血红素氧合酶/一氧化碳体系在妊娠期肝内胆汁淤积症的表达及意义

目的:探讨妊娠肝内胆汁淤积症(ICP)患者的血红素氧合酶/一氧化碳(HO/CO)体系变化意义及其与胎儿预后的关系。方法:采用双波长分光光度计法测定25例ICP患者及25例正常晚孕妇女母血、脐血血浆CO的含量;用免疫组化法测定两组孕妇胎盘组织中HO-2蛋白的相对表达量;用免疫组织化学SABC法确定血红素氧合酶(HO)在体外分离培养人胎盘滋养层细胞上的表达及定位。结果:(1)ICP组母血血浆CO的含量为33.0±10.9μmol/L,与对照组的含量为38.3±6.1μmol/L相比,差异有统计学意义(P<0.05);(2)ICP组脐血血浆CO的含量为26.7±7.0μmol/L,与对照组的含量31.1±7.7μmol/L相比,差异有统计学意义(P<0.05);(3)ICP组母血血浆CO的含量与TBA相关,(r=-0.32,P<0.005);(4)未发现ICP组CO水平与羊水粪染、胎儿出生体重、Apgar评分、脐动脉S/D值及孕周之间相关;(5)ICP组胎盘组织中HO-2蛋白定量结果为OD=0.88±0.41,与对照组的OD=1.24±0.47相比,差异有统计学意义(P<0.05);(6)HO在体外分离培养人胎盘滋养层细胞有表达,阳性物质分布于胞浆内,胞核为阴性反应。结论:(1)ICP患者母血血浆和脐血血浆CO的水平降低,胎盘组织中HO-2表达减少。HO/CO体系与ICP的发生发展及患者胎儿的不良结局有关;(2)HO在体外分离培养人胎盘滋养层细胞有表达,阳性物质分布于胞浆内,胞核为阴性反应。     

子宫平滑肌间隙连接蛋白43、促肾上腺皮质激素释放激素、皮质醇与分娩发动的研究

目的:探讨临产前、后子宫平滑肌细胞间隙连接蛋白Cx-43的表达以及母血、脐血、羊水中促肾上腺皮质激素释放激素(CRH)、皮质醇(Cortisol)的水平变化,分析它们与分娩发动的关系。方法:应用免疫组化SABC法结合计算机图象分析技术分析60例足月妊娠产妇子宫下段平滑肌Cx-43的表达;用放射免疫方法测定产妇的静脉血、羊水及胎儿脐静脉血中CRH、Cortisol的含量。结果:临产组子宫肌细胞Cx-43的表达明显强于未临产组,差异有显著性(P<0.01)。临产组母血、脐血中CRH、Cortisol及羊水中Cor-tisol与临产前比较显著升高(P<0.01),且与子宫肌Cx-43蛋白的表达呈显著正相关(P<0.01);结论:CRH、Cortisol在分娩发动中起重要作用,并可能通过促进子宫平滑肌Cx-43的表达参与分娩发动。     

正常妊娠及妊高征孕妇胎盘组织中细胞凋亡及增殖基因表达的研究

目的 :探讨正常妊娠及妊高征 (PIH)孕妇胎盘组织bcl - 2、bax及ki6 7基因的表达及其相互关系。方法 :采用免疫组化方法测定正常早、中、晚期妊娠 30例及轻、中、重度PIH 36例的胎盘组织bcl - 2、bax及ki6 7的表达。结果 :(1)bcl - 2表达主要定位在绒毛的合体滋养层细胞 (S -cells) ,而bax在S -cells和细胞滋养层细胞 (C -cells)均呈阳性 ,在绒毛间质中bax也呈阳性表达 ,但强度低于滋养层细胞。ki6 7定位于C -cells;(2 )bcl - 2在晚期妊娠组的阳性率低于早、中期妊娠组 (P <0 .0 5 )。ki6 7在正常早、中、晚期妊娠组 ,对照组与PIH组 ,轻、中、重度PIH组之间均有显著性差异 (P <0 .0 1) ;(3)bcl - 2和bax表达及与ki6 7的表达无相关性 (P >0 .0 5 )。结论 :bcl - 2及bax在高水平上达到平衡 ,在胎盘组织中并不起介导细胞凋亡的主导作用 ,而且二者的表达不影响细胞的增殖     

