title: Does a vitrified blastocyst stage embryo transfer program need hormonal priming for endometrial preparation?
abstract: OBJECTIVE
  To compare the clinical outcomes of a vitrified blastocyst stage embryo transfer (ET) program among natural, ovulation induced and artificial cycles.
  
  
  METHODS
  The clinical outcomes were retrospectively analyzed in three groups according to endometrial preparation (natural cycle group [n = 34], ovulation induced [n = 21], and artificial cycles [n = 70]) among women that underwent vitrified blastocyst stage ET.
  
  
  RESULTS
  The overall pregnancy rate was 48.8%. There were no significant differences in the duration of endometrial preparation, endometrial thickness on the day of progesterone or human chorionic gonadotropin administration, implantation and clinical pregnancy rates among the three groups. Triple-line endometrial patterns were more frequently observed in the natural and ovulation induced groups than in the artificial cycle group (85.3% vs 64.3%, P = 0.021; 90.5% vs 64.3%, P = 0.016).
  
  
  CONCLUSIONS
  Our findings suggest that the types of endometrial preparation may have no significant effect on the clinical outcomes of vitrified blastocyst ET. Hormonal priming does not appear to be a prerequisite for endometrial preparation for vitrified blastocyst ET.
authors.affiliation: Department of Obstetrics and Gynecology, College of Medicine, Medical Research Center, Seoul National University, Seoul, Korea.
authors.forename: Yong Jin
authors.initials: YJ
authors.lastname: Kim
authors.forename: Young Sik
authors.initials: YS
authors.lastname: Choi
authors.forename: Won Don
authors.initials: WD
authors.lastname: Lee
authors.forename: Ki Chul
authors.initials: KC
authors.lastname: Kim
authors.forename: Byung Chul
authors.initials: BC
authors.lastname: Jee
authors.forename: Chang Suk
authors.initials: CS
authors.lastname: Suh
authors.forename: Seok Hyun
authors.initials: SH
authors.lastname: Kim
authors.forename: Shin Yong
authors.initials: SY
authors.lastname: Moon
mesh_terms: D004624:Embryo Transfer / Q000379:methods*; D004717:Endometrium / Q000187:drug effects*; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D006801:Humans; D010062:Ovulation Induction / Q000379:methods*; D011247:Pregnancy; D011374:Progesterone / Q000494:pharmacology; D018709:Statistics, Nonparametric; D016896:Treatment Outcome
chemical_list: D011374:Progesterone; D004958:Estradiol