title: Early gonadotropin-releasing hormone antagonist start improves follicular synchronization and pregnancy outcome as compared to the conventional antagonist protocol.
abstract: OBJECTIVE
  To assess whether an early GnRH antagonist start leads to better follicular synchronization and an improved clinical pregnancy rate (CPR).
  
  
  METHODS
  A retrospective cohort study. A total of 218 infertile women who underwent IVF between January 2011 and February 2013. The initial cohort (Cohort I) that underwent IVF between January 2011 and March 2012 included a total of 68 attempted IVF cycles. Thirty-four cycles were treated with the conventional GnRH antagonist protocol, and 34 cycles with an early GnRH antagonist start protocol. The second cohort (Cohort II) that underwent IVF between June 2012 and February 2013 included a total of 150 embryo-transfer (ET) cycles. Forty-three cycles were treated with the conventional GnRH antagonist protocol, 34 cycles with the modified early GnRH antagonist start protocol using highly purified human menopause gonadotropin and an addition of GnRH agonist to the luteal phase support, and 73 cycles with the GnRH agonist long protocol.
  
  
  RESULTS
  The analysis of Cohort I showed that the number of mature oocytes retrieved was significantly higher in the early GnRH antagonist start cycles than in the conventional antagonist cycles (11.9 vs. 8.2, p=0.04). The analysis of Cohort II revealed higher but non-significant CPR/ET in the modified early GnRH antagonist start cycles (41.2%) than in the conventional antagonist cycles (30.2%), which was comparable to that of the GnRH agonist long protocol cycles (39.7%).
  
  
  CONCLUSIONS
  The modified early antagonist start protocol may improve the mature oocyte yield, possibly via enhanced follicular synchronization, while resulting in superior CPR as compared to the conventional antagonist protocol, which needs to be studied further in prospective randomized controlled trials.
authors.affiliation: Division of Reproductive Endocrinology and Infertility, Department Obstetrics and Gynecology, Cheil General Hospital and Women's Healthcare Center, Catholic Kwandong University College of Medicine, Seoul, Korea.
authors.forename: Chan Woo
authors.initials: CW
authors.lastname: Park
authors.affiliation: Division of Reproductive Endocrinology and Infertility, Department Obstetrics and Gynecology, Cheil General Hospital and Women's Healthcare Center, Catholic Kwandong University College of Medicine, Seoul, Korea.
authors.forename: Yu Im
authors.initials: YI
authors.lastname: Hwang
authors.affiliation: Division of Reproductive Endocrinology and Infertility, Department Obstetrics and Gynecology, Cheil General Hospital and Women's Healthcare Center, Catholic Kwandong University College of Medicine, Seoul, Korea.
authors.forename: Hwa Seon
authors.initials: HS
authors.lastname: Koo
authors.affiliation: Division of Reproductive Endocrinology and Infertility, Department Obstetrics and Gynecology, Cheil General Hospital and Women's Healthcare Center, Catholic Kwandong University College of Medicine, Seoul, Korea.
authors.forename: Inn Soo
authors.initials: IS
authors.lastname: Kang
authors.affiliation: Division of Reproductive Endocrinology and Infertility, Department Obstetrics and Gynecology, Cheil General Hospital and Women's Healthcare Center, Catholic Kwandong University College of Medicine, Seoul, Korea.
authors.forename: Kwang Moon
authors.initials: KM
authors.lastname: Yang
authors.affiliation: Division of Reproductive Endocrinology and Infertility, Department Obstetrics and Gynecology, Cheil General Hospital and Women's Healthcare Center, Catholic Kwandong University College of Medicine, Seoul, Korea.
authors.forename: In Ok
authors.initials: IO
authors.lastname: Song
keywords: Follicular synchronization; GnRH antagonist; LH