The effect of prematurity on vaginal birth after cesarean delivery: success and maternal morbidity

OBJECTIVE: We sought to compare vaginal birth after cesarean (VBAC) success and uterine rupture rates between preterm and term gestations in women with a history of one prior cesarean delivery. Our hypothesis was that preterm women undergoing VBAC were more likely to be successful and have a lower rate of complications than term women undergoing VBAC. METHODS: We reviewed medical records of women with a history of a cesarean delivery who either attempted a VBAC or underwent a repeat cesarean delivery from 1995 through 2000 in 17 community and university hospitals. We collected information on demographics, medical and obstetric history, complications, and outcome of the index pregnancy. The primary analysis was limited to women with singleton gestations and one prior cesarean delivery. Statistical analysis consisted of bivariate and multivariable techniques. RESULTS: Among the 20,156 patients with one prior cesarean delivery, 12,463 (61%) attempted a VBAC. Mean gestational ages for the term and preterm women were 39.2 weeks and 33.9 weeks of gestation, respectively. The VBAC success rates for the term and preterm groups were 74% and 82%, respectively (P < .001). Multivariable analysis showed that the VBAC success was higher (adjusted odds ratio 1.54, 95% confidence interval 1.27-1.86) in preterm gestations. A decreased risk of rupture among preterm gestations was suggested in these results (adjusted odds ratio 0.28, 95% confidence interval 0.07-1.17; P = .08). CONCLUSION: Preterm patients undergoing a VBAC have higher success rates when compared with term patients undergoing a VBAC. Preterm patients undergoing VBAC may have lower uterine rupture rates.     

Antepartum glucocorticoid therapy suppresses human placental xenobiotic and steroid metabolizing enzymes

We investigated the effects of maternal gestational corticosteroid therapy on placental xenobiotic and steroid metabolizing enzymes at term in 20 glucocorticoid/betamethasone treated (with various doses) and control (n=10) women. A single dose of betamethasone (12 mg i.m. twice at a 24-h interval) was given to 15 mothers at risk of preterm delivery to prevent respiratory syndrome in their premature newborns. Five mothers were treated more than once. The gestation time in mothers receiving the glucocorticoid therapy varied from 22-38 gestational weeks.Compared with controls, a significant decrease in placental aromatase activity (53.6+/-18.0 pmol/mg/min versus 119+/-30 pmol/mg/min, P=0.0007) and placental CYP19 mRNA content (by 50 per cent ) was observed in mothers treated with glucocorticoids. Also the formation of androstenedione (13.2+/-8.1 pmol/mg/min, steroids versus 30.03+/-5.2 pmol/mg/min, controls, P< 0.001), using testosterone as the substrate, and 7-ethoxycoumarin O-deethylase (P< 0.05) and 7-ethoxyresorufin O-deethylase (P< 0.09) were slightly decreased in the glucocorticoid treated compared to control patients' values. The changes were not dependent on the number of treatments or the time between treatment and delivery.Our results demonstrate that even a single dose of glucocorticoid given to expectant mothers is associated with diminished placental steroid hormone and xenobiotic metabolizing enzymes at term. Further studies are needed to assess whether these changes affect the well-being of the fetus and its later development.     

Risk of recurrent preterm birth and placental pathology

OBJECTIVE: To estimate whether placental pathological lesions from an index preterm birth are associated with an increased risk of recurrent preterm birth and to estimate whether certain pathologic lesions recur in a woman's next delivery. METHODS: We performed a retrospective cohort study of all women who delivered at less than 37 weeks and had their next delivery at our institution during a 5-year period. Women were included in the cohort if placental pathology was available from their preterm birth. Placental pathology from their subsequent birth was also collected. Placental pathology was classified into presence or absence of two classes of lesions-inflammatory and thrombotic. Variables considered as possible confounders included race, gestational age of preterm birth, interpregnancy interval, tobacco use, payor status, years of education, and maternal medical problems. RESULTS: Inflammatory lesions (n=173) were associated with recurrent preterm birth overall as well as recurrent spontaneous preterm birth (P<.001). Thrombotic lesions (n=158) were not associated with recurrent preterm birth or any subtypes of preterm birth. The association between inflammatory lesions and recurrent spontaneous preterm birth remained significant when controlling for gestational age of preterm birth, race, and tobacco use, with an adjusted odds ratio of 2.4 (95% confidence interval 1.2-4.7). Inflammatory placental lesions (n=194) were associated with inflammatory lesions in the subsequent delivery P=.001). CONCLUSION: Recurrent preterm birth is more likely among women with inflammatory lesions on placental pathology from a prior preterm birth. Additionally, these women are more likely to have placental inflammatory lesions with their next delivery. LEVEL OF EVIDENCE: II.     