母胎循环中PGE2浓度与慢性胎儿窘迫的相关性研究

目的探讨母胎循环中前列腺素E2浓度与慢性胎儿窘迫发生的相关性.方法以孕晚期(37～42孕周)未临产孕妇为研究对象,根据慢性胎儿窘迫诊断标准划分为窘迫组36例与对照组30例,分别采集产前母血及分娩时脐动脉血测定PGE2浓度,同时留取脐动脉血进行血气分析.结果胎儿窘迫组母血及脐血PGE2浓度在明显低于对照组(P＜0.01;P＜0.05);母血PGE2浓度与新生儿Apgar评分呈正相关(r=0.41;P＜0.05).结论母胎循环中的PGE2水平与胎儿窘迫的发生相关,晚孕期母血中PGE2低值可能有助于慢性胎儿窘迫的诊断.     

转化生长因子β与妊娠

妊娠期胎盘滋养层细胞、子宫蜕膜细胞、肌层细胞及羊水中均有转化生长因子β(TGFβ)表达.TGFβ对滋养层细胞增殖、分化及浸润,对子宫内膜功能、子宫前列腺素E2(PGE2)分泌,对滋养层细胞和蜕膜细胞内分泌、免疫及黏附分子表达功能及胚胎发育均具有重要的调节作用.TGFβ表达失调可能与宫内发育迟缓、先兆子痫、习惯性流产、滋养层细胞恶性肿瘤等妊娠疾病的发病机制有关.     

分娩发动前后胎盘中白细胞抗原G1 mRNA和NK细胞的变化

目的:检测胎盘及蜕膜组织中白细胞抗原G1(HLA-G1)mRNA和NK细胞在足月妊娠分娩发动前后的变化,探讨其在分娩发动中的作用。方法:通过RT-PCR法检测足月妊娠晚期未临产组(剖宫产组)和临产组胎盘组织中HLA-G1 mRNA的表达,并用免疫组织化学方法测定蜕膜中NK细胞的数量。结果:与未临产组相比临产组胎盘组织中HLA-G1 mRNA表达明显下降,差异有统计学意义(P<0.05);临产组蜕膜中NK细胞数量明显多于未临产组(P<0.05)。结论:分娩发动时胎盘组织表达HLA-G1mRNA下降,蜕膜组织中NK细胞数量明显增多,推测HLA-G1表达下降激活NK细胞可能参与了分娩发动。     

妊娠期高血压疾病患者胎盘细胞凋亡与caspase-3和bcl-2蛋白表达的关系

目的研究妊娠期高血压疾病(HDP)胎盘细胞凋亡以及与caspase-3蛋白和bcl-2蛋白的关系,进一步探讨HDP的可能发病机制。方法流式细胞术(FCM)和western blot法检测胎盘组织(正常胎盘、妊娠期高血压、轻度子痫前期、重度子痫前期各15例)细胞的凋亡率及caspase-3蛋白和bcl-2蛋白表达。结果 FCM发现,随着HDP病情加重,胎盘细胞凋亡率增大,组间比较差异有统计学意义(P<0.05),同时western blot发现与正常对照组比较,caspase-3蛋白随HDP的加重表达逐渐升高(P<0.05),而bcl-2蛋白随HDP的加重表达逐渐降低(P<0.05)。结论 HDP患者胎盘细胞凋亡率明显增高,caspase-3蛋白表达增高,bcl-2蛋白表达降低,caspase-3蛋白和bcl-2蛋白表达失衡可能与HDP发生有关。     

