title: Frozen-thawed day 5 blastocyst transfer is associated with a lower risk of ectopic pregnancy than day 3 transfer and fresh transfer.
abstract: OBJECTIVE
  To determine the ectopic pregnancy rate with fresh versus frozen-thawed embryo transfers, and factors associated with ectopic pregnancy in patients undergoing IVF-ET.
  
  
  METHODS
  Retrospective analysis.
  
  
  METHODS
  Institutional IVF center.
  
  
  METHODS
  A total of 3,183 patients who received 3,340 blastocysts transfers: 1,994 fresh transfers and 1,346 frozen-thawed transfers.
  
  
  METHODS
  Patients received fresh day 3 embryos (F-D3 group), fresh day 5 blastocysts (F-D5 group), frozen-thawed day 3 embryos (T-D3 group), or frozen-thawed day 5 or 6 blastocysts (T-D5 and T-D6 groups).
  
  
  METHODS
  Ectopic pregnancy rate.
  
  
  RESULTS
  The ectopic pregnant rates were 2.4% in the F-D3 group, 1.7% in F-D5, 1.9% in T-D3, 0.3% in T-D5, and 0.5% in T-D6. The ectopic pregnant rate of the T-D3 group was significantly greater than that of the T-D5 and T-D6 groups (1.9% vs. 0.3% and 0.5%). The ectopic pregnancy rate of the F-D5 group was significantly greater than that of the T-D5 group (1.7% vs. 0.3%).
  
  
  CONCLUSIONS
  Frozen-thawed day 5 blastocyst transfer is associated with a lower ectopic pregnancy rate than frozen-thawed day 3 transfer and fresh transfer in patients undergoing IVF-ET.
authors.affiliation: Reproductive Medicine Research Center, Sixth Affiliated Hospital, Sun Yat-Sen University, Guangzhou, People's Republic of China. Electronic address: fangconggd@hotmail.com.
authors.forename: Cong
authors.initials: C
authors.lastname: Fang
authors.affiliation: Reproductive Medicine Research Center, Sixth Affiliated Hospital, Sun Yat-Sen University, Guangzhou, People's Republic of China.
authors.forename: Rui
authors.initials: R
authors.lastname: Huang
authors.affiliation: Reproductive Medicine Research Center, Sixth Affiliated Hospital, Sun Yat-Sen University, Guangzhou, People's Republic of China.
authors.forename: Li-Na
authors.initials: LN
authors.lastname: Wei
authors.affiliation: Reproductive Medicine Research Center, Sixth Affiliated Hospital, Sun Yat-Sen University, Guangzhou, People's Republic of China.
authors.forename: Lei
authors.initials: L
authors.lastname: Jia
mesh_terms: D000328:Adult; D001755:Blastocyst; D002970:Cleavage Stage, Ovum / Q000502:physiology*; D004624:Embryo Transfer / Q000379:methods* / Q000706:statistics & numerical data; D005260:Female; D005615:Freezing; D006801:Humans; D007246:Infertility / Q000453:epidemiology / Q000628:therapy; D011247:Pregnancy; D018873:Pregnancy Rate; D011271:Pregnancy, Ectopic / Q000453:epidemiology / Q000209:etiology*; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors
keywords: Blastocyst; IVF; ectopic pregnancy; embryo; ovarian stimulation