Comparison of endocrine and ultrasound profiles during ovulation induction with clomiphene citrate and letrozole in ovulatory volunteer women

Sublingual human chorionic gonadotropin as an adjuvant to ovulation induction

OBJECTIVE

To evaluate the efficacy of sublingually administered human chorionic gonadotropin (HCG) in combination with clomiphene citrate (CC) or letrozole (LTZ) for ovulation induction.

METHODS

In this prospective, double-blind, randomized study, the patients were divided into two placebo groups and two intervention groups using CC, LTZ, and HCG.

RESULTS

There were no statistically significant differences in ovulation induction between the groups. We compared endometrial thickness at the beginning of the cycle and during the pre-ovulatory period, and detected a moderately positive correlation when CC was administered with HCG.

CONCLUSIONS

Sublingual HCG with CC caused a moderately positive correlation with endometrial thickening when compared with that at the beginning of the cycle and during the pre-ovulatory period. There was no significant change in the number of pre-ovulatory follicles.

Letrozole-stimulated endometrial preparation protocol is a superior alternative to hormone replacement treatment for frozen embryo transfer in women with polycystic ovary syndrome, a cohort study

BACKGROUND

The current routine endometrial preparation protocol for women with polycystic ovary syndrome (PCOS) is hormone replacement treatment (HRT). Letrozole is rarely used in frozen embryo cycles. Evidence confirming whether letrozole-stimulated (LS) protocol is suitable for frozen embryo transfer in patients with PCOS and for whom is suitable remains lacking.

METHODS

This was a retrospective cohort study involving all frozen embryo transfer cycles with LS and HRT for PCOS during the period from Jan 2019 to December 2020 at a tertiary care center. Multivariate Logistic regression was used to analyze the differences in clinical pregnancy rate, live birth rate, miscarriage rate, the incidence of other pregnancy and obstetric outcomes between LS and HRT protocols after adjusting for possible confounding factors. Subgroup analysis was used to explore the population for which LS protocol was suitable.

RESULTS

The results of multivariate logistic regression showed that LS was significantly associated with a higher clinical pregnancy rate (70.9% vs. 64.4%;aOR:1.41, 95%CI: 1.18,1.68), live birth rate (60.5% vs. 51.4% aOR:1.49, 95%CI: 1.27,1.76), and a lower risk of miscarriage (14.7% vs. 20.1% aOR: 0.68, 95%CI: 0.53,0.89), hypertensive disorders of pregnancy (6.7% vs. 8.9% aOR: 0.63, 95%CI: 0.42,0.95), and gestational diabetes mellitus (16.7% vs. 20.7% aOR:0.71, 95%CI: 0.53,0.93) than HRT. There were no significant differences in other outcomes such as preterm birth, cesarean delivery, small for gestational age, or large for gestational age between the two endometrial preparation protocols. Subgroup analysis showed that LS had higher live birth rates than HRT in most of the subgroups; in the three subgroups of maternal age ≥ 35 years, menstrual cycle < 35 days, and no insulin resistance, the live birth rates of the two endometrial preparation protocols were comparable.

CONCLUSIONS

LS protocol could improve the live birth rate and reduce the incidence of miscarriage, hypertensive disorders of pregnancy and gestational diabetes mellitus in patients with PCOS. LS protocol is suitable for all types of patients with PCOS. LS should be considered the preferred endometrial preparation protocol for women with PCOS.

Live birth after letrozole-stimulated cycles versus hormone replacement treatment cycles for the first frozen embryo transfer in women with polycystic ovary syndrome: protocol for a multicentre randomised controlled trial

INTRODUCTION

Hormone replacement treatment (HRT) is the most commonly used endometrial preparation protocol for frozen embryo transfer (FET) in patients with polycystic ovary syndrome (PCOS). However, studies have found that HRT may increase the risk of hypertensive disorders of pregnancy and some obstetric complications. Letrozole is a new first-line ovulation induction drug for PCOS and can effectively induce spontaneous ovulation by reducing oestrogen levels. However, letrozole is still rarely used in FET and has only been reported in a few studies in Asian populations. High-quality, well-powered randomised controlled trials (RCTs) comparing HRT and letrozole-stimulated protocols are lacking. The aim of this study is to compare the efficacy and safety of two protocols in patients with PCOS.