细胞因子(IL-1β、IL-6、TNF-α)在早产宫内感染中的价值

目的 探讨与感染有关的细胞因子(interleukin-1β,IL-1β)、(interleukin-6,IL-6)、(tumor necrosis factor-a,TNF-α)在早产中的应用.方法 取30例早产孕妇和31例足月临产孕妇,46例足月未临产孕妇的血和羊水标本,分别行血IL-6、羊水中IL-1β、IL-6及TNF-α和胎盘行病理检查.结果 (1)早产组的羊水中IL-1β、IL-6、TNF-α及血浆中IL-6水平显著高于妊娠足月组(包括临产组和未临产组).早产组中有宫内感染孕妇的细胞因子水平显著高于无宫内感染者.(2)羊水和血浆中IL-6水平有明显的相关性.结论 早产有宫内感染者血浆及羊水中细胞因子水平高于无宫内感染者,血浆IL-6水平与羊水IL-6水平密切相关.     

胎盘法尼醇X受体的表达及其与妊娠期肝内胆汁淤积症关系的研究

目的:探讨法尼醇X受体(FXR)在正常晚孕胎盘和妊娠期肝内胆汁淤积症(ICP)胎盘的表达,及其与母血、脐血总胆汁酸(TBA)水平的关系,分析胎盘FXR在ICP病理机制中的作用.方法:收集ICP患者(ICP组)及正常晚孕妇女(对照组)胎盘组织及母血、脐血各33例,并将ICP患者根据母血血清TBA是否≥40 μmoL/L将ICP组分为轻度ICP组和重度ICP组.并测定母血、脐血TBA水平和胎盘组织中FXR mRNA的相对表达量.结果:①羊水胎粪污染的发生率:ICP组羊水污染发生率高于对照组(χ~2:7.543,P=0.013);重度ICP组高于轻度ICP组(χ~2=7.637,P=0.013);②胎盘组织中FXR mRNA的表达情况:ICP组胎盘FXR mRNA表达量高于对照组(z=-2.391,P=0.017);重度ICP组胎盘FXR mRNA表达量高于轻度ICP组(z=-2.391,P=0.017);③ICP组胎盘FXR mRNA表达量与母血、脐血TBA呈正相关(r_s=0.348,P=0.047;r_s=0.284,P=0.027);对照组胎盘FXR mRNA表达量与母血、脐静脉血TBA无相关性(r_s=-0.068,P=0.716;r_s=0.010,P=0.959).结论:ICP时增高的胆汁酸水平上调胎盘FXRmRNA的表达,胎盘FXR表达增加可能为ICP时胎盘的一种对抗胎儿胆汁淤积的保护性机制.     

HOXA10基因在分娩发动前、后胎盘绒毛中的表达

目的:探索HOXA10与分娩发动的相关性。方法:采用免疫组织化学、RT-PCR方法和Western blotting方法检测正常自然分娩组(临产组,n=11)和足月未临产组(选期剖宫产组,n=15)胎盘绒毛中HOXA10mRNA和蛋白的表达水平。结果:免疫组织化学结果显示,HOXA10在临产组胎盘绒毛中仅有弱表达,而在剖宫产组胎盘绒毛中呈较明显的阳性表达。RT-PCR和Western blotting检测均显示,HOXA10mRNA和蛋白在临产组胎盘绒毛中仅有弱表达,而在剖宫产组中呈较明显的阳性表达(P<0.05)。结论:临产时HOXA10基因表达下调可能引起孕激素的效应减弱,即"功能性孕激素撤退",从而参与分娩发动。     

表皮生长因子与胎儿宫内发育迟缓关系的研究

探讨表皮生长因子与胎儿宫内发育迟缓的关系。方法用放射免疫分析,测定８６例妊娠晚期妇女血清,羊水和脐静脉血ＥＧＦ浓度;根据新生儿出生体重,将研究对象分成对照组５４例,大于胎龄儿组１８例和ＩＵＧＲ组１４例。对照组中有１１例同时测定脐动脉血清ＥＧＦ浓度,比较各组间羊水和孕妇,脐血清ＥＧＦ水平及脐动,静脉血清间ＥＧＦ水平的差异。     

