A randomized comparison of ovulation induction and hormone profile between the aromatase inhibitor anastrozole and clomiphene citrate in women with infertility

A Review on the Use of Letrozole in Female and Male Infertility

Infertility in developing countries is a distinct and complex problem that disproportionately affects women. Though not a physically restraining disease, it causes a huge social burden on the emotional, financial, and psychosocial quotients of those who suffer from it. Assisted reproductive procedures are frequently used to treat infertility. Years ago, the emergence of ovulation induction represented a significant advancement in treating female infertility. Letrozole, an aromatase inhibitor, is a potential therapy for ovulation induction. Numerous clinical conditions, including anovulatory infertility, polycystic ovarian syndrome, unexplained infertility, and early stages of endometriosis-related infertility, as well as many with improved live birth rates, have been proven to benefit from letrozole treatment. Letrozole is a superior alternative to the widely utilized ovulation induction with clomiphene citrate. While clomiphene citrate has certain limitations, letrozole successfully overcomes these limitations because of its lack of prolonged anti-estrogenic activity, short half-life, and lack of estrogen receptor activation. In most cases, this results in mono-follicular development and excellent live birth rates. According to the most recent research, letrozole can be used as the first-line therapy to treat infertility caused by polycystic ovarian syndrome and other causes. Letrozole is also emerging as a possible treatment for male infertility of unknown cause, proving to be an effective way of influencing hormonal profiles and increasing various seminal parameters such as sperm motility and concentration, as it inhibits aromatization affecting the feedback mechanism to the hypothalamus. This review focuses on our current knowledge of the uses of letrozole for female and male infertility, its mechanisms, and its benefits.

Agents for ovarian stimulation for intrauterine insemination (IUI) in ovulatory women with infertility

BACKGROUND

Intrauterine insemination (IUI), combined with ovarian stimulation (OS), has been demonstrated to be an effective treatment for infertile couples. Several agents for ovarian stimulation, combined with IUI, have been proposed, but it is still not clear which agents for stimulation are the most effective. This is an update of the review, first published in 2007.

OBJECTIVES

To assess the effects of agents for ovarian stimulation for intrauterine insemination in infertile ovulatory women.

SEARCH METHODS

We searched the Cochrane Gynaecology and Fertility Group trials register, CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL and two trial registers from their inception to November 2020. We performed reference checking and contacted study authors and experts in the field to identify additional studies.

SELECTION CRITERIA

We included truly randomised controlled trials (RCTs) that compared different agents for ovarian stimulation combined with IUI for infertile ovulatory women concerning couples with unexplained infertility. mild male factor infertility and minimal to mild endometriosis.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures recommended by Cochrane.

MAIN RESULTS

In this updated review, we have included a total of 82 studies, involving 12,614 women. Due to the multitude of comparisons between different agents for ovarian stimulation, we highlight the seven most often reported here. Gonadotropins versus anti-oestrogens (13 studies) For live birth, the results of five studies were pooled and showed a probable improvement in the cumulative live birth rate for gonadotropins compared to anti-oestrogens (odds ratio (OR) 1.37, 95% confidence interval (CI) 1.05 to 1.79; I² = 30%; 5 studies, 1924 participants; moderate-certainty evidence). This suggests that if the chance of live birth following anti-oestrogens is assumed to be 22.8%, the chance following gonadotropins would be between 23.7% and 34.6%. The pooled effect of seven studies revealed that we are uncertain whether gonadotropins lead to a higher multiple pregnancy rate compared with anti-oestrogens (OR 1.58, 95% CI 0.60 to 4.17; I² = 58%; 7 studies, 2139 participants; low-certainty evidence). Aromatase inhibitors versus anti-oestrogens (8 studies) One study reported live birth rates for this comparison. We are uncertain whether aromatase inhibitors improve live birth rate compared with anti-oestrogens (OR 0.75, CI 95% 0.51 to 1.11; 1 study, 599 participants; low-certainty evidence). This suggests that if the chance of live birth following anti-oestrogens is 23.4%, the chance following aromatase inhibitors would be between 13.5% and 25.3%. The results of pooling four studies revealed that we are uncertain whether aromatase inhibitors compared with anti-oestrogens lead to a higher multiple pregnancy rate (OR 1.28, CI 95% 0.61 to 2.68; I² = 0%; 4 studies, 1000 participants; low-certainty evidence).  Gonadotropins with GnRH (gonadotropin-releasing hormone) agonist versus gonadotropins alone (4 studies) No data were available for live birth. The pooled effect of two studies  revealed that we are uncertain whether gonadotropins with GnRH agonist lead to a higher multiple pregnancy rate compared to gonadotropins alone (OR 2.53, 95% CI 0.82 to 7.86; I² = 0; 2 studies, 264 participants; very low-certainty evidence).  Gonadotropins with GnRH antagonist versus gonadotropins alone (14 studies) Three studies reported live birth rate per couple, and we are uncertain whether gonadotropins with GnRH antagonist improve live birth rate compared to gonadotropins (OR 1.5, 95% CI 0.52 to 4.39; I² = 81%; 3 studies, 419 participants; very low-certainty evidence). This suggests that if the chance of a live birth following gonadotropins alone is 25.7%, the chance following gonadotropins combined with GnRH antagonist would be between 15.2% and 60.3%. We are also uncertain whether gonadotropins combined with GnRH antagonist lead to a higher multiple pregnancy rate compared with gonadotropins alone (OR 1.30, 95% CI 0.74 to 2.28; I² = 0%; 10 studies, 2095 participants; moderate-certainty evidence). Gonadotropins with anti-oestrogens versus gonadotropins alone (2 studies) Neither of the studies reported data for live birth rate. We are uncertain whether gonadotropins combined with anti-oestrogens lead to a higher multiple pregnancy rate compared with gonadotropins alone, based on one study (OR 3.03, 95% CI 0.12 to 75.1; 1 study, 230 participants; low-certainty evidence). Aromatase inhibitors versus gonadotropins (6 studies) Two studies  revealed that aromatase inhibitors may decrease live birth rate compared with gonadotropins (OR 0.49, 95% CI 0.34 to 0.71; I²=0%; 2 studies, 651 participants; low-certainty evidence). This suggests that if the chance of a live birth following gonadotropins alone is 31.9%,  the chance of live birth following aromatase inhibitors would be between 13.7% and 25%. We are uncertain whether aromatase inhibitors compared with gonadotropins lead to a higher multiple pregnancy rate (OR 0.69, 95% CI 0.06 to 8.17; I²=77%; 3 studies, 731 participants; very low-certainty evidence).  Aromatase inhibitors with gonadotropins versus anti-oestrogens with gonadotropins (8 studies) We are uncertain whether aromatase inhibitors combined with gonadotropins improve live birth rate compared with anti-oestrogens plus gonadotropins (OR 0.99, 95% CI 0.3 8 to 2.54;  I² = 69%; 3 studies, 708 participants; very low-certainty evidence). This suggests that if the chance of a live birth following anti-oestrogens plus gonadotropins is 13.8%, the chance following aromatase inhibitors plus gonadotropins would be between 5.7% and 28.9%. We are uncertain of the effect of aromatase inhibitors combined with gonadotropins compared to anti-oestrogens combined with gonadotropins on multiple pregnancy rate (OR 1.31, 95% CI 0.39 to 4.37;  I² = 0%; 5 studies, 901 participants; low-certainty evidence).

AUTHORS' CONCLUSIONS

Based on the available results, gonadotropins probably improve cumulative live birth rate compared with anti-oestrogens (moderate-certainty evidence). Gonadotropins may also improve cumulative live birth rate when compared with aromatase inhibitors (low-certainty evidence). From the available data, there is no convincing evidence that aromatase inhibitors lead to higher live birth rates compared to anti-oestrogens. None of the agents compared lead to significantly higher multiple pregnancy rates. Based on low-certainty evidence, there does not seem to be a role for different combined therapies, nor for adding GnRH agonists or GnRH antagonists in IUI programs.

Add-On Selective Estrogen Receptor Modulators for Methadone Maintenance Treatment

Methadone maintenance treatment (MMT) remains the cornerstone for the management of opiate abuse. However, MMT can be associated with complex factors, including complications during the tolerance phase, the inability of some patients to maintain treatment effects during the tapering or abstinence phases, and the development of methadone dependence. Previous studies have revealed a sex disparity in MMT efficacy, showing that women undergoing MMT experiencing an increase in psychological symptoms compared with men and suggesting a link between disparate responses and the effects of estrogen signaling on methadone metabolism. More specifically, estradiol levels are positively associated with MMT dosing, and the expression of a single-nucleotide polymorphism (SNP) associated with estrogen receptor (ER) regulation is also associated with MMT dosing. In addition to performing mechanistic dissections of estrogen signaling in the presence of methadone, past studies have also proposed the targeting of estrogen signaling during MMT. The present report provides an overview of the relevant literature regarding sex effects, including differences in sex hormones and their potential impacts on MMT regimens. Moreover, this article provides a pharmacological perspective on the targeting of estrogen signals through the use of selective ER modulators (SERMs) during MMT. Preliminary preclinical experiments were also performed to evaluate the potential effects of targeting estrogen signaling with tamoxifen on methadone metabolism.