METHODS AND ANALYSIS

This is a multicentre, open-label RCT in four reproductive medical centres in China. In total, 1078 women with PCOS will be randomised (1:1) to the letrozole-stimulated or HRT group in their first FET cycle and their pregnancy and perinatal outcomes during this cycle will be followed up and analysed. The primary outcome is live birth. Secondary outcomes are cycle cancellation rate, biochemical pregnancy, clinical pregnancy, miscarriage, ectopic pregnancy, obstetric and perinatal complications, neonatal complications and birth weight.

ETHICS AND DISSEMINATION

Ethical approval was obtained from the Institutional Review Board of Reproductive and Genetic Hospital of CITIC-XIANGYA (LL-SC-2022-001). Written informed consent will be obtained from each participant. The findings will be disseminated through conference presentations and publication in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT05227391.

Letrozole increases preantral follicle growth and decreases estradiol production without impairing follicle survival

BACKGROUND

Letrozole has been reported to be effective in treating anovulation, preventing ovarian hyperstimulation syndrome (OHSS), and retrieving oocytes in breast cancer patients. However, the role and mechanism of letrozole in follicular development remain unclear.

RESULTS

We treated mouse preantral follicles with various treatments; we found no significant difference in follicle survival rates in the letrozole (LET) group compared with the control group, but the average diameter of follicles in the LET group tended to be larger (CTRL vs. LET 30, p = 0.064; CTRL vs. LET 100, p = 0.025). The estradiol concentrations in culture media of the LET group were significantly lower than those observed in the control group (CTRL vs. LET 30, p = 0.038; CTRL vs. LET 100, p = 0.025). We further found a marked increase in follicle-stimulating hormone receptor (FSHR) gene expression in response to letrozole treatment (CTRL vs. LET 30, p = 0.075; CTRL vs. LET 100, p = 0.034). This result suggested that increased FSHR expression promotes follicle development. Letrozole inhibited aromatase activity, but the effect was limited. Letrozole did not significantly reduce vascular endothelial growth factor (VEGF) gene expression.

CONCLUSIONS

Letrozole may promote follicle development by increasing the expression of FSHR. Letrozole may be useful for fertility preservation of patients with estrogen-dependent cancers such as breast cancer and various other cancers. Whether letrozole has a direct effect in reducing OHSS requires further investigation.

Aromatase inhibitors (letrozole) for ovulation induction in infertile women with polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) is the most common cause of infrequent periods (oligomenorrhoea) and absence of periods (amenorrhoea). It affects about 5% to 20% of women worldwide and often leads to anovulatory infertility. Aromatase inhibitors (AIs) are a class of drugs that were introduced for ovulation induction in 2001. Since about 2001 clinical trials have reached differing conclusions as to whether the AI, letrozole, is at least as effective as the first-line treatment clomiphene citrate (CC), a selective oestrogen receptor modulator (SERM).

OBJECTIVES

To evaluate the effectiveness and safety of AIs (letrozole) (with or without adjuncts) compared to SERMs (with or without adjuncts) for infertile women with anovulatory PCOS for ovulation induction followed by timed intercourse or intrauterine insemination.

SEARCH METHODS

We searched the following sources, from their inception to 4 November 2021, to identify relevant randomised controlled trials (RCTs): the Cochrane Gynaecology and Fertility Group Specialised Register, CENTRAL, MEDLINE, Embase and PsycINFO. We also checked reference lists of relevant trials, searched the trial registers and contacted experts in the field for any additional trials. We did not restrict the searches by language or publication status.

