A Comparative Study of Letrozole Vs Clomiphene Citrate as First Line for Anovulatory Infertility– An Institutional Experience

Background: Anovulatory infertility is a common problem and accounts for 40% of female infertility. In most of the cases, it further cannot be attributed to a specific treatable cause, thus ovulation induction becomes an empiric, organized and incremental titration intended to identify the successful treatment regimen associated with the least cost and risk. Clomiphene citrate has been traditionally used as the drug of choice. In the last decade letrozole has emerged as an alternative. However, its role as an alternative to clomiphene as first line therapy continues to be debated.

Objective: To compare letrozole and clomiphene citrate in anovulatory infertility, with respect to ovulation rate and pregnancy rate.

Materials and Methods: 50 cases of primary infertility with anovulation were taken, in whom bilateral fallopian tubes were patent at laparoscopic chromopertubation, or hysterosalphingography or sonosalphingography. Their spouse had male factor fertility confirmed by adequate seminal parameters according to latest WHO guidelines. Patients were randomized into two groups. From day 3 – 7 of the menstrual cycle, patients (25 each) either received tablet letrozole 2.5mg OD orally or tablet clomiphene citrate 100mg OD orally. Transvaginal ultrasound on day 14 and 16 of the cycle were done for follow up. Advice for timed intercourse daily around the time of ovulation was given. Main outcomes measured were number of follicles, endometrial thickness, ovulation rate, pregnancy rate and miscarriage rates.

Results: Letrozole was found to be more effective than clomiphene citrate in terms of monofollicular ovulation (98.70% vs 75.00%), significant improvement in endometrial thickness (9.5 ± 1.1 mm vs 8.3 ± 1.3 mm) and no cases with lag endometrium. All 25 cases in the letrozole group (100%) achieved ovulation in the first cycle of treatment out of which 6 cases (24.00%) became pregnant. There were no multiple pregnancies or miscarriages. We observed a statistically significant difference among both the groups in terms of outcome (p<0.05). There is a positive correlation (ρ=0.7) between letrozole and number of pregnancies in this study.

Conclusion: Letrozole is a more effective drug; as a first line agent for ovulation induction in anovulatory infertility; alternative to clomiphene citrate.