title: In unselected patients, elective single embryo transfer prevents all multiples, but results in significantly lower pregnancy rates compared with double embryo transfer: a randomized controlled trial.
abstract: BACKGROUND
  Elective single embryo transfer (eSET) in a selected group of patients (i.e. young patients with at least one good quality embryo) reduces the number of multiple pregnancies in an IVF programme. However, the reduced overall multiple pregnancy rate (PR) is still unacceptably high. Therefore, a randomized controlled trial (RCT) was conducted comparing eSET and double embryo transfer (DET) in an unselected group of patients (i.e. irrespective of the woman's age or embryo quality).
  
  
  METHODS
  Consenting unselected patients were randomized between eSET (RCT-eSET) (n = 154) or DET (RCT-DET) (n = 154). Randomization was performed just prior to the first embryo transfer, provided that at least two 2PN zygotes were available. Non-participants received our standard transfer policy [SP-eSET in a selected group of patients (n = 100), otherwise SP-DET (n = 122)].
  
  
  RESULTS
  The ongoing PR after RCT-eSET was significantly lower as compared with RCT-DET (21.4 versus 40.3%) and the twin PR was reduced from 21.0% after RCT-DET to 0% after RCT-eSET. The ongoing PRs after SP-eSET and SP-DET did not differ significantly (33.0 versus 30.3%), with an overall twin PR of 12.9%.
  
  
  CONCLUSIONS
  To avoid twin pregnancies resulting from an IVF treatment, eSET should be applied in all patients. The consequence would be a halving of the ongoing PR as compared with applying a DET policy in all patients. The transfer of one embryo in a selected group of good prognosis patients leads to a less drastic reduction in PR but maintains a twin PR of 12.9%.
authors.affiliation: Research Institute Growth & Development (GROW), Department of Obstetrics & Gynaecology, Academic Hospital Maastricht, PO Box 5800, 6202 AZ Maastricht, The Netherlands. avmn@sgyn.azm.nl
authors.forename: Aafke P A
authors.initials: AP
authors.lastname: van Montfoort
authors.forename: Audrey A A
authors.initials: AA
authors.lastname: Fiddelers
authors.forename: J Marij
authors.initials: JM
authors.lastname: Janssen
authors.forename: Josien G
authors.initials: JG
authors.lastname: Derhaag
authors.forename: Carmen D
authors.initials: CD
authors.lastname: Dirksen
authors.forename: Gerard A J
authors.initials: GA
authors.lastname: Dunselman
authors.forename: Jolande A
authors.initials: JA
authors.lastname: Land
authors.forename: Joep P M
authors.initials: JP
authors.lastname: Geraedts
authors.forename: Johannes L H
authors.initials: JL
authors.lastname: Evers
authors.forename: John C M
authors.initials: JC
authors.lastname: Dumoulin
mesh_terms: D000328:Adult; D004624:Embryo Transfer; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D009426:Netherlands; D018579:Patient Selection; D011247:Pregnancy; D018873:Pregnancy Rate; D011272:Pregnancy, Multiple / Q000706:statistics & numerical data; D014427:Twins