SELECTION CRITERIA

We included all RCTs of AIs used alone or with other medical therapies for ovulation induction in women of reproductive age with anovulatory PCOS.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials, extracted the data and assessed risks of bias using RoB 1. We pooled trials where appropriate using a fixed-effect model to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for most outcomes, and risk differences (RDs) for ovarian hyperstimulation syndrome (OHSS). The primary outcomes were live birth rate and OHSS rate. Secondary outcomes were clinical pregnancy, miscarriage and multiple pregnancy rates. We assessed the certainty of the evidence for each comparison using GRADE methods.

MAIN RESULTS

This is a substantive update of a previous review; of six previously included trials, we excluded four from this update and moved two to 'awaiting classification' due to concerns about validity of trial data. We included five additional trials for this update that now includes a total of 41 RCTs (6522 women). The AI, letrozole, was used in all trials. Letrozole compared to SERMs with or without adjuncts followed by timed intercourse Live birth rates were higher with letrozole (with or without adjuncts) compared to SERMs followed by timed intercourse (OR 1.72, 95% CI 1.40 to 2.11; I2 = 0%; number needed to treat for an additional beneficial outcome (NNTB) = 10; 11 trials, 2060 participants; high-certainty evidence). This suggests that in women with a 20% chance of live birth using SERMs, the live birth rate in women using letrozole with or without adjuncts would be 27% to 35%. There is high-certainty evidence that OHSS rates are similar with letrozole or SERMs (0.5% in both arms: risk difference (RD) -0.00, 95% CI -0.01 to 0.01; I2 = 0%; 10 trials, 1848 participants; high-certainty evidence). There is evidence for a higher pregnancy rate in favour of letrozole (OR 1.69, 95% CI 1.45 to 1.98; I2 = 0%; NNTB = 10; 23 trials, 3321 participants; high-certainty evidence). This suggests that in women with a 24% chance of clinical pregnancy using SERMs, the clinical pregnancy rate in women using letrozole with or without adjuncts would be 32% to 39%. There is little or no difference between treatment groups in the rate of miscarriage per pregnancy (25% with SERMs versus 24% with letrozole: OR 0.94, 95% CI 0.66 to 1.32; I2 = 0%; 15 trials, 736 participants; high-certainty evidence) and multiple pregnancy rate (2.2% with SERMs versus 1.6% with letrozole: OR 0.74, 95% CI 0.42 to 1.32; I2 = 0%; 14 trials, 2247 participants; high-certainty evidence). However, a funnel plot showed mild asymmetry, indicating that some trials in favour of SERMs might be missing.  Letrozole compared to laparoscopic ovarian drilling (LOD) One trial reported very low-certainty evidence that live birth rates may be higher with letrozole compared to LOD (OR 2.07, 95% CI 0.99 to 4.32; 1 trial, 141 participants; very low-certainty evidence). This suggests that in women with a 22% chance of live birth using LOD with or without adjuncts, the live birth rate in women using letrozole with or without adjuncts would be 24% to 47%. No trial reported OHSS rates. Due to the low-certainty evidence we are uncertain if letrozole improves pregnancy rates compared to LOD (OR 1.47, 95% CI 0.95 to 2.28; I² = 0%; 3 trials, 367 participants; low-certainty evidence). This suggests that in women with a 29% chance of clinical pregnancy using LOD with or without adjuncts, the clinical pregnancy rate in women using letrozole with or without adjuncts would be 28% to 45%. There seems to be no evidence of a difference in miscarriage rates per pregnancy comparing letrozole to LOD (OR 0.65, 95% CI 0.22 to 1.92; I² = 0%; 3 trials, 122 participants; low-certainty evidence). This also applies to multiple pregnancies (OR 3.00, 95% CI 0.12 to 74.90; 1 trial, 141 participants; very low-certainty evidence).

AUTHORS' CONCLUSIONS

Letrozole appears to improve live birth rates and pregnancy rates in infertile women with anovulatory PCOS, compared to SERMs, when used for ovulation induction, followed by intercourse. There is high-certainty evidence that OHSS rates are similar with letrozole or SERMs. There was high-certainty evidence of no difference in miscarriage rate and multiple pregnancy rate. We are uncertain if letrozole increases live birth rates compared to LOD. In this update, we added good quality trials and removed trials with concerns over data validity, thereby upgrading the certainty of the evidence base.