Placental neurokinin B mRNA expression increases at preterm labor

INTRODUCTION: Neurokinin B (NKB) is a neuropeptide belonging to the family of tachykinins-related peptides that elicits contractility of human myometrial strips in vitro. The present study evaluates whether placental mRNA and peptide expression of NKB change in women at preterm labor. METHODS: A group of 26 women with singleton pregnancies were enrolled in the study. Placental tissue specimens were collected from pregnant women delivering after elective cesarean section, after labor at term, or after preterm labor. Changes in placental NKB mRNA and protein expression were evaluated by real-time quantitative RT-PCR analysis and by immunofluorescence respectively. RESULTS: Placental mRNA expression of NKB was significantly higher after term and preterm labor (P<0.001) than cesarean section, and highest after preterm labor. Immunofluorescent staining in placentas from preterm or term labor was more intense than after cesarean section (P<0.001). In particular, NKB protein expression was higher in placentas collected after preterm labor than those collected after term labor. DISCUSSION: Neurokinin B mRNA and protein are highly expressed in placenta at term and preterm labor; thus, the involvement of this neuropeptide in the events cascade leading to parturition may be suggested.     

Cytokine abundance in placental tissues: evidence of inflammatory activation in gestational membranes with term and preterm parturition

OBJECTIVES: This study of the changes in cytokine concentrations in gestational tissues from women with term and preterm labor was undertaken to assess the extent of inflammatory activation associated with spontaneous labor and delivery. STUDY DESIGN: Extracts of amniotic, chorionic-decidual, and placental tissues from women delivered at term before labor (n = 15), at term after labor (n = 15), and preterm (n = 31) were assayed for interleukin 1beta, interleukin 6, and interleukin 8. RESULTS: In amniotic tissues of women delivered by spontaneous labor at term the median interleukin-6, interleukin-8, and interleukin-1beta concentrations were 3.8 to 5.4 times those of tissues from women delivered at term without labor (P <.05, Mann-Whitney U test). Interleukin-6 and interleukin-8 concentrations were also significantly increased (3. 3-4 times) in chorionic-decidual tissues. Marked increases (approximately 3-6 times) in the concentrations of all 3 cytokines were observed in both amniotic and chorionic-decidual tissues from women with preterm deliveries with respect to those from women with term deliveries after labor. Cytokine concentrations were significantly correlated within amniotic tissues from both women with term delivery after labor and women with preterm delivery and also in preterm chorionic-decidual tissues but not preterm placental tissues. Concentrations of cytokines in the tissues of women delivered preterm were not significantly affected by mode of delivery, treatment with antibiotics, or twin birth. In preterm tissues with evidence of intrauterine infection only amniotic interleukin-1beta concentrations were significantly elevated (P <. 05). Little or no labor-related change in cytokine concentrations was seen within placental tissues. CONCLUSIONS: Increased cytokine abundance in gestational membranes associated with labor supports the view that an inflammatory process is involved in both term and preterm labor. This process does not, however, appear to be evident in the villous placenta.     

