Lipid peroxidation in cord blood at birth: the effect of labour

Objective To determine the effect of labour on free oxygen radical activity in the fetus, as reflected by lipid peroxide levels in umbilical cord arterial blood.
Design Prospective, observational study.
Setting Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong.
Methods Umbilical cord arterial and venous blood samples were collected from singleton term infants delivered by elective caesarean section. Base excess, PO₂, pCO₂, and pH were measured in both samples and compared to identify double venous samples. Cord arterial acid-base balance and concentrations of organic hydroperoxides and malondialdehyde were compared with those obtained from normal vaginal deliveries.
Results Cord arterial blood samples, obtained from cases of uncomplicated labour followed by spontaneous vaginal delivery, had significantly higher lipid peroxide concentrations than those delivered following elective caesarean section. This was most marked for malondialdehyde with a median value increased by 105%, whilst organic hydroperoxide was increased by only 27%. Of the acid-base parameters, base excess was increased by 78%, with only minimal changes in pH, PCO₂, and PO₂. These differences remained highly significant after including other pregnancy characteristics in multivariate analysis.
Conclusion The findings indicate that high levels of free oxygen radical activity in the fetus are a function of the labour process, as are changes in acid-base balance.     

Lipid peroxidation in cord blood: the effect of amniotic fluid volume

Objective To assess the effect of amniotic fluid volume on umbilical cord arterial lipid peroxide levels in relation to intrapartum events.
Design Prospective observational study.
Setting Delivery suite of a teaching hospital, the Chinese University of Hong Kong.
Population Women with singleton, term, cephalic presentation, and an initially normal fetal heart rate tracing.
Methods All pregnancies had amniotic fluid index assessments before and after amniotomy and cord arterial lipid peroxide determination at delivery. Multiple regression analysis.
Main outcome measures Cord arterial malondialdehyde and organic hydroperoxide levels.
Results In 247 cases following amniotomy levels were inversely correlated with intrapartum amniotic fluid index. Amniotic fluid index during labour was an independent determinant of cord arterial lipid peroxide concentration, along with duration of second stage, absence of epidural, presence of tight nuchal cord entanglement and evidence of fetal distress.
Conclusions Oligohydramnios during labour is associated with high levels of lipid peroxidation in the fetus, reflecting an increase in hypoxic cellular damage by free radicals.     

Determinants of umbilical cord arterial 8-iso-prostaglandin F2alpha concentrations

Objective To determine the concentration of 8-isoPGF_2α in cord blood as a measure of oxidative stress during labour, and to compare them with other established parameters of in vivo lipid peroxidation and with the acid-base status of the newborn.
Method Umbilical cord arterial and venous blood samples were collected from 81 singleton term deliveries for determination of 8-isoPGF_2α, malondialdehyde and organic hydroperoxides. In addition, metabolites derived from the oxidative metabolism of purines during hypoxia-reoxygenation and routine cord blood of oxygen saturation, pH, pO₂, pCO₂, HCO₃ and base excess were measured.
Results Arterial concentrations of 8-isoPGF_2α were significantly higher in cases with fetal distress, tight nuchal cord (   P < 0.001  ), the umbilical coiling index, and male sex (   P < 0.05  ) (R²= 0.48). No correlation was found with any parameter of acid-base status. In arterial and venous blood the concentrations of organic hydroperoxides and hypoxanthine significantly correlated with the fetal nuchal cord (   P < 0.001  ) (R²= 0.26 and 0.16, respectively).
Conclusion Our findings indicate that 8-isoPGF_2α in cord arterial blood is a suitable parameter to quantify a possible oxidative stress in the fetus during labour. Measurements of the F₂-isoprostane concentrations in cord blood at labour provide a clinically useful method to assess the perinatal outcome.     

