title: Live birth rate is significantly higher after blastocyst transfer than after cleavage-stage embryo transfer when at least four embryos are available on day 3 of embryo culture. A randomized prospective study.
abstract: BACKGROUND
  In a randomized controlled trial, we assessed whether pregnancy outcome would be improved by extending embryo culture to day 5 and transferring a blastocyst in patients with at least four good-quality embryos on day 3.
  
  
  METHODS
  Multifollicular ovarian stimulation was performed with a GnRH agonist in 44% of patients and with a GnRH antagonist in 56%. Overall, 164 patients younger than 37 years fulfilled embryo quality criteria (at least four having at least six cells on the morning of day 3, maximum 20% anucleate fragments) on the third day of culture and were randomized to the day 3 (n = 84) or day 5 (n = 80) groups. Equal numbers of embryos (n = 2) were transferred in each group.
  
  
  RESULTS
  Demographics, stimulation parameters and embryological data were comparable in the two groups. Blastocyst-stage transfer resulted in a significantly higher ongoing pregnancy rate [51.3 versus 27.4%; odds ratio (OR) 2.78, 95% confidence interval (CI) 1.45-5.34] and live birth rate (47.5 versus 27.4%; OR 2.40, 95% CI 1.25-4.59) compared with day-3 embryo transfer. A high twin birth rate was observed in both groups (36.8 versus 30.4%; P > 0.05).
  
  
  CONCLUSIONS
  A threshold of four good embryos on the third day of embryo culture appears to indicate that the patient will benefit from embryo transfer at the blastocyst stage and have a better chance of achieving a live delivery than with cleavage-stage embryo transfer.
authors.affiliation: Centre for Reproductive Medicine, University Hospital, Vrije Univestiteit Brussel (Free University of Brussels), Laarbeeklaaan 101, B-1090, Brussels, Belgium. Evangelos.Papanikolau@vib.ac.be
authors.forename: Evangelos G
authors.initials: EG
authors.lastname: Papanikolaou
authors.forename: Elke
authors.initials: E
authors.lastname: D'haeseleer
authors.forename: Greta
authors.initials: G
authors.lastname: Verheyen
authors.forename: Hilde
authors.initials: H
authors.lastname: Van de Velde
authors.forename: Michael
authors.initials: M
authors.lastname: Camus
authors.forename: Andre
authors.initials: A
authors.lastname: Van Steirteghem
authors.forename: Paul
authors.initials: P
authors.lastname: Devroey
authors.forename: Herman
authors.initials: H
authors.lastname: Tournaye
mesh_terms: D000328:Adult; D001755:Blastocyst; D002064:Buserelin / Q000627:therapeutic use; D002970:Cleavage Stage, Ovum / Q000637:transplantation; D046149:Embryo Culture Techniques; D004624:Embryo Transfer; D005260:Female; D006801:Humans; D050498:Live Birth; D008596:Menotropins / Q000627:therapeutic use; D011247:Pregnancy; D011272:Pregnancy, Multiple; D013997:Time Factors
chemical_list: D008596:Menotropins; D002064:Buserelin