The effects of letrozole and clomiphene citrate on ligands expression of Wnt3, Wnt7a, and Wnt8b in proliferative endometrium of women with Polycystic ovarian syndrome

Polycystic ovarian syndrome (PCOS) is a common endocrinologic disorder in women of reproductive age characterized by polycystic ovaries, oligo/anovulation, and hyperandrogenism. Not only anovulation but also endometrial dysfunction can reduce fertility in PCOS patients. Wnt pathway is responsible for endometrial proliferation which be strongly regulated by estradiol. To determine the effects of clomiphene citrate (CC) and letrozole, we measured the expression of some main ligands of Wnt/β-catenin signaling including Wnt7a, Wnt3, and Wnt8b in the endometrial samples taken from PCOS women on day 12 of the menses who received 100 mg CC or 5 mg letrozole as well as from women without treatment. Significantly, the mean estrogen and progesterone concentration were lower and higher, respectively, in letrozole than CC. The mean endometrial thickness (ET) was significantly greater in letrozole compared to CC. Assessment of the mRNA and protein expression of Wnt7a, Wnt3, and Wnt8b showed significantly lower expression in CC than the letrozole and control groups. Collectively, letrozole provided a better molecular response in the endometrium of PCOS patients during the proliferative phase, similar to natural cycles, compared to CC. CC decreased the ligands expression of Wnt3, Wnt7a, and Wnt8b, resulting in endometrial dysfunction.

Metformin use in women with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is an endocrinopathy characterised by increased resistance to insulin. Metformin is one of the longest established oral insulin sensitising agents. For decades its use was restricted to management of type 2 diabetes. However, in the past two decades, its properties as an insulin sensitising agent have been explored in relation to its applicability for women with PCOS. Metformin is an effective ovulation induction agent for non-obese women with PCOS and offers some advantages over other first line treatments for anovulatory infertility such as clomiphene. For clomiphene-resistant women, metformin alone or in combination with clomiphene is an effective next step. Women with PCOS undergoing in vitro fertilisation should be offered metformin to reduce their risk of ovarian hyperstimulation syndrome. Limited evidence suggests that metformin may be a suitable alternative to the oral contraceptive pill (OCP) for treating hyperandrogenic symptoms of PCOS including hirsutism and acne. More research is required to define whether metformin has a role in improving long term health outcomes for women with PCOS, including the prevention of diabetes, cardiovascular disease and endometrial cancer.

Fertility drugs and young-onset breast cancer: results from the Two Sister Study

BACKGROUND

Fertility drugs stimulate hyperovulation, which may have implications for breast cancer. We examined the association between use of fertility drugs (clomiphene citrate [CC] and follicle-stimulating hormone [FSH]) and subsequent risk of young-onset (<50 years at diagnosis) breast cancer.

METHODS

We conducted the Two Sister Study, a sister-matched case-control study, by enrolling 1422 women between September 2008 and December 2010, who were younger than age 50 years at diagnosis with breast cancer and were enrolled within 4 years of diagnosis, and 1669 breast cancer-free control sisters from the Sister Study. Participants reported their use of fertility drugs (CC and FSH) and ever-users reported whether a pregnancy had resulted that lasted 10 or more (10+) weeks. Conditional logistic regression was used to estimate confounder-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for fertility drug use with or without conception of a 10+ week pregnancy.

RESULTS

A total of 288 participants reported having used ovulation-stimulating drugs (193 CC only, 29 FSH only, and 66 both). Overall, women who had used fertility drugs showed a non-statistically significantly decreased risk of breast cancer, compared with nonusers (OR = 0.82, 95% CI = 0.63 to 1.08). Women who had used fertility drugs but had not conceived a 10+ week pregnancy under treatment showed a statistically significantly decreased risk of breast cancer compared with nonusers (OR = 0.62, 95% CI = 0.43 to 0.89). Women who had used fertility drugs and conceived a 10+ week pregnancy under treatment showed a statistically significantly increased risk of breast cancer compared with unsuccessfully treated women (OR = 1.82, 95% CI = 1.10 to 3.00), although their risk was not increased compared with women who had not used fertility drugs (OR = 1.13, 95% CI = 0.78 to 1.64).

