title: Can fresh embryo transfers be replaced by cryopreserved-thawed embryo transfers in assisted reproductive cycles? A randomized controlled trial.
abstract: OBJECTIVE
  Controlled ovarian hyperstimulation has been shown to advance endometrial maturation and adversely affects implantation in ART. It has been reported that there is a better embryo-endometrium synchrony in frozen-thawed embryo transfer cycles than fresh embryo transfer cycles. The objective of this study was to compare ongoing pregnancy rates between fresh ET and FET cycles.
  
  
  METHODS
  In an open prospective, controlled study, the patients who were classified as high responders, were randomized to either fresh ET or FET. The embryos in FET group were cryopreserved with vitrification by Cryotop method.
  
  
  RESULTS
  A total of 374 patients were included, 187 of which were randomized to FET and 187 to fresh ET. There were 39% (n = 73) ongoing pregnancy in FET group compared with 27.8% (n = 52) in fresh ET group[odds ratio = 1.66;95% confidence interval = 1.07-2.56; p = 0.02].
  
  
  CONCLUSIONS
  FETs can be performed instead of fresh ETs to improve the outcome of ART in highly selected patients.
authors.affiliation: Research and Clinical Center for Infertility, Department of Obstetrics and Gynecology, Shahid Sadoughi University of Medical Science, Safaieh, Yazd, Iran. abbas_aflatoonian@yahoo.com
authors.forename: Abbas
authors.initials: A
authors.lastname: Aflatoonian
authors.forename: Homa
authors.initials: H
authors.lastname: Oskouian
authors.forename: Shahnaz
authors.initials: S
authors.lastname: Ahmadi
authors.forename: Leila
authors.initials: L
authors.lastname: Oskouian
mesh_terms: D000328:Adult; D015925:Cryopreservation / Q000379:methods*; D010064:Embryo Implantation; D004624:Embryo Transfer / Q000379:methods*; D004622:Embryo, Mammalian; D005260:Female; D006801:Humans; D011247:Pregnancy; D018873:Pregnancy Rate; D011446:Prospective Studies