title: Frozen-thawed embryo transfer is associated with a significantly reduced incidence of ectopic pregnancy.
abstract: OBJECTIVE
  To compare the incidence of ectopic pregnancy (EP) after fresh ET and thawed ET.
  
  
  METHODS
  Retrospective cohort study.
  
  
  METHODS
  Private fertility center.
  
  
  METHODS
  This retrospective study included 2,150 blastocyst transfers, including all 1,460 fresh autologous blastocyst transfers and all 690 transfers of autologous blastocysts derived from post-thaw extended culture of thawed bipronuclear oocytes in the 8-year study period 2004-2011.
  
  
  METHODS
  None.
  
  
  METHODS
  Visualized EP and treated persistent pregnancy of unknown location.
  
  
  RESULTS
  The rate of visualized EP was 1.5% in pregnancies in fresh autologous cycles, which was significantly more than the rate of 0 with autologous post-thaw extended culture. The rates of treated persistent pregnancy of unknown location were 2.5% and 0.3% in these two groups, respectively, a difference that was also statistically significant (relative risk 7.3, 95% confidence interval 1.7-31.0).
  
  
  CONCLUSIONS
  Relative to fresh transfer, thawed ET was associated with significantly reduced incidence of EP. These findings are consistent with ovarian stimulation increasing the risk of EP.
authors.affiliation: Fertility Center of Las Vegas, Las Vegas, Nevada 89117, USA. bsshapiro@aol.com
authors.forename: Bruce S
authors.initials: BS
authors.lastname: Shapiro
authors.forename: Said T
authors.initials: ST
authors.lastname: Daneshmand
authors.forename: Laura
authors.initials: L
authors.lastname: De Leon
authors.forename: Forest C
authors.initials: FC
authors.lastname: Garner
authors.forename: Martha
authors.initials: M
authors.lastname: Aguirre
authors.forename: Cynthia
authors.initials: C
authors.lastname: Hudson
mesh_terms: D000328:Adult; D015925:Cryopreservation / Q000706:statistics & numerical data*; D004624:Embryo Transfer / Q000379:methods* / Q000706:statistics & numerical data*; D005260:Female; D059247:Fertility Preservation / Q000706:statistics & numerical data*; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D009505:Nevada / Q000453:epidemiology; D011247:Pregnancy; D011271:Pregnancy, Ectopic / Q000453:epidemiology* / Q000517:prevention & control*; D012307:Risk Factors; D055815:Young Adult