title: Aneuploidy analysis in day 7 human blastocysts produced by in vitro fertilization.
abstract: BACKGROUND
  Human embryos produced by in vitro fertilization (IVF) are usually cultured to day 6 after insemination, and good quality of embryos should develop to blastocyst stage at days 5 and 6. However, some embryos develop slowly, thus they may form blastocysts on day 7. Most IVF laboratories culture embryos to day 6 and then discard retarded embryos that do not develop to blastocyst stage. It has been reported that transfer of day 7 blastocysts can yield pregnancy although the rates were very low. In the present study, we evaluated the prevalence of aneuploidy in day 7 human blastocysts and also assessed embryo implantation after transfer of normal euploid blastocysts developed on day 7.
  
  
  METHODS
  Day 7 blastocysts were biopsied and screened for aneuploidy. Embryo implantation was assessed by transferring of euploid blastocysts.
  
  
  RESULTS
  A total of 1966 blastocysts from 367 IVF cycles were biopsied and screened for aneuploidy. It was found that 81.5 % of the patients had days 5 and 6 blastocysts and 18.5 % (68) patients had blastocysts developed on day 7, including 15.3 % had days 5-7 blastocysts and 3.3 % had only day 7 blastocysts. A total of 151 day 7 blastocysts, which accounted for 7.7 % of total blastocysts, were analyzed. It was found that 36.7 % of the blastocysts were euploid and 63.3 % had abnormal chromosomes, including aneuploidy and euploid with partial chromosome deletion. The aneuploidy rate was also maternal age dependent and was as high as 91.7 % in patients who were ≥40 years old. During the study period, transfer of day 7 euploid blastocysts in 15 patients resulted in 2 healthy live births.
  
  
  CONCLUSIONS
  Aneuploidy rates in day 7 human blastocysts produced by IVF are very high. However, good euploid blastocysts have potential to implant and transfer of day 7 euploid blastocysts can result in healthy live birth. It is suggested that day 7 blastocyst culture may be necessary in patients who need aneuploidy screening.
authors.affiliation: Center for Reproductive Medicine, Changsha Hospital for Maternal and Child Health Care, Changsha, Hunan, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Su
authors.affiliation: Center for Reproductive Medicine, Changsha Hospital for Maternal and Child Health Care, Changsha, Hunan, China.
authors.forename: Jian-Jun
authors.initials: JJ
authors.lastname: Li
authors.affiliation: Vivere-Houston Fertility Laboratory, 2500 Fondren Road, Suite 350, Houston, TX, USA.
authors.forename: Cassie
authors.initials: C
authors.lastname: Wang
authors.affiliation: Houston Fertility Institute, Houston, TX, USA.|Vivere Health, Franklin, TN, USA.
authors.forename: Ghassan
authors.initials: G
authors.lastname: Haddad
authors.affiliation: Vivere-Houston Fertility Laboratory, 2500 Fondren Road, Suite 350, Houston, TX, USA. wangweihua11@yahoo.com.|Vivere Health, Franklin, TN, USA. wangweihua11@yahoo.com.
authors.forename: Wei-Hua
authors.initials: WH
authors.lastname: Wang
mesh_terms: D000782:Aneuploidy; D001755:Blastocyst / Q000502:physiology*; D046149:Embryo Culture Techniques; D010064:Embryo Implantation; D004624:Embryo Transfer; D005307:Fertilization in Vitro; D006801:Humans; D019836:Preimplantation Diagnosis; D013997:Time Factors
keywords: Aneuploidy; Delayed blastocyst; Implantation; PGS