Fetal and maternal levels of lipid peroxides in term pregnancies

OBJECTIVE: To examine the relationships between maternal and fetal concentrations of lipid peroxides in term pregnancies before the onset of labor. METHODS: Umbilical cord arterial and venous blood samples were collected from 114 singleton term pregnancies delivered by elective cesarean section. Base excess, oxygen, carbon dioxide and pH were measured in both samples and compared to identify double venous samples. Maternal venous and umbilical cord arterial and venous concentrations of organic hydroperoxides and malondialdehyde were assayed. RESULTS: Maternal plasma malondialdehyde was, on average, double that of cord blood, whereas maternal organic hydroperoxide was only 18% higher. Maternal organic hydroperoxide was correlated with cord arterial and venous levels of organic hydroperoxide but not with pH, carbon dioxide, oxygen or base excess. Maternal malondialdehyde concentration was significantly correlated with both umbilical arterial and venous values of malondialdehyde and with arterial oxygen. Multiple regression shows that 70% of the variation in maternal malondialdehyde can be accounted for by variation in arterial and venous malondialdehyde, and arterial oxygen and base excess. A similar regression analysis with maternal organic hydroperoxide as dependant variable incorporated only umbilical arterial organic hydroperoxide concentration. CONCLUSION: These findings suggest that there is significant trans-placental transport of malondialdehyde from the fetal circulation.     

Lipid peroxidation in cord blood: a randomised sequential pairs study of prophylactic saline amnioinfusion for intrapartum oligohydramnios

Objective To determine the efficacy of prophylactic intrapartum amnioinfusion in reducing cord arterial lipid peroxide levels in cases of intrapartum oligohydramnios.
Design Sequential randomised pairs trial.
Setting Delivery suite of a teaching hospital, the Chinese University of Hong Kong.
Population Women with singleton, term pregnancy, cephalic presentation, clear amniotic fluid and an amniotic fluid index 5 cm, with a normal intrapartum fetal heart rate tracing within 30 minutes of amniotomy.
Methods Selected patients were randomised either for prophylactic saline amnioinfusion or as control cases. Cord arterial lipid peroxide concentrations and acid base balance were determined at delivery.
Main outcome measures Operative intervention for fetal distress, cord arterial malondialdehyde and organic hydroperoxide levels, pH and base excess.
Results Amnioinfusion was associated with significant reductions in the incidence of operative delivery for fetal distress and in lipid peroxide levels, an increase hi base excess, but no significant alteration in pH.
Conclusions Oligohydramnios in labour is associated with high levels of lipid peroxidation, reflecting cellular damage by release of free radicals following hypoxia reperfusion. Prophylactic intrapartum saline amnioinfusion is an effective technique for the reduction of lipid peroxidation and of the incidence of operative intervention for fetal distress but has no significant effect on overall operative delivery rates.     

Lipid peroxidation in nuchal cord cases: implication for fetal distress

Objective. To examine whether nuchal cord affects fetal lipid peroxidation and cord arterial blood gases, and thus to determine whether lipid peroxidation can show intrapartum distress.

Methods. Pregnant women giving birth to a baby with nuchal cord (n = 32) formed the study group and others without this condition made up the control group (n = 36). The maternal malondialdehyde levels (MDA) before and after delivery as well as fetal umbilical cord MDA and arterial blood gases were measured in both the groups.

Results. Mean cord MDA level was higher in the study group (p < 0.02) and was significantly higher than maternal MDA level after birth within the same group (p = 0.007). Cord blood gases as well as neonatal and labour characteristics showed no difference, except for variable decelerations, which were 2.2 times more common in the study group. Correlations between maternal MDA levels before and after delivery, umbilical cord MDA and arterial blood gases were non-significant in the nuchal cord group.

Conclusions. During delivery, nuchal cord increases lipid peroxidation without causing significant fetal acidemia. Level of lipid peroxidation may be a more sensitive indicator of intrapartum distress than results of acid–base studies.     

