Effects of letrozole on superovulation with gonadotropins in women undergoing intrauterine insemination

Optimal lead follicle size in letrozole human menopausal gonadotrophin intrauterine insemination cycles with and without spontaneous LH surge

RESEARCH QUESTION

What is the optimal lead follicle size in letrozole, human menopausal gonadotrophin and intrauterine insemination (IUI) cycles with and without spontaneous LH surges?

DESIGN

This retrospective cohort study included 3797 letrozole HMG IUI cycles between January 2010 and May 2021. All cycles were divided into two groups: the HCG trigger group (trigger day LH ≤15 mIU/ml) and the spontaneous LH surge group (trigger day LH >15 mIU/ml). These two groups were subdivided into smaller groups based on the diameter of the follicles. The primary outcome measure was clinical pregnancy rate. Logistic regression analysis was conducted to explore other risk factors.

RESULTS

In the HCG trigger group, the clinical pregnancy rate varied significantly, with rates of 20.8%, 14.9% and 11.8% for the 16.1-18.0, 18.1-20.0 and 20.1-22.0 mm groups, respectively (P = 0.005). In the spontaneous LH surge group, the pregnancy rate of follicles within 14.1-16.0 mm was significantly higher than that of follicles within 20.1-22.0 mm (adjusted OR 0.533, 95% CI 0.308 to 0.923, P = 0.025). Also, patients with two lead follicles were 2.569 times more likely to achieve a clinical pregnancy than those with only one lead follicle (adjusted OR 2.569, 95% CI 1.258 to 5.246, P = 0.010). The duration of infertility was also found to be a common influencing factor in both groups.

CONCLUSIONS

The optimal lead follicle size was between 16.1 and 18.0 mm in HCG-triggered letrozole HMG IUI cycles. If the lead follicle size is relatively small (14.1-18.0 mm) when a spontaneous LH surge occurs, there is no need to cancel the IUI cycle.

Comparison of Perinatal Outcomes of Letrozole-Induced Ovulation and Hormone Replacement Therapy Protocols in Patients With Abnormal Ovulation Undergoing Frozen-Thawed Embryo Transfer: A Propensity Score Matching Analysis

BACKGROUND

With the increasing use of frozen embryo transfer (FET), the best endometrial preparation protocol is continuously being discussed. The hormone replacement therapy (HRT) cycle and letrozole-induced ovulation (L-OI) cycle are available protocols for patients with abnormal ovulation. Previous comparisons of the two protocols have focused on pregnancy outcomes, with less attention to perinatal outcomes, and population heterogeneity was large; thus, convincing conclusions about which protocol is more appropriate could not be drawn.

METHODS

We performed a retrospective cohort study using propensity score matching (PSM) analysis for a population of patients undergoing FET cycles in the reproductive center of the Third Affiliated Hospital of Zhengzhou University from January 2016 to September 2020. The main outcome measures were clinical pregnancy rate, live birth rate, very preterm delivery (VPTD), preterm delivery (PTD), low birth weight (LBW), macrosomia, small for gestational age (SGA), large for gestational age (LGA), hypertensive disorders of pregnancy (HDP), gestational diabetes mellitus (GDM), premature rupture of membranes (PROM), placenta previa, and congenital abnormality.

RESULTS

A total of 8010 women were enrolled. Due to the large heterogeneity among the patients, we conducted 1:1 PSM, and 1461 women matched in each group. Compared with the HRT group, the L-OI group had a smaller proportion of thin endometrium (27.38% vs. 41.07%) and thicker endometrium on the day of embryo transfer (9.63 ± 1.82 vs. 8.91 ± 1.38). There were no significant differences in clinical pregnancy rate, early abortion rate or live birth rate between the groups. There was no significant difference in perinatal outcomes of singleton live birth, including VPTD, PTD, postterm delivery, LBW, macrosomia, SGA, LGA, GDM, HDP, placenta previa, and congenital malformation.

CONCLUSION

For women with abnormal ovulation, the pregnancy and perinatal outcomes of HRT and L-OI protocols are reassuring. It seems that both protocols are safe and effective for endometrial preparation in frozen-thawed embryo transfer in the clinic.

Pregnancy Outcomes Following Letrozole Use in Frozen-thawed Embryo Transfer Cycles: A Systematic Review and Meta-analysis

While widely used for ovulation induction in assisted reproductive technology, the clinical efficacy of letrozole for endometrial preparation prior to frozen-thawed embryo transfer (FET) cycles remains yet to be elucidated. We performed a meta-analysis to compare pregnancy outcomes after letrozole use with those of other endometrial preparation protocols in patients undergoing FET. PubMed, Scopus, Embase and the Cochrane Library were searched for eligible studies. Clinical pregnancy rate (CPR), live birth rate (LBR) and birth defect rate (BDR) were analysed using odds ratio (OR) and 95% confidence interval (CI). A total of 10 studies representing 75 968 FET cycles were included. Comparable CPR and LBR were observed when comparing letrozole administration with natural cycle (OR 1.24, 95% CI: 0.69 – 2.24; OR 1.18, 95% CI: 0.60 – 2.32), artificial cycle (OR 1.46, 95% CI: 0.87 – 2.44; OR 1.39, 95% CI: 0.77 – 2.52), and artificial cycle with gonadotropin-releasing hormone agonist suppression (OR 1.11, 95% CI: 0.78 – 1.59; OR 1.18, 95% CI: 0.82 – 1.68). Pooled results of the limited studies comparing letrozole with human menopausal gonadotropin demonstrated a similar CPR between groups (OR 1.46, 95% CI: 0.29 – 7.21, two studies), but the letrozole group had a statistically lower LBR (OR 0.67, 95% CI: 0.52 – 0.86, one study). No increased BDR was observed in the letrozole group compared to natural cycles or artificial cycles (OR 0.98, 95% CI: 0.60 – 1.61; OR 1.39, 95% CI; 0.84 – 2.28). This pooled analysis supports the use of letrozole as an efficacious and safe alternative to mainstream regimens for endometrial preparation in FET cycles.

Comparison of clomiphene and letrozole for superovulation in patients with unexplained infertility undergoing intrauterine insemination: A systematic review and meta-analysis

BACKGROUND

With the medical advancement some studies put forward that letrozole (LE), a specific aromatase inhibitor with the function of reducing oestrogen synthesis, has recently been applied as a potentially better alternative compared with clomiphene citrate (CC), owing to that it has a superior efficacy as compared with CC in patients of unexplained infertility undergoing intrauterine insemination (IUI). However, there is no one study can clear and definite whether LE can replace the CC as first line drug.

OBJECTIVE

Our objective is to compare the LE with CC in the induction of ovulation in patients with unexplained infertility IUI.

