title: A prospective, randomized trial on the effect of atmospheric versus reduced oxygen concentration on the outcome of intracytoplasmic sperm injection cycles.
abstract: OBJECTIVE
  To assess whether the embryo cultivation at different oxygen tensions had any effect on intracytoplasmic sperm injection (ICSI) outcome.
  
  
  METHODS
  Prospective randomized trial.
  
  
  METHODS
  University clinical center.
  
  
  METHODS
  Women undergoing ICSI (n = 647).
  
  
  METHODS
  Culturing of embryos, either at 6% CO(2), 5% O(2), 89% N(2), or at 6% CO(2) in air.
  
  
  METHODS
  The primary outcome was ongoing pregnancy rates (PR).
  
  
  RESULTS
  cumulative PRs, implantation, and embryo quality, for both treatment groups and clinical outcomes for subgroups (optimal cycles, poor responders, older women).
  
  
  RESULTS
  Although low oxygen resulted in a higher proportion of good day 2 embryos (0.547 +/- 0.021 vs. 0.39 +/- 0.019) and optimal blastocysts (0.162 +/- 0.199 vs. 0.083 +/- 0.128), the ongoing PRs (31.6% vs. 27.1%) and implantation rates (28.8% vs. 25.2%) were similar in both oxygen groups. Low oxygen caused a higher cumulative PR (38% vs. 28.3%) in the main group and a higher PR in the poor responder subgroup (23% vs. 9.8%) with embryo transfers performed mostly on day 3.
  
  
  CONCLUSIONS
  The use of reduced oxygen in IVF is reasonable, irrespective of the duration of embryo culture. It improves embryo development and cumulative PR and is also recommended in poor responding cycles.
authors.affiliation: Department of Reproductive Medicine and Gynecologic Endocrinology, University Clinical Centre Maribor, Maribor, Slovenia. borut.kov@ukc-mb.si
authors.forename: Borut
authors.initials: B
authors.lastname: Kovacic
authors.forename: Mojca Cizek
authors.initials: MC
authors.lastname: Sajko
authors.forename: Veljko
authors.initials: V
authors.lastname: Vlaisavljević
mesh_terms: D000388:Air; D001755:Blastocyst / Q000166:cytology / Q000502:physiology; D002245:Carbon Dioxide / Q000494:pharmacology*; D046149:Embryo Culture Techniques / Q000379:methods*; D004624:Embryo Transfer; D005260:Female; D006801:Humans; D007246:Infertility / Q000628:therapy*; D008297:Male; D010062:Ovulation Induction; D010100:Oxygen / Q000494:pharmacology*; D011247:Pregnancy; D011256:Pregnancy Outcome; D018873:Pregnancy Rate; D011446:Prospective Studies; D020554:Sperm Injections, Intracytoplasmic / Q000379:methods*
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen