title: Lack of carbon air filtration impacts early embryo development.
abstract: OBJECTIVE
  To assess human fertilization and preimplantation embryo development in the presence and in the absence of carbon filtration
  
  
  METHODS
  This is a retrospective cohort analysis of fresh, controlled ovarian hyperstimulation cycles as well as previously cryopreserved pronuclear stage embryo transfer cycles in a single IVF center. Embryo development and cycle-based outcomes were compared among three groups: 1) when carbon filtration was present, 2) when carbon filtration was absent, and 3) when carbon filtration had been restored.
  
  
  RESULTS
  A total of 524 fresh cycles and 156 cryopreserved embryo cycles were analyzed. Fertilization, cleavage, and blastocyst conversion rates for fresh cycles all declined during the period of absent carbon filtration and recovered after the restoration of carbon filtration. Cryopreserved embryos that were thawed and cultured during the period of absent filtration did not have changes in cleavage or blastocyst conversion rates compared to periods where carbon filtration was present. Clinical pregnancy and live birth rates were unchanged among the three time periods.
  
  
  CONCLUSIONS
  The absence of carbon filtration in an IVF laboratory air handler is associated with poor fertilization and early embryo development for fresh cycles. Because development of previously frozen pronuclear stage embryos was unaffected, the lack of carbon filtration may preferentially affect embryos in the peri-fertilization period. Carbon filtration is an integral part to a successful human in-vitro fertilization laboratory.
authors.affiliation: Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA.
authors.forename: Erika M
authors.initials: EM
authors.lastname: Munch
authors.forename: Amy E
authors.initials: AE
authors.lastname: Sparks
authors.forename: Hakan E
authors.initials: HE
authors.lastname: Duran
authors.forename: Bradley J
authors.initials: BJ
authors.lastname: Van Voorhis
mesh_terms: D000328:Adult; D016902:Air Pollution, Indoor / Q000009:adverse effects*; D001755:Blastocyst / Q000166:cytology / Q000502:physiology*; D002244:Carbon; D015331:Cohort Studies; D015925:Cryopreservation / Q000379:methods; D046149:Embryo Culture Techniques; D047108:Embryonic Development; D005260:Female; D005307:Fertilization in Vitro; D005374:Filtration; D006801:Humans; D007231:Infant, Newborn; D007753:Laboratories / Q000592:standards; D008297:Male; D010062:Ovulation Induction; D011247:Pregnancy; D011256:Pregnancy Outcome; D018873:Pregnancy Rate; D012189:Retrospective Studies
chemical_list: D002244:Carbon