Previous preterm cesarean delivery and risk of subsequent uterine rupture

OBJECTIVE: To determine if women with a history of a previous preterm cesarean delivery experienced an increased risk of subsequent uterine rupture compared with women who had a previous nonclassic term cesarean delivery. METHODS: A prospective observational study was performed in singleton gestations that had a previous nonclassic cesarean delivery from 1999 to 2002. Women with a history of a previous preterm cesarean delivery were compared with women who had a previous term cesarean delivery. Women who had both a preterm and term cesarean delivery were included in the preterm group. RESULTS: A prior preterm cesarean delivery was significantly associated with an increased risk of subsequent uterine rupture (0.58% compared with 0.28%, P<.001). When women who had a subsequent elective cesarean delivery were removed (remaining n=26,454) women with a previous preterm cesarean delivery were still significantly more likely to sustain a uterine rupture (0.79% compared with 0.46%, P=.001). However, when only women who had a subsequent trial of labor were included, there was still an absolute increased risk of uterine rupture, but it was not statistically significant (1.00% compared with 0.68%, P=.081). In a multivariable analysis controlling for confounding variables (oxytocin use, two or more previous cesarean deliveries, a cesarean delivery within the past 2 years, and preterm delivery in the current pregnancy), patients with a previous preterm cesarean delivery remained at an increased risk of subsequent uterine rupture (P=.043, odds ratio 1.6, 95% confidence interval 1.01-2.50) compared with women with previous term cesarean delivery. CONCLUSION: Women who have had a previous preterm cesarean delivery are at a minimally increased risk for uterine rupture in a subsequent pregnancy when compared with women who have had previous term cesarean deliveries.     

Does an obese prepregnancy body mass index influence outcome in pregnancies complicated by mild gestational hypertension remote from term?

OBJECTIVES: This study was undertaken to determine the influence of increased prepregnancy body mass index (BMI) on pregnancy outcome in women with mild gestational hypertension remote from term. STUDY DESIGN: A matched cohort design was used. A total of 365 pregnant women with mild gestational hypertension and a normal prepregnancy BMI (20-25 kg/m2) were matched 1:1 for gestational age at diagnosis, race and parity to 365 women with mild gestational hypertension, but an obese prepregnancy BMI (> or = 30 kg/m2). RESULTS: Matched characteristics were distributed as follows: gestational age at diagnosis 32.2 +/- 2.4 weeks; race 80.8% white; parity 59.7% nulliparous. The rate of progression to preeclampsia was the primary endpoint of the study and was similar between the prepregnancy normal and obese BMI groups (37.8% vs 41.1%, P = .352). Birth weight at delivery (3033 +/- 747 g vs 2833 +/- 659 g, P < .001) and cesarean delivery rate (56.7% vs 40.3%, P < .001) were greater in the obese prepregnancy BMI group. CONCLUSION: In patients with mild gestational hypertension remote from term, an obese prepregnancy BMI was associated with similar rates of progression to preeclampsia. Secondarily, an obese prepregnancy BMI was associated with higher birth weights and an increased incidence of cesarean delivery.     

Demographic and obstetric factors influencing pregnancy outcome in twin gestations

OBJECTIVE: Our purpose was to identify the influence of parity and previous preterm delivery on pregnancy outcome in twin gestations. STUDY DESIGN: A retrospective comparative analysis of women with twin gestations completing an outpatient preterm labor surveillance program between April 1995 and February 2000 was performed. Included were those enrolled at <24 weeks' gestation. Parity, maternal age, prepregnancy body mass index (BMI), cerclage, tocolytic use, and pregnancy outcome were identified. Data were divided into nulliparas, multiparas without previous preterm delivery, and those with previous preterm delivery. Analysis of variance and the Pearson chi2 test were used for statistical analysis. RESULTS: Data were analyzed for 1268 twin pregnancies. The mean gestational age at delivery for the multiparous women without a history of previous preterm delivery (35.3 +/- 2.7 weeks) was significantly greater than the mean gestational age at delivery for nulliparous (34.4 +/- 3.2 weeks) and multiparous women with a previous preterm delivery (34.0 +/- 3.1 weeks), P <.001. The greater gestational age at delivery in the multiparous women without a previous preterm delivery was associated with a significantly shorter newborn hospital stay and a lower need for mechanical ventilation use compared with the other groups (all P values < or =.001). CONCLUSION: In twin gestations, multiparous women without history of previous preterm delivery have a significantly greater gestational age at delivery, a lower incidence of cerclage, and a reduced neonatal hospital stay than do nulliparous women or those with a history of a previous preterm delivery.     

