Comparison of the use of letrozole and clomiphene citrate in regularly ovulating women undergoing intrauterine insemination

Objective: To compare the effects of letrozole 5mg and clomiphene citrate (CC) 100mg on total follicle number, endometrial thickness, hormone levels, pregnancy, miscarriage and OHSS rate in women undergoing superovulation and I.U.I.
Material and methods: This study was done as a prospective randomized trial in Research and Clinical Center for Infertility (Shahid Sadoughi University) and Mother Hospital, Yazd, Iran. In this study, 115 patients with unexplained and mild male factor infertility were studied. Patients were randomized, using a computer-generated random table into two groups which were treated with 5 mg of letrozole daily (60patients, 60 cycles) or 100mg of CC daily (55 patients, 55 cycles) from day 3-7 followed by FSH on day 8 of the cycle. Then data were analyzed using student's T Test and chi-square.
Results: The mean age and duration of infertility in both groups were similar. There was a significant difference in the total numbers of follicles during stimulation between two groups (5.45± 4.3 in CC group vs. 3.28± 2.5 in letrozole group) (p-value= 0.01). No significant difference was found in the endometrial thickness between two groups (letrozole group= 6.9±2.5, CC group= 7.6±1.8) .The mean level of LH (IU/L) and FSH (IU/L) in both groups were similar. (P-value of hormone levels between two groups were respectively: 0.33 and 0.47), but there was a significant difference in mean estrogen (pg/ml) levels between the groups (220.28±150.5 in letrozole group vs. 867.34±240.6 in CC group) (p-value=0.018). The mean number of used gonadotropin ampoule was the same in both groups. Chemical pregnancy rate per cycle was 8.3% in the letrozole group and 5.5% in the CC group. Clinical pregnancy rate per cycle was 6.6%in the letrozole group and 1.8% in the CC group (p-value= 0.6).Two out of the three pregnancies in the CC group and one out of the five pregnancies in the letrozole group resulted in a miscarriage. One twin pregnancy occurred in the letrozole group and none in the CC group. Ovarian hyperstimulation syndrome (OHSS) has not occurred in any group.
Conclusions: In spite of comparable pregnancy rate in clomiphene citrate and letrozole group, C.C. in these patients could be prescribed because of its lower cost.