Obstetrical factors related to nuchal cord

BACKGROUND: To investigate the intrapartum factors related to umbilical cord nuchal loops (nuchal cord) with particular reference to shoulder dystocia. METHODS: We studied all singleton pregnancies with a vertex presentation and a birth weight of at least 2500 g from 1 January 1978 to 31 March 1997 and the 13,717 pregnancies with nuchal cord were compared to the 44,136 without nuchal cord. RESULTS: When compared to pregnant women without nuchal cord, a greater proportion of pregnant women with nuchal cord underwent induction of labor (adjusted OR 1.09, 95% CI 1.04-1.15) and augmentation with oxytocin (adjusted OR 1.06, 95% CI 1.01-1.11). They had a longer second stage of labor (p=0.0013) and a greater proportion of primiparous women with tight nuchal cord had second stage of labor that lasted longer than two hours (adjusted OR 1.21, 95% CI 1.03-1.41). The proportion of abnormal fetal heart rate patterns was higher in the presence of nuchal cord (adjusted OR 1.61, 95% CI 1.55-1.68). Shoulder dystocia occurred more commonly in association with nuchal cord, especially when the nuchal cord was tight (adjusted OR 1.50, 95% CI 1.30-1.72 for all nuchal cord; adjusted OR 1.82, 95% CI 1.42-2.34 for tight nuchal cord). CONCLUSIONS: Umbilical cord nuchal loops are associated with induction of labor, slow progress of labor, and shoulder dystocia.     

Relationship between umbilical cord morphology and nuchal cord entanglement

OBJECTIVE: To determine whether tightening of nuchal cord entanglement is more likely to occur where normal cord coiling is absent and there is deficient Wharton's jelly. The study was carried out in the delivery suite of a university teaching hospital, using a prospective matched controlled-pairs survey. METHODS: Midwives identified index cases with nuchal cord entanglement at the time of delivery. The next delivery of equivalent gestation (+/- 1 week) without cord entanglement was taken as the control. Only singleton pregnancies with cephalic presentation undergoing spontaneous labor were studied. Placental insertion, nuchal entanglement (tight or loose), length, presence of knots, umbilical coiling index (UCI), and the amount of Wharton's jelly were recorded. RESULTS: Longer cords were more frequent amongst male infants and were predisposed towards entanglement. There were no significant differences in the amount of Wharton's jelly, or in the UCI between tight and loose nuchal cord groups. The only measurement that differed significantly was the total cord length, with shorter cords predisposed towards tightening. CONCLUSION: Whilst nuchal cord entanglement amongst male babies is frequently associated with long and straight umbilical cords, tightening is more likely to occur if the cord is of short or normal length. Neither low UCI nor low percentage of Wharton's jelly are predisposed towards tightening of cord entanglement.     

Differences in umbilical cord serum lipid levels with mode of delivery

Objective To investigate whether umbilical cord serum lipid levels differ with mode of delivery.
Design Retrospective observation study.
Population Two hundred and ninety mothers aged 29.1 years (SD 4.7) who had vaginal delivery, and 44 mothers aged 30.4 years (SD 4.7) who had elective caesarean section were enrolled.
Main outcome measures Maternal and umbilical cord blood were obtained immediately after delivery. Serum lipid levels including total cholesterol, high density lipoprotein cholesterol, saturated fatty acid, mono-unsaturated fatty acid and polyunsaturated fatty acid were measured. Obstetric variables and serum lipid levels were compared between the two groups. In each group the correlations of fetal serum lipid levels with maternal serum lipid levels were investigated.
Results There were no significant differences in maternal age, neonatal weight, gestational duration, placental weight and neonatal gender distribution between the two groups. Only the two fetal serum lipid levels (including total cholesterol and non-high density lipoprotein cholesterol) showed a correlation with maternal fetal lipid levels with correlation coefficients > 0.3 in the caesarean section group. However, saturated fatty acid, mono-unsaturated fatty acid and total fatty acid levels in the non-high density lipoprotein low density lipoprotein, very low density lipoprotein, intermediate density lipoprotein and free fatty acid fraction in the umbilical cord serum were significantly higher in the vaginal delivery cases (   P < 0.01  ).
Conclusions Umbilical cord serum levels of saturated and mono-unsaturated fatty acids increase during vaginal delivery.     

