, especially in patients with an EMT of less than 4 mm. Even in assisted reproductive technology cycles with high success rates, clinical pregnancy cases in patients with such thin endometrium are reported to be very few, let alone in natural conception cycles. Therefore, a thin endometrium poses significant challenges for infertility patients. In this study, patients with an extremely thin endometrium were able to achieve clinical pregnancy and successful live births through natural conception, highlighting the possibility of success even in challenging cases.

PATIENT CONCERNS

The patient presented with polycystic ovary syndrome and ovulation disorders. She underwent a natural cycle of letrozole-induced ovulation. On the day of the human chorionic gonadotropin trigger, she had an EMT of 3.8 mm.

DIAGNOSES

Polycystic ovary syndrome, ovulation disorders, thin endometrium.

INTERVENTIONS

The patient received medications including Progynova, Aspirin, and Dydrogesterone.

OUTCOMES

The patient achieved spontaneous conception and subsequently had a live birth.

LESSONS

This case report underscores the significance of managing a thin endometrium during letrozole-induced ovulation. While EMT is traditionally pivotal for predicting embryo implantation success, our findings indicate that endometrial receptivity extends beyond thickness alone. Factors such as endometrial morphology, type, and blood supply play crucial roles. Successful pregnancies with a 3.8 mm EMT are rare, making this case a beacon of hope for such patients. It highlights that, with appropriate interventions, successful pregnancies remain attainable. For those with a thin endometrium, emphasis should extend beyond thickness, addressing ways to enhance both endometrial blood supply and morphology for improved pregnancy rates.

The effects of first-line pharmacological treatments for reproductive outcomes in infertile women with PCOS: a systematic review and network meta-analysis

BACKGROUND

Polycystic ovarian syndrome (PCOS) is one of the most common causes of infertility in reproductive-age women. However, the efficacy and optimal therapeutic strategy for reproductive outcomes are still under debate. We conducted a systematic review and network meta-analysis to compare the efficacy of different first-line pharmacological therapies in terms of reproductive outcomes for women with PCOS and infertility.

METHODS

A systematic retrieval of databases was conducted, and randomized clinical trials (RCTs) of pharmacological interventions for infertile PCOS women were included. The primary outcomes were clinical pregnancy and live birth, and the secondary outcomes were miscarriage, ectopic pregnancy and multiple pregnancy. A network meta-analysis based on a Bayesian model was performed to compare the effects of the pharmacological strategies.

RESULTS

A total of 27 RCTs with 12 interventions were included, and all therapies tended to increase clinical pregnancy, especially pioglitazone (PIO) (log OR 3.14, 95% CI 1.56 ~ 4.70, moderate confidence), clomiphene citrate (CC) + exenatide (EXE) (2.96, 1.07 ~ 4.82, moderate confidence) and CC + metformin (MET) + PIO (2.82, 0.99 ~ 4.60, moderate confidence). Moreover, CC + MET + PIO (2.8, -0.25 ~ 6.06, very low confidence) could increase live birth most when compared to placebo, even without a significant difference. For secondary outcomes, PIO showed a tendency to increase miscarriage (1.44, -1.69 ~ 5.28, very low confidence). MET (-11.25, -33.7 ~ 0.57, low confidence) and LZ + MET (-10.44, -59.56 ~ 42.11, very low confidence) were beneficial for decreasing ectopic pregnancy. MET (0.07, -4.26 ~ 4.34, low confidence) showed a neutral effect in multiple pregnancy. Subgroup analysis demonstrated no significant difference between these medications and placebo in obese participants.

CONCLUSIONS

Most first-line pharmacological treatments were effective in improving clinical pregnancy. CC + MET + PIO should be recommended as the optimal therapeutic strategy to improve pregnancy outcomes. However, none of the above treatments had a beneficial effect on clinical pregnancy in obese PCOS.

TRIAL REGISTRATION

CRD42020183541; 05 July 2020.

Letrozole Compared With Clomiphene Citrate for Polycystic Ovarian Syndrome: A Systematic Review and Meta-analysis

OBJECTIVE

To estimate the effect of letrozole and clomiphene citrate in women with infertility and polycystic ovarian syndrome (PCOS).

METHODS OF STUDY SELECTION

MEDLINE through PubMed, Web of Science, EMBASE, Cochrane Library, and ClinicalTrials.gov were searched for relevant studies from inception to February 1, 2022. Two reviewers retrieved, filtered, and extracted data independently using the bibliographic software EndNote X9 and Excel workbook. We included randomized controlled trials (RCTs) reporting ovulation induction outcomes in women with infertility and PCOS treated with either letrozole or clomiphene citrate followed by timed intercourse or intrauterine insemination. The data were merged into a mean difference or risk ratio (RR) with 95% CI, depending on variable types.

