Biphasic oxygen tension promotes the formation of transferable blastocysts in patients without euploid embryos in previous monophasic oxygen cycles

This study evaluated whether the concentration of biphasic O 2 (5–2%) promotes the formation of qualified blastocysts (QBs) and euploid blastocysts and the probability of cycles with transferable blastocysts. The paired experimental design included a total 90 patients (180 cycles) without euploid blastocysts in previous monophasic O 2 (5%) cycles were enrolled for an additional cycle of biphasic O 2 (5–2%). In the biphasic O 2 (5–2%) group, the QB rate (35.8%, 225/628) was significantly higher than that in the monophasic O 2 (5%) group (23.5%, 137/582; p