Objective: This study was conducted to compare maternal and fetal plasma, amniotic fluid, and chorioamnion levels of vitamins C and E in term (>38 weeks' gestation) subjects undergoing elective repeat cesarean section (CS) without labor with values of subjects of similar gestational age and dietary intake undergoing labor and vaginal delivery (VD).
Study design: Healthy women undergoing elective repeat CS (n = 5) or uncomplicated VD (n = 5) at term (>38 weeks' gestation) were studied. For CS patients, maternal and fetal (cord) blood, amniotic fluid, and chorioamnion samples were collected at time of surgery. For VD patients, maternal blood and amniotic fluid were obtained at 5 cm cervical dilation and fetal cord blood and chorioamnion were collected at delivery. Each patient completed a nutritional questionnaire. Plasma and membrane vitamin E concentrations were determined by reversed-phase high-performance liquid chromatography and standardized to cholesterol or membrane protein, respectively. Vitamin C was determined with the use of the 2,4-DNPH method.
Results: Dietary intakes for vitamins C and E as well as maternal and fetal vitamin E plasma concentrations were similar for CS and VD patients. In both groups, maternal levels were higher than fetal levels(P <.05). Chorioamnion membrane vitamin E measurements in both groups were similar. Vitamin C concentrations in CS and VD patients were highest in amniotic fluid, lower in fetal plasma, and lowest in maternal plasma. However, mean vitamin C concentrations in maternal plasma, amniotic fluid, and fetal plasma of VD patients were significantly lower, being only 20% +/- 6%, 29% +/- 11%, and 22% +/- 2% of values obtained from CS patients.
Conclusion: During labor in healthy women at term, uterine contractile activity may generate reactive oxygen species (ROS) through the process of repetitive ischemia and reperfusion. With the significant depletion of vitamin C during labor, we speculate that water-soluble vitamin C scavenges ROS in the aqueous phase and recycles lipid-soluble vitamin E to combat ROS-induced tissue damage.