title: Evidence of impaired endometrial receptivity after ovarian stimulation for in vitro fertilization: a prospective randomized trial comparing fresh and frozen-thawed embryo transfer in normal responders.
abstract: OBJECTIVE
  To compare success rates between fresh ETs after ovarian stimulation and frozen-thawed ETs (FET) after artificial endometrial preparation, to compare endometrial receptivity.
  
  
  METHODS
  Randomized, controlled trial.
  
  
  METHODS
  Private fertility center.
  
  
  METHODS
  There were 53 patients completing fresh blastocyst transfer (fresh group) and 50 patients completing FET (cryopreservation group). All were first-time IVF patients aged <41 years, with cycle day 3 FSH <10 mIU/mL and 8-15 antral follicles.
  
  
  METHODS
  Randomized to fresh or thawed ET.
  
  
  METHODS
  Clinical pregnancy rate per transfer.
  
  
  RESULTS
  The clinical pregnancy rate per transfer was 84.0% in the cryopreservation group and 54.7% in the fresh group. The implantation rates were 70.8% and 38.9%, respectively. The ongoing pregnancy rates per transfer (at 10 weeks' gestation) were 78.0% and 50.9%, respectively. The attributable risk percentage of implantation failure due to reduced endometrial receptivity in the fresh group was 64.7%.
  
  
  CONCLUSIONS
  The clinical pregnancy rate per transfer was significantly greater in the cryopreservation group than in the fresh group. These results strongly suggest impaired endometrial receptivity in fresh ET cycles after ovarian stimulation, when compared with FET cycles with artificial endometrial preparation. Impaired endometrial receptivity apparently accounted for most implantation failures in the fresh group. ClinicalTrials.gov Identifier: NCT00963625.
authors: Fertility Center of Las Vegas, Las Vegas, Nevada, USA. bsshapiro@aol.com
authors: Bruce S
authors: BS
authors: Shapiro
authors: Said T
authors: ST
authors: Daneshmand
authors: Forest C
authors: FC
authors: Garner
authors: Martha
authors: M
authors: Aguirre
authors: Cynthia
authors: C
authors: Hudson
authors: Shyni
authors: S
authors: Thomas
mesh_terms: D000328:Adult; D015925:Cryopreservation; D010064:Embryo Implantation; D004624:Embryo Transfer / Q000009:adverse effects; D004622:Embryo, Mammalian; D004717:Endometrium / Q000503:physiopathology*; D005260:Female; D005307:Fertilization in Vitro / Q000009:adverse effects; D006801:Humans; D007246:Infertility / Q000503:physiopathology / Q000628:therapy*; D016015:Logistic Models; D009505:Nevada; D010062:Ovulation Induction / Q000009:adverse effects; D011247:Pregnancy; D018873:Pregnancy Rate; D011446:Prospective Studies; D016896:Treatment Outcome