Emulating a target trial of the comparative effectiveness of clomiphene citrate and letrozole for ovulation induction

STUDY QUESTION

What are the comparative pregnancy outcomes in women who receive up to six consecutive cycles of ovulation induction with letrozole versus clomiphene citrate?

SUMMARY ANSWER

The risks of pregnancy, livebirth, multiple gestation, preterm birth, neonatal intensive care unit (NICU) admission and congenital malformations were higher for letrozole compared with clomiphene in participants with polycystic ovarian syndrome (PCOS), though no treatment differences were observed in those with unexplained infertility.

WHAT IS KNOWN ALREADY

Randomized trials have reported higher pregnancy and livebirth rates for letrozole versus clomiphene among individuals with PCOS, but no differences among those with unexplained infertility. None of these trials were designed to study maternal or neonatal complications.

STUDY DESIGN, SIZE, DURATION

We emulated a hypothetical trial of the comparative effectiveness of letrozole versus clomiphene citrate for ovulation induction among all women, then stratified by PCOS and unexplained infertility status. We used real-world data from a large healthcare claims database in the USA (2011-2015).

PARTICIPANTS/MATERIALS, SETTING, METHODS

We analyzed data from 18 120 women who initiated letrozole and 49 647 women who initiated clomiphene during 2011-2014, and who were aged 18-45 years with no history of diabetes, thyroid disease, liver disease or breast cancer and had no fertility treatments for 3 months before trial initiation. The treatment strategies were clomiphene citrate or letrozole for six consecutive cycles. The outcomes were pregnancy, livebirth, multiple gestation, preterm birth, small for gestational age (SGA), NICU admission and major congenital malformations. We estimated the probability of each outcome under each strategy via pooled logistic regression and used standardization to adjust for confounding and selection bias due to loss to follow-up.

MAIN RESULTS AND THE ROLE OF CHANCE

The estimated probabilities of pregnancy, livebirth and neonatal outcomes were similar under each strategy, both overall and among individuals with unexplained infertility. Among women with PCOS, the probability of pregnancy was 43% for letrozole vs 37% for clomiphene (risk difference [RD] = 6.0%; 95% CI: 4.4, 7.7) in the intention-to-treat analyses. The corresponding probability of livebirth was 32% vs 29% (RD = 3.1%; 95% CI: 1.5, 4.8). In per protocol analyses, the risk of multiple gestation was 19% vs 9%, the risk of preterm birth was 20% vs 15%, the risk of SGA was 5% vs 3%, the risk of NICU admission was 22% vs 16% and the risk of congenital malformation was 8% vs 2% among those with a livebirth.

LIMITATIONS, REASONS FOR CAUTION

We cannot completely rule out the possibility of residual confounding by body mass index or duration of infertility. However, we adjusted for proxies identified in administrative data and results did not change.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings suggest that for women with unexplained infertility, the two treatments result in comparable probabilities of a livebirth. For women with PCOS, letrozole appears slightly more effective for attaining a livebirth. Neonatal outcomes were similar for the two treatments among women with unexplained infertility; we did not confirm the hypothesized higher risk of adverse neonatal outcomes for clomiphene versus letrozole. The risks of adverse neonatal outcomes were slightly greater among women with PCOS who were treated with letrozole versus clomiphene. It is likely that these effects are partially mediated through an increased risk of multiple gestation among women who received letrozole.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the National Institute of Child Health and Human Development (R01HD088393). Y.-H.C. reports grants from the American Heart Association (834106) and NIH (R01HD097778). P.R. reports grants from the National Institutes of Health. J.H. reports grants from the National Institutes of Health, the Agency for Healthcare Research and Quality, and the California Health Care Foundation during the conduct of the study; and consulting for several health care delivery organizations including Cambridge Health Alliance, Columbia University, University of Southern California, Community Servings, and the Delta Health Alliance. S.H.-D. reports grants from the National Institutes of Health and the US Food and Drug Administration during the conduct of the study; grants to her institution from Takeda outside the submitted work; consulting for UCB (biopharmaceutical company) and Roche; and being an adviser for the Antipsychotics Pregnancy Registry and epidemiologist for the North American Antiepileptics Pregnancy Registry, both at Massachusetts General Hospital. M.A.H. reports grants from the National Institutes of Health and the U.S. Veterans Administration during the conduct of the study; being a consultant for Cytel; and being an adviser for ProPublica.

TRIAL REGISTRATION NUMBER

N/A.

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.

Aromatase inhibitors (letrozole) for subfertile women with polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) is the most common cause of infrequent periods (oligomenorrhoea) and absence of periods (amenorrhoea). It affects about 4% to 8% of women worldwide and often leads to anovulatory subfertility. Aromatase inhibitors (AIs) are a class of drugs that were introduced for ovulation induction in 2001. Since about 2001 clinical trials have reached differing conclusions as to whether the AI letrozole is at least as effective as the first-line treatment clomiphene citrate (CC).

OBJECTIVES

To evaluate the effectiveness and safety of aromatase inhibitors for subfertile women with anovulatory PCOS for ovulation induction followed by timed intercourse or intrauterine insemination (IUI).

SEARCH METHODS

We searched the following sources from inception to November 2017 to identify relevant randomised controlled trials (RCTs): the Cochrane Gynaecology and Fertility Group Specialised Register, the Cochrane Central Register of Controlled Trials, MEDLINE, Embase, PsycINFO, Pubmed, LILACS, Web of Knowledge, the World Health Organization (WHO) clinical trials register and Clinicaltrials.gov. We also searched the references of relevant articles. We did not restrict the searches by language or publication status.

SELECTION CRITERIA

We included all RCTs of AIs used alone or with other medical therapies for ovulation induction in women of reproductive age with anovulatory PCOS.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials, extracted the data and assessed risks of bias. We pooled studies where appropriate using a fixed-effect model to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for most outcomes, and risk differences (RDs) for ovarian hyperstimulation syndrome (OHSS). The primary outcomes were live birth and OHSS. Secondary outcomes were clinical pregnancy, miscarriage and multiple pregnancy. We assessed the quality of the evidence for each comparison using GRADE methods.

MAIN RESULTS

This is a substantive update of a previous review. We identified 16 additional studies for the 2018 update. We include 42 RCTs (7935 women). The aromatase inhibitor letrozole was used in all studies.Letrozole compared to clomiphene citrate (CC) with or without adjuncts followed by timed intercourseLive birth rates were higher with letrozole (with or without adjuncts) compared to clomiphene citrate (with our without adjuncts) followed by timed intercourse (OR 1.68, 95% CI 1.42 to 1.99; 2954 participants; 13 studies; I² = 0%; number needed to treat for an additional beneficial outcome (NNTB) = 10; moderate-quality evidence). There is high-quality evidence that OHSS rates are similar with letrozole or clomiphene citrate (0.5% in both arms: risk difference (RD) -0.00, 95% CI -0.01 to 0.00; 2536 participants; 12 studies; I² = 0%; high-quality evidence). There is evidence for a higher pregnancy rate in favour of letrozole (OR 1.56, 95% CI 1.37 to 1.78; 4629 participants; 25 studies; I² = 1%; NNTB = 10; moderate-quality evidence). There is little or no difference between treatment groups in the rate of miscarriage by pregnancy (20% with CC versus 19% with letrozole; OR 0.94, 95% CI 0.70 to 1.26; 1210 participants; 18 studies; I² = 0%; high-quality evidence) and multiple pregnancy rate (1.7% with CC versus 1.3% with letrozole; OR 0.69, 95% CI 0.41 to 1.16; 3579 participants; 17 studies; I² = 0%; high-quality evidence). However, a funnel plot showed mild asymmetry, indicating that some studies in favour of clomiphene might be missing.Letrozole compared to laparoscopic ovarian drillingThere is low-quality evidence that live birth rates are similar with letrozole or laparoscopic ovarian drilling (OR 1.38, 95% CI 0.95 to 2.02; 548 participants; 3 studies; I² = 23%; low-quality evidence). There is insufficient evidence for a difference in OHSS rates (RD 0.00, 95% CI -0.01 to 0.01; 260 participants; 1 study; low-quality evidence). There is low-quality evidence that pregnancy rates are similar (OR 1.28, 95% CI 0.94 to 1.74; 774 participants; 5 studies; I² = 0%; moderate-quality evidence). There is insufficient evidence for a difference in miscarriage rate by pregnancy (OR 0.66, 95% CI 0.30 to 1.43; 240 participants; 5 studies; I² = 0%; moderate-quality evidence), or multiple pregnancies (OR 3.00, 95% CI 0.12 to 74.90; 548 participants; 3 studies; I² = 0%; low-quality evidence).Additional comparisons were made for Letrozole versus placebo, Selective oestrogen receptor modulators (SERMS) followed by intrauterine insemination (IUI), follicle stimulating hormone (FSH), Anastrozole, as well as dosage and administration protocols. There is insufficient evidence for a difference in either group of treatment due to a limited number of studies. Hence more research is necessary.

