title: The added value of embryo cryopreservation to cumulative ongoing pregnancy rates per IVF treatment: is cryopreservation worth the effort?
abstract: OBJECTIVE
  To calculate the added benefit of a cryopreservation program to the cumulative ongoing pregnancy rate over a maximum of three cycles of IVF.
  
  
  METHODS
  A total of 1251 couples beginning their first IVF treatment between January 1995 and December 1999 were evaluated. Ongoing pregnancies from fresh and subsequent cryopreserved embryo transfer cycles were analyzed. Pregnancies arising from the cryopreservation cycle were considered to augment the cumulative pregnancy rate when no ongoing pregnancy arose from the fresh embryo transfer cycle.
  
  
  RESULTS
  The ongoing pregnancy rate per cryopreserved embryo transfer was 11.7%. The cumulative ongoing pregnancy rate following three successive started fresh IVF cycles was 42.5%. When pregnancies arising from the transfer of thawed cryopreserved embryos were included, the cumulative ongoing pregnancy rate increased to 43.8%, rising to 44.8% when extrapolated data from as yet unthawed embryos was included.
  
  
  CONCLUSIONS
  When analyzed in these terms, the supplementary benefit of cryopreserving supranumerical embryos appears limited.
authors.affiliation: Division of Reproductive Medicine, Department of Obstetrics and Gynaecology, Erasmus Medical Centre, Rotterdam, The Netherlands.
authors.forename: D
authors.initials: D
authors.lastname: de Jong
authors.forename: M J C
authors.initials: MJ
authors.lastname: Eijkemans
authors.forename: N G M
authors.initials: NG
authors.lastname: Beckers
authors.forename: R V
authors.initials: RV
authors.lastname: Pruijsten
authors.forename: B C J M
authors.initials: BC
authors.lastname: Fauser
authors.forename: N S
authors.initials: NS
authors.lastname: Macklon
mesh_terms: D000328:Adult; D015925:Cryopreservation / Q000706:statistics & numerical data*; D004624:Embryo Transfer / Q000706:statistics & numerical data; D004622:Embryo, Mammalian; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods / Q000706:statistics & numerical data*; D006801:Humans; D008137:Longitudinal Studies; D011247:Pregnancy; D018873:Pregnancy Rate; D016896:Treatment Outcome