METHOD

Searching databases consist of all kinds of searching tools, such as Medline, The Cochrane Library, Embase, PubMed, etc. All the include studies should meet our demand of this meta-analysis: RESULT:: Based on the current meta-analysis, we rigorously consider that LE has a likelihood to improve dominant follicles (MD= -0.56, I= 100%, P= .04; MD= -0.39, I= 73%, P = .0003, respectively) and reduces the miscarriage rate (RR= 0.61, I= 0%, P = .03). There is no significant differences between the 2 groups in The total rate of pregnancy, pregnancy rate per cycle, multiple pregnancy and endometrial thickness. (RR= 1.06, I= 11%, P = .38; RR= 1.09, I= 7%, P = .32; RR= 0.79, I= 0%, P = .46; respectively) CONCLUSION:: Combined with the results of current systematic review and meta-analysis through subgroup analysis and sensitivity analysis, we can be cautious: in general, compared with CC, LE is an effective treatment in the IUI cycle, has a likelihood to improve dominant follicles and reduces the miscarriage rate.

Does daily co administration of gonadotropins and letrozole during the ovarian stimulation improve IVF outcome for poor and sub optimal responders?

Background

Co-administration of letrozole during the first 5 days of ovarian stimulation was suggested to improve IVF outcomes in poor responders. We aimed to determine whether poor/sub-optimal responders might benefit from Letrozole co-treatment throughout the entire stimulation course.

Methods

We retrospectively reviewed the medical files of women who demonstrated poor (oocyte yield ≤3) and sub-optimal (4 ≤ oocyte yield ≤9) ovarian response during conventional multiple-dose antagonist stimulation protocols and were co-treated in a subsequent cycle with 5 mg Letrozole from the first day of stimulation until trigger day. A self-paired comparison between gonadotropins-only and gonadotropins-letrozole cycles was performed.

Results

Twenty-four patients were included. Mean patients’ age was 39.83 ± 4.60 and mean day-3-FSH was 12.77 ± 4.49 IU/m. Duration of stimulation and total gonadotropins dose were comparable between the two cycle groups. Peak estradiol levels were significantly lower in gonadotropins-letrozole cycles (2786.74 ± 2118.53 vs 1200.13 ± 535.98, p < 0.05). Number of retrieved oocytes (3.29 ± 2.15 vs 6.46 ± 3.20, p < 0.05), MII-oocytes (2.47 ± 1.65 vs 5.59 ± 3.20, p < 0.05), 2PN-embryos (1.78 ± 1.50, 4.04 ± 2.74, p < 0.05) and top-quality embryos (0.91 ± 0.97 vs. 2.35 ± 1.66, p < 0.05) were significantly higher in the gonadotropins-letrozole cycles. Clinical pregnancy rate in gonadotropins-letrozole cycles was 31.5%.

Conclusion

Letrozole co-treatment during the entire stimulation course improves ovarian response and IVF outcomes in poor/sub-optimal responders.

Prospective randomized trial comparing efficacy of letrozole step-up protocol with letrozole plus gonadotropins for controlled ovarian stimulation and intrauterine insemination in patients with unexplained infertility

PURPOSE

Empirical treatment options for unexplained infertility treatment include controlled ovarian stimulation (COS) with clomiphene citrate, letrozole or gonadotropins followed by intrauterine insemination (IUI). Achieving consistent multifollicular development with letrozole generally requires addition of gonadotropins. However, the cost and discomfort of injections remains a drawback of this regimen. Therefore, there is a need for evolving newer cost-effective regimens for COS/IUI using orally administered drugs like letrozole.

METHODS

Sixty couples with unexplained infertility (on standard infertility investigations) visiting the infertility clinic at a tertiary centre in North India were randomized into two groups. Group A COS was done by step-up protocol of letrozole from day 2 or 3 of menstrual cycle, starting with 2.5 mg and increased by 2.5 mg per day for next 3 days (2.5 mg, 5 mg, 7.5 mg, 10 mg). Group B COS was done with combination of letrozole and hMG (human menopausal gonadotropin). Starting from day 2 or 3 of menses, tablet letrozole 2.5 mg twice a day was given for 5 days. Intramuscular injection of hMG 150 IU was given every alternate day starting from day 7 and titrated according to the response. HCG was given when leading follicle was 17 mm and IUI done 36 h after HCG.

RESULTS

Twenty-eight couples in letrozole step-up group (group A) and 30 couples in letrozole plus hMG group (group B), completed follow up for 44 and 55 cycles, respectively. Mean numbers of follicle ≥ 16 mm in both groups were comparable: 1.74 (± 0.83) in group A and 1.94 (± 0.68) in group B (p = 0.178). Ovulation rate of 90.9% (40/44) was achieved in group A, whereas it was 100% (55/55) in group B (p = 0.022), although there was no significant difference in clinical pregnancy rate per patient, which was 3/28 (10.7%) in group A versus 5/30 (16.67%) in group B (p = 0.707). The mean (SD) cost of medicines was significantly lower in group A Rs. 345.00 (00) compared to group B Rs. 2148.64 (515.67) [p < 0.0001]. There was one case each of hyperstimulation and multiple pregnancies in group B, while none in group A.

CONCLUSION

It is possible to achieve multifollicular development with use of novel letrozole step-up protocol, even without addition of gonadotropins, at significantly lower cost.

Evidence summaries and recommendations from the international evidence-based guideline for the assessment and management of polycystic ovary syndrome: assessment and treatment of infertility

STUDY QUESTION

What is the recommended assessment and management of infertile women with polycystic ovary syndrome (PCOS), based on the best available evidence, clinical expertize and consumer preference?

SUMMARY ANSWER

International evidence-based guidelines, including 44 recommendations and practice points, addressed prioritized questions to promote consistent, evidence-based care and improve the experience and health outcomes of infertile women with PCOS.

WHAT IS KNOWN ALREADY

Previous guidelines on PCOS lacked rigorous evidence-based processes, failed to engage consumer and multidisciplinary perspectives or were outdated. The assessment and management of infertile women with PCOS are inconsistent. The needs of women with PCOS are not being adequately met and evidence practice gaps persist.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Governance included a six continent international advisory and a project board, a multidisciplinary international guideline development group (GDG), consumer and translation committees. Extensive health professional and consumer engagement informed the guideline scope and priorities. The engaged international society-nominated panel included endocrinology, gynaecology, reproductive endocrinology, obstetrics, public health and other experts, alongside consumers, project management, evidence synthesis and translation experts. Thirty-seven societies and organizations covering 71 countries engaged in the process. Extensive online communication and two face-to-face meetings over 15 months addressed 19 prioritized clinical questions involving nine evidence-based reviews and 10 narrative reviews. Evidence-based recommendations (EBRs) were formulated prior to consensus voting within the guideline panel.

STUDY DESIGN, SIZE, DURATION

International evidence-based guideline development engaged professional societies and consumer organizations with multidisciplinary experts and women with PCOS directly involved at all stages. A (AGREE) II-compliant processes were followed, with extensive evidence synthesis. The Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) framework was applied across evidence quality, desirable and undesirable consequences, feasibility, acceptability, cost, implementation and ultimately recommendation strength. The guideline was peer-reviewed by special interest groups across our partner and collaborating societies and consumer organizations, was independently assessed against AGREE II criteria and underwent methodological review. This guideline was approved by all members of the GDG and has been approved by the NHMRC.

