Letrozole versus clomiphene citrate in polycystic ovary syndrome: a meta-analysis of randomized controlled trials

Effects of letrozole alone or in combination with gonadotropins on ovulation induction and clinical pregnancy in women with polycystic ovarian syndrome: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

To compare letrozole in combination with gonadotropins versus letrozole monotherapy in ovulation induction and clinical pregnancy among infertile women with polycystic ovarian syndrome (PCOS).

METHODS

Several databases were searched for available clinical trials from inception until March 2023. We selected randomized controlled trials (RCTs) that compared sequential letrozole/gonadotropin versus letrozole alone among infertile women who met the Rotterdam criteria for PCOS. RevMan software was used to perform our meta-analysis. Our primary outcomes were ovulation and clinical pregnancy rates. Our secondary outcomes were endometrial thickness, number of mature follicles (diameter ≥ 18 mm), and incidence of miscarriage and ovarian hyperstimulation syndrome (OHSS).

RESULTS

Six RCTs were retrieved with a total number of 723 patients. The ovulation and clinical pregnancy rates were significantly higher among the letrozole/gonadotropin group versus the letrozole monotherapy group (p < 0.001). In addition, there were significant improvements in endometrial thickness and number of mature follicles in the letrozole/gonadotropin group. There were no significant differences between the two groups regarding incidence of miscarriage and ovarian hyperstimulation syndrome.

CONCLUSION

Letrozole in combination with gonadotropin is superior to letrozole alone in improving ovulation induction and clinical pregnancy among PCOS patients. More trials are required to confirm our findings.

Strong Early Impact of Letrozole on Ovulation Induction Outperforms Clomiphene Citrate in Polycystic Ovary Syndrome

Polycystic ovary syndrome is a common endocrine disorder, characterized by hyperandrogenism and/or chronic oligo/anovulation, which leads to infertility. The aim of this systematic review and meta-analysis was to explore the efficacy of letrozole compared with clomiphene citrate for ovulation induction in women with polycystic ovarian syndrome. The study protocol has been registered with PROSPERO (registration number CRD42022376611). The literature search included randomized clinical trials. We conducted our systematic literature search across three medical databases: MEDLINE (via PubMed), Cochrane Library (CENTRAL), and Embase. The data synthesis employed a random effects model. Out of the 1994 articles screened, 25 studies fulfilled the inclusion criteria. The letrozole group exhibited a significant increase in endometrial thickness (mean difference = 1.70, confidence interval: 0.55-2.86; I2 = 97%, p-value = 0.008). The odds of ovulation (odds ratio = 1.8, confidence interval: 1.21-2.69; I2 = 51%, p-value = 0.010) and pregnancy (odds ratio = 1.96, confidence interval: 1.37-2.81; I2 = 32%, p-value = 0.002) were significantly higher. The resistance index of the subendometrial arteries showed a significant decrease (mean difference = -0.15, confidence interval: -0.27 to -0.04; I2 = 92%, p-value = 0.030). Women diagnosed with polycystic ovarian syndrome and treated with letrozole for ovulation induction had increased ovulation and pregnancy rates and increased endometrial thickness. The lower resistance index of subendometrial arteries can enhance intrauterine circulation, creating more favorable conditions for embryo implantation and development.

Comparison of Letrozole and Clomiphene Citrate in Pregnancy Outcomes in Patients with Polycystic Ovary Syndrome: A Systematic Review and Meta-analysis

Clomiphene citrate (CC) and letrozole are the predominant medical interventions for the management of infertility in patients with polycystic ovary syndrome (PCOS). To comprehensively summarize the evidence, a systematic review and meta-analysis of randomized clinical trials (RCTs) was carried out to assess the effect of letrozole and CC on pregnancy outcomes in PCOS patients. We searched PubMed/MEDLINE, Scopus, and Cochrane Central Register of Controlled Trials from inception to January 2023. We included RCTs conducted on PCOS women comparing letrozole to CC and assessing endometrial thickness, the number and size of follicles, and ovulation and pregnancy rates. The endpoints were summarized as risk ratio (RR) or standardized mean difference (SMD) with 95% confidence interval (CI) using the random-effects model. Heterogeneity was examined using the I2 statistic. Fifty trials met our inclusion criteria. The mean endometrial thickness was significantly higher in the letrozole group compared to CC group (SMD: 0.89; 95% CI: 0.49, 1.28; I2=97.72%); however, the number of follicles was higher in the CC group (SMD: -0.56; 95% CI: -0.96, -0.17; I2=96.34%). Furthermore, letrozole intake induced higher ovulation rate (RR: 1.20; 95% CI: 1.13, 1.26; I2=54.49%) and pregnancy rate (RR: 1.44; 95% CI: 1.28, 1.62; I2=65.58%) compared to CC. Compared to CC, letrozole has a positive effect on endometrial thickness, monofollicular development, and ovulation and pregnancy rates suggesting that letrozole may be a strong alternative to CC as a first-line medical intervention for chronic anovulation in PCOS women. Larger studies are warranted to further clarify these findings.