CONCLUSIONS

In the absence of a 10+ week pregnancy under treatment, exposure to ovulation-stimulating fertility drugs was associated with reduced risk of young-onset breast cancer. This apparent association was absent in women who conceived a 10+ week pregnancy under treatment, for whom risk was higher than that of unsuccessfully treated women, but similar to that of untreated women.

Hemorrhagic onset of rhabdoid meningioma after initiating treatment for infertility

Rhabdoid meningioma (RM) is a rare aggressive phenotype and is classified as a grade III neoplasm by the World Health Organization. A 29-year-old woman initiated treatment with clomiphene citrate for infertility. Two weeks later, she presented with acute headache and nausea. Brain computed tomography and magnetic resonance imaging demonstrated a tumor with hematoma in the left frontoparietal region. Surgical resection was performed, and the tumor was subtotally removed. The tumor was diagnosed as a rhabdoid meningioma (RM). Despite radiation and chemotherapy, she experienced regrowth and dissemination to the spinal cord. She died 11 months after onset of symptoms. Spontaneous hemorrhage is an unusual presentation of RM. In our case, infertility treatment may have triggered progression and bleeding because of an imbalance of sex hormones.

Anastrozole single-dose protocol in women with oligo- or anovulatory infertility: results of a randomized phase II dose-response study

OBJECTIVE

To compare the effects of anastrozole and clomiphene citrate (CC) on follicular development and ovulation in infertile women with ovulatory dysfunction.

DESIGN

Phase II, prospective, randomized, assessor-blind, multicenter, dose-finding, noninferiority study.

SETTING

Outpatient.

PATIENT(S)

Infertile women with ovulatory dysfunction, aged 18-35 years, and body mass index <35 kg/m(2).

INTERVENTION(S)

Single-dose anastrozole at 5 mg (n = 39), 10 mg (n = 39), 20 mg (n = 39), or 30 mg (n = 38) or a 5-day course of CC at 50 mg/d (n = 39) as starting doses.

MAIN OUTCOME MEASURE(S)

The primary endpoint was the ovulation rate in the first treatment cycle (cycle 1). Ovulation was defined as a midluteal phase serum P level ≥ 10 ng/mL or clinical pregnancy.

RESULT(S)

In cycle 1 the ovulation rates for a single dose of anastrozole at 5, 10, 20, and 30 mg were 46.2%, 41.0%, 23.1%, and 28.9%, respectively, whereas that for CC at 50 mg/d was 61.5%. Among women with fewer than six menses per year, the cumulative ovulation rates over three cycles were comparable in the anastrozole 5 mg (52.4%) and CC 50 mg/d (42.3%) groups.

CONCLUSION(S)

In terms of ovulation rates in cycle 1, single-dose anastrozole at 5, 10, 20, and 30 mg was not as effective as CC at 50 mg/d for 5 days (noninferiority was not shown).

Anastrozole vs. clomiphene citrate in infertile women with ovulatory dysfunction: a phase II, randomized, dose-finding study

OBJECTIVE

To determine an effective multiple-dose regimen of anastrozole compared with clomiphene citrate (CC) to induce follicular growth and ovulation in infertile women with ovulatory dysfunction.

DESIGN

Phase II, prospective, randomized, double-blind, multicenter, dose-finding, noninferiority study.

SETTING

Outpatient.

PATIENT(S)

Infertile women (n = 271) with ovulatory dysfunction, aged 18-40 years, with body mass index <37 kg/m(2).

INTERVENTION(S)

Five days of anastrozole at 1, 5, or 10 mg/d or CC at 50 mg/d.

MAIN OUTCOME MEASURE(S)

The primary endpoint was the ovulation rate (mid-luteal phase serum P level ≥ 10 ng/mL or clinical pregnancy) in the first treatment cycle (cycle 1).

RESULT(S)

In cycle 1 the ovulation rates for anastrozole at 1, 5, and 10 mg/d were 30.4% (n = 24), 36.8% (n = 28), and 35.9% (n = 14), respectively, compared with 64.9% (n = 50) for CC at 50 mg/d. In up to three cycles of treatment, cumulative ovulation rates did not differ between groups. No cases of ovarian hyperstimulation syndrome were reported, and both anastrozole and CC were well tolerated.

CONCLUSION(S)

In terms of ovulation rates, 5-day anastrozole at 1, 5, and 10 mg/d was less effective than CC at 50 mg/d for cycle 1 (noninferiority was not shown).

Metformin is a reasonable first-line treatment option for non-obese women with infertility related to anovulatory polycystic ovary syndrome--a meta-analysis of randomised trials

BACKGROUND

There are differences in opinion as to whether metformin should play a role in the primary treatment of anovulatory infertility for women with polycystic ovary syndrome (PCOS).

AIM

The aim of this study was to ascertain the best available evidence comparing metformin versus clomiphene treatment for non-obese women with anovulatory infertility related to PCOS.

METHODS

 Meta-analysis of available data from randomised controlled trials that examined metformin versus clomiphene for the subgroup of women in the lower body mass index (BMI) range (primarily non-obese). Primary outcomes were clinical pregnancy and live birth.

RESULTS

For women with BMI ≤ 30-32 kg/m2 , clinical pregnancy rates were 36.7% (52/142) for metformin and 35.7% (51/143) for clomiphene; live birth rates were 30.3% (43/142) for metformin and 30.8% (44/143) for clomiphene.

CONCLUSION

 The available randomised trial data show no significant difference in effectiveness of metformin versus clomiphene as ovulation induction agents for non-obese women with anovulatory PCOS. Metformin and clomiphene are both suitable options for first-line treatment.

PCOSMIC: a multi-centre randomized trial in women with PolyCystic Ovary Syndrome evaluating Metformin for Infertility with Clomiphene

BACKGROUND

Ovulation induction treatment with metformin, either alone or in combination with clomiphene citrate (CC), remains controversial even though previous randomized trials have examined this.

METHODS

A double blinded multi-centre randomized trial was undertaken including 171 women with anovulatory or oligo-ovulatory polycystic ovary syndrome. Women with high body mass index (BMI) > 32 kg/m(2) received placebo ('standard care') or metformin; women with BMI < or = 32 kg/m(2) received CC ('standard care'), metformin or both. Treatment continued for 6 months or until pregnancy was confirmed. Primary outcomes were clinical pregnancy and live birth.

RESULTS

For women with BMI > 32 kg/m(2), clinical pregnancy and live birth rates were 22% (7/32) and 16% (5/32) with metformin, 15% (5/33) and 6% (2/33) with placebo. For women with BMI < or = 32 kg/m(2), clinical pregnancy and live birth rates were 40% (14/35) and 29% (10/35) with metformin, 39% (14/36) and 36% (13/36) with CC, 54% (19/35) and 43% (15/35) with combination metformin plus CC.

CONCLUSIONS

There is no evidence that adding metformin to 'standard care' is beneficial. Pregnancy and live birth rates are low in women with BMI > 32 kg/m(2) whatever treatment is used, with no evidence of benefit of metformin over placebo. For women with BMI < or = 32 kg/m(2) there is no evidence of significant differences in outcomes whether treated with metformin, CC or both. ClinicalTrials.gov number NCT00795808; trial protocol accepted for publication November 2005: Johnson, Aust N Z Journal Obstet Gynaecol 2006;46:141-145.

Aromatase inhibitors for female infertility: a systematic review of the literature

Ovulation induction remains a milestone in the treatment of women with anovulatory infertility. Clomiphene citrate (CC) is considered the first line treatment for induction of ovulation in women with polycystic ovary syndrome (PCOS), while it may be used for ovulation induction in unexplained infertility. Aromatase inhibitors (AI) have been introduced as a new treatment option that could challenge CC for ovulation induction. A systematic review of the literature was conducted in order to highlight the efficacy and safety of AI in female infertility. Current data from randomized and non-randomized trials suggest that AI may have a role in ovulation induction regimens in PCOS patients, as well as for ovarian stimulation, since they achieve comparable clinical pregnancy rates to CC. Furthermore, when combined with gonadotrophins, AI improve the ovarian response of poor responders and reduce the gonadotrophin dose required. However, the current review is based on small trials with a limited number of patients. If solid data from future large adequately powered randomized trials support current evidence regarding efficacy and safety, AI might offer a new treatment choice for infertile women.

