Effect of oxygen concentration during the incubation of embryos of women undergoing ICSI and embryo transfer:: a prospective randomized study

The hypothesis that ICSI outcome can be improved by culturing human embryos in an atmosphere of controlled O-2 concentration (5%) compared with 20% was tested in a prospective randomized study of 712 transfer cycles. The cycle characteristics and the embryology parameters were similar between groups. The embryo qualities were similar with day 2 transfers, however, they were better with day 3 transfers incubated in 5% O-2 than in 20% O-2. The clinical outcome parameters did not differ between groups according to the O-2 concentration. The results indicated that culture of embryos under atmospheric conditions of O-2 for the first 2 or 3 days did not alter the clinical outcome in ICSI cycles.