Evaluation of the Impact of Reduced Oxygen Concentration on Embryonic Development

"At the time that embryos are changed from cleavage stage media to blastocyst stage media on day 3 of development, half of a given patient's embryos will randomly be placed in an incubator set at 2% oxygen concentration. The splitting of the embryos will be done under low magnification such that the embryologist will have no ability to bias allocation of embryos to 2% or 5% oxygen based on embryo morphology on day 3. The embryos will remain in this incubator until their developmental assessments on day 5 and 6."