Use of letrozole in assisted reproduction: a systematic review and meta-analysis

BACKGROUND

Letrozole is the third-generation aromatase inhibitor (AI) most widely used in assisted reproduction. AIs induce ovulation by inhibiting estrogen production; the consequent hypoestrogenic state increases GnRH release and pituitary follicle-stimulating hormone (FSH) synthesis.

METHODS

A systematic search of the literature was performed for both prospective and retrospective studies. Meta-analyses of randomized clinical trials (RCTs) were performed for three comparisons: letrozole versus clomiphene citrate (CC), letrozole + FSH versus FSH in intrauterine insemination (IUI) and letrozole + FSH versus FSH in IVF. In the absence of RCTs, non-randomized studies were pooled.

RESULTS

Nine studies were included in the meta-analysis. Four RCTs compared the overall effect of letrozole with CC in patients with polycystic ovary syndrome. The pooled result was not significant for ovulatory cycles (OR = 1.17; 95% CI 0.66–2.09), or for pregnancy rate per cycle (OR = 1.47; 95% CI 0.73–2.96) or for pregnancy rate per patient (OR = 1.37; 95% CI 0.70–2.71). In three retrospective studies which compared L + FSH with FSH in ovarian stimulation for IUI, the pooled OR was 1.15 (95% CI 0.78−1.71). A final meta-analysis included one RCT and one cohort study that compared letrozole + gonadotrophin versus gonadotrophin alone: the pooled pregnancy rate per patient was not significantly different (OR = 1.40; 95% CI 0.67–2.91).

CONCLUSIONS

Letrozole is as effective as other methods of ovulation induction. Further randomized-controlled studies are warranted to define more clearly the efficacy and safety of letrozole in human reproduction.

Oral agents for ovulation induction--clomiphene citrate versus aromatase inhibitors

The purpose of this review is to compare clomiphene citrate (CC) with aromatase inhibitors (AI) as the first-line therapy for WHO Group II (eu-oestrogenic) infertility. For the past 45 years CC has been the first-line therapy, as it is a simple, cheap treatment, almost devoid of side effects, and yields ovulation in 73%, pregnancy in 36% and a singleton live birth rate of 25%. The gap between ovulation and pregnancy rates has mainly been attributed to its anti-oestrogen effects on endometrium. AI block oestrogen production, not oestrogen receptors, and would therefore be expected to produce superior conception rates and less multiple pregnancies. AI have yet to undergo further large, robust clinical trials in order to fulfill this promise as a feasible alternative to CC in this role, but some preliminary trials have shown at least equality and some superiority.

Effect of letrozole at 2.5 mg or 5.0 mg/day on ovarian stimulation with gonadotropins in women undergoing intrauterine insemination

OBJECTIVE

To determine the effect of combined therapy of letrozole (2.5 mg or 5.0 mg) with recombinant follicle-stimulating hormone (FSH) in comparison with the administration of recombinant FSH alone in an intrauterine insemination (IUI) program.

DESIGN

Retrospective study.

SETTING

Assisted fertilization program in a specialized infertility center.

PATIENT(S)

110 women undergoing IUI and gonadotropin therapy.

INTERVENTION(S)

Recombinant FSH alone administered from day 3 or combined with letrozole, 2.5 or 5.0 mg/day, on days 3 to 7, and gonadotropins starting on day 7 of the menstrual cycle. Transvaginal ultrasound examinations were done until the dominant follicle reached 18 mm in diameter. Ovulation was triggered with 10,000 IU of human chorionic gonadotropin (hCG), and IUI performed 30 to 40 hours later.

MAIN OUTCOME MEASURE(S)

Recombinant FSH dose required, number of follicles greater than 14 mm and 18 mm, endometrial thickness, pregnancy rates, miscarriages, and characteristics of newborns.

RESULT(S)

Women treated with FSH and 5.0 mg/day of letrozole required a lower dose of FSH than the group cotreated with 2.5 mg/day of letrozole or with FSH alone. Throughout most of the follicular phase, the endometrial thickness was statistically significantly less in both letrozole cotreatment groups compared with the FSH control group. By the day of hCG administration, the endometrial thickness was comparable among all the groups. The pregnancy rates were the same with recombinant FSH alone or combined with letrozole.

CONCLUSION(S)

In terms of cost-effectiveness, 5.0 mg/day of letrozole is more effective than the 2.5 mg/day in cotreatment with no adverse effect on pregnancy rate or outcome.