Granulocyte colony-stimulating factor in preterm and term pregnancy, parturition, and intra-amniotic infection

OJBECTIVE: To determine the sources of granulocyte colony-stimulating factor (G-CSF) in amniotic fluid and to examine its relation to labor and clinically diagnosed intra-amniotic infection. METHODS: We assessed G-CSF and G-CSF receptor expression in placentas (n = 50) from 5-40 weeks' gestation, and G-CSF concentrations were measured in amniotic fluid (n = 146), bronchoalveolar lavage fluid (n = 8), and paired maternal serum, cord blood, neonatal serum, and neonatal urine samples (n = 16). RESULTS: Immunohistochemical staining and messenger RNA analysis showed placental expression of G-CSF and G-CSF receptor throughout gestation. The number of decidual stromal cells expressing G-CSF receptor was significantly higher in women with intra-amniotic infection compared with women without infection (27 +/- 2 versus 18 +/- 3 cells per high power field, P =.02). Amniotic fluid concentrations of G-CSF were not significantly different in noninfected preterm compared with term samples (1708 +/- 1673 versus 1612 +/- 2100 pg/mL, P =.9). Labor was not associated with a significant increase in amniotic fluid G-CSF concentrations (1864 +/- 3151 versus 1612 +/- 2100 pg/mL, P =.77, term labor versus no labor; 3335 +/- 5364 versus 1708 +/- 1673 pg/mL, P =.09, preterm). Concentrations of G-CSF in maternal serum, amniotic fluid, bronchoalveolar lavage fluid, and neonatal urine were increased during intra-amniotic infection (all P <.05). CONCLUSION: Amniotic fluid G-CSF concentrations were similar in preterm and term pregnancies and were not significantly influenced by labor. Intra-amniotic infection was associated with an increased number of placental cells expressing the G-CSF receptor and higher concentrations of G-CSF in amniotic fluid, maternal serum, neonatal urine, and neonatal bronchoalveolar lavage samples.     

表皮生长因子及其受体与胎儿出生体重的关系

目的探讨表皮生长因子（ＥＧＦ）及其受体与胎儿出生体重的关系。方法采用酶联免疫吸附测定法对正常非孕妇女１５例（对照组）、足月正常体重儿４０例（正常体重儿组）、ＩＵＧＲ儿４０例（ＩＵＧＲ儿组）、巨大儿２５例（巨大儿组）的母血清、脐血清及羊水中ＥＧＦ浓度进行测定,同时采用免疫组化方法对以上各组胎盘及胎膜上ＥＧＦ受体（ＥＧＦＲ）进行测定。结果各组母血、脐血及羊水中ＥＧＦ浓度明显高于对照组（Ｐ＜００５）。ＩＵＧＲ儿组母血、脐血及羊水中ＥＧＦ浓度低于正常体重儿组,差异有显著性。巨大儿组母血、脐血及羊水中ＥＧＦ浓度与正常体重儿组比较,差异无显著性。在ＩＵＧＲ儿组胎盘及胎膜上ＥＧＦＲ表达明显低于正常体重儿组（Ｐ＜０．０１）,巨大儿组胎盘上ＥＧＦＲ表达高于正常体重儿组。结论ＥＧＦ及其受体与ＩＵＧＲ的发生有关,在妊娠后期测定母血及羊水中ＥＧＦ浓度,对评价胎儿的生长发育具有重要意义。     

