OBJECTIVETo investigate the effect of low and high oxygen concentration on embryo development, pregnancy outcome and birth defects offertilization-embryo transfer (IVF-ET).

METHODSAccording to the oxygen concentration ofculture environment, the IVF-ET performed in the Women's Hospital, Zhejiang University School of Medicine during 2013 and 2015 were divided into low oxygen concentration group (=2036, 5% O) and high oxygen concentration group (=4617, 20% O). The rate of fertilization, good quality embryo, clinical pregnancy, ectopic pregnancy, abortion and birth defect were compared between two groups.

RESULTSThe good quality embryo rate was significantly higher in the low oxygen concentration group (<0.05). However, no significant differences were found between two groups in the rate of fertilization, clinical pregnancy, ectopic pregnancy, abortion and birth defect (all>0.05).

CONCLUSIONSLow oxygen environment may improve the potential of embryonic development, but its impact on pregnancy outcome and birth defect is not significant.