RESUMEN
According to side effects of clomiphen citrate [cc], especially on thendometrium, it was replaced with letrozole, an aromatase inhibitor, for induction of ovulation. In this study, effects of these drugs on ovulation and fertility were compared in patients with polycystic ovarian [PCO] syndrome. In a randomized clinical trial, women with PCO and history of infertility referred to gynecology clinic of Rasoul Akram hospital and private office between 2007 and 2008 were studied. Subjects were randomly assigned to two groups of clomiphen citrate and letrozole. In CC group, subjects were received 100 milligram per day clomiphen citrate between 3rd and 7th day of each cycle for 3 cycles. In letrozole group, women treated with letrozole 2.5 mg daily between 3 and 7 day of each for 3 cycles. Number of follicles in days of 12-16 of cycle, diameter of the greatest one, pregnancy and outcome of pregnancy were compared in two groups. 40 patients in each group were studied. Numbers of follicles, mean diameter of the greatest one were not significantly different in two groups. Pregnancy was occurred in 15 patients [37.5%] of letrozole group Vs 13 patients [32.5%] of CC group. There was no abortion in letrozole group Vs 3 abortion in CC group. Preterm labor was significantly lower in letrozole treated patients [p=0.04]. This study showed that letrozole could be proper substitution of clomiphen citrate for induction of ovulation in patients with PCO and infertility