title: Implantation rates after in vitro fertilization and transfer of a maximum of two embryos that have undergone three to five days of culture.
abstract: OBJECTIVE
  To evaluate implantation and pregnancy rates in patients undergoing IVF after the transfer of a maximum of two embryos that had been cultured for 3-5 days.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  An IVF laboratory at a tertiary referral university hospital.
  
  
  METHODS
  One thousand seven hundred eighty-seven couples who underwent their first IVF cycle between January 1995 and December 1997.
  
  
  METHODS
  In vitro fertilization and transfer of embryos after 3, 4, or 5 days of culture using a single medium without coculture.
  
  
  METHODS
  Implantation and pregnancy rates.
  
  
  RESULTS
  Overall implantation and pregnancy rates were not significantly different with different culture periods. Forty-one percent of all available embryos developed into blastocysts on day 5. The transfer of at least one good-quality blastocyst could be performed in 62% of patients. Blastocysts had an implantation rate of 26% per embryo, whereas the implantation rate of eight-cell embryos on day 3 was 18%. Implantation rates for retarded, normal, and advanced embryos were not significantly different with an extended culture period.
  
  
  CONCLUSIONS
  Under the study conditions, the transfer of embryos after 5 days rather than 3 days of embryo culture did not change the overall implantation and pregnancy rates. The implantation potential of embryos available for transfer can be assessed better after an extended culture period. Five days of culture allows the transfer of a reduced number of embryos without decreasing overall pregnancy rates.
authors.affiliation: Department of Obstetrics and Gynecology, Erasmus University Medical Center Rotterdam, Rotterdam, The Netherlands.
authors.forename: G J
authors.initials: GJ
authors.lastname: Huisman
authors.forename: B C
authors.initials: BC
authors.lastname: Fauser
authors.forename: M J
authors.initials: MJ
authors.lastname: Eijkemans
authors.forename: M H
authors.initials: MH
authors.lastname: Pieters
mesh_terms: D000328:Adult; D001755:Blastocyst / Q000502:physiology; D046508:Culture Techniques; D010064:Embryo Implantation; D004624:Embryo Transfer; D004622:Embryo, Mammalian / Q000502:physiology; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D011247:Pregnancy; D011446:Prospective Studies; D013997:Time Factors