Comparing the combined effect of letrozole and clomiphene regimen plus gonadotropins on pregnancy rate in clomiphene resistant-polycystic ovarian syndrome

Background: Although clomiphene citrate is the first line in ovulation induction in anovulatory infertile women, but some of polycystic ovarian syndrome (PCOS) patients are clomipheneresistant. This study was carried out to compare the combined effect of letrozole and clomiphene with gonadotropins on pregnancy rate in clomiphene-resistant PCOS patients. Materials and Methods: This clinical trial study was carried out on 120 clomiphene-resistant PCOS patients. The patients were randomly divided into two groups: group 1 received clomiphene (100 mg/day) and group 2 received letrozole (5 mg/day) on the 3–7 th days of menstrual cycle. Both groups received (150 IU/im) HMG on the 5–8 th days of menstrual cycle. On 10-11 th days of menstrual cycle, transvaginal sonography was performed to determine endometrial thickness, dominant follicle number and increase HMG dose, if required. HCG at a dose of 5000 IU was administered when at least one mature follicle was observed. β-HCG level was evaluated 2 weeks after HCG administration. The two groups were compared for mature follicles numbers, endometrial thickness, gonadotropin consumption and pregnancy rate. Chi– square, Kolomogrov–Smirnov, t-test, Levene, Mann-Whitney tests were used to analyze data. Results: Although the pregnancy rate in letrozole group was higher than in the clomiphene one, the difference was not significant (36.7% vs 33.3%, P=0.702). The mean endometrial thickness in letrozole and clomiphene group was 7.47 mm and 7.49 mm, respectively (P=0.685). In letrozole and clomiphene group the mean of dominant follicles numbers was 2.18 and 2.83, respectively (P=0.087) while the gonadotropin level mean in both groups was 6.78 (P=0.941). Conclusion: In clomiphene resistant PCOS patients, similar to clomiphene, letrozole in combined regimens with gonadotropin can be effective for the induction of ovulation.