Maternal serum and umbilical cord blood leptin concentrations with fetal growth restriction

OBJECTIVE: To ascertain whether fetal growth restriction is associated with alterations of leptin concentrations in umbilical cord blood and maternal serum. METHODS: Maternal serum and umbilical cord blood leptin concentrations were determined by immunoradiometric assay at term in 43 women with uncomplicated singleton pregnancies (group A) and in 27 women with singleton pregnancies complicated by fetal growth restriction (group B), all with normal pregravid body mass index (BMI). RESULTS: Maternal serum leptin concentrations were significantly higher in group B compared with group A (45.0 ng/mL [range 34.2-54.9] versus 29.0 ng/mL [range 24.7-33.3]; P<.01). Umbilical cord blood leptin levels were significantly lower in group B compared with group A (8.4 ng/mL [range 3.6-13.2] versus 13.1 ng/mL [9.7-16.5]; P<.01). Maternal serum leptin levels were not significantly correlated with maternal BMI or with neonatal birth weight in either group. Umbilical cord blood leptin concentrations were significantly correlated with neonatal birth weight in both groups. CONCLUSION: Growth restricted fetuses at term show umbilical cord blood leptin concentrations significantly lower than those in normal fetuses, suggesting that fetal adipose tissue is a major source of leptin. Maternal serum leptin concentrations are higher in the presence of a growth restricted fetus. This increase might be due to an intrinsic placental mechanism, by which small placentas produce more leptin as a compensatory mechanism, or to early hypoxia.     

The effect of delivery on umbilical arterial cord blood gases and lipid peroxides: comparison of vaginal delivery and cesarean section

Umbilical arterial blood gas analysis is the most objective method to assess fetal well being at birth, is the gold standard assessment of uteroplacental function and fetal oxygenation/acid-base status at birth, and it excludes the diagnosis of birth asphyxia in approximately 80% of depressed newborns at term. This study was designed to determine the effect of the type of delivery on umbilical cord blood gases and on free radical activity together with antioxidation in the fetus. Ninety-six pregnant women between 37 and 42 weeks of gestation were included to the study and randomly assigned to the one of three groups: Group 1 (n = 40) were vaginally delivered, Group 2 (n = 26) had cesarean section with epidural anaesthesia, and Group 3 (n = 30) had cesarean section under general anaesthesia. Umbilical artery blood gas analysis was performed just after the delivery of the fetus together with melondealdehyde and glutathione. The umbilical arterial PO2 was found to be higher in Group 3, and malondealdehyde and glutathione levels were lower in newborns of Group 2. It can be concluded that cesarean section with epidural anaesthesia is safer when lipid peroxides are concerned.     

Lactate concentration in umbilical cord blood is gestational age-dependent: a population-based study of 17 867 newborns

Objective  To study the influence of gestational age on lactate concentration in arterial and venous umbilical cord blood at birth and to define gestational age-specific reference values for lactate in vigorous newborns.
Design  Population-based comparative.
Setting  University hospitals.
Sample  Vigorous newborns with validated umbilical cord blood samples.
Material and methods  From 2000 to 2004, routine cord blood gases, lactate and obstetric data from two university hospitals were available for 17 867 newborns from gestational week 24 to 43. After validation of blood samples and inclusion only of singleton pregnancies aimed for vaginal delivery, 10 700 women remained. Among those, reference values were defined in 10 169 vigorous newborns, that is in newborns with a 5-minute Apgar score corresponding to the gestational age-specific median value minus 1 point score, or better.
Main outcome measures  Cord lactate concentration relative to gestational age.
Results  The arterial and venous lactate concentrations increased monotonously with gestational age from 34 weeks. Considerable differences were found between mean and median values, but after logarithmic transformation the log-lactate values were normally distributed. Simple linear regression analysis showed a significant association between the log-lactate values and gestational age ( P < 10⁻⁶, R ²= 0.024). Reference curves were constructed after anti-logarithmic transformation. Both the gestational age and the time of the second stage of labour influenced, independently of each other, the lactate concentrations.
Conclusions  Lactate concentrations in arterial and venous umbilical cord blood are increasing significantly with advancing gestational age.     

Umbilical cord blood gas analysis

Umbilical cord blood gas and pH values should always be obtained in the high-risk delivery and whenever newborn depression occurs. This practice is important because umbilical cord blood gas analysis may assist with clinical management and excludes the diagnosis of birth asphyxia in approximately 80% of depressed newborns at term. The most useful umbilical cord blood parameter is arterial pH. Sampling umbilical venous blood alone is not recommended because arterial blood is more representative of the fetal metabolic condition and because arterial acidemia may occur with a normal venous pH. A complete blood gas analysis may provide important information regarding the type and cause of acidemia and sampling the artery and vein may provide a more clear assessment. The sampling technique is simple and easily mastered by any treatment person in the delivery room. Preheparinized syringes ensure a consistent dose and amount of heparin. Depending on how normality is defined and on the population studied, normal ranges for umbilical cord blood gas values vary (see Table 1). In general, the lower range for normal arterial pH extends to at least 7.10 and that for venous pH to at least 7.20. Many different factors during pregnancy, labor, and delivery can affect cord blood gases. Umbilical blood sampling for acid-base status at all deliveries cannot be universally recommended because many facilities do not have the capabilities to support such a practice and in doing so may impose an excessive financial burden. Considering the costs, the accumulated published data, and the nonspecificity of electronic fetal monitoring in the evaluation of fetal oxygenation, it may be more rational to implement universal cord blood gas analysis. Care providers and institutions with the logistical capabilities in place should consider the cost efficacy of routine cord blood gas analysis because it is the gold standard assessment of uteroplacental function and fetal oxygenation/acid-base status at birth.     

Hormonal regulation of neonatal weight: placental leptin and leptin receptors

Objective To examine whether umbilical and maternal leptin levels correlate with birthweight, placental weight, and maternal weight; and to detect membrane-bound leptin receptors in placental tissue as well as soluble leptin receptors in umbilical and maternal blood.
Design Prospective observational study.
Setting University teaching hospital.
Methods Serum levels of leptin and soluble leptin receptors were analysed in 31 randomly selected mother/newborn pairs at delivery. In addition, placental tissue was assayed for leptin receptors using immunocytochemistry and Western blot.
Results The mean [SD] leptin level in umbilical cord venous blood (7.1 ng/mL [4.0]) was significantly lower (   P < 0.001  ) than in maternal blood (22.5 ng/mL [10.8]). Umbilical cord leptin concentrations correlated significantly with birthweight (   P < 0.001  ), placental weight (   P < 0.005  ) but not with maternal leptin. Maternal leptin concentrations correlated only with maternal weight (   P < 0.001  ). In chorionic villous tissue, trophoblasts stained strongly positive for leptin receptor-like immunoreactivity. Two membrane-bound isoforms of the leptin receptor were also detected in placental tissue. In both umbilical and maternal serum, a soluble leptin receptor was found migrating as broad band at M_r 97,000 D.
Conclusion The present data strongly reinforce the idea that circulating leptin levels may provide a growth-promoting signal for fetal development during late pregnancy. While membrane-bound leptin receptors may be involved in autocrine regulation of placental leptin production, the soluble receptor form may serve as a transport vehicle for leptin to fetal tissues.     

脐血流测定对脐带绕颈的产时监护

目的 :研究脐血流测定对脐带绕颈的产时监护作用。方法 :对 5 5 0例单胎足月妊娠孕妇进行脐血流测定 ,其中脐带绕颈 138例。分A、B、C 3组 ,分析其产时胎儿宫内窘迫发生率 (简称 :胎窘率 )及剖宫产率 ,并动态观察 14 0例(其中脐带绕颈 5 2例 ,无绕颈 88例 )产妇 ,产程中的脐血流变化。结果 :3组脐带长度、绕颈周数、新生儿Apgar评分 ,差异无显著性 (P >0 0 5 )。B组与C组的产时胎窘率及剖宫产率均较A组高 (P <0 0 1,P <0 0 5 )。产程中 ,S/D升高 >0 1,有脐带绕颈组明显高于无绕颈组 (P <0 0 1) ,S/D >3 0与 2 70 相似文献   

Routine umbilical cord blood gas determinations?

Between 1986 and 1988, 1924 term nulliparous patients with spontaneous onset of labor were studied to assess the importance of obtaining umbilical cord blood gas levels on all deliveries. The umbilical cord arterial and venous pH values (expressed as mean +/- 2 SD) were 7.24 +/- 0.14 (n = 1694) and 7.32 +/- 0.12 (n = 1820), respectively. The incidence of newborn depression (1- or 5-minute Apgar score less than 7) was 14.1%; of these depressed newborns, the incidence of normal umbilical cord arterial pH values (greater than or equal to -2 SD) was 77.8%. Of the vigorous newborns, there was a 2.1% incidence of umbilical cord arterial blood acidemia. Umbilical cord arterial blood acidemia in vigorous newborns was not highly predictive of specific morbidity in the immediate newborn period. Regression analysis demonstrated the umbilical cord arterial pH to correlate best with the Apgar scores when compared with all other arterial or venous blood gas measurements. We reached the following conclusions: (1) that obtaining cord arterial pH values in vigorous newborns should be considered since the values will provide objective documentation or normal fetal acid base balance in 98% of infants. (2) Only a cord arterial pH determination is recommended since it reflects fetal or newborn status more accurately than all other measurements. Additional measurements increase the likelihood of abnormal results and do not contribute to neonatal management. (3) An umbilical cord blood pH value is extremely useful in ruling out the diagnosis of birth asphyxia in the depressed newborn.     

Circulating markers of oxidative stress are raised in normal pregnancy and pre-eclampsia

Objective To determine whether circulating markers of oxidative stress are elevated in pre-eclampsia when appropriate precautions are taken to prevent in vitro oxidation
Design A prospective study.
Setting Nuffield Department of Obstetrics and Gynaecology, Oxford and The William Harvey Institute, London.
Sample Three groups of women: those with pre-eclampsia (  n = 19  ), control pregnant (  n = 19  ) matched for gestation, age and parity and a group of non pregnant individuals reproductive age (n = 7).
Methods Citrated plasma was stored at −80°C with 20 μmol β hydroxytoluene to prevent auto-oxidation. Plasma samples were assayed for levels of 8 epi-prostaglandin F_2α, lipid hydroperoxides, malondialdehyde and also the lipid soluble antioxidant vitamin E.
Results There were no differences in 8 epi-prostaglandin F_2α lipid peroxide or malondialdehyde levels between the groups of women with pre-eclampsia and those acting as pregnant controls. However, lipid hydroperoxides and malondialdehyde were significantly raised in both pre-eclampsia and normal pregnancy, compared with nonpregnant women. Vitamin E levels were similar in women with pre-eclampsia and those with a normal pregnancy, but in both groups levels were significantly higher than in nonpregnant women.
Conclusion Circulating markers of oxidative stress are raised in normal pregnancy and pre-eclampsia.     

Fetal Oxygen Saturation Monitoring in Labour: An Analysis of 118 Cases

Summary: Fetal oxygen saturation (FSpO₂) was recorded during labour to determine the relationship between FSpO₂ and indicators of fetal well-being, including umbilical blood gases, xanthine (X), hypoxanthine (Hx) and Apgar scores. This is one of me largest reported series of fetal pulse oximetry, with 118 fetuses monitored for over 329 hours. Mean FSpO, for all cases was 46.9% (SD=9.1%). There was no correlation between FSpO, during the last 10 minutes of monitoring and arterial pH, Hx or X. A mean FSpO₂, ≤ 30% was associated with a 5 minute Apgar score of ≤ 7 in the majority of cases. One fetus had a mean FSpO₂, <30% during the final 10 minutes of monitoring and an umbilical arterial pH<7.20, while there were 10 fetuses with an umbilical arterial pH<7.20, and mean FSpO₂, ≥ 30%. As these numbers are small, a larger series is necessary to further characterize the small number of fetuses who are significantly hypoxic.     

Lipid peroxidation and antioxidant activity in patients in labor with nonreassuring fetal status

OBJECTIVE: The aim of our study was to evaluate lipid peroxidation products and antioxidant enzyme activity in placental tissue and umbilical cord blood, as a marker for fetal hypoxia in patients in labor with nonreassuring fetal status. STUDY DESIGN: Umbilical cord arterial blood and placental tissue samples were collected from 24 patients with term pregnancies in labor and nonreassuring fetal heart rate (FHR) patterns (study) and 24 women with normal pregnancies in labor and normal FHR tracings (controls) for determination of malondialdehyde (MDA) as a marker for lipid peroxidation and superoxide dismutase (SOD) for the antioxidant activity. Measured values were compared statistically between two groups using independent samples t-test or Mann-Whitney U-test. RESULTS: The median 1min Apgar score was 8 (range 4-9) in the study group and 9 (range 8-10) in the control group, respectively (p < 0.001). There was no statistically significant difference between study and control groups in terms of mean 5 min Apgar scores (p > 0.05). Placental MDA levels in patients with nonreassuring fetal status were found to be significantly elevated compared to the control group (12.14 nmol/g tissue versus 9.75 nmol/g tissue; p < 0.01). The placental SOD activity in the study group was significantly higher (p < 0.01) compared to controls (3.57 U/mg protein versus 2.63 U/mg protein). The umbilical cord blood MDA levels in the study group were higher than in normal pregnancies (4.99 nmol/mL, 3.88 nmol/mL; p < 0.05). The activity of SOD in umbilical cord blood was significantly higher (p < 0.001) in patients with nonreassuring fetal status when compared with the control group (11.62 versus 6.95 U/mL). CONCLUSION: Lipid peroxidation products and antioxidant functions were elevated in the umbilical cord blood and placenta of patients having nonreassuring FHR tracings during labor. These findings indicate that lipid peroxidation products in placenta and umbilical cord blood can be used as a possible marker for fetal hypoxia during labor and SOD levels may discriminate acute from chronic hypoxia. Further investigations are needed with large number of series to clarify the variations of lipid peroxidation and antioxidant activity due to acute or chronic fetal hypoxia.     

ACOG Committee Opinion No. 348, November 2006: Umbilical cord blood gas and acid-base analysis

Umbilical cord blood gas and acid-base assessment are the most objective determinations of the fetal metabolic condition at the moment of birth. Moderate and severe newborn encephalopathy, respiratory complications, and composite complication scores increase with an umbilical arterial base deficit of 12-16 mmol/L. Moderate or severe newborn complications occur in 10% of neonates who have this level of acidemia and the rate increases to 40% in neonates who have an umbilical arterial base deficit greater than 16 mmol/L at birth. Immediately after the delivery of the neonate, a segment of umbilical cord should be double-clamped, divided, and placed on the delivery table. Physicians should attempt to obtain venous and arterial blood cord samples in circumstances of cesarean delivery for fetal compromise, low 5-minute Apgar score, severe growth restriction, abnormal fetal heart rate tracing, maternal thyroid disease, intrapartum fever, or multifetal gestation.