AUTHORS' CONCLUSIONS

Letrozole appears to improve live birth and pregnancy rates in subfertile women with anovulatory polycystic ovary syndrome, compared to clomiphene citrate. There is high-quality evidence that OHSS rates are similar with letrozole or clomiphene citrate. There is high-quality evidence of no difference in miscarriage rates or multiple pregnancy rates. There is low-quality evidence of no difference in live birth and pregnancy rates between letrozole and laparoscopic ovarian drilling, although there were few relevant studies. For the 2018 update, we added good-quality trials, upgrading the quality of the evidence.

Obligatory role of hypothalamic neuroestradiol during the estrogen-induced LH surge in female ovariectomized rhesus monkeys

Negative and positive feedback effects of ovarian 17β-estradiol (E₂) regulating release of gonadotropin releasing hormone (GnRH) and luteinizing hormone (LH) are pivotal events in female reproductive function. While ovarian feedback on hypothalamo-pituitary function is a well-established concept, the present study shows that neuroestradiol, locally synthesized in the hypothalamus, is a part of estrogen's positive feedback loop. In experiment 1, E₂ benzoate-induced LH surges in ovariectomized female monkeys were severely attenuated by systemic administration of the aromatase inhibitor, letrozole. Aromatase is the enzyme responsible for synthesis of E₂ from androgens. In experiment 2, using microdialysis, GnRH and kisspeptin surges induced by E₂ benzoate were similarly attenuated by infusion of letrozole into the median eminence of the hypothalamus. Therefore, neuroestradiol is an integral part of the hypothalamic engagement in response to elevated circulating E₂ Collectively, we will need to modify the concept of estrogen's positive feedback mechanism.

Tadalafil for Endometrial Growth in Clomiphene Citrate stimulated cycles in an IUI programma: A pilot study

AIM OF THE STUDY

The objective of this study was to assess the impact of tadalafil on endometrial growth, the uterine artery pulsatility index (PI) and the uterine artery resistance index (RI) in patients under clomiphene ovarian stimulation for intrauterine insemination (IUI).

METHODS

This randomized crossover study included 30 patients with a normal endometrium over 53 cycles, and 46 of those cycles in 23 patients were included in the analysis. In group A the patients were under 100 mg clomiphene daily for five days (2-6) and 5 mg tadalafil daily for 7 days (4-10). For Group B (control) the patients only received clomiphene. Measurements of the endometrium, PI, RI and estradiol determinations were taken on cycle days 4, 8 and 10.

