Abstract: AIM: To observe the induced ovulation outcomes using either letrozole (LE) or clomiphene citrate (CC) in women with polycystic ovary syndrome (PCOS).METHODS: After medication of ethinylestradiol/ cyproterone acetate tablets and metformin hydrochloride enteric-coated tablets, 72 PCOS women with normal function of endocrine scheduled ovulation induction were randomly allocated to LE group and CC group (n=36 for each). The drug was administered orally at the 4th day of the menstrual cycle, and transvaginal ultrasound was performed to monitor the follicle development. By the follicular diameter≥18 mm, human chorionic gonadotropin (HCG) was injected to induce the ovulation, and the blood was simultaneously taken at the same day to determine the levels of luteinizing hormone (LH), estradiol (E2) and testosterone (T). The two groups were examined and compared regarding the thickness of endometrium, number of dominant follicle, amount of HMG used, ovulation rate, incidence of LUF and clinical pregnancy rate.RESULTS: The periodic ovulation rate and pregnancy rate had no significance between LE group and CC group. E2 level detected at the day of HCG administration was lower in LE group than the CC group (P＜0.05), yet thicker endometrium was seen in LE group (P＜0.05). Additionally, LE group had a lower incidence of ovarian hyper stimulation syndrome (OHSS) (P＜0.05), and was superior to CC group concerning single follicle ovulation rate.CONCLUSION: Administration of LE for ovulation induction in women with PCOS may produce higher rate of single follicle ovulation and better endometrial receptivity, but reduce the multiple pregnancy and incidence of OHSS, suggesting that it is favorable to ovulation induction therapy and a promising drug in PCOS patients.

Key words: Letrozole, Clomiphene citrate, Polycystic ovarian syndrome, Ovulation induction