- To determine whether neonates are subject to oxidative stress by the labor process and the mode of delivery by measuring glutathione (GSH) concentrations in umbilical cord venous blood. Forty-eight women with singleton term pregnancies were prospectively recruited and classified as follows: 26 women had a spontaneous uncomplicated vaginal delivery (VD), and 22 women had an elective cesarean delivery (CD). GSH concentration in umbilical venous blood samples was determined by a spectroscopic method. Umbilical cord venous blood GSH levels were significantly lower in the elective CD group than in the VD group (2.2 and 2.7 mM, respectively, P = 0.0003). There was a significantly negative correlation between cord blood pO(2) and GSH levels; however, the negative correlation was significantly higher in the elective CD group (P < 0.05). Neonates delivered by CD were exposed to a higher oxidative stress as determined by GSH levels compared to those who had an uncomplicated VD.