title: Insights on blastomere nuclearity.
abstract: OBJECTIVE
  To analyze the results of our transferred embryos, especially those that "changed" their blastomere nuclearity from Multinucleated (MN) to Mono-nucleated during development.
  
  
  METHODS
  Pregnancies where at least one MN embryo was transferred were retrospectively evaluated and categorized in order to record and follow-up on the ones that were implanted. Embryos were classified as normal (when all blastomeres were mono-nucleated on day one and two of development), corrected (multinucleated embryos on day one that became mono-nucleated on day two) and non-corrected (multinucleated either on day one, on day two or both days).
  
  
  RESULTS
  There were 633 transfer cycles analyzed. Thirty-three percent (206) had at least one embryo with a MN blastomere at a given stage of development. Pregnancy and implantation rates were 29.0% and 19.0% for the group of exclusively mono-nucleated embryo transfers, and 28.6% and 15.8% for the group with at least one MN embryo transferred. The pregnancy outcome for "corrected" and "non-corrected" embryos could be corroborated unequivocally in only 9 cases, with an outcome of 8 and 4 normal babies, respectively.
  
  
  CONCLUSIONS
  Because the amount of data analyzed is not satisfactorily large, differences were not significantly different; however, a trend may exist showing that normal at term pregnancies obtained from corrected embryos are more likely to occur than those from non-corrected embryos. Nuclear observation on a daily basis should be one of the strategies used to select the best embryos for transferring, to improve implantation rates and avoid multiple pregnancies.
authors.affiliation: Clínica de Fertilidad, Centro Médico Docente La Trinidad, Caracas, Venezuela. mgilco@cantv.net
authors.forename: Mónica
authors.initials: M
authors.lastname: Gil
authors.forename: Gustavo
authors.initials: G
authors.lastname: D'Ommar
authors.forename: Maria E
authors.initials: ME
authors.lastname: Póo
authors.forename: Anna
authors.initials: A
authors.lastname: Sosa
authors.forename: Marta
authors.initials: M
authors.lastname: Piras
authors.forename: Romano
authors.initials: R
authors.lastname: Piras
authors.forename: Francisco
authors.initials: F
authors.lastname: Rísquez
mesh_terms: D001757:Blastomeres / Q000166:cytology*; D002467:Cell Nucleus; D004624:Embryo Transfer; D004622:Embryo, Mammalian / Q000166:cytology; D047108:Embryonic Development; D005260:Female; D006801:Humans; D011247:Pregnancy; D011256:Pregnancy Outcome