Sequential 2.5 mg letrozole/FSH therapy is more effective for promoting pregnancy in infertile women with PCOS: a pragmatic randomized controlled trial

Study question

In infertile women with polycystic ovary syndrome (PCOS), is the sequential use of letrozole 2.5 mg/follicle stimulating hormone(FSH) more effective than letrozole 5 mg/FSH in stimulating ovulation and promoting pregnancy?

Research design and methods

The study was designed as a prospective, single-center, randomized, controlled pragmatic clinical trial. 220 infertile women between the ages of 20 and 40, who matched the Rotterdam criteria for PCOS and had no other identified reasons for infertility were enrolled from April 2023 to July 2023.The participants were randomly assigned to two groups in a 1:1 ratio. One group received 2.5 mg of letrozole on cycle days 3-7 with a sequential injection of 75 IU FSH on cycle days 8-10 (n = 110), while the other group received 5 mg of letrozole on cycle days 3-7 with a sequential injection of 75 IU FSH on cycle days 8-10 (n = 110). The duration of FSH treatment varied depending on the follicular development stage. Each participant underwent one to three treatment cycles until achieving pregnancy.The primary outcome was the cumulative pregnancy rate of all the participants. Secondary outcomes included characteristics and clinical pregnancy rates of all the intervention cycles.

Results

For all 220 participants, the sequential letrozole 2.5 mg/FSH treatment group had a significantly higher cumulative pregnancy rate compared to the letrozole 5 mg/FSH treatment group (72.7% versus 59.1%, RR (95%CI) = 1.23 (1.02, 1.49), P-value = 0.033). For all 468 intervention cycles, letrozole 2.5 mg/FSH group had a significantly higher clinical pregnancy rate than the letrozole 5 mg/FSH group (36.2% versus 26.3%, P-value = 0.021), no statistically significant differences were observed in ovulation rates or adverse effects.

Conclusions

The data indicate that the sequential letrozole 2.5mg/FSH protocol may be more effective than the sequential letrozole 5mg/FSH protocol for promoting pregnancy in infertile women with PCOS.

Clinical trial registration

www.chictr.org.cn, identifier ChiCTR2300069638.

Clomiphene citrate plus letrozole versus clomiphene citrate alone for ovulation induction in infertile women with ovulatory dysfunction: a randomized controlled trial

BACKGROUND

The aim of this study was to compare the efficacy of the combination of clomiphene citrate (CC) and letrozole to that of CC alone in inducing ovulation in infertile women with ovulatory dysfunction.

METHODS

A randomized controlled trial was conducted at a single academic medical center between November 2020 and December 2021. Anovulatory infertility females, aged 18 to 40, were evenly distributed by a computer-generated block of four into two treatment groups. A "combination group" received a daily dose of CC (50 mg) and letrozole (2.5 mg), while a "CC-alone group" received a daily dose of CC alone (50 mg). The study medications were administered on days 3 through 7 of menstrual cycle. The primary outcome was the ovulation rate, defined by serum progesterone levels exceeding 3 ng/mL at the mid-luteal phase. The secondary outcomes were ovulation induction cycle characteristics, endometrial thickness, conception rate, and adverse events.

RESULTS

One hundred women (50 per group) were enrolled in the study. The mean age was not significantly different in both groups: 31.8 years in the combination group and 32.4 years in the CC-alone groups (P = 0.54). The prevalence of polycystic ovary syndrome in the combination and CC-alone groups was 48% and 44%, respectively (P = 0.841). According to intention-to-treat analysis, the ovulation rates were 78% and 70% in the combination and CC-alone groups, respectively (P > 0.05). There was no significant difference in the mean endometrial thickness or the number of dominant follicles of the groups. No serious adverse events were observed in either group.

CONCLUSIONS

Our study found no significant difference between the combination of CC and letrozole and CC alone in inducing ovulation in infertile women with ovulatory dysfunction in one cycle. The small number of live births precluded any meaningful statistical analysis. Further studies are needed to validate and extend our findings beyond the scope of the current study.

TRIAL REGISTRATION

The study was registered at https://www.thaiclinicaltrials.org with the following number: TCTR20201108004 and was approved on 08/11/2020.

Transvaginal needle versus laparoscopic ovarian drilling in hormonal profile and pregnancy outcomes of polycystic ovary syndrome: a systematic review and meta-analysis

BACKGROUND

Polycystic ovary syndrome (PCOS) is a prevalent hormonal disorder distinguished by a persistent absence of ovulation. Ovarian drilling is a recognized therapeutic approach for PCOS patients who are unresponsive to medication and can be performed through invasive laparoscopic access or less-invasive transvaginal access. The aim of this systematic review and meta-analysis was to assess the efficacy of transvaginal ultrasound -guided ovarian needle drilling with conventional laparoscopic ovarian drilling (LOD) in patients with PCOS.

