title: Cryopreserved-thawed human embryo transfer: spontaneous natural cycle is superior to human chorionic gonadotropin-induced natural cycle.
abstract: OBJECTIVE
  To assess whether there is a difference in the ongoing pregnancy rate after transferring frozen-thawed embryos in natural cycles with spontaneous LH-P rise compared with natural cycles controlled by hCG for final oocyte maturation and ovulation.
  
  
  METHODS
  Randomized controlled trial.
  
  
  METHODS
  Tertiary referral center.
  
  
  METHODS
  A total of 168 patients were assigned randomly to undergo frozen ET on day 3 from October 2007 until November 2008. Finally, analysis was performed in 124 patients; 61 belonged to the spontaneous LH group and 63 to the hCG group.
  
  
  METHODS
  In the spontaneous LH group the transfer was planned 5 days after the LH surge. In the hCG group, the cryopreserve ET was planned 5 days after the administration of 5000 IU of hCG, when an endometrial thickness of ≥7 mm and a follicle of ≥17 mm were present on ultrasound examination.
  
  
  METHODS
  Ongoing pregnancy rate.
  
  
  RESULTS
  The study was terminated early, when a prespecified interim analysis found a significantly higher ongoing pregnancy rate in the spontaneous LH group as compared with the hCG group (31.1% vs. 14.3%; difference 16.9%, 95% confidence interval 4.4%-28.8%).
  
  
  CONCLUSIONS
  The results suggest the superiority of the natural cycle as compared with the natural cycle controlled by hCG administration in cryothawed ET cycles.
authors.affiliation: Center for Reproductive Medicine, Department of Pathology, Dutch-Speaking Free University Brussels, Brussels, Belgium. hmousavi@uzbrussel.be
authors.forename: Human Mousavi
authors.initials: HM
authors.lastname: Fatemi
authors.forename: Dimitra
authors.initials: D
authors.lastname: Kyrou
authors.forename: Claire
authors.initials: C
authors.lastname: Bourgain
authors.forename: Etienne
authors.initials: E
authors.lastname: Van den Abbeel
authors.forename: Georg
authors.initials: G
authors.lastname: Griesinger
authors.forename: Paul
authors.initials: P
authors.lastname: Devroey
mesh_terms: D000328:Adult; D001755:Blastocyst; D006063:Chorionic Gonadotropin / Q000009:adverse effects / Q000097:blood / Q000494:pharmacology / Q000627:therapeutic use*; D015925:Cryopreservation; D004624:Embryo Transfer / Q000379:methods*; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods; D006801:Humans; D007986:Luteinizing Hormone / Q000097:blood; D008597:Menstrual Cycle / Q000097:blood / Q000187:drug effects* / Q000502:physiology*; D010062:Ovulation Induction / Q000009:adverse effects; D011247:Pregnancy; D018873:Pregnancy Rate; D011786:Quality Control
chemical_list: D006063:Chorionic Gonadotropin; D007986:Luteinizing Hormone