RESUMO
OBJECTIVE: The purpose of our study was to investigate the effect of the mode of delivery on the oxidant and antioxidant system in umbilical cord blood. METHODS: We performed gas analysis of umbilical venous blood and umbilical arterial blood immediately after delivery in 38 women; eighteen women had a vaginal delivery while 20 women delivered via cesarean section at over 37 weeks gestation. We examined lipid peroxide concentration by thiobarbituric acid reaction, protein carbonyl content by 2,4-dinitrophenylhydrazine reaction, and total antioxidant capacity by oxygen radical absorbance capacity assay. RESULTS: Lipid peroxide levels in umbilical venous blood were significantly higher in patients delivering by planned cesarean section (1.81 +/- 0.06 nmol/mg protein) than those with vaginal delivery (1.24 +/- 0.05 nmol/mg protein) (P < 0.05). Antioxidant capacity in umbilical venous blood was significantly higher in patients delivering by planned cesarean section (119.70 +/- 0.13 microM/microL) than those with a vaginal delivery (118.70 +/- 0.29 microM/microL) (P < 0.05). There was no significant difference in the carbonyl content of umbilical venous blood or in the lipid peroxide, carbonyl content, and total antioxidant capacity of umbilical arterial blood. CONCLUSION: Lipid peroxidation levels and antioxidant capacity in umbilical venous blood were higher in patients delivering by planned cesarean section than those with a vaginal delivery. Therefore, we propose that both the mother and neonate are exposed to higher oxidative stress during cesarean section delivery.