MAIN RESULTS AND THE ROLE OF CHANCE

The quality of evidence (QOE) for the EBRs in the assessment and management of infertility in PCOS included very low (n = 1), low (n = 9) and moderate (n = 4) quality with no EBRs based on high-quality evidence. The guideline provides 14 EBRs, 10 clinical consensus recommendations (CCRs) and 20 clinical practice points on the assessment and management of infertility in PCOS. Key changes in this guideline include emphasizing evidence-based fertility therapy, including cheaper and safer fertility management.

LIMITATIONS, REASONS FOR CAUTION

Overall evidence is generally of low to moderate quality, requiring significantly greater research in this neglected, yet common condition. Regional health systems vary and a process for adaptation of this guideline is provided.

WIDER IMPLICATIONS OF THE FINDINGS

The international guideline for the assessment and management of infertility in PCOS provides clinicians with clear advice on best practice based on the best available evidence, expert multidisciplinary input and consumer preferences. Research recommendations have been generated and a comprehensive multifaceted dissemination and translation program supports the guideline with an integrated evaluation program.

STUDY FUNDING/COMPETING INTEREST(S)

The guideline was primarily funded by the Australian National Health and Medical Research Council of Australia (NHMRC) supported by a partnership with ESHRE and the American Society for Reproductive Medicine (ASRM). GDG members did not receive payment. Travel expenses were covered by the sponsoring organizations. Disclosures of conflicts of interest were declared at the outset and updated throughout the guideline process, aligned with NHMRC guideline processes. Dr Costello has declared shares in Virtus Health and past sponsorship from Merck Serono for conference presentations. Prof. Norman has declared a minor shareholder interest in the IVF unit Fertility SA, travel support from Merck and grants from Ferring. Prof. Norman also has scientific advisory board duties for Ferring. The remaining authors have no conflicts of interest to declare.

This article was not externally peer-reviewed by Human Reproduction Open.

Ovulation induction and controlled ovarian stimulation using letrozole gonadotropin combination: A single center retrospective cohort study

OBJECTIVE

To assess the effect of letrozole in combination with low dose gonadotropins for ovulation induction in anovulatory infertility from polycystic ovary syndrome (PCOS) and controlled ovarian stimulation for endometriosis, and unexplained infertility patients.

STUDY DESIGN

Retrospective cohort study in a setting of private Reproductive Endocrinology and Infertility Clinic affiliated with the University. Three hundred couples (650 cycles) requiring OI/COS for PCOS (92 patients, 195 cycles), endometriosis (89 patients, 217 cycles), and unexplained infertility (119 patients, 238 cycles). Patients received 2.5mg or 5mg letrozole for 5days (D3-D7) and recombinant follicle-stimulating hormone on alternating D3-D7 and human menopausal gonadotropin-highly purified alternating D5-D10 until growth of ideally 2 mature follicles. Ovulation was triggered with 10,000 IU of HCG. Maximum number of cycles per patient was four.

RESULTS

Main outcome measures were clinical pregnancy rates, multiple order pregnancy rates, miscarriage rates, number of follicles and endometrial thickness on the day of HCG administration. The cumulative incidence of pregnancy was estimated as 35% (95%CI: 29%-41%) overall and was highest in patients with PCOS (36.6%), followed by unexplained infertility (34.6%) and endometriosis (32.5%). The pregnancy rates per cycle in PCOS, endometriosis and unexplained infertility patients were 17%, 13.2% and 17.2% respectively, no statistically significant difference between the groups. There were three twin pregnancies in PCOS, and one in unexplained infertility group. Monofolliculogenesis was noted in 48% of patients.

CONCLUSION(S)

Letrozole-low dose gonadotropins combination appears to be effective across different causes of infertility for superovulation. The letrozole-low dose gonadotropin combination resulted in high rate of monofolliculogenesis, low occurrence of multiple gestations and no case of OHSS or cycle cancellation.

A retrospective analysis of ovarian stimulation with letrozole in women undergoing artificial insemination by donor

The aim of this retrospective study was to determine the clinical pregnancy rate in women undergoing letrozole ovarian stimulation and artificial insemination by donor (AID). Between 2012 and 2015, 130 natural cycles, 939 letrozole cycles and 130 letrozole plus gonadotrophin cycles were conducted. Letrozole cycles were divided into three groups according to LH concentration on the day of HCG administration (LH <10 mIU/ml and follicle size ≥18 cm; LH ≤10 to <20 mIU/ml; and LH ≥20 mIU/ml). Pregnancy rates were 17.3%, 22.4% and 26.8%, respectively (P = 0.012). In women given 10 mIU/ml LH or more, logistic regression identified oestradiol (OR 1.002, 95% CI, 1.000 to 1.004, P = 0.029) and leading follicle size (OR 0.861, 95% CI, 0.772 to 0.960, P = 0.007) as significant predictive factors of pregnancy rate; the higher the oestradiol and the smaller the follicles, the better the pregnancy rate. The pregnancy rate was significantly higher in the letrozole plus gonadotrophin group than the letrozole group (P = 0.04). Better pregnancy rates can be achieved if LH surge occurs before HCG administration, especially with higher oestradiol and lower follicle size; treatment with letrozole plus gonadotrophin was significantly more effective than letrozole alone in AID.

A Study of Controlled Ovarian Stimulation with Clomiphene Citrate or Letrozole in Combination with Gonadotropins and IUI in Unexplained Infertility

Aim:

To compare the effect of clomiphene citrate (CC) + human menopausal gonadotropin (hMG) with letrozole + hMG on size, number of follicles, endometrial thickness, serum levels of oestradiol and progesterone and pregnancy rate.

Settings and Design:

Non-randomised interventional study.

Patients and Methods:

A total number of 60 patients in the age group of 20–35 years with unexplained infertility were divided into two groups, 30 in each. Group A received CC + hMG and group B received letrozole + hMG. In both the groups, ovulation was triggered by hCG followed by intrauterine insemination.

Results:

The number of follicles on day 8 were significantly higher in the CC + hMG group than that in the letrozole + hMG group. Serum oestradiol level was significantly higher in the CC + hMG group on day 10 and on the day of hCG administration. Pregnancy rate in the CC + hMG group was 23.3% and 13.3% in the letrozole + hMG group.

Conclusion:

The sequential protocol was cost-effective. CC + hMG could be a preferred ovarian stimulation protocol in couples with unexplained infertility with the added advantage of having no significant complications in properly monitored cycles.

Controlled ovarian hyperstimulation with sequential letrozole co-treatment in normo/high responders

OBJECTIVE

To investigate the effect of co-administration of letrozole in an ovarian stimulation protocol using recombinant FSH and GnRH antagonists for ICSI in normo/high responders.