METHODS

PUBMED, Scopus, and Cochrane databases were systematically searched for eligible randomized controlled trials (RCTs) from articles published from inception to January 2023. We include RCTs of PCOS that compared transvaginal ovarian drilling and LOD and reported on ovulation and pregnancy rates as the main outcome variable. We evaluated study quality using the Cochrane Risk of bias 2 tool. A random-effects meta-analysis was performed and the certainty of the evidence was assessed according to the GRADE approach. We registered the protocol prospectively in PROSPERO (CRD42023397481).

RESULTS

Six RCTs including 899 women with PCOS met the inclusion criteria. LOD was found to significantly reduce anti-Mullerian hormone (AMH) (SMD: -0.22; 95% CI: -0.38, -0.05; I² = 39.85%) and antral follicle count (AFC) (SMD: -1.22; 95% CI: -2.26, -0.19; I² = 97.55%) compared to transvaginal ovarian drilling. Our findings also indicated that LOD significantly increased the ovulation rate by 25% compared to transvaginal ovarian drilling (RR: 1.25; 95% CI: 1.02, 1.54; I2 = 64.58%). However, we found no significant difference between the two groups in terms of follicle stimulating hormone (SMD: 0.04; 95% CI: -0.26, 0.33; I2 = 61.53%), luteinizing hormone (SMD: -0.07; 95% CI: -0.90, 0.77; I2 = 94.92%), and pregnancy rate (RR: 1.37; 95% CI: 0.94, 1.98; I2 = 50.49%).

CONCLUSION

LOD significantly lowers circulating AMH and AFC and significantly increases ovulation rate in PCOS patients compared to transvaginal ovarian drilling. As transvaginal ovarian drillingremains a less-invasive, more cost-effective, and simpler alternative, further studies are warranted to compare these two techniques in large cohorts, with a particular focus on ovarian reserve and pregnancy outcomes.

Factors associated with spontaneous miscarriage risk in IUI treatment: A retrospectively cohort of 31,933 cycles

To determine the factors associated with intrauterine insemination (IUI) miscarriages and reduce the IUI miscarriage rate, a retrospective study was performed by reviewing 31,933 IUI cycles from 2006 to 2018. The overall there were 14.50% clinical pregnancies, and 16.74% miscarriages. Logistic regression revealed the following three predictive variables: females aged ≥ 35 years (odds ratio [OR] = 2.131; p < 0.001), spontaneous miscarriage history (OR = 1.513; p = 0.005), and ovarian stimulation schemes such as clomiphene citrate (CC) (OR = 1.459; p = 0.003). The natural cycle led to a lower miscarriage rate for patients without spontaneous miscarriage history both for those over 35 years old (OR = 0.402; p = 0.034) and for those under 35 years old (OR = 0.806; p = 0.017). Gonadotropin (Gn) showed the lowest miscarriage rate for patients without abortion history, though no significant differences were found. Patients under 35 with a history of miscarriage were protected from miscarriage by using CC and Gn together (OR = 0.516; p = 0.032). No significant differences were found between various ovarian protocols when patients with abortion history were aged ≥ 35 years (p = 0.606). CC + Gn showed the lowest miscarriage rate. In conclusion, the natural cycle could be suggested for infertility couples to minimize abortion risk. When ovarian induction is required, CC + Gn had the lowest miscarriage rate for women with a history of spontaneous miscarriage while Gn is more successful for individuals without such a history.

Comparing efficacy and safety of stair step protocols for clomiphene citrate and letrozole in ovulation induction for women with polycystic ovary syndrome (PCOS): a randomized controlled clinical trial

Polycystic ovary syndrome (PCOS) is characterized by menstrual irregularities, high androgen levels, and ovarian cysts. Clomiphene citrate (Clomid) and letrozole have both been investigated as ovulation induction therapies for PCOS. This interventional study aimed to compare the efficacy and safety of a stairstep practice of letrozole versus clomiphene citrate in women with PCOS. A total of 100 women diagnosed with PCOS and infertility participated in the study, which took place from March 2021 to July 2022 at the Maternity and Children Teaching Hospital in Adiwaniyah Province, Iraq. Participants were randomly assigned to one of two groups (each with 50 women): the first group received clomiphene citrate in a stair step pattern (single dose of 50 mg, 100 mg, and 150 mg) for five days, for a maximum of three cycles; the second group received letrozole in a stair step pattern (single dose of 2.5, 5, and 7.5 mg) for five days, for a maximum of three cycles. Follicle size was monitored using ultrasound to achieve a follicle size >18 mm. The ovulation rate was higher in the letrozole group (86.0%) compared to the clomiphene citrate group (72.0%), although the difference was not statistically significant (p=0.086). The pregnancy rate was slightly higher in the letrozole group (22.0% vs 18.0%), but also not statistically significant (p=0.617). However, the mean time from menstruation to ovulation was significantly shorter in the letrozole group (17.20±1.32 days) compared to the clomiphene citrate group (24.08 ± 1.56 days, p<0.001). There were no significant differences in common side effects between the two groups. Overall, letrozole was found to be as safe as clomiphene citrate but demonstrated a shorter time to ovulation. Further studies with larger sample sizes are necessary to validate these findings and determine their clinical implications.

