Comparison of efficacy of letrozole and clomiphene citrate for induction of ovulation

Background and objective: Ovulatory dysfunction is a common cause of infertility. This study aimed to determine if letrozole is more efficient than clomiphene for the induction of ovulation in a group of un ovulatory infertile women. Methods: A prospective, comparative study was conducted at the Fertility Center Out-patient Department of Maternity Teaching Hospital, Erbil city, Kurdistan Region, Iraq, from May 2011, to May 2012. Hundred infertile couples having anovulatory infertility were included in the study; 50 women (146 cycles) were given letrozole 5 mg for three cycles, and 50 (148 cycles) women were put on clomiphene citrate (CC) 100 mg for three cycles, from day 2 to day 6 of the menstrual cycle. The diagnosis of pregnancy was confirmed by ultrasound. Two-tailed independent t-test was used to compare means, while proportions were compared with the Chi-Square test. Results: Ovulation occurred in 131/150 women in the clomiphene citrate group and 124/150 women in the letrozole group. The total number of mature follicles for clomiphene citrate was 1.44 ±0.56mm, while it was 1.13 ±0.32mm for letrozole, which was highly significant (P = 0.001). Endometrial thickness at the time of hCG administration for clomiphene citrate versus letrozole was (7.95 ±1.53mm versus 9.37 ± 2.04mm, P = 0.001) respectively. The pregnancy rate was 16/148 cycles in the clomiphene citrate group and 20/146 cycles in the letrozole group. Conclusion: Letrozole and clomiphene citrate are equally effective for the induction of ovulation and achieving pregnancy in patients with anovulatory infertility.