Materials and Methods: Sixty women undergoing CS and 60 women undergoing painless labor using Entonox gas were included in the study after obtaining a written informed consent. Three tests including lipid peroxidation, total thiol molecules (TTMs), and ferric reducing ability of plasma (FRAP) assay were performed. To this end, venous blood samples (5 mL) were obtained from the mothers at the end of the second stage of labor or after surgery. The same indices were measured for 5 mL of blood sample taken from the umbilical artery of the infants. Descriptive (means) and analytical (independent t test) tests were employed for data analysis.

Results: Mean maternal lipid peroxidation level in the CS and Entonox groups were 5.798 ± 4.210 and 5.105 ± 2.892 nmol/mm, respectively (P = 0.544). TTMs were 0.2846 ± 0.2632 and 0.2656 ± 0.2437 mmol/mm in the CS and Entonox groups (P = 0.687). Moreover, mean scores of FRAP were 0.766 ± 0.516 and 1.057 ± 0.626 nmol/mm in the CS and Entonox groups, respectively (P = 0.007). However, oxidative stress indices of the infants were not different between 2 groups (P > 0.05).

Conclusion: Since total antioxidant capacity in the CS group was lower compared to the Entonox group, it seems that maternal antioxidant defense decreases. Thus, Entonox can be used safely from the perspective of oxidative stress indices.