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.

Ovulation induction using sequential letrozole/gonadotrophin in infertile women with PCOS: a randomized controlled trial

RESEARCH QUESTION

Is sequential letrozole/human menopausal gonadotrophin (HMG) superior to letrozole alone in ovulation induction and pregnancy promotion among infertile women with polycystic ovary syndrome (PCOS)?

DESIGN

This open-label randomized controlled trial comparing sequential letrozole/HMG and letrozole alone included 174 participants enrolled from August 2019 to January 2020 at the Union Hospital of Tongji Medical College, Huazhong University of Science and Technology. Infertile women aged between 18 and 40 years who met Rotterdam criteria for PCOS and without other known causes of infertility were selected for this study. Patients were randomly assigned at a 1:1 ratio to receive 2.5 mg letrozole on cycle days 3-7 (n = 87) or 2.5 mg letrozole on cycle days 3-7 with a sequential injection of 75 IU HMG on cycle days 8-10 for one treatment cycle (n = 87). The pregnancy outcome was recorded after one treatment cycle.

RESULTS

Women receiving sequential treatment achieved a significantly higher ovulation rate than those in the letrozole group (90.8% versus 70.1%, P = 0.001) and the live birth rate of the sequential group was significantly higher than that of the letrozole protocol (23.0% versus 10.3%, P = 0.025); there was no statistical variation with respect to adverse events.

CONCLUSIONS

The data suggest that the sequential letrozole/HMG protocol may be superior to the letrozole alone protocol in terms of ovulation induction and pregnancy promotion among infertile women with PCOS.

Evaluation of The Effect of Letrozole in the Ovarian Hyperstimulation Syndrome Prevention in Participants at Risk of Treatment with Ovulation-Stimulating Drugs:A Randomized Controlled Trial

Background

This study aims to evaluate the effect of Letrozole (LE) in reducing ovarian hyperstimulation syndrome (OHSS) in high-risk participants with polycystic ovary syndrome (PCOS) treated with In vitro fertilization (IVF).

Methods

This study was a randomized clinical trial in which participants were randomly divided into two groups (n= 25 per group). Based on GnRH-antagonist protocol, recombinant follicle-stimulating hormone 150 units/day subcutaneously and human menopausal gonadotropin 75 units/ day intramuscularly used from day 2 of the menstrual cycle. In the study group, Letrozole 5 mg daily was added simultaneously with gonadotropin during the first five days of the IVF cycle and in the control group placebo was added.

Results

There were statistically significant differences among the groups in terms of Estradiol level on Trigger Day (p= 0.04). The total days of stimulation and cumulative Gonadotropin dose were significantly lower in the Letrozole group (p= 0.00). There were no significant differences between the groups in terms of the number of oocytes retrieved, numbers of implanted embryos, and clinical pregnancy rates (p-value> 0.05). There was only one moderate case in the intervention group and 9 moderate symptoms in the control group (p= 0.04).

Discussion

Administration of Letrozole with GnRH antagonist protocol, conventional protocol in PCOS cases in IVF cycle, had a significant effect on reducing the incidence of OHSS. So, if the future studies prove LE co-administration may lessen the incidence of OHSS, LE will be a highly potent drug for preventing OHSS in PCOS cases.

An update of polycystic ovary syndrome: causes and therapeutics options

Polycystic ovary syndrome (PCOS) is a heterogeneous disorder characterized by menstrual irregularities, chronic anovulation, hirsutism, androgenic alopecia, and acne. At diagnosis, patients can with different manifestations according to the disease phenotype, patient's age, and lifestyle. However, most patients pursue medical care because of the clinical symptoms of PCOS, such as hyperandrogenism, menstrual irregularities and infertility. Recent studies have shown that PCOS is associated with 80% of anovulatory infertility; however, the precise mechanism of PCOS-induced anovulation is still undetermined. The treatment strategies of PCOS are symptomatic depending mainly on the desired goals and clinical benefits. Life style intervention is still the first line treatment option for overweight females seeking pregnancy. In addition, there are many pharmacological agents that could be added to induce ovulation such as metformin, and clomiphene citrate. Nowadays, many patients preferred to use some herbal medicine that was proved to have potential therapeutic benefits in many studies in the management of PCOS. The purpose of this review was to discuss PCOS-induced infertility and the available therapeutic options as well as the impact of COVID-19 infection on the success of fertility attempts. To address this purpose, Pubmed, Scopus, EMBASE and Google databases were searched for studies discussing PCOS-induced infertility. The literature search revealed the proper therapeutic plans to treat PCOS-induced infertility, and that treatment should be modified according to patient's complaints, reproductive desires, and disease phenotypes. In conclusion, the use of specific therapeutic agents and patients' adherence to lifestyle interventions could help patients recover their reproductive and metabolic health.