TABULATION, INTEGRATION, AND RESULTS

Data collection and organization were conducted in accordance with the 2020 PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analyses) statement. Twenty-nine RCTs were eligible, which included 3,952 women and 7,633 ovulation induction cycles. We acquired evidence from 22 RCTs for the ovulation rate, 28 RCTs for the clinical pregnancy rate, and eight RCTs for live-birth rate. Pooled analysis indicated that letrozole treatment prevailed against clomiphene citrate in ovulation rate (RR 1.14, 95% CI 1.06-1.21, P <.001), clinical pregnancy rate (RR 1.48, 95% CI 1.34-1.63, P <.001), and live-birth rate (RR 1.49, 95% CI 1.27-1.74, P <.001).

CONCLUSIONS

Letrozole was associated with improved ovulation, pregnancy, and live-birth rates compared with clomiphene citrate. We recommend letrozole over clomiphene citrate as an ovulation induction drug in women with infertility and PCOS, although the quality of the evidence is mixed.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO, CRD42022308777.

Hormonal and Metabolic Factors Influence the Action of Progesterone on the Endometrium of Women with Polycystic Ovary Syndrome

Hormonal and metabolic factors may influence endometrial quality and interfere with the action of progesterone. Therefore, the aim of our study was to address this issue. Participants were recruited from an outpatient reproductive endocrinology clinic at an academic tertiary medical care centre. All subjects underwent endometrial biopsy (EB) in the follicular phase of the cycle prior to treatment. Thereafter, they were treated with micronized progesterone (400 mg/day × 10 days intravaginally) from days 14-28 of the next cycle. A second EB was performed between days 21-24 of the cycle (the second phase). The metabolic and hormonal serum levels were evaluated during the implantation window. EB samples were analysed using light microscopy for histomorphometric analysis. The endometrium of women with Polycystic Ovarian Syndrome (PCOS) in the second phase demonstrated a uniform surface epithelium with less leukocyte infiltration and an absence of apoptotic figures compared to the control group. (p < 0.021). The thickness of the surface epithelium in the second phase of the PCOS group correlated positively with free and bioavailable testosterone values. The number of stromal cells increases with increasing insulin levels. Our results suggest that histomorphometric abnormalities of the endometrium persist and are linked to androgen and insulin levels despite progesterone supplementation in PCOS.

Altered Molecular Pathways and Biomarkers of Endometrial Receptivity in Infertile Women with Polycystic Ovary Syndrome

Anovulation is the most prominent cause of infertility in polycystic ovary syndrome (PCOS) patients. Although ovulation can be corrected pharmacologically, the number of pregnancies remains low. Even if excellent embryos are transferred by IVF, it does not change the high miscarriage rate of PCOS patients. These facts collectively indicate that there is a disorder of endometrial development and receptivity to the embryo in PCOS patients, including the decrease of receptive ability, inhibition of embryo adhesion, undersupply of energy, poor blood perfusion, and pro-inflammatory status in the endometrium. However, it has never received the same attention as ovulatory dysfunction. Here we list some alternations of endometrial receptivity in women with PCOS, discuss the underlying intricate mechanisms, and try to find out the possible therapeutic targets, which may bring new perspectives to those who are able to provide high-quality embryos.

The Dose-Related Efficacy of Acupuncture on Endometrial Receptivity in Infertile Women: A Systematic Review and Meta-Analysis

Background

Progress has been achieved by using acupuncture widely for poor endometrial receptivity (PER). However, different acupuncture dosages may lead to controversy over efficacy.

Objective

To evaluate the evidence-based conclusions of dose-related acupuncture on infertile women with PER.

Method

References were retrieved from nine databases from inception to 26 February 2022. This meta-analysis included randomized controlled trials (RCTs) that investigated the dose-related efficacy of acupuncture for PER with outcomes of endometrium receptivity (ER) parameters by transvaginal sonography (TVS) and the subsequent pregnancy outcomes in three acupuncture-dose groups: the high-dosage group (three menstrual cycles), the moderate-dosage group (one menstrual cycle), and the low-dosage group (two or four days). Since there remained sufficient heterogeneity among the three subsets, we prespecified seven subgroup variables (four clinical and three methodological) to investigate the heterogeneities.

Results

A total of 14 RCTs (1,564 women) of moderate or low overall quality were included. The results were different when the dosage of acupuncture was restricted. For the moderate or high-dosage group, CPR and part of ER parameters were improved in the acupuncture group (i.e., CPR: OR = 2.00, 95% CI [1.24, 3.22], p = 0.004, I ² = 0% in one menstrual cycle; OR = 2.49, 95%CI [1.67, 3.72], p < 0.05, I ² = 0% in three menstrual cycles). However, for the low-dosage group, no statistical difference was observed in CPR (OR = 0.07, 95% CI [-0.10, 0.23], p = 0.44, I ² = 82%) and a part of the ER parameters. In subgroup analysis, four subgroup variables (the routine treatment, risk of performance bias, duration of acupuncture treatment, and the age of participants) could explain some of the heterogeneities across all trials.

Conclusion

The finding indicated that the trend of relatively more acupuncture dosage showed better effects for poor endometrial receptivity among PER women. It remains a potential heterogeneity in our studies. Further high-quality trials with a homogeneity trial design need to be conducted.

Systematic review update and meta-analysis of randomized and non-randomized controlled trials of ovarian stimulation versus artificial cycle for endometrial preparation prior to frozen embryo transfer in women with polycystic ovary syndrome

PURPOSE

This systematic review and meta-analysis aimed to compare the short-term reproductive and long-term obstetric outcomes after endometrial preparations by ovarian stimulation protocols and hormone replacement therapy (HRT) in women with polycystic ovary syndrome (PCOS) prior to frozen embryo transfer (FET).

METHOD

PubMed, EMBASE, Web of Science and the Cochrane Library were searched to identify relevant studies. Primary outcome was live birth rate, secondary outcomes included the rates of clinical pregnancy, miscarriage, implantation and hCG-postive, cycle cancellation, ectopic pregnancy, preterm birth, preeclampsia, gestational hypertension, gestational diabetes mellitus and abnormal placentation.

RESULTS

Nine studies, including 8327 patients with PCOS, were identified. Live birth rate was significantly higher (RR = 1.11, 95% CI = 1.03-1.19) and miscarriage rate (RR = 0.60, 95% CI = 0.46-0.78) was significantly lower in stimulated protocol compared to the rates in HRT. While the rates of ongoing pregnancy, clinical pregnancy, implantation, hCG-positive, cycle cancellation and ectopic pregnancy showed no significant difference between the two protocols. Compared HRT with different stimulation protocols, significantly higher clinical pregnancy rate (RR = 1.54, 95% CI = 1.20-1.98) were found in letrozole group, but not in the other subgroups. For the obstetric outcomes, the preterm birth and preeclampsia rates were significantly lower in the stimulated group compared to that in the HRT group (RR = 0.85, 95% CI = 0.74-0.98; RR = 0.57, 95% CI = 0.40-0.82, respectively), while gestational hypertension, gestational diabetes mellitus and abnormal placentation rates showed no significant difference.

CONCLUSIONS

The present data suggest that ovarian stimulation protocol as an endometrial preparation regimen prior to FET might be superior to HRT protocol with a significantly higher rate of live birth, lower risk of miscarriage, preterm birth and preeclampsia. Our study showed stimulated protocol is better than HRT regimen as an endometrial preparation for women with PCOS. However, quality of the evidence is low, more well-designed RCT studies are still needed to confirm the results before clinical recommendation, particularly direct comparisons between letrozole and other stimulated regimens.

The efficiency of low-dose letrozole plus clomiphene citrate for ovulation induction in intrauterine insemination cycles: A randomized clinical trial

OBJECTIVE

To investigate if combination therapy with clomiphene citrate (CC) plus letrozole (L) was associated with a higher efficacy than L and CC alone in patients undergoing ovarian induction plus intrauterine insemination.

METHODS

The present multicenter randomized controlled clinical trial was performed between 2018 and 2020. Participants were randomized into three groups: L (n = 167; 5 mg/day), CC (n = 167; 100 mg/day), and L + CC (n = 167) (2.5 mg/day + 50 mg/day) from day 3. Ovarian stimulation was continued with the appropriate dose of gonadotropins daily starting from day 8 and continued until follicular size was 20 mm or more followed by administration of human chorionic gonadotropin (10 000 IU). Semen samples were prepared by direct swim-up technique.

RESULTS

In the CC group, gonadotropin dose was significantly higher but endometrial thickness was significantly lower compared with other groups. Number of follicles of 18 mm or more was significantly lower in the L group compared with the other two groups. Number of follicles less than 15 mm was meaningfully higher in the CC group compared with the other groups. In the L + CC group, total and largest follicular size, and the rates of chemical, clinical, and ongoing pregnancy, and live birth were significantly higher compared with other groups.

CONCLUSION

Combination therapy with L + CC was superior to either L or CC for achieving pregnancy in women undergoing ovarian induction plus intrauterine insemination.

The regulatory effects of clomiphene and tamoxifen on mTOR and LC3-II expressions in relation to autophagy in experimental polycystic ovary syndrome (PCOS)

BACKGROUND

Polycystic ovary syndrome (PCOS) is a metabolic disease that causes infertility due to anovulation in women in reproductive age. It is known that clomiphene citrate (CC) and tamoxifen citrate (TMX) induce ovulation in women with PCOS. In this study, we aimed to investigate the effects of CC and TMX on the autophagy pathway in PCOS.

METHODS AND RESULTS

Experimental PCOS model was induced by letrozole (1 mg/kg) in rats by gavage for 21 days. After the last letrozole administration, rats were treated TMX (1 mg/kg) or CC (1 mg/kg) for 5 days. At the end of the experimental procedures, rats in all groups were sacrificed and ovarian tissues were removed. It was observed that mRNA and protein expressions of LC3-II were significantly higher in TMX and CC groups than control and PCOS groups (p < 0.05), while mRNA and protein expressions of mTOR in TMX and CC groups were found significantly lower than control and PCOS groups (p < 0.05).

CONCLUSIONS

In conclusion, present study suggests that TMX and CC induce autophagy in ovaries with PCOS. Autophagy is a promising target for understanding pathophysiology of this disease and for developing more effective and safe new protocols for the treatment of PCOS-related anovulation.