Predictors and characteristics of letrozole induced ovulation in comparison with clomiphene induced ovulation in anovulatory PCOS women

ObjectiveTo evaluate predictors and characteristics of letrozole induced ovulation in comparison with clomiphene induced ovulation in a group of PCOS women.DesignProspective randomized controlled double blind trial.SettingInfertility unit of university hospital.Patients124 PCOS patients undergoing ovulation induction for one cycle using either clomiphene or letrozole.Intervention100mg of CC/day for 5 days or 5 mg of Letrozole/day for the same duration starting within 5 days of progestin induced withdrawal bleeding.Main outcome measuresOvulation rate, number of follicles, final endometrial thickness, mid-luteal progesterone, and pregnancy.ResultsComparable ovulation and pregnancy rates were obtained with clomiphene and letrozole. Endometrium at ⩾18 mm follicle diameter was significantly thinner and mid luteal progesterone was significantly lower in clomiphene group. Within each group there was no significant difference in any of the baseline variables between responders and non-responders. High basal LH was associated with non-response in the whole study population.ConclusionLetrozole is at least as good as CC in inducing ovulation and achieving pregnancy in PCOS cases. Serum progesterone and endometrium were significantly more favorable with letrozole. High basal LH correlated with failure in both groups.