Higher ovulation rate with letrozole as compared with clomiphene citrate in infertile women with polycystic ovary syndrome: a systematic review and meta-analysis

BACKGROUND

Polycystic ovary syndrome (PCOS) is a common cause of anovulatory infertility. According to the latest guidelines, letrozole should be considered as the first-line pharmacological treatment for women with WHO Group II anovulation or PCOS. However, the use of letrozole as an ovulation induction agent is not FDA or EMA approved, and its use is "off-label." The main concern with respect to letrozole regards its potential teratogenic effect on the fetus.

PURPOSE

To determine whether the probability of ovulation is higher with letrozole as compared to clomiphene citrate (CC) in anovulatory women with PCOS.

METHODS

Randomized controlled trials (RCTs) comparing letrozole versus CC used for ovulation induction in infertile women with PCOS followed by timed intercourse (TI) or intrauterine insemination (IUI) were included in this meta-analysis. Primary outcome was ovulation. Secondary outcomes were live birth, clinical pregnancy, miscarriage, multiple pregnancy, and congenital anomalies. Subgroup analysis included patients who received letrozole or CC as first-line treatment, and patients with PCOS diagnosed according to the Rotterdam criteria.

RESULTS

Twenty-six RCTs published between 2006 and 2019, involving 4168 patients who underwent 8310 cycles of ovulation induction, were included. The probability of ovulation was significantly higher in letrozole as compared to CC cycles (RR: 1.148, 95% CI: 1.077 to 1.223, 3017 women, 19 trials, I²: 47.7%, low-quality evidence).

CONCLUSION

A higher probability of ovulation is expected in infertile patients with PCOS treated with letrozole as compared to CC. The higher ovulation rate might have contributed to the higher clinical pregnancy and live birth rate. This finding is also true for patients who were administered letrozole as first-line treatment.

TRIAL REGISTRATION

CRD42019125166.

Improved hormonal and oxidative changes by Royal Jelly in the rat model of PCOS: An experimental study

BACKGROUND

Polycystic ovarian syndrome (PCOS) is an endocrine and complex metabolic disorder, associated with anovulation, changes in sex hormone, biochemical factors, and ovarian tissue. Royal Jelly (RJ) has antioxidant and anti-inflammatory properties.

OBJECTIVE

To examine the therapeutic effect of RJ on PCOS-related hormonal and biochemical changes in a rat model of PCOS.

MATERIALS AND METHODS

In this experimental study, 42 female Wistar rats (weighing 180-200 gr, aged 10-12 wk) were divided into six groups (n = 7/each): control; PCOS; RJ 100 mg/kg; RJ 200 mg/kg; PCOS + RJ 100 mg/kg; and PCOS + RJ 200 mg/kg. After 21 days, the animals were weighed and dissected. The serums were used for nitric oxide (NO) and ferric-reducing antioxidant power (FRAP) assay and estradiol and progesterone measurements. The ovaries were assessed for histological changes.

RESULTS

PCOS increased estradiol and NO levels, and decreased progesterone and FRAP levels. In PCOS + RJ groups, the progesterone (p = 0.01) and FRAP levels (p ≤ 0.001) increased and the estradiol and NO (p ≤ 0.001) levels decreased significantly. Moreover, the number of mature follicles (p = 0.01) and corpus luteum increased (p ≤ 0.001), and ovarian and uterus weight deceased significantly (p ≤ 0.001).

CONCLUSION

RJ improved estradiol, progesterone, FRAP, and NO levels, and ovarian structure in the rat model of PCOS.

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

Objective

Numerous studies have reported on ovulation and pregnancy rates in patients with polycystic ovary syndrome (PCOS). However, relevant data on endometrial receptivity are limited. This study was conducted to compare endometrial receptivity during implantation windows among letrozole (LE), clomiphene citrate (CC), and natural cycle, and to assess the predictive value for pregnancy of observed indicators.

Methods

This randomized controlled trial study enrolled 270 patients with PCOS. Patients were given LE (n=90) at a dose of 2.5mg/day or CC (n=90) at a dose of 50 mg/day on cycle days 5-9 for ovulation induction. Patients in the natural cycle group (n=90) did not receive any drug for ovulation induction. Endometrial ultrasonic parameters, integrin αvβ3, and vascular endothelial growth factor (VEGF) concentrations in uterine secretion were detected during the implantation window. The endometrial receptivity, ovulation rate, pregnancy rates, and predictive value of observed indicators for pregnancy were analyzed.

Results

The successful ovulation rate did not differ between the LE group and CC group (P>0.05). Endometrial ultrasonic parameters [endometrial thickness (ET), endometrial volume (EV), vascularization index (VI), flow index (FI), vascularization flow index (VFI)], integrin αvβ3, and VEGF concentrations in uterine fluid were significantly higher in the LE group compared with the CC group and natural cycle group (P<0.05). The clinical pregnancy and ongoing pregnancy rates of the LE group were significantly higher than in the CC group (P<0.05). Endometrial ultrasonic parameters (VI, FI, and VFI), integrin αvβ3, and VEGF concentrations in uterine fluid of all pregnancy groups were significantly higher compared with the no pregnancy group (P<0.05), and the above parameters in ongoing pregnancy were significantly higher than in biochemical pregnancy (P<0.05). The endometrial FI during the implantation window had the highest predictive value for pregnancy (AUC=0.889). The integrin αvβ3 in uterine fluid had better predictive value (AUC=0.876) than VEGF.

