title: The likelihood of live birth and multiple birth after single versus double embryo transfer at the cleavage stage: a systematic review and meta-analysis.
abstract: OBJECTIVE
  To determine whether a policy of elective single-embryo transfer (e-SET) lowers the multiple birth rate without compromising the live birth rate.
  
  
  METHODS
  Systematic review and meta-analysis.
  
  
  METHODS
  Tertiary referral center for reproductive medicine and IVF unit.
  
  
  METHODS
  None.
  
  
  METHODS
  Searches of the Cochrane Controlled Trials Register, Meta-register for Randomized Controlled Trials (RCTs), EMBASE, MEDLINE, and SCISEARCH with no limitation on language and publication year, 1974 to 2008.
  
  
  METHODS
  randomized, controlled trials comparing e-SET with double-embryo transfer (DET) for live birth and multiple birth rates after in vitro fertilization (IVF) with or without intracytoplasmic sperm injection (ICSI). Nonrandomized trials and studies that included only patients who had blastocyst transfer were excluded.
  
  
  METHODS
  The likelihood of live birth per patient and multiple birth per total number of live births. Other outcomes included implantation rate, pregnancy rate, miscarriage and ectopic pregnancy rates, clinical pregnancy rate, ongoing pregnancy rate per patient, and preterm delivery rate per live birth.
  
  
  RESULTS
  Six trials (n=1354 patients) were included in the meta-analysis. Compared with DET, the e-SET policy was associated with a statistically significant reduction in the probability of live birth (RR 0.62; 95% CI, 0.53-0.72) and multiple birth (RR 0.06; 95% CI, 0.02-0.18).
  
  
  CONCLUSIONS
  Elective-SET of embryos at the cleavage stage reduces the likelihood of live birth by 38% and multiple birth by 94%. Evidence from randomized, controlled trials suggests that increasing the number of e-SET attempts (fresh and/or frozen) results in a cumulative live birth rate similar to that of DET. Offering subfertile women three cycles of IVF will have a major impact on the uptake of an e-SET policy.
authors.affiliation: Department of Reproductive Medicine, IVF Unit, Saint Mary's Hospital, Manchester, United Kingdom.
authors.forename: Tarek A
authors.initials: TA
authors.lastname: Gelbaya
authors.forename: Ioanna
authors.initials: I
authors.lastname: Tsoumpou
authors.forename: Luciano G
authors.initials: LG
authors.lastname: Nardo
mesh_terms: D002970:Cleavage Stage, Ovum / Q000502:physiology*; D004624:Embryo Transfer / Q000379:methods / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D016013:Likelihood Functions; D050498:Live Birth / Q000453:epidemiology*; D011247:Pregnancy; D018873:Pregnancy Rate; D011272:Pregnancy, Multiple / Q000706:statistics & numerical data*; D056826:Single Embryo Transfer / Q000706:statistics & numerical data*; D016896:Treatment Outcome