title: The strategy of group embryo culture based on pronuclear pattern on blastocyst development: a two center analysis.
abstract: OBJECTIVE
  To compare two embryo grouping strategies.
  
  
  METHODS
  Retrospective time-course analysis in two different centres. Two culture protocols were used at the zygote stage: "Random Group" in which zygotes were randomly grouped and "Definite Group" in which zygotes were grouped based on pronuclear pattern. Embryo culture was extended to blastocyst stage. Primary and secondary outcomes were respectively the blastulation rate and the cumulative clinical pregnancy and implantation rates.
  
  
  RESULTS
  A similar blastulation rate [42 and 41% day (5 + 6) blastocysts] was obtained in the two groups. Conversely, after adjusting for baseline and cycle variables, cumulative pregnancy [adjusted Odds Ratio = 2.10 (95%CI: 1.08-4.07)] and implantation [adjusted Odds Ratio = 1.78 (95%CI: 1.06-2.97)] rates were significantly higher in the "Random Group" compared to the "Definite Group".
  
  
  CONCLUSIONS
  Two strategies of group culture gave similar results in terms of blastulation rate but the random grouping of zygotes improves pregnancy and implantation rates in IVF-cycles.
authors.affiliation: Infertility Unit, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Ca' Granda, Ospedale Maggiore Policlinico, Via M. Fanti 6, 20122, Milan, Italy.
authors.forename: Liliana
authors.initials: L
authors.lastname: Restelli
authors.forename: Alessio
authors.initials: A
authors.lastname: Paffoni
authors.forename: Laura
authors.initials: L
authors.lastname: Corti
authors.forename: Elisa
authors.initials: E
authors.lastname: Rabellotti
authors.forename: Alice
authors.initials: A
authors.lastname: Mangiarini
authors.forename: Paola
authors.initials: P
authors.lastname: Viganò
authors.forename: Edgardo
authors.initials: E
authors.lastname: Somigliana
authors.forename: Enrico
authors.initials: E
authors.lastname: Papaleo
mesh_terms: D000328:Adult; D001755:Blastocyst / Q000502:physiology*; D002970:Cleavage Stage, Ovum / Q000502:physiology; D015925:Cryopreservation; D010064:Embryo Implantation / Q000502:physiology*; D004624:Embryo Transfer; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D011247:Pregnancy; D018873:Pregnancy Rate