Umbilical blood oxidative sress: arteriovenous difference

Oxidative stress, due to an imbalance between prooxidants and antioxidants, has been shown to aggravate a variety of neonatal pathological states. We tested whether neonates are subject to oxidative stress, by comparing lipid oxidative parameters of umbilical arterial- and venous blood. Our study groups consisted of 32 pregnant women who delivered by elective cesarean section (CS), and of 32 age- and gestational age matched pregnant women who delivered by spontaneous vaginal delivery (SVD). Arterial- and venous blood were drawn from the umbilcal cords and serum was prepared and frozen immediately at −70°. Copper-induced oxidation of serum samples was monitored spectroscopically by continuous recording of absorbance at 245 nm. The time dependent increase of absorbance at 245 nm is caused by the formation of conjugated dienic hydroperoxides and 7-ketocholesterol during lipid peroxidation. The lag preceding oxidation reflects the resistance of serum lipids to oxidative stress. The lag preceding copper induced oxidation was significantly shorter in umbilical arteries when compared to umbilical veins irrespective of mode of delivery (14.0±1.8 vs. 50.6±8.25 min, p = 0.0004 in SVD group; 17.7±1.6 vs. 39.2±7.6 min, p = 0.006 in CS group). Concentrations of total cholesterol, triglycerides, HDL and LDL in arterial- and venous serum were similar in both of these vessels irrespective of mode of delivery. Arterial blood gasses exhibited lower pH values, and lower base excess values when compared to the respective venous values in both modes of delivery. The lag preceding oxidation of umbilical arterial serum lipids is shorter when compared to umbilical venous blood, indicating high oxidative stress in the fetal circulation irrespective of mode of delivery. This may be due to lack of antioxidants and/or high generation of prooxidants by the fetus.These possibilities and the plausible role for antioxidant supplementation during pregnancy warrant further studies.