RESULTS

We observed a better endometrial growth in Group A compared to Group B: 7.5 ± 2.1 mm vs 5.5 ± 1.2 mm, P < 0.0002 and 8.9 ± 1.8 mm vs 6.3 ± 1.8 mm, P < 0.0002 on days 8 and 10, respectively. Additionally, a progressive decrease in the RI was observed in Group A but not in Group B from day 8 (0.77 ± 0.15 vs 0.85 ± 0.18, P = 0.059) to day 10 (0.74 ± 0.20 vs 0.87 ± 0.14, P < 0.017). However, no differences were observed in PI or serum estradiol between Group A and Group B.

CONCLUSION

The use of tadalafil improved endometrial growth in patients under clomiphene ovarian stimulation with no significant effect on the uterine artery Pulsatility Index and serum estradiol.

Aromatase inhibitors for subfertile women with polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) is the most common cause of infrequent periods (oligomenorrhoea) and absence of periods (amenorrhoea). It affects about 4% to 8% of women worldwide and often leads to anovulatory subfertility. Aromatase inhibitors (AIs) are a novel class of drugs that were introduced for ovulation induction in 2001. Over the last ten years clinical trials have reached differing conclusions as to whether the AI letrozole is at least as effective as the first-line treatment clomiphene citrate (CC).

OBJECTIVES

To evaluate the effectiveness and safety of aromatase inhibitors for subfertile women with anovulatory PCOS.

SEARCH METHODS

We searched the following sources from inception to 24/10/2013 to identify relevant randomised controlled trials (RCTs): the Menstrual Disorders and Subfertility Group Specialised Register, the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, PsycINFO, Pubmed, LILACS, Web of Knowledge, the World Health Organisation (WHO) clinical trials register and Clinicaltrials.gov. Furthermore, we manually searched the references of relevant articles.The search was not restricted by language or publication status.

SELECTION CRITERIA

We included all RCTs of aromatase inhibitors used alone or with other medical therapies for ovulation induction in women of reproductive age with anovulatory PCOS.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials, extracted the data and assessed trial quality. Studies were pooled where appropriate using a fixed effect model to calculate pooled odds ratios (ORs) and 95% confidence intervals (CIs) for most outcomes and risk differences (RDs) for ovarian hyperstimulation syndrome (OHSS). The primary outcomes were live birth and OHSS. Secondary outcomes were pregnancy, miscarriage and multiple pregnancy. The quality of the evidence for each comparison was assessed using GRADE methods.

MAIN RESULTS

We included 26 RCTs (5560 women). In all studies the aromatase inhibitor was letrozole. Live birth (12 RCTs) One RCT compared letrozole with placebo in women who were clomiphene resistant and the results were inconclusive (OR 3.17, 95% CI 0.12 to 83.17, n=36)Nine RCTs compared letrozole with clomiphene citrate (with or without adjuncts) followed by timed intercourse. The birth rate was higher in the letrozole group (OR 1.63, 95% CI 1.31 to 2.03, n=1783, I²=3%)Two RCTs compared letrozole with laparoscopic ovarian drilling. There was no evidence of a difference between the groups in live birth rate (OR 1.19, 95% CI 0.76 to 1.86, n=407, I²=0%) OHSS (16 RCTs) There was no evidence of a difference in OHSS rates when letrozole was compared with placebo (one RCT, n=36), clomiphene citrate (with or without adjuncts) followed by timed intercourse (nine RCTs, n=2179), clomiphene citrate (with or without adjuncts) followed by intrauterine insemination (IUI) (two RCTs, n=1494), laparoscopic ovarian drilling (one RCT, n=260) or anastrozole (one RCT, n=220). Events were absent or very rare, and no study had more than 2 cases of OHSS. Clinical pregnancy (25 RCTs) One RCT compared letrozole versus placebo in women who were clomiphene resistant and the results were inconclusive (OR 3.17, 95% CI 0.12 to 83.17, n=36)Fourteen RCTs compared letrozole versus clomiphene citrate (with or without adjuncts) followed by timed intercourse. The pregnancy rate was higher in the letrozole group (OR 1.32, 95% CI 1.09 to 1.60, n=2066, I²=25%)Three RCTs compared letrozole versus clomiphene citrate (with or without adjuncts) followed by IUI. The pregnancy rate was higher in the letrozole group (OR 1.71, 95% CI 1.30 to 2.25, n=1597)Three RCTs compared letrozole versus laparoscopic ovarian drilling. There was no evidence of a difference in the clinical pregnancy rate (OR 1.14, 95% CI 0.80 to 1.65, n=553, I²=0%)Two RCTs compared letrozole versus anastrozole, one RCT compared a five day versus a 10 day administration protocol for letrozole and another RCT compared 5 mg of letrozole versus 7.5 mg of letrozole. There was no evidence of a difference in the clinical pregnancy rate in these comparisons.The quality of the evidence was rated as low for live birth and pregnancy outcomes. The reasons for downgrading the evidence were poor reporting of study methods, possible publication bias and the tendency for studies that reported live birth to report higher clinical pregnancy rates in the letrozole group than studies that failed to report live birth (suggesting that results might be somewhat less favourable to letrozole if all studies reported live birth).

AUTHORS' CONCLUSIONS

Letrozole appears to improve live birth and pregnancy rates in subfertile women with anovulatory PCOS, compared to clomiphene citrate. The quality of this evidence is low and findings should be regarded with some caution. There appears to be no difference in effectiveness between letrozole and laparoscopic ovarian drilling, though there were few relevant studies. OHSS was a very rare event, with no occurrences in most studies.

Combined letrozole and clomiphene versus letrozole and clomiphene alone in infertile patients with polycystic ovary syndrome

Background

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of childbearing age (6.8%–18%), is among the most common causes of infertility due to ovulation factors, and accounts for 55%–70% of infertility cases caused by chronic anovulation. In this study, we used a combination of letrozole and clomiphene in patients resistant to both drugs individually, and studied the effects of this combination in ovulation and pregnancy in resistant PCOS patients.

Methods

The study population included infertile couples diagnosed as PCOS in the wife. The women used clomiphene for at least six cycles in order to ovulate after failure to form the dominant follicle, and were then put on letrozole for four cycles. Patients who were unable to form the dominant follicle were enrolled on letrozole and clomiphene combination therapy.

Results

One hundred enrolled patients underwent 257 cycles of a combination of letrozole and clomiphene, in which 213 were able to form the dominant follicle (82.9%) and 44 were unable to do so (17.1%). The number of mature follicles was 2.3±1.1. The mean endometrial thickness in patients on the day of human chorionic gonadotropin administration was 8.17±1.3 mm. The pregnancy rate was 42%.

Conclusion

According to the results of this study, it can be proposed that in PCOS patients resistant to clomiphene and letrozole used as single agents, a combination of the two drugs can be administered before using more aggressive treatment that may have severe complications or surgery. This combination may also be used as a first-line therapy to induce ovulation in severe cases of PCOS in order to save time and expense.

Letrozole for ovulation induction and controlled ovarian hyperstimulation

PURPOSE OF REVIEW

Letrozole, an aromatase inhibitor, is the newest addition to our armamentarium in the treatment of infertility. It is utilized in much the same way as clomiphene citrate, but with some additional benefits. In this review, the latest studies will be summarized with emphasis on dose, duration of use, safety, number of mature follicles, and pregnancy outcomes.

RECENT FINDINGS

Letrozole has fewer side effects, and a shorter half-life than clomiphene citrate, and no demonstrable effect upon the receptivity of the endometrium. It is efficacious in treating women with chronic anovulation, unexplained infertility and diminished ovarian reserve. Its safety is superior to clomiphene citrate. Utilizing bio-equivalent doses, letrozole pregnancy rates are equal or superior to clomiphene citrate. Several studies suggest situations where it is more efficacious than gonadotropin treatment.

SUMMARY

With further study, this drug could replace clomiphene citrate as the primary medication for chronic anovulation and/or unexplained infertility. It could augment or even obviate the use of gonadotropins in the treatment of women who have been unsuccessful in achieving pregnancy with clomiphene citrate. It may also be an adjunct for women with diminished ovarian reserve. Further studies are needed to determine optimal dosing and long term safety for women treated with the drug.