Influence of labor on fetoplacental adrenomedullin concentrations

OBJECTIVE: Circulating adrenomedullin is increased in pregnancy, and placental and fetal membranes participate significantly in its secretion. Recent studies have suggested a potential role for this peptide in the regulation of fetoplacental circulation and placental hormonal secretion. Because adrenomedullin acts also as a uterorelaxant in rats, this study was designed to investigate whether fetoplacental adrenomedullin production changes with human labor, either at term or preterm. STUDY DESIGN: Eighty pregnant women grouped according to gestational age and presence of labor were studied. Adrenomedullin concentrations in plasma, amniotic fluid, and placental tissue extracts were measured by means of radioimmunoassay and immunohistochemistry. In addition, the ability of amnion and chorion-decidua to secrete adrenomedullin was investigated in vitro. RESULTS: Adrenomedullin concentrations in amniotic fluid were higher in preterm labor, whereas no differences were found in adrenomedullin expression or concentrations in tissues or in maternal and fetal plasma between vaginal delivery or elective cesarean section, both at term and preterm. During term labor (8 patients), maternal plasma adrenomedullin concentration decreased with advancing cervical dilatation, being 173 pg/mL at the beginning of the active stage of labor and 57 pg/mL at the time of delivery. Adrenomedullin concentration in the medium of amnion- and chorion-decidua-cultured cells was higher after vaginal delivery. CONCLUSION: These results suggest that a decrease in adrenomedullin production is not involved in the onset of labor in human subjects but rather that it may play a role other than that of a myometrial relaxant in human parturition.     

Level of S100B protein expression in the amnion at various gestational ages in the third trimester of normal pregnancies

BACKGROUND: S100B protein is a unique calcium-binding protein. Its biological role within the cell populations is not completely defined. Some pathological conditions that develop during pregnancy could affect S100B concentrations in the amniotic fluid, cord blood, and maternal serum. The aim of our study was to assess the correlation between S100B protein expression in the amnion, amniotic fluid and gestational age in the third trimester of uncomplicated pregnancies. METHODS: Amnion, amniotic fluid, maternal peripheral and umbilical cord blood samples were collected from healthy women who delivered at 31-36 weeks (n=17), 37-40 weeks (n=22), and 41-42 weeks (n=21). The expression of S100B in the amnion was assessed by immunohistochemistry and real-time (RT)-PCR, and its concentrations in amniotic fluid, maternal and cord blood sera were determined by ELISA. RESULTS: The S100B protein expression in the amnion and its concentrations in amniotic fluid, maternal and cord blood sera of patients in the third trimester were not significantly different at various gestational ages. CONCLUSIONS: The S100B protein expression in the amnion and the S100B protein concentrations in amniotic fluid, maternal and cord blood do not vary significantly in the third trimester of uncomplicated pregnancies.     

Influence of misoprostol (PGE1) on amniotic fluid and maternal serum adrenomedullin levels

OBJECTIVE: The purpose of this study was to determine the levels of adrenomedullin (AdM) in amniotic fluid (AF) and maternal serum of misoprostol (PGE1)-induced pregnant women. MATERIALS AND METHODS: A total of 40 women were included in the study: 20 were in active labor and were delivered vaginally and a further 20 were not in labor and misoprostol induction was performed. Women who were undergoing labor induction received 50 microg of misoprostol, which was placed in the posterior fornix of the vagina every 4 hrs until the onset of labor. In each patient, maternal plasma and AF samples were collected. Samples of AF were collected by transvaginal route at the time of rupture of the membranes. The labor was at the same stage in both the groups during the sample collection. In all pregnant subjects, maternal blood samples were drawn from the cubital vein at the time of AF sampling. Amniotic fluid and serum AdM concentration was measured by using reverse-phase high-performance liquid chromatography. RESULTS: Misoprostol-induced pregnant women showed significantly higher AdM concentrations than control pregnant women in AF (79.48 +/- 6.14 pmol/ml versus 21.28 +/- 0.90 pmol/ml, P = 0.000) and maternal serum (88.20 +/- 4.34 pmol/ml versus 29.78 +/- 4.51 pmol/ml, P = 0.000). There was no significant difference between maternal serum and AF-AdM concentrations in misoprostol and control subjects. CONCLUSION: Increased serum and AF-AdM concentrations may be necessary to initiate cervical ripening in misoprostol-induced pregnant women.     

