The Effect of Clomiphene Citrate Versus Letrozole on Pregnancy Rate in Women With Polycystic Ovary Syndrome: A Randomized Clinical Trial

Objectives: Polycystic ovarian syndrome (PCOS) is one of the most common endocrine disorders in women of reproductive age (6.8%-18%) and is one of the leading causes of infertility due to ovulation factors in 55%-70% of infertile women. In this study, we compared the first-line and second-line treatments of infertility through ovulation induction with clomiphene citrate and letrozole, respectively, in the infertile patients with PCOS. Patients and Methods: This randomized clinical trial included 80 infertile patients with PCOS intent on pregnancy. Having considered the inclusion criteria and obtaining the informed consent, the patients were divided into two groups of 40 and treated with either clomiphene citrate or letrozole. In the first group, two tablets of clomiphene (50 mg/d) were taken and in the second group, two tablets of letrozole (2.5 mg/d) were prescribed on the third to seventh days of the menstrual cycle for 5 days. Over the course of the treatment for 3 months, pregnancy rate was detected at every menstrual cycle by performing BHCG titers. Data were entered into SPSS software version 21.0. All data were analyzed using independent t-test, and chi-square test with a significance level less than 0.05. Results: Mean age of patients, and mean body mass index (BMI), as well as duration of infertility were not significantly different between letrozole and clomiphene groups. Fifteen patients in the clomiphene group (37.5%) reported a history of infertility treatment, compared to the letrozole group in which 12 patients (30%) reported such treatment, though this difference was not statistically significant. In the clomiphene group, the menstrual cycle was compatible with PCOS in 30 patients (75%), while in the group receiving letrozole, it was compatible in 33 patients (82.5%). Hyperandrogenism consistent with PCOS was present in 25 patients (62.5%) in the clomiphene group and in the group receiving letrozole in 22 patients (55%). The evidence of PCOS-compatible ultrasonography was found in 31 patients (77.5%) in the clomiphene group and in 35 patients (87.5%) in the letrozole group. The frequency of pregnancy in the clomiphene group (45%) was lower than that in the letrozole group (50%). Chi-square test showed that this difference was not statistically significant. Conclusions: It seems that the efficacy and success rate of clomiphene and letrozole in the treatment of infertility due to ovulation failures are similar in patients with PCOS in that both could increase ovulation and pregnancy rate. In other words, these two drugs are not superior to each other and can be selected according to the patient's tolerance, cost, and side effects.