Comparison of the success rate of letrozole and clomiphene citrate in women undergoing intrauterine insemination.

Background: this study was conducted to compare the success rate of daily administration of aromatase inhibitor letrozole at a dose of 5 mg when administrating clomiphene citrate (cc) 100 mg daily in women undergoing superovulation and iui. methods: this prospective randomized trial was done in research and clinical center for infertility (shahid sadoughi university), yazd, iran. ninety-five patients with unexplained and mild male factor infertility were studied. using acomputer-generated random table, the patients were randomized into two groups, which were treated with 5 mg of letrozole daily (42 patients, 42 cycles) or 100 mg of cc daily (53 patients, 53 cycles). the data were analyzed using student's t-test and chi square test. results: the mean age and duration of infertility in both groups were similar. there was a significant difference between the two groups in the total numbers of follicles during stimulation (5.45 (plus-minus) 4.2 in cc group vs. 3.07 (plus-minus) 2.1 in letrozole group) (p = 0.01). no significant difference in the endometrial thickness was found between the two groups (letrozole group = 6.9 (plus-minus) 2.2, cc group = 7.8 (plus-minus) 1.8). the mean levels of lh and fsh in both groups were similar. p value of difference in hormone levels between two groups were 0.33 and 0.47, respectively, but there was a significant difference in mean e2 levels between the two groups (241.28 (plus-minus) 167.537 in letrozole group vs. 867.34 (plus-minus) 296.689 in cc group) (p = 0.018). the mean number of gonadotropin ampules used in both groups was the same. pregnancy rate per cycle was 9.5% in the letrozole group and 5.7% in the cc group (p = 0.6). two out of the three pregnancies in the cc group (66.6%) and one out of the four pregnancies in the letrozole group resulted in a miscarriage (25%). one twin pregnancy (33%) occurred in the letrozole group and none in the cc group. ovarian hyperstimulation syndrome (ohss) did not occur in either of the two groups. conclusions: in iui, superovulation with clomiphene citrate and letrozole was associated with similar pregnancy rates, but the miscarriage rate was higher with clomiphene citrate.