title: Serum Oestradiol Pattern during Coasting is Different in Antagonist Cycles Compared with Long Agonist Cycles in In Vitro Fertilisation.
abstract: BACKGROUND
  GnRH agonists and antagonists have different mechanism of action, and therefore serum estradiol levels might differ during coasting in IVF.
  
  
  OBJECTIVE
  To compare the change in serum oestradiol levels after withholding the gonadotropins for coasting between long agonist and antagonist cycles.
  
  
  METHODS
  Retrospective study.
  
  
  METHODS
  Antagonist and long agonist cycles, in which coasting was performed, were analysed in this retrospective analysis. Antagonist cycles (n=50) were compared with long agonist cycles (n=52) with respect to daily serum oestradiol levels following withholding of gonadotropins.
  
  
  RESULTS
  The pattern of change in serum oestradiol was different between groups; it increased on the first day by 11.2% and decreased thereafter on the second and third days in the agonist group. However, it began to decrease from the first day in the antagonist group. Therefore, peak serum oestradiol levels were significantly higher in the agonist group than in the antagonist group (mean±standard deviation; 5798±1748 vs 5104±1351 pg/mL). The duration of coasting was shorter in the antagonist group compared with that in the agonist group (mean±standard deviation; 2.60±1.40 vs 1.96±0.88 days).
  
  
  CONCLUSIONS
  Serum oestradiol pattern during coasting is different in antagonist cycles compared with long agonist cycles in in vitro fertilisation.
authors.affiliation: Department of Obstetrics and Gynecology, Trakya University Faculty of Medicine, Edirne, Turkey.
authors.forename: Koray
authors.initials: K
authors.lastname: Elter
authors.affiliation: Eurofertil Reproductive Health Center, İstanbul, Turkey.
authors.forename: Tijen Alev
authors.initials: TA
authors.lastname: Ozay
authors.affiliation: Eurofertil Reproductive Health Center, İstanbul, Turkey.
authors.forename: Elif
authors.initials: E
authors.lastname: Ergin
authors.affiliation: Eurofertil Reproductive Health Center, İstanbul, Turkey.
authors.forename: Murat Hakan
authors.initials: MH
authors.lastname: Ozörnek
keywords: Estradiol; GnRH antagonists; Ovarian Hyperstimulation Syndrome; coasting