METHODS

Computerized data of 320 antagonist ICSI/ET cycles with or without letrozole were retrospectively analyzed. In 105 cases, letrozole (5 mg/day) was started at the second day of the cycle continued for 5 days. At the second day of letrozole, gonadotropins were added. The remaining 215 cases were stimulated with recombinant FSH only. In all cases on day 6, GnRH antagonist was started. Ovarian stimulation protocols with or without letrozole were compared for cycle outcome parameters.

RESULTS

In cycles with letrozole, significantly lower gonadotropin consumption and lower peak estradiol levels were found. In cycles with letrozole, mean number of metaphase II and fertilized oocytes retrieved were significantly higher compared to cycles without letrozole. The pregnancy and clinical pregnancy rates were similar.

CONCLUSION

Should the number of oocytes retrieved being higher in letrozole group might indicate that letrozole might contribute to successful ovarian stimulation with a lower dosage of gonadotropins. Despite the lower peak estradiol levels, pregnancy rates being similar to other group also support the idea that letrozole can contribute to normal potential of implantation.

Use of letrozole and clomiphene citrate combined with gonadotropins in clomiphene-resistant infertile women with polycystic ovary syndrome: a prospective study

Background

Gonadotropin has been used to stimulate ovulation in clomiphene-resistant infertile women with polycystic ovary syndrome (PCOS), but it is associated with overstimulated cycles with the development of many follicles. The aim of the study was to evaluate the effectiveness and efficacy of letrozole and clomiphene citrate (CC) combined with human menopausal gonadotropin (HMG) in CC-resistant infertile women with PCOS.

Methods

Ninety-four women received the letrozole + HMG, 90 women received CC + HMG, and 71 women received HMG only. All women received one treatment regimen in one treatment cycle. All patients were given HMG 75 IU on alternate days daily starting on day 3 or day 7 until the day of administration of human chorionic gonadotropin.

Results

The rate of monofollicular development was 80.2% in the letrozole + HMG group, 65.3% in the CC + HMG group, and 54.7% in the HMG-only group (P<0.05 for letrozole + HMG vs the other two groups). The number of developing follicles (≥14 mm follicles) and the cycle cancellation rate due to ovarian hyperresponse were the lowest in the letrozole + HMG group, but the difference was not significant. The ovulation and pregnancy rate were similar among the three protocols. The HMG dose needed and the mean duration of treatment were significantly lower in the letrozole + HMG and CC + HMG groups compared with the HMG-only group.

Conclusion

Letrozole in combination with HMG is an effective protocol for reducing the risks of hyperstimulation for ovarian induction in CC-resistant women with PCOS. This combination may be more appropriate in patients who are particularly sensitive to gonadotropin.

Anastrozole is a dose-specific superovulator and favors implantation in rats: a prospective study

An alternative superovulator to replace clomiphene citrate (CC) is needed as it is unsuitable for women with polycystic ovarian syndrome and is associated with low pregnancy rates. Anastrozole is an effective superovulator, but has not been well researched. The aim of this study was to determine the optimal dose of anastrozole as a superovulator and ascertain its effects on implantation and uterine ultrastructure during early pregnancy in Wistar rats using scanning electron microscopy. The uterine morphological characteristics which were studied in day 1 and 6 pregnant rats include microvilli density, length, surface "beads", surface glycocalyx, cell borders and apices, uterine surface fording and large surface protrusions. A significant increase in implantation sites is seen in the 15 mg/kg anastrozole group, compared to control. Day 1 and 6 anastrozole groups have similar morphology to the control and different to the CC group. At day 6, large surface protrusions are mostly noted but not limited to anastrozole-treated rats; anastrozole also appears to retain glycocalyx to some extent. The increased number of implantation sites in the 15 mg/kg anastrozole group suggests that this dose superovulates and favors implantation. Anastrozole is probably dose-/species-specific and additionally the surface uterine morphology suggests that anastrozole is implantation friendly.

Women who deliver twins are more likely to smoke and have high frequencies of specific SNPs: Results from a sample of African-American women who delivered preterm, low birth weight babies

OBJECTIVES

We examine if there are genetic and environmental differences between mothers of singleton and multiple pregnancies in a sample of African-American mothers.

METHODS

We focus on genomic areas suggested to increase or decrease the odds of multiple pregnancies. We computed the odds ratio (OR) and the 95% confidence interval (CI) for each SNP unadjusted or adjusted with smoking. SNPs' allelic differences between mothers of multiple pregnancies and singletons were also tested using Fisher's exact test. We considered additive terms for the SNPs' genotypes, smoking, and a multiplicative interaction term of two selected SNPs' genotypes.

RESULTS

We found significant interactions between smoking and SNPs of the CYP19A, MDM4, MTHFR and TP53 genes which correlated with higher odds of twinning. We also found a significant interaction between SNPs at the TP53 (rs8079544) and MTHFR gene (rs4846049), where the interaction between the homozygotes (TT for rs8079544, GG for rs4846049) correlated with lowered odds of multiple pregnancy.

CONCLUSIONS

We provide a mechanistic explanation and preliminary evidence for previous reports that mothers of twins are more likely to have smoked, despite seemingly conflicting evidence for the fertility-reducing effects of nicotine. Nicotine, as an aromatase inhibitor, inhibits estrogen synthesis and may allow for greater production of gonadotropins. While smoking may have deleterious effects on fertility across many genotypes, in women of specific genotypes it may raise their odds of producing twins. TP53 involvement suggests the necessity of future work examining relationships between women who bear multiples and cancer risk.

Minimal stimulation using gonadotropin combined with clomiphene citrate or letrozole for intrauterine insemination

PURPOSE

To evaluate the efficacy of minimal stimulation using discretely administered gonadotropin combined with clomiphene citrate (CC) or letrozole (LTZ) for intrauterine insemination (IUI) cycles.

MATERIALS AND METHODS

Total 257 IUI cycles from 158 infertile couples were assessed. A CC dose of 100 mg/day (n=126 cycles) or a LTZ dose of 5 mg/day (n=131 cycles) was administered on days 3-5 of the menstrual cycle for 5 days. Each group received human menopausal gonadotropin at a dose of 150 IU by two or three alternative day: CC combined with alternate-day regimen for 2 or 3 days (CC+300, n=37; CC+450, n=89) and LTZ combined with alternate-day regimen for 2 or 3 days (LTZ+300, n=36; LTZ+450, n=95).

RESULTS

The clinical pregnancy rate was comparable between the CC and LTZ groups (18.3% vs. 13.0%, p=0.243). The clinical pregnancy rate also showed no significant difference among the 4 groups (21.6% vs. 16.9% vs. 11.1% vs. 12.6%, p=0.507). The multiple pregnancy rate was significantly higher in LTZ compared to CC group (37.5% vs. 8.7%, p=0.028) and in the LTZ+450 compared to CC+450 group (50% vs. 13.3%, p=0.038). Overall, there were 15 cases of ovarian hyperstimulation syndrome (OHSS), with the prevalence being significantly lower in the LTZ compared to CC group (1.5% vs. 10.3%, p=0.003). OHSS was more prevalent in the CC+450 compared to the LTZ+450 group (12.4% vs. 1.1%, p=0.002).

