A comparison among different methods of letrozole combined with gonadotropin in an antagonist protocol and high-dose gonadotropin ovarian stimulation antagonist protocol in poor ovarian responders undergoing in vitro fertilization

Effects of using letrozole in combination with the GnRH antagonist protocol for patients with poor ovarian response: A meta-analysis

This meta-analysis aimed to compare the outcomes of the gonadotrophin-releasing hormone (GnRH) antagonist/letrozole protocol with those of the conventional GnRH antagonist protocol for poor responders undergoing in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI). We searched for relevant articles in PubMed, EMBASE, Google Scholar, and retrieved 452 records. Eventually, we selected five eligible trials with data for 564 patients characterized as poor ovarian responders. Our meta-analysis revealed that the clinical pregnancy rate (per cycle) with administration of letrozole might be a higher than that in the control groups (risk rate [RR]: 1.57, 95% confidence interval [CI]: 1.00-2.44, p = 0.05). .Moreover,it indicated that the total dose of gonadotrophin was significantly decreased with the administration of letrozole compared to control groups(mean difference [MD]: -529.37, 95% CI: -1207.45 to -111.25, p = 0.001),.However, there was no statistical difference in the number of retrieved oocytes(MD: 0.59, 95% CI: -0.36-1.54, p = 0.22), cycle cancelation rate (RR: 0.81, 95% CI: 0.58-1.12, p = 0.20), or estradiol concentration on the day of HCG administration(MD: -28.19, 95% CI: -77.71-21.33, p = 0.26) in the presence or absence of letrozole combination in the GnRH antagonist protocol. In conclusion, letrozole administration might improve clinical pregnancy rate in conventional GnRH antagonist protocol for poor responders. Moreover, letrozole co-treatment aslo can reduce the economic burden of poor responders during the GnRH antagonist cycle. Nevertheless, large-scale and multi-center randomized controlled trials are needed to further evaluate the efficacy of adjunctive letrozole administration in the GnRH antagonist protocol.

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.

Letrozole as co-treatment agent in ovarian stimulation antagonist protocol in poor responders: A double-blind randomized clinical trial

Background

Ovarian stimulation (OS) for poor ovarian response (POR) patients is still a major challenge in assisted reproductive techniques. Aromatase inhibitors as co-treatment in antagonist protocol are suggested to these patients, but there are controversial reports.

Objective

To evaluate the effectiveness Letrozole (LZ) as adjuvant treatment in gonadotropin-releasing hormone (GnRH)-antagonist protocol in POR patients undergoing in vitro fertilization/ intracytoplasmic sperm injection cycles.

Materials and Methods

This double-blind randomized clinical trial was conducted in Arash women's hospital. One hundred sixty infertile women with POR based on Bologna criteria were allocated into two groups randomly: LZ + GnRH-antagonist (LA) and placebo + GnRH-antagonist (PA) groups. In the experimental group, the patients received 5 mg LZ on the first five days of OS with 150 IU of recombinant human follicle-stimulating hormone (rFSH) and 150 IUof human menopausal gonadotropin (HMG). The cycle outcomes were compared between groups.

Results

The total number of retrieved oocytes and the metaphase II oocytes in LA-treated group were significantly higher than those in the control group (p = 0.008, p = 0.002). The dosage of hMG used and the duration of OS and antagonist administration in LZ-treated group were significantly lower than those of the control group. The number of patients with no oocyte, in the control group, was higher than the LZ-treated group, and the clinical pregnancy rate in LA-treated group (25%) was higher than the control group (18%); however, the differences were not significant statistically.

Conclusion

Adding 5 mg of LZ to rFSH/hMG antagonist protocol may improve the in vitro fertilization/intracytoplasmic sperm injectioncycle outcome in POR patients.

Fertility with early reduction of ovarian reserve: the last straw that breaks the Camel's back

Diminished fertility and poor ovarian response pose a conundrum to the experts in the field of reproductive medicine. There is limited knowledge about the risk factors of diminished ovarian reserve other than the iatrogenic ones. One of the leading causes of infertility in women today is diminished ovarian reserve (DOR). DOR is characterized by a low number of eggs in a woman's ovaries and/or with poor quality of the remaining eggs, which boils down to impaired development of the existing eggs, even with assisted reproductive techniques. A good number of such women with low ovarian reserve may conceive with their own eggs, if they are given individualized treatment that is tailored for their profile. Such patients should be counseled appropriately for an aggressive approach towards achieving fertility. The sooner the treatment is started, the better the chances of pregnancy.