Pregnancy outcome in women with preterm labor symptoms without cervical change

OBJECTIVE: This study was undertaken to determine pregnancy outcome in women who have preterm labor symptoms without cervical change according to fetal fibronectin status. STUDY DESIGN: Patients who were examined at the obstetric emergency department with symptoms of preterm labor but without cervical change underwent fetal fibronectin collection. Pregnancy outcome and fetal fibronectin results were analyzed after delivery. RESULTS: Of the 235 patients sampled, 20% (n = 48) had positive fetal fibronectin results. The mean +/- SD gestational age at delivery was lower in women with positive fetal fibronectin results (34.2 +/- 4.1 vs 37.7 +/- 2.3 weeks; P <.001); these women were more likely to deliver preterm as a result of preterm labor than women with other obstetric indications (46% vs 19%; P <.001). Infants born to these women demonstrated lower birth weight (2317 +/- 895 g vs 2877 +/- 557 g; P =.003), were more likely to be admitted to the neonatal intensive care unit (42% vs 14%; P <.001), and were more likely to die in the neonatal period (11% vs 0%; P <.001). CONCLUSION: Patients with symptoms of preterm labor but without cervical change who have negative fetal fibronectin results are less likely to deliver preterm. Therefore in women with symptoms but without cervical change fetal fibronectin should be considered for risk assessment.     

Plasma corticotropin-releasing hormone and unconjugated estriol in human pregnancy: gestational patterns and ability to predict preterm delivery.

OBJECTIVE: The purpose of this study was to compare the patterns and timing of the increases in plasma levels of corticotropin-releasing hormone and unconjugated estriol during human pregnancy. STUDY DESIGN: Corticotropin-releasing hormone and unconjugated estriol were measured in serial samples that were collected from preterm subjects and from spontaneous term control subjects who were selected randomly from a study cohort of 297 women. RESULTS: Gestational increases in log corticotropin-releasing hormone and log unconjugated estriol concentrations were best described by linear and cubic polynomial functions, respectively. Plasma unconjugated estriol levels were similar in preterm and term singleton pregnancies at equivalent gestation, whereas corticotropin-releasing hormone was elevated earlier in premature subjects. Mean corticotropin-releasing hormone levels relative to term control subjects (n = 40 women) were shifted forward 16.5 +/- 8.1 days (P =.027, singleton preterm, spontaneous labor; n = 16) and 33.0 +/- 7.9 days (P <.001, singleton preterm, obstetric intervention; n = 10). The corresponding shifts in unconjugated estriol values were -3.8 +/- 2.0 days and -2.7 +/- 5.6 days (both not significant). The prematurity of delivery showed a significant regression on shifts in corticotropin-releasing hormone (P =.004 and P <.001) but not in unconjugated estriol for the 2 groups. The ability to predict prematurity was not significantly improved by regression on corticotropin-releasing hormone and unconjugated estriol shift values together. CONCLUSION: The patterns and timing of gestational changes in corticotropin-releasing hormone and unconjugated estriol differ in humans. The usefulness of corticotropin-releasing hormone as a biochemical preterm marker in singleton pregnancies is not enhanced by the additional measurement of plasma unconjugated estriol.     

Natural history of cervical funneling in women at high risk for spontaneous preterm birth

OBJECTIVE: To estimate the natural history of funneling in the second trimester by transvaginal ultrasonograms and whether funneling increases the risk of spontaneous birth. METHODS: Secondary analysis of a blinded, multi-center observational study of women with at least one prior spontaneous preterm birth at 16.0-31.9 weeks who subsequently carried singleton gestations. Cervical length, funneling (membrane prolapse greater than or equal to 5 mm), funnel shape, and dynamic changes were recorded at 16-18 weeks, and then every 2 weeks until 23.9 weeks. Managing obstetricians were blinded to the ultrasonography results. The primary outcome was gestational age at delivery. RESULTS: Five hundred ninety scans were performed in 183 women, of which 60 (33%) had funneling observed on at least one of the serial evaluations. These 60 women delivered at an earlier gestational age at delivery than the 123 women without funneling (31.7+/-7.9 weeks compared with 36.9+/-4.4 weeks; P<.001). In the 60 women with funneling on at least one evaluation, the progression over time of internal os cervical anatomy from a "T" to a "V" to a "U" shape was associated with earlier gestational age at delivery, whereas resolution of "V" shape funnels was associated with term delivery. Women with a shortened cervical length less than 25 mm (n=60) had a similar gestational age at birth with or without funneling (30.6+/-8.0 weeks compared with 31.9+/-6.6 weeks; P=.59). After controlling for the shortest observed cervical length, largest funnel percent was not a significant independent risk factor. CONCLUSION: The natural history of second-trimester funneling has significant variability and a significant association with earlier gestational age at delivery. As an independent finding, funneling does not add appreciably to the risk of early gestational age at delivery associated with a shortened cervical length. LEVEL OF EVIDENCE: II.     