CONCLUSION

Our findings suggest that minimal stimulation using two alternate-day gonadotropin with LTZ decreases the development of OHSS and multiple pregnancies, while maintaining comparable pregnancy rates in IUI cycles.

A comparison of the efficacy of two doses of letrozole alone or with continuous recombinant follicle-stimulating hormone for ovulation induction in anovulatory women

AIMS

To determine the efficacy of letrozole alone or with recombinant follicle-stimulating hormone (rFSH) for ovarian induction in anovulatory women.

METHODS

A total of 322 patients undergoing intrauterine insemination (IUI) were included in this retrospective study. Letrozole (2.5 or 5.0 mg) was administered from days 5 to 9 of menses, alone or followed with rFSH started on day 9 until the day of human chorionic gonadotropin administration. A single IUI was performed 24 h after ovulation.

RESULTS

The number of follicles, endometrial thickness and serum estradiol levels were significantly higher in the letrozole + rFSH groups than in the letrozole-alone groups (p < 0.05), but no significant difference was found between the two doses of letrozole, whether alone or with rFSH. Women treated with 5.0 mg/day of letrozole + rFSH required a total dose of rFSH similar to women treated with 2.5 mg/day of letrozole + rFSH (230.77 ± 118.29 vs. 258.55 ± 130.13 IU, respectively; p = 0.205). There was no significant difference in pregnancy rates between the two doses of letrozole, whether alone or with rFSH.

CONCLUSION

Treatment with letrozole + rFSH was more efficacious than letrozole alone for pregnancy in the IUI program; however, the effect of 5.0 mg/day of letrozole versus 2.5 mg/day of letrozole on ovulation was equivalent, regardless of whether rFSH was used.

Comparison of IVF Outcomes between Minimal Stimulation and High-Dose Stimulation for Patients with Poor Ovarian Reserve

We examined whether treatment with minimum-dose stimulation (MS) protocol enhances clinical pregnancy rates compared to high-dose stimulation (HS) protocol. A retrospective cohort study was performed comparing IVF and pregnancy outcomes between MS and HS gonadotropin-antagonist protocol for patients with poor ovarian reserve (POR). Inclusion criteria included patients with an anti-Müllerian hormone (AMH) ≤8 pmol/L and/or antral follicle count (AFC) ≤5 on days 2-3 of the cycle. Patients from 2008 exclusively had a HS protocol treatment, while patients in 2010 had treatment with a MS protocol exclusively. The MS protocol involved letrozole at 2.5 mg over 5 days, starting from day 2, overlapping with gonadotropins, starting from the third day of letrozole at 150 units daily. GnRH antagonist was introduced once one or more follicles reached 14 mm or larger. The HS group received gonadotropins (≥300 IU/day) throughout their antagonist cycle. Clinical pregnancy rate was significantly higher in the MS protocol compared to the HS protocol (P = 0.007). Furthermore, the live birth rate was significantly higher in the MS group compare to the HS group (P = 0.034). In conclusion, the MS IVF protocol is less expensive (lower gonadotropin dosage) and resulted in a higher clinical pregnancy rate and live birth rate than a HS protocol for poor responders.

The effect of aromatase inhibitor letrozole incorporated in gonadotrophin-releasing hormone antagonist multiple dose protocol in poor responders undergoing in vitro fertilization

OBJECTIVE

To evaluate whether letrozole incorporated in a gonadotrophin-releasing hormone (GnRH) antagonist multiple dose protocol (MDP) improved controlled ovarian stimulation (COS) and in vitro fertilization (IVF) results in poor responders who underwent IVF treatment.

METHODS

In this retrospective cohort study, a total of 103 consecutive IVF cycles that were performed during either the letrozole/GnRH antagonist MDP cycles (letrozole group, n=46) or the standard GnRH antagonist MDP cycles (control group, n=57) were included in 103 poor responders. COS results and IVF outcomes were compared between the two groups.

RESULTS

Total dose and days of recombinant human follicle stimulating hormone (rhFSH) administered were significantly fewer in the letrozole group than in the control group. Duration of GnRH antagonist administered was also shorter in the letrozole group. The number of oocytes retrieved was significantly higher in the letrozole group. However, clinical pregnancy rate per cycle initiated, clinical pregnancy rate per embryo transfer, embryo implantation rate and miscarriage rate were similar in the two groups.

CONCLUSION

The letrozole incorporated in GnRH antagonist MDP may be more effective because it results comparable pregnancy outcomes with shorter duration and smaller dose of rhFSH, when compared with the standard GnRH antagonist MDP.

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 ovulation induction: an effective option in endometrial preparation for frozen-thawed embryo transfer

PURPOSE

To evaluate the clinical efficacy of letrozole on ovulation induction and hormone replacement therapy (HRT) during endometrial preparation for frozen-thawed embryo transfer (FET).

METHODS

We analyzed totally 1,230 cycles of patients that underwent FET from October 2010 to September 2012. Seven hundred and thirteen cycles of patients with ovulation disorders that underwent FET were randomly assigned to two groups by case control study. 359 cycles received letrozole ovulation induction and 354 cycles received HRT during endometrial preparation for FET, respectively. In the corresponding period, 517 cycles of patients with normal ovulation in the natural cycle group for FET endometrial preparation served as controls. Reproduction-related clinical outcomes of patients in the three groups were compared.

RESULTS

The embryo implantation rate of patients in letrozole group (30.4 %) was significantly higher than the HRT group (22.8 %, P < 0.05). The clinical pregnancy rate of patients in the letrozole group (53.2 %) was significantly higher than the HRT group (44.4 %, P < 0.05), while no significant difference was observed between the letrozole and natural cycle groups (51.3 %, P > 0.05). Estradiol levels on the day of human chorionic gonadotropin administration in the letrozole group were significantly lower than those in the natural cycle group (280.32 ± 125.39 pg/ml and 351.06 ± 123.03 pg/ml, respectively; P < 0.05). The live birth rate of patients in letrozole group (44.6 %) was significantly higher than the HRT group (32.5 %, P < 0.05), while abortion rate (12.0 %) was significantly lower than the HRT group (21.0 %, P < 0.05). There were no significant differences in number of mature follicles, endometrial thickness, duration of follicle growth between the letrozole and the natural cycle groups, and there were no significant differences in twin birth rate and ectopic pregnancy rate among the three groups (all P values >0.05).