Conclusions

Endometrial receptivity during the implantation window of LE is superior to CC in PCOS women, which may be related to higher clinical pregnancy and ongoing pregnancy rates. Endometrial FI examined by 3-D power Doppler, and integrin αvβ3 in uterine secretion during the implantation window, could be preferable non-invasive predictor markers for pregnancy.

Clinical Trial Registration

www.chictr.org.cn, ChiCTR1900023423.

Letrozole for Female Infertility

Letrozole, an aromatase inhibitor that blocks estrogen synthesis by inhibiting the final step of the estrogen biosynthetic pathway, has been used in the applications of a wide range of infertility settings. It has been more than 20 years since the initial clinical trial of letrozole for ovulation induction. In light of the accumulating clinical and basic evidence, the efficacy and safety of letrozole have been identified. This mini review focuses on our current knowledge of the applications and mechanisms of letrozole for female infertility and various questions are put forward about how letrozole could be more effectively used.

Risk of foetal harm with letrozole use in fertility treatment: a systematic review and meta-analysis

BACKGROUND

The aromatase inhibitor letrozole is increasingly recommended for ovulation induction, as it is more effective with fewer side-effects than other agents. But many clinicians are reluctant to use the drug for fertility treatment due to a strong-label warning against its use, which warns about congenital malformation risk to the foetus in women seeking pregnancy.

OBJECTIVE AND RATIONALE

The aim of this study was to determine the risks of congenital malformations and pregnancy loss with letrozole compared with clomiphene primarily, and with other fertility drugs and natural conception.

SEARCH METHODS

A systematic review and meta-analysis using PRISMA harms guidelines. We searched MEDLINE, EMBASE and other sources from inception until January 2020, with the MeSH words for 'letrozole' and pregnancy OR foetal/neonatal outcome. We included studies reported on congenital malformations in foetuses born to mothers conceived after fertility treatment, with letrozole versus clomiphene, placebo, gonadotrophins, metformin, natural conception or other agents, from randomised trials, comparative cohort studies and non-comparative observational cohorts. Quality of the studies was assessed using Cochrane risk of bias tool and Newcastle Ottawa Scale. The McMaster tool was used to assess the quality of reported harm for foetal congenital malformations in the studies. We compared the absolute risk of events using risk difference measures and pooled the findings using a fixed-effect model. We evaluated the statistical heterogeneity using forest plots and the I2 statistic and funnel plot to assess publication bias. We assessed the strength of evidence for congenital malformation and pregnancy loss as per the GRADE recommendations and with the Fragility index.

OUTCOMES

We included 46 studies (18 randomised trials; 21 comparative cohorts; 7 non-comparative cohorts). Overall 2.15% (101/4697; 95% CI 1.7 to 2.5) of babies conceived on letrozole for fertility treatment had congenital foetal malformations. We did not observe a significant increase in congenital malformations with letrozole versus clomiphene in the randomised trials (risk difference (RD) 0.01, 95% CI -0.02, 0.03; I2 = 0%; 14 studies) and found a significant reduction in the cohort studies (RD -0.02, 95% CI -0.04, -0.01; I2 = 0%, 11 studies). The fragility index was 44% (7/16) (either an increase in the intervention arm or a decrease in control arm was needed to alter the results). The risks of pregnancy loss were not increased with letrozole versus clomiphene in the 14 randomised trials (RD -0.01, 95% CI -0.06, 0.04; I2 = 0%), and the risks were reduced in the six cohort studies (RD -0.09, 95% CI -0.17, -0.00; I2 = 68%). The GRADE quality of evidence was low to moderate for congenital malformations and pregnancy loss. We did not find any increased congenital malformation risk with letrozole versus gonadotrophins, natural conception or natural cycle ART, but the number of studies was small.

WIDER IMPLICATIONS

There is no evidence that letrozole increases the risk of congenital foetal malformation or pregnancy loss compared with clomiphene, natural conception or other fertility agents, to warrant warning against its use. Given its therapeutic benefits and lack of evidence of harm to the foetus, clinicians should consider letrozole as first-line agent for ovulation induction.

