title: The effect of aromatase inhibitor letrozole incorporated in gonadotrophin-releasing hormone antagonist multiple dose protocol in poor responders undergoing in vitro fertilization.
abstract: OBJECTIVE
  To evaluate whether letrozole incorporated in a gonadotrophin-releasing hormone (GnRH) antagonist multiple dose protocol (MDP) improved controlled ovarian stimulation (COS) and in vitro fertilization (IVF) results in poor responders who underwent IVF treatment.
  
  
  METHODS
  In this retrospective cohort study, a total of 103 consecutive IVF cycles that were performed during either the letrozole/GnRH antagonist MDP cycles (letrozole group, n=46) or the standard GnRH antagonist MDP cycles (control group, n=57) were included in 103 poor responders. COS results and IVF outcomes were compared between the two groups.
  
  
  RESULTS
  Total dose and days of recombinant human follicle stimulating hormone (rhFSH) administered were significantly fewer in the letrozole group than in the control group. Duration of GnRH antagonist administered was also shorter in the letrozole group. The number of oocytes retrieved was significantly higher in the letrozole group. However, clinical pregnancy rate per cycle initiated, clinical pregnancy rate per embryo transfer, embryo implantation rate and miscarriage rate were similar in the two groups.
  
  
  CONCLUSIONS
  The letrozole incorporated in GnRH antagonist MDP may be more effective because it results comparable pregnancy outcomes with shorter duration and smaller dose of rhFSH, when compared with the standard GnRH antagonist MDP.
authors.affiliation: Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Kyung-Hee
authors.initials: KH
authors.lastname: Lee
authors.affiliation: Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Chung-Hoon
authors.initials: CH
authors.lastname: Kim
authors.affiliation: Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Hye-Jin
authors.initials: HJ
authors.lastname: Suk
authors.affiliation: Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: You-Jeong
authors.initials: YJ
authors.lastname: Lee
authors.affiliation: Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Su-Kyung
authors.initials: SK
authors.lastname: Kwon
authors.affiliation: Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Sung-Hoon
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Hee-Dong
authors.initials: HD
authors.lastname: Chae
authors.affiliation: Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Byung-Moon
authors.initials: BM
authors.lastname: Kang
keywords: Gonadotrophin-releasing hormone antagonist; In vitro fertilization; Letrozole; Poor responder