CONCLUSIONS

Ovulation induction with letrozole during endometrial preparation for FET has a higher rate of pregnancy success and a lower abortion rate than HRT. Letrozole treatment exhibits clinical progression and outcomes similar to those patients undergoing a natural cycle or normal ovulation cycle. Therefore, letrozole treatment may be an effective option in endometrial preparation for FET in patients with ovulation disorders or irregular menstruation.

Effect of letrozole on estradiol production and P450 aromatase messenger RNA expression of cultured luteinized granulosa cells from women with and without endometriosis

OBJECTIVE

To compare the estradiol production and P450 aromatase messenger RNA (mRNA) expression of cultured luteinized granulosa cells and the effect of letrozole on these parameters between women with and without endometriosis.

DESIGN

In vitro assays.

SETTING

Reproductive medical center.

PATIENT(S)

Patients undergoing in vitro fertilization (IVF): 23 patients with endometriosis and 19 controls without endometriosis.

INTERVENTION(S)

Luteinized granulosa cells examined for estradiol levels and P450 aromatase mRNA expression in conditioned media at different letrozole concentrations of 0.0, 0.1, 1.0, and 10.0 μmol/L.

MAIN OUTCOME MEASURE(S)

Estradiol levels of the conditioned medium measured with an enzyme-linked immunosorbent assay (ELISA) kit and P450 aromatase mRNA expression determined by quantitative reverse transcription-polymerase chain reaction (QT RT-PCR).

RESULT(S)

The estradiol concentration of the conditioned media and P450 aromatase mRNA expression in the endometriosis group were statistically significantly lower than that of the control group, irrespective of letrozole concentrations. A statistically significant reduction of these two parameters was observed in both endometriosis and control groups at letrozole concentrations of 1 μmol/L and 10 μmol/L, but there were no statistically significant differences between letrozole concentrations of 1 μmol/L and 10 μmol/L. The number of high-quality embryos in the endometriosis group was statistically significantly lower than that of the control group.

CONCLUSION(S)

Lower estradiol production and P450 aromatase mRNA expression of cultured granulosa cells were found in women with endometriosis. Letrozole in the conditioned media further reduced these parameters.

Evidence-Based Lifestyle and Pharmacological Management of Infertility in Women with Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is the most prevalent endocrine disorder in women of reproductive age and by far the most common cause of anovulatory infertility. Lifestyle change alone, and not in combination with pharmacological ovulation induction such as clomifene citrate or metformin, is generally considered the first-line treatment for the management of infertile anovulatory women with PCOS who are overweight or obese. Clomifene citrate should be considered as a first-line pharmacological therapy to improve fertility outcomes. Second-line medical treatments may include ovulation induction with gonadotropins (in clomifene citrate-resistant or clomifene citrate failure women) or laparoscopic ovarian drilling (in clomifene citrate-resistant women) or possibly with metformin combined with clomifene citrate (in clomifene citrate-resistant women). There is currently insufficient evidence to recommend aromatase inhibitors over that of clomifene citrate in infertile anovulatory women with PCOS in general or specifically in therapy-naive or clomifene citrate-resistant women with PCOS.

Aromatase inhibitors for PCOS: a systematic review and meta-analysis

BACKGROUND

The effectiveness of aromatase inhibitors (AIs) in the treatment of anovulatory polycystic ovary syndrome (PCOS) remains unclear. The objective was to determine whether AIs are effective in improving fertility outcomes in women with PCOS.

METHODS

Databases were searched until July 2011. Inclusion criteria were women with PCOS, who are infertile, receiving any type, dose and frequency of AI compared with placebo, no other treatment or other infertility treatment. Outcomes were rates of: ovulation, pregnancy, live birth, multiple pregnancies, miscarriage and adverse events, as well as quality of life and cost effectiveness. Data were extracted and risk of bias was assessed. A random-effects model was used for the meta-analyses, using odds ratios (ORs) and rate ratios (RRs).

RESULTS

The search returned 4981 articles, 78 articles addressed AIs and 13 randomized controlled trials (RCTs) met the inclusion criteria. No RCTs compared AIs versus placebo or no treatment, in therapy naïve women with PCOS. Meta-analyses of six RCTs comparing letrozole with clompihene citrate (CC) demonstrated that letrozole improved the ovulation rate per patient [OR 2.90 (95% confidence interval (CI) 1.72, 4.88), I(2) = 0%, P < 0.0001]; however, there was no statistical difference for the ovulation rate per cycle or the pregnancy, live birth, multiple pregnancy or miscarriage rates. Letrozole also did not improve pregnancy or live birth rates compared with placebo or with CC plus metoformin in women with CC-resistant PCOS. Results of comparisons of letrozole and anastrozole in women with CC-resistant PCOS were conflicting in terms of ovulation and pregnancy rates.

CONCLUSIONS

In the absence of supportive high-quality evidence, AIs should not be recommended as the first-line pharmacological therapy for infertility in women with PCOS, and further research is needed.

Extended high dose letrozole regimen versus short low dose letrozole regimen as an adjuvant to gonadotropin releasing hormone antagonist protocol in poor responders undergoing IVF-ET

OBJECTIVE

To compare the efficacy and cost-effectiveness of extended high dose letrozole regimen/HPuFSH-gonadotropin releasing hormone antagonist (GnRHant) protocol with short low dose letrozole regimen/HPuFSH-GnRHant protocol in poor responders undergoing IVF-ET.

METHODS

In this randomized controlled trial, 136 women who responded poorly to GnRH agonist long protocol in their first IVF cycle were randomized into two equal groups using computer generated list and were treated in the second IVF cycle by either extended letrozole regimen (5 mg/day during the first 5 days of cycle and 2.5 mg/day during the subsequent 3 days) combined with HPuFSH-GnRHant protocol or short letrozole regimen (2.5 mg/day from cycle day 3-7) combined with HPuFSH-GnRHant protocol.

RESULTS

There were no significant differences between both groups with regard to number of oocytes retrieved and clinical pregnancy rate (5.39 ± 2.08 vs. 5.20 ± 1.88 and 22.06% vs. 16.18%, respectively).The total gonadotropins dose and medications cost per cycle were significantly lower in extended letrozole group (44.87 ± 9.16 vs. 59.97 ± 14.91 ampoules and 616.52 ± 94.97 vs. 746.84 ± 149.21 US Dollars ($), respectively).The cost-effectiveness ratio was 2794 $ in extended letrozole group and 4616 $ in short letrozole group.

CONCLUSION

Extended letrozole regimen/HPuFSH-GnRHant protocol was more cost-effective than short letrozole regimen/HPuFSH-GnRHant protocol in poor responders undergoing IVF-ET.