Placental isoferritin measured by a specific monoclonal antibody as a predictive marker for preterm contraction outcome

The serum levels of placental isoferritin and normal ferritin in 25 women with preterm contractions (mean +/- SE gestational age 28.8 +/- 4.7 weeks) were compared with those in 14 control women with uncomplicated pregnancies (29.1 +/- 7.3 weeks). The serum concentration of placental isoferritin in women with preterm contractions (15.3 +/- 6.2 U/mL) was significantly lower than that in normal pregnant women (87.6 +/- 22.6 U/mL) (P = .005). The level of normal ferritin in women with preterm contractions (30.6 +/- 4.16 ng/ml) was lower than that in women with normal pregnancies (67 +/- 9.6 ng/mL) (P = .01); however, both were within the normal range. Serum placental isoferritin levels correlated with pregnancy outcome; low placental isoferritin (up to 10 U/mL) was a sensitive (71.5%) indicator of preterm labor. Low placental isoferritin had a positive predictive value of 59% and a negative predictive value of 71%. These results suggest that placental isoferritin may serve as a predictive marker for the prognosis of preterm contractions.     

重度子痫前期胎盘组织中NFAT5表达与围生儿结局的相关性研究

目的:探讨核转录因子5(NFAT5)在重度子痫前期(sPE)胎盘中的表达及其与围生儿结局的相关性。方法:收集2015年1月至2016年1月在郑州大学第三附属医院行剖宫产分娩的sPE孕妇(试验组)60例。选取同期非PE行剖宫产术的孕妇60例作为对照组。免疫组化法检测胎盘组织中NFAT5表达;RT-PCR法检测胎盘组织中NFAT5 mRNA表达。对胎盘中NFAT5 mRNA水平与围生儿结局进行相关分析。结果:sPE组的新生儿体重、胎盘重量、Apgar评分及分娩孕周均低于对照组(P均0.05)。两组胎盘中NFAT5蛋白多位于胎盘滋养细胞的胞核与胞质中,绒毛间质细胞内有少量表达。sPE组的NFAT5蛋白和mRNA表达水平均高于对照组,差异均有统计学意义(t=-40.434,P=0.001;t=-6.696,P=0.001)。sPE组的NFAT5 mRNA相对表达量与新生儿出生体重、胎盘重量、分娩孕周均呈负相关(r分别为-0.554,-0.698,-0.612,P均0.05),与孕妇体重指数(BMI)呈正相关(r=0.630,P=0.012)。结论:sPE组胎盘组织中NFAT5表达水平升高,与围生儿不良结局有关。     

The effect of magnesium sulfate on the placental corticotropin-releasing factor (CRF) and CRF binding protein mRNA expression in perfused human placental cotyledon

Objectives: Stress stimuli and inflammation influence the secretion of the placental corticotropin-releasing factor CRF (CRF) that has a significant role in controlling the timing of birth. The CRF-binding protein (CRF-BP) binds CRF with high affinity and inhibits its activity. Magnesium sulfate (MgSO₄) has been known to ameliorate maternal, fetal and gestational tissue-associated inflammatory response. We aimed to study the effect of MgSO₄ on the CRF and CRF-BP mRNA expression levels in perfused human cotyledon.

Methods: Placentas from elective caesarean section were obtained and selected cotyledons were cannulated and dually perfused ex-vivo within 30?min. MgSO₄ (7?mg/dl) was added to the maternal reservoir. Each perfusion experiment was conducted for 180?min. At the end of the experiment, RNA was extracted from the perfused cotyledon, and RT-PCR was performed to quantify the expression of CRF and CRF-BP. Human HPRT gene served as a reference gene.

Results: Perfusion with MgSO₄ (n?=?3) induced a significantly lower CRF and higher CRF-BP mRNA expression compared to placentas perfused only with medium (n?=?3).

Conclusion: In the human placenta, MgSO₄ possibly exerts its action through different modulation on the CRF and CRF-BP expression.     