In Search of New Therapeutics-Molecular Aspects of the PCOS Pathophysiology: Genetics, Hormones, Metabolism and Beyond

In a healthy female reproductive system, a subtle hormonal and metabolic dance leads to repetitive cyclic changes in the ovaries and uterus, which make an effective ovulation and potential implantation of an embryo possible. However, that is not so in the case of polycystic ovary syndrome (PCOS), in which case the central mechanism responsible for entraining hormonal and metabolic rhythms during the menstrual cycle is notably disrupted. In this review we provide a detailed description of the possible scenario of PCOS pathogenesis. We begin from the analysis of how a set of genetic disorders related to PCOS leads to particular malfunctions at a molecular level (e.g., increased enzyme activities of cytochrome P450 (CYP) type 17A1 (17α-hydroxylase), 3β-HSD type II and CYP type 11A1 (side-chain cleavage enzyme) in theca cells, or changes in the expression of aquaporins in granulosa cells) and discuss further cellular- and tissue-level consequences (e.g., anovulation, elevated levels of the advanced glycation end products in ovaries), which in turn lead to the observed subsequent systemic symptoms. Since gene-editing therapy is currently out of reach, herein special emphasis is placed on discussing what kinds of drug targets and which potentially active substances seem promising for an effective medication, acting on the primary causes of PCOS on a molecular level.

Fertility and Pregnancy Outcomes in Women with Polycystic Ovary Syndrome Following Bariatric Surgery

CONTEXT

Restoration of ovulation is quite common in women with polycystic ovary syndrome (PCOS) after surgically induced weight loss. Whether or not this results in an improvement of PCOS-associated infertility is uncertain.

OBJECTIVE

To study fertility and gestational outcomes in women with PCOS after bariatric surgery.

DESIGN

Unicenter cohort study.

SETTING

Academic hospital.

PATIENTS

Two hundred and sixteen premenopausal women were screened for PCOS before bariatric surgery. Women were followed-up after the intervention until mid-2019 regardless of having or not PCOS.

INTERVENTIONS

All participants underwent bariatric surgery from 2005 to 2015.

MAIN OUTCOME MEASURES

Pregnancy and live birth rates in the PCOS and control groups.

RESULTS

In women seeking fertility, pregnancy rates were 95.2% in PCOS and 76.9% in controls (P = 0.096) and live birth rates were 81.0% and 69.2%, respectively (P = 0.403). The time to achieve the first pregnancy after surgery was 34 ± 28 months in women with PCOS and 32 ± 25 months in controls. Albeit the mean birth weight was lower (P = 0.040) in newborns from women with PCOS (2763 ± 618 g) compared with those from controls (3155 ± 586 g), the number of newborns with low birth weight was similar in both groups (3 in the PCOS group and 1 in the controls, P = 0.137). Maternal (17.6% in PCOS and 22.2% in controls, P = 0.843) and neonatal (23.5% in PCOS and 14.8% in controls, P = 0.466) complications were rare, showing no differences between groups.

CONCLUSIONS

Pregnancy and fertility rates in very obese women with PCOS after bariatric surgery were high, with few maternal and neonatal complications.

Basal Anti Mullerian hormone levels and endometrial thickness at midcycle can predict the outcome after clomiphene citrate stimulation in anovulatory women with PCOS, a retrospective study

Purpose

Recent studies reported that in polycystic ovary syndrome (PCOS) patients, other stimulation agents are superior to the popular first-line regimen, clomiphene citrate (CC) for ovarian stimulation. Nonetheless, CC is still widely used since it is not clear which patients will not respond to it. Furthermore, the prognostic value of endometrium thickness at midcycle is controversial. We aimed to find factors predicting the response to CC and the prognostic value of endometrial thickness at midcycle.

Methods

We collected data retrospectively from 89 anovulatory PCOS patients who had the first stimulation with 50 mg CC. We analyzed the basal levels of AMH, testosterone, LH, LH:FSH ratio and the endometrial thickness at midcycle by univariate, followed by multivariate regression. The outcome measures were pregnancy, follicle maturation and endometrial thickness at midcycle.

Results

Stimulation with 50 mg CC resulted in follicle maturation in 50.6% of the women and in 27.0% pregnancies. In the univariate analysis, greater endometrial thickness, lower LH and AMH levels and a lower LH:FSH ratio were associated with pregnancy (p < 0.05). In the multivariate analysis, only endometrial thickness remained predictive (p = 0.045). The endometrial thickness cutoff level of ≥ 8 mm showed a sensitivity of 87.5% (96% CI 67.6–97.3) and a specificity of 66.7% (95% CI 43.0–85.4) for prediction of pregnancy. In the multivariate analysis AMH levels 5.4 (3.4; 7.0) (ng/mL) predicted pregnancy (β = − 0.194 ± 0.092; p = 0.034)

Conclusion

We suggest to refrain from CC as first-line regimen in patients with AMH > 7 ng/ml. Under CC treatment, the cutoff value of ≥ 8 mm endometrium thickness at midcycle is associated with a better outcome.

Changes in serum markers of patients with PCOS during consecutive clomiphene stimulation cycles: a retrospective study

BACKGROUND

A retrospective case-control study was performed to evaluate whether PCOS-specific serum markers would change in women with polycystic ovary syndrome (PCOS) during the course of two consecutive cycles of clomiphene citrate (CC)-stimulation, which did not lead to a pregnancy.

METHODS

Anovulatory PCOS patients who underwent two consecutive CC-cycles (n = 41) and anovulatory PCOS controls who chose an observational approach for two months (n = 24) were included in the study. The main outcome measures were levels of follicle stimulating hormone (FSH), luteinizing hormone (LH), anti-Mullerian hormone (AMH), total testosterone, androstenedione, and sexual hormone binding globulin (SHBG).

