title: Comparison of pregnancy outcome after letrozole versus clomiphene treatment for mild ovarian stimulation protocol in poor responders.
abstract: BACKGROUND
  Poor ovarian response to controlled ovarian stimulation is one of the most important interest points in assisted reproduction. Mild ovarian stimulation seems to be preferable to high dose of FSH regimens in women with a history of poor ovarian response in previous protocol. Clomiphene citrate and letrozole alone or in combination with FSH have been used in mild ovarian stimulation protocol.
  
  
  OBJECTIVE
  To compare the efficacy of letrozole and clomiphene citrate for mild ovarian stimulation on assisted reproductive technology outcomes in poor responders.
  
  
  METHODS
  In a randomized control study, 184 women aged between 20 and 45 years with the history of poor response to ovarian stimulation who were candidate for ART were randomly subdivided into two groups: group I (n= 80), women who underwent the clomiphene/gonadotropin/antagonist protocol; and group II (n= 87), patients who underwent the letrozole/gonadotropin/antagonist protocol. Groups were compared regarding implantation, chemical and clinical pregnancy rates.
  
  
  RESULTS
  There was a significant difference in the mean endometrial thickness between two groups (9.16±1.2 mm vs. 8.3±0.3 mm). The implantation rate was significantly higher in letrozole group compare to clomiphene group (7.2 vs. 6.6%, p=0.024 respectively). No significant differences were found in chemical and clinical pregnancy rate between two groups.
  
  
  CONCLUSIONS
  In mild ovarian stimulation protocol, letrozole and clomiphene have similar value for the poor responder. The optimal treatment strategy for these patients remains debated.
authors.affiliation: Research and Clinical Center for Infertility, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Eftekhar
authors.affiliation: Department of Obstetrics and Gynecology, Zanjan University of Medical Sciences, Zanjan, Iran.
authors.forename: Farnaz
authors.initials: F
authors.lastname: Mohammadian
authors.affiliation: Research and Clinical Center for Infertility, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
authors.forename: Robab
authors.initials: R
authors.lastname: Davar
authors.affiliation: Research and Clinical Center for Infertility, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
authors.forename: Soheila
authors.initials: S
authors.lastname: Pourmasumi
keywords: Clomiphene; Letrozole; Mild ovarian stimulation protocol; Poor responders