Effect of reduced oxygen concentrations on the outcome of in vitro fertilization

We compared the effects of two standard oxygen concentrations, physiological (5% O2, 5% CO2, and 90% N2) and atmospheric (5% CO2 with the balance as air), on fertilization, embryo development, and pregnancy rate in 106 patients undergoing IVF, excluding donor oocyte cycles and preimplantation genetic diagnosis cycles. The differences in oxygen concentration did not significantly affect fertilization rate, blastocyst formation, or pregnancy rate, but there was a significant difference in mean embryo score between physiological and atmospheric groups on day 3.