Treatment of Unexplained Infertility With Aromatase Inhibitors or Clomiphene Citrate: A Systematic Review and Meta-Analysis

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Letrozole Compared With Clomiphene Citrate for Unexplained Infertility: A Systematic Review and Meta-analysis

OBJECTIVE

To estimate the clinical effectiveness, as determined by positive pregnancy test, of letrozole compared with clomiphene citrate for ovarian stimulation in patients with unexplained infertility.

DATA SOURCES

We conducted a systematic review and meta-analysis of data from electronic databases including Ovid-MEDLINE, EMBASE, Scopus, Cochrane Database of Systematic Reviews, Cochrane Register of Controlled Trials, Database of Abstracts of Reviews of Effects, and ClinicalTrials.gov.

METHODS

We searched for concepts of unexplained infertility, letrozole, clomiphene citrate, and clinical outcomes including pregnancy and live birth. Studies were included if they were randomized controlled trials (RCTs) comparing clomiphene citrate with letrozole in patients with unexplained infertility. Eight RCTs including 2,647 patients with unexplained infertility were included. Primary outcome was positive pregnancy test per patient. Secondary outcomes included positive pregnancy test per cycle, clinical pregnancy, live birth, spontaneous miscarriage, twin gestation, mean serum estradiol (E2), endometrial thickness, and number of dominant follicles. The Cochrane Q test and Higgin's I were used to assess heterogeneity. Random effects models were used to obtain pooled relative risks (RR) and 95% CIs.

TABULATION, INTEGRATION, AND RESULTS

In analysis per patient, there was no significant difference in positive pregnancy test between patients treated with letrozole compared with clomiphene citrate (24% vs 23%, pooled RR 1.08, 95% CI 0.85-1.36). Significant heterogeneity was noted between studies (I=60.8%). There were no significant differences in clinical pregnancy (pooled RR 1.15, 95% CI 0.71-1.85), live birth (pooled RR 0.94, 95% CI 0.83-1.08), spontaneous miscarriage (pooled RR 0.92, 95% CI 0.61-1.38), or twin gestation (pooled RR 0.81, 95% CI 0.39-1.68). Mean serum E2 was significantly lower in the letrozole group than in the clomiphene citrate group.

CONCLUSION

Although limited by heterogeneity, studies of ovarian stimulation in women with unexplained infertility show no difference in clinical outcomes between letrozole and clomiphene citrate.

Chronic endometritis in patients with unexplained infertility: Prevalence and effects of antibiotic treatment on spontaneous conception

PROBLEM

The correlations between chronic endometritis and unexplained infertility are unexplored.

METHOD OF STUDY

We performed a retrospective study on consecutive patients referred to our hysteroscopy service due to unexplained infertility. All women underwent endometrial sampling with histological and cultural examinations. If chronic endometritis was diagnosed, patients received antibiotic therapy, and chronic endometritis resolution was subsequently ascertained by histological examination. We aimed to estimate chronic endometritis prevalence and the effects of antibiotic therapy on spontaneous conception during the year following hysteroscopy.

RESULTS

A total number of 95 women were included. Pooled prevalence of chronic endometritis was 56.8%. Antibiotic therapy resulted in chronic endometritis resolution in 82.3% of patients, while in 17.6% disease was persistent. Women with cured chronic endometritis showed higher pregnancy rate and live birth rate in comparison with both women with persistent disease and women without chronic endometritis diagnosis (pregnancy rate = 76.3% vs 20% vs 9.5%, P < .0001; live birth rate = 65.8% vs 6.6% vs 4.8%, P < .0001).

CONCLUSION

Chronic endometritis is highly prevalent in patients with unexplained infertility. Diagnosis and treatment of chronic endometritis improve spontaneous pregnancy rate and live birth rate in such patients.

A New Dawn for Intrauterine Insemination: Efficient and Prudent Practice will Benefit Patients, the Fertility Industry and the Healthcare Bodies

This review addresses the misplaced facts about the IUI procedure within a lucrative fertility industry. Evidence suggests IUI must be a first-line treatment option for most couples except in cases of bilateral tubal blockage and severe oligozoospermia. We introduce the concept of using 'consecutive ejaculation' in men with subfertility and one which can radically alter the male infertility definition, thereby providing a new approach to examining and managing male factor infertility. The review also explores various aspects affecting the IUI procedure, its determinants of success, risks and areas for future improvements. Areas such as choice of patients, clinical management of patients, the type of stimulation regime, timing and the management of sperm usage have significant bearing to whether IUI will succeed. The paper asserts that IUI should be the first choice of fertility treatment.

