Woods James R, Cavanaugh Judith L, Norkus Edward P, Plessinger Mark A, Miller Richard K
Department of Obstetrics and Gynecology, School of Medicine and Dentistry, University of Rochester, NY 14642-8668, USA.
Am J Obstet Gynecol. 2002 Nov;187(5):1179-83. doi: 10.1067/mob.2002.127131.
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).
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.
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.
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.
本研究旨在比较择期再次剖宫产（CS）且未临产的足月（妊娠>38周）产妇和胎儿的血浆、羊水及绒毛膜中维生素C和维生素E的水平，与孕周和饮食摄入量相似且经阴道分娩（VD）的产妇和胎儿的相应水平。
对足月（妊娠>38周）接受择期再次剖宫产（n = 5）或无并发症经阴道分娩（n = 5）的健康女性进行研究。对于剖宫产患者，在手术时采集产妇和胎儿（脐带）血、羊水及绒毛膜样本。对于经阴道分娩患者，在宫颈扩张5 cm时采集产妇血液和羊水，在分娩时采集胎儿脐带血和绒毛膜。每位患者均完成一份营养问卷。血浆和膜维生素E浓度分别采用反相高效液相色谱法测定，并分别以胆固醇或膜蛋白进行标准化。维生素C采用2,4 -二硝基苯肼法测定。
剖宫产和经阴道分娩患者的维生素C和维生素E饮食摄入量以及产妇和胎儿维生素E血浆浓度相似。两组中，产妇水平均高于胎儿水平（P <.05）。两组的绒毛膜维生素E测量值相似。剖宫产和经阴道分娩患者的维生素C浓度在羊水中最高，在胎儿血浆中较低，在产妇血浆中最低。然而，经阴道分娩患者的产妇血浆、羊水和胎儿血浆中的平均维生素C浓度显著较低，仅为剖宫产患者相应值的20%±6%、29%±11%和22%±2%。
足月健康女性分娩期间，子宫收缩活动可能通过反复缺血和再灌注过程产生活性氧（ROS）。鉴于分娩期间维生素C显著消耗，我们推测水溶性维生素C在水相中清除ROS，并使脂溶性维生素E循环利用以对抗ROS诱导的组织损伤。
