[Clinical effect of letrozole on the ovulation induction in endometrial preparation for frozen-thawed embryo transfer].

OBJECTIVE: To evaluate the clinical effect of letrozole (LE) alone on the ovulation induction in endometrial preparation for frozen-thawed embryo transfer (FET). METHODS: Totally 253 FET cycles were analyzed by case control study from October 2010 to June 2011. We divided ovulation disorders or menstrual disorders divided into 2 groups: a LE group on ovulation induction cycle (n=85), and a hormone replacement therapy (HRT) cycle group (n=84). Meanwhile those who ovulated normally were included in a natural cycle group (n=84). Demographics and clinical parameters of reproductive correlation of all patients were observed among these groups. RESULTS: The average clinical pregnancy rate of the LE group was higher than that of HRT cycle group (54.1% vs 44.04%; P<0.05). The difference in the parameters such as patients' demographics and other clinical indexs had no statistical significance (P>0.05). The estradiol level on human chorionic gonadotrophin (HCG) administration day in the natural cycle group [(341.19±113.14) pg/mL] was higher than that of the LE group [(279.70±127.80) pg/mL] (P<0.05). There was no significant difference in the number of maturation follicles and endometrial thickness on the HCG administration day between the LE group and the natural cycle group (P>0.05). CONCLUSION: Ovulation induction with LE alone for endometrial preparation is superior to HRT cycle in FET and has similar clinical process and outcome to those of the natural cycle. It can be applied in endometrial preparation for FET effectively for those with anovulation or menstrual disorder.