Reactive oxygen species (ROS) are active chemical compounds created by the body's metabolic process and are crucial in human reproduction. Excessive ROS can contribute to oxidative stress, which has been linked to poor fertility. Embryo culture medium plays an essential role in IVF/ICSI cycles. Eighty participants underwent ovarian stimulation and ICSI cycles; ROS levels were measured in blood samples on the ovum pickup (OPU) day and in each embryo culture dish on ET day using enzyme-linked immunosorbent assay (ELISA). These values were associated with the quality of generated embryos. Women were divided into two groups, the first had day 3 embryo transfers, whereas the second received blastocyst transfers on day 5. Grades I embryos count was shown to be inversely related to the serum and culture medium ROS levels. Pregnant women had significantly greater levels of GI embryos (p=0.011) and lower levels of GIII embryos (p=0.024). Pregnancy rates for the third- and fifth-days of the embryo transfers were 24% and 50%, respectively, with (p=0.045). Pregnancy success rates were increased after ET day 5, and were strongly influenced by transfer day. Blastocyst-stage embryos with high serum ROS levels were found to be underdeveloped. Culture medium ROS levels can be used as an adjuvant criterion for embryo selection and metabolic marker for developing embryos.