title: [Clinical effect of letrozole on the ovulation induction in endometrial preparation for frozen-thawed embryo transfer].
abstract: 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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Central South University, Changsha, China.
authors.forename: Songjun
authors.initials: S
authors.lastname: Li
authors.forename: Xiaoshan
authors.initials: X
authors.lastname: Chai
authors.forename: Yuyan
authors.initials: Y
authors.lastname: Zhou
authors.forename: Jianlin
authors.initials: J
authors.lastname: Chen
authors.forename: Guangshi
authors.initials: G
authors.lastname: Tao
mesh_terms: D016022:Case-Control Studies; D015925:Cryopreservation; D004624:Embryo Transfer; D004717:Endometrium / Q000187:drug effects* / Q000502:physiology; D005260:Female; D005300:Fertility Agents, Female / Q000627:therapeutic use; D005307:Fertilization in Vitro; D006801:Humans; D000077289:Letrozole; D009570:Nitriles / Q000627:therapeutic use*; D010062:Ovulation Induction / Q000379:methods*; D014230:Triazoles / Q000627:therapeutic use*
chemical_list: D005300:Fertility Agents, Female; D009570:Nitriles; D014230:Triazoles; D000077289:Letrozole