title: Fresh embryo transfer versus frozen embryo transfer in in vitro fertilization cycles: a systematic review and meta-analysis.
abstract: OBJECTIVE
  To examine the available evidence to assess if cryopreservation of all embryos and subsequent frozen embryo transfer (FET) results in better outcomes compared with fresh transfer.
  
  
  METHODS
  Systematic review and meta-analysis.
  
  
  METHODS
  Centers for reproductive care.
  
  
  METHODS
  Infertility patient(s).
  
  
  METHODS
  An exhaustive electronic literature search in MEDLINE, EMBASE, and the Cochrane Library was performed through December 2011. We included randomized clinical trials comparing outcomes of IVF cycles between fresh and frozen embryo transfers.
  
  
  METHODS
  The outcomes of interest were ongoing pregnancy rate, clinical pregnancy rate, and miscarriage.
  
  
  RESULTS
  We included three trials accounting for 633 cycles in women aged 27-33 years. Data analysis showed that FET resulted in significantly higher ongoing pregnancy rates and clinical pregnancy rates.
  
  
  CONCLUSIONS
  Our results suggest that there is evidence that IVF outcomes may be improved by performing FET compared with fresh embryo transfer. This could be explained by a better embryo-endometrium synchrony achieved with endometrium preparation cycles.
authors.affiliation: Máster Internacional Medicina Reproductiva, Hospital del Mar, Universitat Autònoma de Barcelona, Barcelona, Spain; Origen Center for Reproductive Medicine, Belo Horizonte, Brazil.
authors.forename: Matheus
authors.initials: M
authors.lastname: Roque
authors.affiliation: Máster Internacional Medicina Reproductiva, Hospital del Mar, Universitat Autònoma de Barcelona, Barcelona, Spain; Centro de Infertilidad y Reproducción Humana, Barcelona, Spain.
authors.forename: Karinna
authors.initials: K
authors.lastname: Lattes
authors.affiliation: Máster Internacional Medicina Reproductiva, Hospital del Mar, Universitat Autònoma de Barcelona, Barcelona, Spain; Centro de Infertilidad y Reproducción Humana, Barcelona, Spain.
authors.forename: Sandra
authors.initials: S
authors.lastname: Serra
authors.affiliation: Iberoamerican Cochrane Center, Barcelona, Spain; Institute of Biomedical Research (IIB Sant Pau), Barcelona, Spain; CIBER Epidemiología y Salud Pública, Barcelona, Spain.
authors.forename: Ivan
authors.initials: I
authors.lastname: Solà
authors.affiliation: Origen Center for Reproductive Medicine, Belo Horizonte, Brazil; Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
authors.forename: Selmo
authors.initials: S
authors.lastname: Geber
authors.affiliation: Department of Obstetrics and Gynecology, Parc de Salut Mar, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Ramón
authors.initials: R
authors.lastname: Carreras
authors.affiliation: Department of Obstetrics and Gynecology, Parc de Salut Mar, Universitat Autònoma de Barcelona, Barcelona, Spain; Centro de Infertilidad y Reproducción Humana, Barcelona, Spain. Electronic address: macheca@parcdesalutmar.cat.
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Checa
mesh_terms: D000022:Abortion, Spontaneous; D000328:Adult; D015925:Cryopreservation; D004624:Embryo Transfer / Q000379:methods*; D004717:Endometrium / Q000502:physiology; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods*; D006801:Humans; D007247:Infertility, Female / Q000628:therapy*; D017063:Outcome Assessment, Health Care; D011247:Pregnancy; D018873:Pregnancy Rate