Epidermal growth factor (EGF) concentrations in amniotic fluid and maternal urine during pregnancy

Epidermal growth factor (EGF) was measured in amniotic fluid and maternal urine from women undergoing amniocentesis for genetic studies (15-22 weeks' gestation, n = 36) and lung maturational studies (35-39 weeks' gestation, n = 20). Amniotic fluid EGF concentrations (mean +/- SD) were higher near term (87 +/- 71 pM) than mid-gestation (35 +/- 8 pM) (p less than 0.0001). Urinary EGF concentrations were higher near mid-gestation (53.9 +/- 30.8 micrograms EGF/g creatinine) than near term (33.4 +/- 14.1 micrograms EGF/g creatinine) (p less than 0.006). There was no correlation between individual amniotic fluid and urinary EGF concentrations. The amniotic fluid EGF concentrations correlated with gestational age. However, there was no relationship between EGF concentrations and pulmonary maturity studies or placental weight from the pregnancies studied near term. We conclude that the concentration of EGF in amniotic fluid increases towards term. The lack of correlation between amniotic fluid and maternal urinary EGF concentrations suggests that there probably is a different source of EGF in the two compartments and that EGF does not cross the placenta to any great extent.     

Fetal death: A condition with a dissociation in the concentrations of soluble vascular endothelial growth factor receptor-2 between the maternal and fetal compartments

Objective.?An anti-angiogenic state has been implicated in the pathophysiology of preeclampsia, fetal growth restriction and fetal death. Vascular endothelial growth factor (VEGF), an indispensible angiogenic factor for embryonic and placental development exerts its angiogenic properties through the VEGF receptor (VEGFR)-2. A soluble form of this protein (sVEGFR-2) has been recently detected in maternal blood. The aim of this study was to determine if fetal death was associated with changes in the concentrations of sVEGFR-2 in maternal plasma and amniotic fluid.

Study Design.?Maternal plasma was obtained from patients with fetal death (n?=?59) and normal pregnant women (n?=?134). Amniotic fluid was collected from 36 patients with fetal death and the control group consisting of patients who had an amniocentesis and delivered at term (n?=?160). Patients with fetal death were classified according to the clinical circumstances into the following groups: (1) unexplained; (2) preeclampsia and/or placental abruption; (3) chromosomal and/or congenital anomalies. Plasma and amniotic fluid concentrations of sVEGFR-2 were determined by ELISA. Non-parametric statistics and logistic regression analysis were applied.

Results.?(1) Patients with a fetal death had a significantly lower median plasma concentration of sVEGFR-2 than normal pregnant women (p?<?0.001). The median plasma concentration of sVEGFR-2 in patients with unexplained fetal death and in those with preeclampsia/abruption, but not that of those with congenital anomalies, was lower than that of normal pregnant women (p?=?0.006, p?<?0.001 and p?=?0.2, respectively); (2) the association between plasma sVEGFR-2 concentrations and preterm unexplained fetal death remained significant after adjusting for potential confounders (OR: 3.2; 95% CI: 1.4–7.3 per each quartile decrease in plasma sVEGFR-2 concentrations); (3) each subgroup of fetal death had a higher median amniotic fluid concentration of sVEGFR-2 than the control group (p?<?0.001 for each); (4) the association between amniotic fluid sVEGFR-2 concentrations and preterm unexplained fetal death remained significant after adjusting for potential confounders (OR: 15.6; 95% CI: 1.5–164.2 per each quartile increase in amniotic fluid sVEGFR-2 concentrations); (5) among women with fetal death, there was no relationship between maternal plasma and amniotic fluid concentrations of sVEGFR-2 (Spearman Rho: 0.02; p?=?0.9).

Conclusion.?Pregnancies with a fetal death, at the time of diagnosis, are characterized by a decrease in the maternal plasma concentration of sVEGFR-2, but an increase in the amniotic fluid concentration of this protein. Although a decrease in sVEGFR-2 concentration in maternal circulation depends upon the clinical circumstances of fetal death, an increase in sVEGFR-2 concentration in amniotic fluid seems to be a common feature of fetal death. It remains to be determined if the perturbation in sVEGFR-2 concentrations in maternal and fetal compartments observed herein preceded the death of a fetus.     

The effect of labor on maternal and fetal vitamins C and E

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.