title: Increased blastomere number in cleavage-stage embryos is associated with higher aneuploidy.
abstract: OBJECTIVE
  To evaluate the relationship between blastomere number and aneuploidy.
  
  
  METHODS
  Historical cohort study.
  
  
  METHODS
  In vitro fertilization clinic.
  
  
  METHODS
  Two hundred fifty-nine patients undergoing in vitro fertilization (IVF) in combination with comprehensive chromosomal screening of embryos.
  
  
  METHODS
  A total of 1,915 embryos were biopsied on day 3 and underwent comprehensive chromosomal screening with microarray-based comparative genomic hybridization.
  
  
  METHODS
  Relationship between day 3 blastomere number, aneuploidy rate, and progression to the blastocyst stage.
  
  
  RESULTS
  A number of day 3 blastomeres >9 was associated with significantly increased aneuploidy rates. Rapidly developing embryos were significantly more likely to blastulate regardless of their chromosomal status. Number of embryos per patient greater than 13 was independently associated with lower aneuploidy rates after controlling for maternal age. This trend was not significant with the use of a more clinically relevant threshold of greater than six embryos per patient.
  
  
  CONCLUSIONS
  Embryos with 6-9 cells at the cleavage stage should be considered for transfer over embryos with >9 cells. Day 3 blastomere number may be used in conjunction with extended culture to improve selection of euploid embryos, especially when supernumerary embryos are available. Further studies are needed to show if these selection criteria improve clinical outcomes.
authors.affiliation: Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of California, Los Angeles, California; Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Cedars Sinai Medical Center, Los Angeles, California. Electronic address: lkroener@mednet.ucla.edu.
authors.forename: Lindsay L
authors.initials: LL
authors.lastname: Kroener
authors.affiliation: Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of California, Los Angeles, California; Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Cedars Sinai Medical Center, Los Angeles, California.
authors.forename: Gayane
authors.initials: G
authors.lastname: Ambartsumyan
authors.affiliation: Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of California, Los Angeles, California; Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Cedars Sinai Medical Center, Los Angeles, California.
authors.forename: Margareta D
authors.initials: MD
authors.lastname: Pisarska
authors.affiliation: Southern California Reproductive Center, Beverly Hills, California.
authors.forename: Christine
authors.initials: C
authors.lastname: Briton-Jones
authors.affiliation: Southern California Reproductive Center, Beverly Hills, California.
authors.forename: Mark
authors.initials: M
authors.lastname: Surrey
authors.affiliation: Southern California Reproductive Center, Beverly Hills, California.
authors.forename: David
authors.initials: D
authors.lastname: Hill
mesh_terms: D000328:Adult; D000782:Aneuploidy; D001755:Blastocyst / Q000166:cytology; D001757:Blastomeres / Q000166:cytology*; D002452:Cell Count; D002970:Cleavage Stage, Ovum / Q000166:cytology*; D015331:Cohort Studies; D055028:Comparative Genomic Hybridization; D005260:Female; D006801:Humans; D008297:Male; D046228:Microarray Analysis; D008875:Middle Aged; D011247:Pregnancy; D019836:Preimplantation Diagnosis; D055815:Young Adult
keywords: Cleavage-stage embryo; aneuploidy; blastomere number; comparative genomic hybridization; embryo progression; in vitro fertilization