Role of androgens in the treatment of patients with low ovarian response

The objective of the current report was to provide a summary of knowledge concerning the treatment of women with poor ovarian response with androgens and androgen modulating agents. This involved a review of the literature. The literature search was performed using PubMed. Information concerning the role of androgens and androgen modulating agents in treating women with poor ovarian response is limited. The search of the literature yielded five studies and one case report concerning the treatment of poor responders with androgens. The variations in patient selection, type of androgens employed and the different duration of exposure preclude drawing any definite conclusions. Aromatase inhibitors block the conversion of androgens to oestrogens, thereby promoting an androgen-rich intrafollicular environment. The evidence presented in this review suggests a potential beneficial role for the use of aromatase inhibitors in treating women who have previously experienced failure of standard IVF protocols. The optimal dose and duration of this treatment is yet to be determined. Although the results of studies concerning LH supplementation in poor responders are conflicting, the latest Cochrane review on the use of recombinant LH for ovarian stimulation supports its use in poor responders, based on pooled pregnancy estimates.

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.

RETRACTED: Clomiphene citrate or letrozole for ovulation induction in women with polycystic ovarian syndrome: a prospective randomized trial

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the ASRM Publications Committee Several reports of randomized clinical trials were recently the subject of an investigation conducted by the publications committee of the ASRM. The committee reviewed concerns related to the validity of data reported in those reports. The committee noted significant duplication of data reported in this manuscript with data reported in another journal (PMID 17364286; https://doi.org/10.1080/00016340601090337) and another publication in Fertility and Sterility (PMID: 18692823; https://doi.org/10.1016/j.fertnstert.2008.06.013) pertaining to different study groups that could not be explained. As we cannot vouch for the validity of the data, we have issued a retraction of this paper.

Resumption of Menses with Initiation of Letrozole After Five Years of Amenorrhea on Tamoxifen: Caution Needed When Using Tamoxifen Followed by Aromatase Inhibitors

BACKGROUND

Randomized trials in postmenopausal women have shown a benefit to substituting aromatase inhibitors for tamoxifen or using them sequentially following a full course of tamoxifen. The aromatase inhibitor letrozole has also been utilized for ovarian induction in premenopausal women.

CASE REPORT

A premenopausal woman with early stage breast cancer became amenorrheic with adjuvant chemotherapy, and remained so during 5 years of daily tamoxifen. After discontinuing tamoxifen, laboratory studies confirmed an apparent postmenopausal state. Menses resumed following a 2-week course of letrozole.

CONCLUSION

Aromatase inhibitors need to be used with caution in women who stop menstruating following adjuvant chemotherapy or tamoxifen.

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.

RETRACTED: Anastrozole or letrozole for ovulation induction in clomiphene-resistant women with polycystic ovarian syndrome: a prospective randomized trial

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the ASRM Publications Committee. Several reports of randomized clinical trials were recently the subject of an investigation conducted by the publications committee of the ASRM. The committee reviewed concerns related to the validity of data reported in those reports. The committee noted significant duplication of data reported in this manuscript with data reported in another report (PMID: 19732888; https://doi.org/10.1016/j.fertnstert.2009.07.985) pertaining to a different study group that could not be explained. As we cannot vouch for the validity of the data, we have issued a retraction of this paper.

A comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on superovulation in Asian women with normal ovulatory cycles

OBJECTIVE

To compare the effect of the aromatase inhibitor letrozole and clomiphene citrate (CC) on superovulation in women with normal ovulation.

METHODS

A cross-over randomized study of 22 women with normal ovulation, divided randomly into two equal cohorts, was carried out. Each group of 11 women was randomly allocated to take letrozole or CC for one cycle. After washing out for one cycle, the alternative drug was administered in the subsequent cycle. The number and size of mature follicles, endometrial thickness, and estradiol and progesterone levels were monitored.

RESULTS

The number of mature follicles and estradiol levels on ovulation day were significantly lower in the letrozole group than the CC group (p < 0.05 for both). However, no differences between the two groups in endometrial thickness and pattern were observed. Progesterone levels showed ovulation in all cycles.

CONCLUSIONS

The administration of 50 mg CC on days 3-5 was superior to 2.5 mg letrozole for superovulation induction in women with normal ovulation.

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.

Different ovarian stimulation protocols for women with diminished ovarian reserve

PURPOSE

To review the available treatments for women with significantly diminished ovarian reserve and assess the efficacy of different ovarian stimulation protocols.

METHODS

Literature research performed among studies that have been published in the Pubmed, in the Scopus Search Machine and in Cohrane database of systematic reviews.

RESULTS

A lack of clear, uniform definition of the poor responders and a lack of large-scale randomized studies make data interpretation very difficult for precise conclusions. Optimistic data have been presented by the use of high doses of gonadotropins, flare up Gn RH-a protocol (standard or microdose), stop protocols, luteal onset of Gn RH-a and the short protocol. Natural cycle or a modified natural cycle seems to be an appropriate strategy. Low dose hCG in the first days of ovarian stimulation has promising results. Molecular biology tools (mutations, single nucleotide polymorphisms (SNPs)) have been also considered to assist the management of this group of patients.

CONCLUSIONS

The ideal stimulation for these patients with diminished ovarian reserve remains a great challenge for the clinician, within the limits of our pharmaceutical quiver.

Randomized controlled trial comparing superovulation with letrozole versus recombinant follicle-stimulating hormone combined with intrauterine insemination for couples with unexplained infertility who had failed clomiphene citrate stimulation and intrauterine insemination

OBJECTIVE

To compare the efficacy of letrozole to recombinant FSH for ovarian stimulation combined with IUI in a group of patients that had failed to conceive after clomiphene citrate (CC) and IUI.

DESIGN

Prospective randomized trial with human subjects.

SETTING

University-based fertility center.

PATIENT(S)

Fifty couples with unexplained infertility that failed to conceive after three cycles of CC combined to IUI.

INTERVENTION(S)

Couples were randomized to undergo superovulation either with letrozole or with recombinant FSH combined to IUI.

MAIN OUTCOME MEASURE(S)

Clinical pregnancy per cycle of treatment and clinical pregnancy per couple.

RESULT(S)

Pregnancy rate (PR) per cycle was 8.9% in the letrozole group as compared with 14% in the gonadotropin IUI group. This resulted in a cumulative PR per couple of 24% versus 36% and a take home baby rate of 20% versus 28%. Endometrial thickness was significantly lower in the letrozole group (7.1 +/- 2.3 vs 8.6 +/- 1.8).

CONCLUSION(S)

Ovarian stimulation with letrozole is associated with acceptable PRs compared with gonadotropin with significant less cost, risks, and patient inconvenience.

New advances in ovulation induction

PURPOSE OF REVIEW

To review recent advances in ovulation induction.

RECENT FINDINGS

Aromatase inhibitors can replace clomiphene citrate as ovulation-inducing substances. The most widely used aromatase inhibitor for this purpose is letrozole and the optimal dose is 5 mg daily for 5 days. Compared to clomiphene citrate, it is associated with a thicker endometrium and a better pregnancy rate. It is as effective as gonadotropin but yet less expensive. The overall rates of congenital malformation among newborns conceived after infertility treatment with letrozole or clomiphene citrate are similar. When letrozole is combined with gonadotropin, it leads to lower gonadotropin requirements with pregnancy rates comparable to gonadotropin treatment alone. Another promising aromatase inhibitor is anastrazole. Recent evidence suggests that luteinizing hormone activity in human menopausal gonadotropin modifies follicular development so that fewer intermediate-sized follicles develop. Compared to the use of follicular stimulating hormone only, human menopausal gonadotropin is associated with less ovarian hyperstimulation.