RESULTS

In the control group, PCOS-specific serum parameters did not change during two months (p > 0.05). In the CC-group, there were decreases in LH (11.8 ± 4.9 mU/mL vs. 10.9 ± 4.0 mU/mL; p = 0.029), the LH:FSH ratio (2.1 ± 0.8 mU/mL vs. 1.8 ± 0.5 mU/mL; p = 0.007), and AMH (8.08 ± 4.27 ng/mL vs. 7.17 ± 3.37 ng/mL; p = 0.011), as well as an increase in SHBG (46.0 ± 20.2 nmol/L vs. 51.2 ± 21.0 nmol/L; p < 0.001). A higher age and lower baseline total testosterone and AMH levels were predictive of an AMH decline (p < 0.05).

CONCLUSION

Two cycles of CC-stimulation that did not lead to a pregnancy were accompanied by mean LH, AMH, and LH:FSH ratio declines and an SHBG increase. The clinical significance seems of minor relevance.

The role of Letrozole (LE) in controlled ovarian stimulation (COS) in patients at high risk to develop ovarian hyper stimulation syndrome (OHSS). A prospective randomized controlled pilot study

BACKGROUND

Recently, it has been shown that PCOS patients with extremely high anti-Mullerian hormone (AMH) level are more likely to experience OHSS during IVF, compared to PCOS patients with lower AMH level. While recent data questioned the effect of Letrozole (LE) on the occurrence of OHSS in non-PCOS patients, it role in PCOS patients with very high AMH level was never investigated in a prospective manners. Hence, our main objective was to evaluate the clinical outcome of PCOS patients at very high risk for OHSS undergoing two different COS protocols (with or without LE).

METHODS

A prospective randomized controlled study (RCT) of 51 patients with specifically high levels of AMH undergoing one of two COS protocols. The control group (group A) consisted of 24 PCOS women who received low-dose gonadotropins using the multiple-dose GnRH-antagonist protocol, GnRH agonist-triggered and "freeze all". The study group (group B) consisted of 24 women with PCOS who received the same protocol combined with LE. High risk criteria for OHSS were: PCOS patients with low BMI, young age, and extremely high level of serum AMH (inclusion criteria for AMH > 50 pmol/L).

RESULTS

Cumulative live birth rates per retrieval were similar in both groups. While no single case of severe OHSS was observed in, in the study group (group B), the rate of moderate and mild OHSS was 5 times lower compared to the control group (P < 0.05).

CONCLUSION

In PCOS patients with extremely high AMH levels the LE co-administration to GnRH-Ant protocols results in reduced incidence of OHSS than conventional GnRH-Ant protocols. LE co-administration may prove to be highly effective in preventing OHSS, even in the women who are at high risk to these dangerous complications.

A Review of First Line Infertility Treatments and Supporting Evidence in Women with Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is the most common cause of anovulatory infertility in women of reproductive age. Lifestyle change is considered the first line treatment for the management of infertile anovulatory women with PCOS, and weight loss for those who are overweight or obese. First line medical ovulation induction therapy to improve fertility outcomes is letrozole, whilst other less efficacious ovulation induction agents, such as clomiphene citrate, metformin, and metformin combined with clomiphene citrate, may also be considered. Metformin combined with clomiphene citrate is more effective than clomiphene citrate alone. In obese women with PCOS, clomiphene citrate could be used in preference to metformin alone whilst clomiphene citrate could be added to metformin alone in order to improve reproductive outcome in all women with PCOS. Gonadotrophins, which are more effective than clomiphene citrate in therapy naïve women with PCOS, can be considered a first line therapy in the presence of ultrasound monitoring, following counselling on the cost and the potential risk of multiple pregnancy.

Letrozole for patients with polycystic ovary syndrome: A retrospective study

This retrospective study investigated the efficacy and safety of letrozole for patients with polycystic ovary syndrome (PCOS).Totally, 136 cases of infertility women with PCOS were analyzed. Of those, 68 patients received letrozole, and were assigned to Letrozole group. The other 68 cases received clomiphene, and were assigned to clomiphene group. Patients in both groups were treated up to 5 treatment cycles. The primary endpoint included infant outcomes. The secondary endpoints consisted of the number of women in conception, pregnancy, pregnancy loss, and ovulation. In addition, any kinds of adverse events were also recorded.Cases in the Letrozole group did not show better outcomes neither in primary endpoint (live birth, P = .11; birth weight, P = .95; infant gender, P = .85), nor in secondary endpoints (the number of women in conception, P = .07; pregnancy, P = .12; pregnancy loss, P = .47; pregnancy loss in first trimester, P = .70; and ovulation, P = .09), compared with cases in the clomiphene group. Moreover, no adverse events differ significantly between 2 groups.This study demonstrated that the efficacy of letrozole is not superior to the clomiphene in patients with PCOS.