Correlation between fertility drugs use and malignant melanoma incidence: the state of the art

The relationship between fertility, reproductive hormones, and risk of malignant melanoma has acquired much interest in recent years. Melanocytes are hormonally responsive cells, and some in vitro studies demonstrated that estrogen hormones stimulate the growth of melanocytes. Moreover, estrogen receptors have been identified in melanoma cells, as well as in melanocytic nevi and in normal skin. Some evidences suggest a possible link between fertility treatments and the increased risk of malignant melanoma. This article addresses this association through a scrupulous search of the literature published thus far. The aim of this review is to determine the incidence of malignant melanoma in women treated with fertility drugs and to examine if the exposure to fertility treatments really increases the risk of malignant melanoma. In particular, our analysis focused on the different types of drugs and different treatment schedules used. Finally, this study provides additional insights regarding the long-term relationships between fertility drugs and the risk of malignant melanoma.

Fertility drugs, reproductive strategies and ovarian cancer risk

Several adverse effects have been related to infertility treatments, such as cancer development. In particular, the relationship between infertility, reproductive strategies, and risk of gynecological cancers has aroused much interest in recent years. The evaluation of cancer risk among women treated for infertility is very complex, mainly because of many factors that can contribute to occurrence of cancer in these patients (including parity status). This article addresses the possible association between the use of fertility treatments and the risk of ovarian cancer, through a scrupulous search of the literature published thus far in this field. Our principal objective was to give more conclusive answers on the question whether the use of fertility drug significantly increases ovarian cancer risk. Our analysis focused on the different types of drugs and different treatment schedules used. This study provides additional insights regarding the long-term relationships between fertility drugs and risk of ovarian cancer.

Aromatase inhibitors in stimulated IVF cycles

Aromatase inhibitors have been introduced as a new treatment modality that could challenge clomiphene citrate as an ovulation induction regiment in patients with PCOS. Although several randomized trials have been conducted regarding their use as ovulation induction agents, only few trials are available regarding their efficacy in IVF stimulated cycles. Current available evidence support that letrozole may have a promising role in stimulated IVF cycles, either when administered during the follicular phase for ovarian stimulation. Especially for women with poor ovarian response, letrozole appears to have the potential to increase clinical pregnancy rates when combined with gonadotropins, whereas at the same time reduces the total gonadotropin dose required for ovarian stimulation. However, given that in all of the trials letrozole has been administered in GnRH antagonist cycles, it is intriguing to test in the future how it may perform when used in GnRH agonist cycles. Finally administration of letrozole during luteal phase in IVF cycles offers another treatment modality for patients at high risk for OHSS taking into account that it drastically reduces estradiol levels.

Extended letrozole regimen versus clomiphene citrate for superovulation in patients with unexplained infertility undergoing intrauterine insemination: a randomized controlled trial

BACKGROUND

The aim of this randomized controlled trial was to compare the efficacy of extended letrozole regimen with clomiphene citrate in women with unexplained infertility undergoing superovulation and intrauterine insemination (IUI).

METHODS

Two hundred and fourteen patients with unexplained infertility were randomized into two equal groups using computer generated list and were treated by either letrozole 2.5 mg/day from cycle day 1 to 9 (extended letrozole group, 211 cycles) or clomiphene citrate 100 mg/day from cycle day 3 to 7 (clomiphene citrate group,210 cycles). Intrauterine insemination was performed 36 to 40 hours after HCG administration.

RESULTS

Both groups were comparable with regard to number of mature follicles (2.24 +/- 0.80 Vs 2.13 +/- 0.76) and the day of HCG administration. Serum estradiol was significantly greater in clomiphene citrate group (356 +/- 151 Vs 822 +/- 302 pg/ml, P = < 0.001) and the endometrial thickness was significantly greater in extended letrozole group (9.10 +/- 1.84 Vs 8.18 +/- 1.93 mm, P = < 0.001).The pregnancy rate per cycle and cumulative pregnancy rate were significantly greater in extended letrozole group (18.96% Vs 11.43% and 37.73% Vs 22.86%, respectively).

CONCLUSION

The extended letrozole regimen had a superior efficacy as compared with clomiphene citrate in patients of unexplained infertility undergoing superovulation and IUI.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01232075.

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.