SUMMARY

Aromatase inhibitors are alternative drugs to clomiphene or gonadotropin for ovulation induction or superovulation.

Management of poor responders: can outcomes be improved with a novel gonadotropin-releasing hormone antagonist/letrozole protocol?

OBJECTIVE

To compare the efficacy of a microdose GnRH agonist flare (ML) with a GnRH antagonist/letrozole (AL) protocol before IVF-ET in poor responders.

DESIGN

Prospective controlled trial.

SETTING

Private assisted reproductive technology center.

PATIENT(S)

Five hundred thirty-four infertile women classified as past or potential poor responders based on clinic-specific criteria.

INTERVENTION(S)

Poor responders were prospectively assigned to an ML or AL protocol in a 2:1 ratio, respectively.

MAIN OUTCOME MEASURE(S)

Results of controlled ovarian hyperstimulation and implantation and ongoing pregnancy rates.

RESULT(S)

Patient characteristics were similar between the two protocol groups. There were no significant differences in mean age, number of oocytes, fertilization rates, number of embryos transferred, or embryo score. Peak E(2) levels were significantly lower in the AL group. Ongoing pregnancy rates were significantly higher in the ML group (52% vs. 37%). Trends toward increased implantation and lower cancellation rates were also noted, but these did not reach statistical significance.

CONCLUSION(S)

Quantitative results of stimulation between the ML and AL protocols were equivalent with the exception of peak E(2) levels. However, the higher ongoing pregnancy rates and trend toward superior implantation rates would suggest that ML represents a preferred approach for the poor responder. An increased sample size would be necessary to verify these findings.

Potential of aromatase inhibitors for ovulation and superovulation induction in infertile women

For almost half a century, the first-line treatment for ovulation induction in cases of anovulation, unexplained infertility, or mild male factor has been clomifene (clomiphene citrate). Clomifene is an effective and safely used oral agent, but is known to have relatively common antiestrogenic endometrial and cervical mucous adverse effects that could prevent pregnancy in the face of successful ovulation. In addition, there is a significant risk of multiple pregnancies with clomifene compared with natural cycles. These drawbacks are mainly a result of the extended antiestrogenic effect of clomifene as a result of its accumulation in the body (clomifene isomers have a half-life of several days up to few weeks). Because of these problems, we proposed the concept of aromatase inhibition as a new method of ovulation induction that could avoid many of the adverse effects of clomifene. Over the last few years several published studies, both controlled and noncontrolled, compared clomifene and treatment with aromatase inhibitors (AIs), either alone or in combination with gonadotropins, for ovulation induction or augmentation. These studies found AIs as effective as clomifene in inducing ovulation, with the major advantage of absence of any antiestrogenic adverse effects. Several other major advantages of AIs include the lower serum estrogen production per developing follicle resulting in more physiological estrogen levels around the time of ovulation and good pregnancy rates with a lower incidence of multiple pregnancy than with clomifene. When combined with gonadotropins for assisted reproductive technologies, AIs reduce the dose of gonadotropins required for optimal follicle recruitment and improve the response to gonadotropin stimulation in poor responders. Such preliminary evidence suggests that AIs may replace clomifene in the future because of similar efficacy with a reduced adverse-effect profile. However, we believe that definitive studies in the form of randomised controlled trials comparing clomifene with AIs are needed.

Follicular phase dynamics with combined aromatase inhibitor and follicle stimulating hormone treatment

OBJECTIVE

The objective of this study was to evaluate follicular phase parameters during ovarian stimulation with FSH alone or with the aromatase inhibitor letrozole.

METHODS

Two groups of women undergoing intrauterine insemination (IUI): group I (389 patients; mean age 35 +/- 4.3 yr) underwent 630 IUI cycles stimulated with letrozole and FSH; and group II (134 patients; mean age 36.0 +/- 4.6 yr) underwent 166 IUI cycles stimulated with FSH only. Each group was stratified into ovulatory and anovulatory cycles. Patients were monitored by ultrasound for folliculometry and blood sampling for hormonal assay on d 3, 7, 9, or 10 of the cycle, and on the day of human chorionic gonadotropin administration.

RESULTS

Group I had a significantly lower follicular count greater than 10 mm on d 7, greater than 12 mm on d 9 or 10, and greater than 15 mm on the day of human chorionic gonadotropin administration compared to group II (P = 0.006, <0.001, and <0.001, respectively). After stratifying patients by diagnosis, this relationship was maintained only for patients with ovulatory infertility (P = 0.003, <0.001, and <0.001, respectively). Serum estradiol (E2) was significantly lower in the group I ovulatory and anovulatory at the last three monitoring visits (P < 0.001). However, the difference in E2 levels decreased in the preovulatory period with similar E2 levels per mature follicle. No premature preovulatory progesterone rise was observed in either group. However, significantly lower progesterone levels were observed in the second half of the follicular phase in group I (P = 0.02 and <0.001). Endometrial thickness was significantly lower in group I at the second and third visits (P < 0.001, 0.01) but was comparable to group II at the last monitoring visit. Although, the pregnancy rates were similar between the two groups, the multiple pregnancy rate was significantly higher in the FSH-only group (P = 0.039).

CONCLUSION

The addition of letrozole modifies the follicular, hormonal, and endometrial dynamics of FSH-stimulated cycles with possible positive effects on the overall cycle outcome.

Aromatase inhibitors in ovarian stimulation for IVF/ICSI: a pilot study

This prospective randomized pilot study was aimed at investigating the effect of the novel addition of aromatase inhibitors to an ovarian stimulation protocol for IVF or intracytoplasmic sperm injection, on endocrine parameters including serum androgen, oestrogen, progesterone, LH and FSH concentrations. The patients were randomized to receiving letrozole (group A; n = 10), versus no letrozole (group B; n = 10) in an ovarian stimulation protocol with recombinant FSH 150 IU/day starting on day 2 of the cycle, and gonadotrophin-releasing hormone antagonist 0.25 mg/day starting on day 6 of the cycle. Median LH concentrations were significantly higher (P < 0.01) in group A versus group B during letrozole administration. Median serum oestradiol concentrations were lower in group A versus group B, and median serum FSH, testosterone and androstenedione concentrations were higher in group A versus group B, throughout the follicular phase, without reaching significance. Median endometrial thickness was significantly higher (P < 0.05) in group A versus group B on the day of human chorionic gonadotrophin administration. Pregnancies were achieved. This pilot study supports the idea that aromatase inhibitors can contribute to normal potential of implantation and follicular response, without having negative anti-oestrogenic effects.