Role of transvaginal sonographic cervical length in predicting spontaneous preterm delivery in triplet pregnancies with therapeutic cerclage

OBJECTIVE: To assess the role of transvaginal sonographic cervical length in predicting spontaneous preterm delivery at < 32 weeks in patients with both triplet pregnancy and therapeutic cerclage. STUDY DESIGN: The maternal records of all triplet pregnancies with therapeutic cerclage and sonographic cervical length before and after cerclage were reviewed (n = 17). Each of these triplet gestations was matched with 2 triplet pregnancies without cerclage based on cervical length after cerclage (+/- 0.5 cm) and gestational age (+/- 3 weeks). Statistical analysis included Fisher's exact test or chi 2 analysis, one-way analysis of variance, logistic regression analysis and receiver operating characteristic curve analysis. RESULTS: Cerclage was placed at a gestational age of 19.0 +/- 3.1 weeks (mean +/- SD) and increased cervical length from 2.0 +/- 0.7 cm to 3.1 +/- 1.4 cm (P < .05). The rate of spontaneous preterm delivery at < 32 weeks was higher among cases than controls (7/17 vs. 4/27, P = .08). Logistic regression analysis demonstrated that only postcerclage cervical length was predictive of spontaneous preterm delivery at < 32 weeks, with a cervical length of 3.3 cm the optimal predictor. CONCLUSION: In women with triplets and therapeutic cerclage, the only significant predictor of spontaneous preterm delivery at < 32 weeks is cervical length after cerclage placement.     

Beneficial impact of term labor: nonenzymatic antioxidant reserve in the human fetus

OBJECTIVE: Oxidative stress occurs when the production of damaging free radicals and other oxidative molecules exceeds the capacity of the body's antioxidant defenses. Oxidative stress is implicated in diseases that are associated with prematurity (such as retinopathy, cerebral palsy, intraventricular hemorrhage, and necrotizing enterocolitis). Nonenzymatic antioxidant reserve is the first line of defense against free radicals. We hypothesized that an in utero redox imbalance because of stress would diminish the fetal antioxidant reserve. We tested aspects of this hypothesis by investigating whether the presence of labor or gestational age at delivery (term vs preterm) alters the maternal/fetal nonenzymatic antioxidant reserve peripartum. STUDY DESIGN: Fetal redox consumption was calculated from the difference in the nonenzymatic antioxidant reserve that was measured in umbilical venous and arterial blood that was collected prospectively at delivery from 39 newborn infants. Eight women were delivered at term by elective cesarean delivery in the absence of labor; 31 women labored either at term (n = 20) or preterm (<37 weeks, n = 11). Maternal venous blood was collected on admission and within 1 hour of delivery. Nonenzymatic antioxidant reserve was measured in the plasma and red blood cells of each specimen by the quantitation of glutathione content (glutathione in red blood cell lysate) and the plasma total free radical-trapping antioxidant potential. Glutathione was measured with the use of a colorimetric assay and expressed in nanomoles per milligram of hemoglobin. The plasma total radical-trapping antioxidant potential was estimated with the use of a controlled, kinetic assay based on the time that was required to inhibit peroxyl-free radical generated under controlled conditions. The differences between both umbilical venous and umbilical arterial total radical-trapping antioxidant potential and glutathione were computed to estimate fetal nonenzymatic antioxidant reserve consumption. The differences between maternal total radical-trapping antioxidant potential and glutathione before and after delivery were computed to estimate maternal peripartal nonenzymatic antioxidant reserve consumption. RESULTS: Fetal red blood cell glutathione content was significantly greater than maternal red blood cell glutathione content, independent of delivery route. The calculation of the fetal nonenzymatic antioxidant reserve consumption and maternal peripartal nonenzymatic antioxidant reserve consumption revealed that women who labored at term experienced an up-regulation in red blood cell glutathione content, while their fetuses had significantly lower red blood cell glutathione consumption. In contrast, there was consumption of plasma antioxidants in preterm fetuses, as illustrated by a doubling of the fetal nonenzymatic antioxidant reserve consumption (elective cesarean delivery in the absence of labor, 0.9 +/- 0.5 min/microL; term labor, 1.0 +/- 0.1 min/microL; preterm labor, 2.0 +/- 0.4 min/microL; one-way analysis of variance; P =.04). This was mostly due to a lower umbilical arterial total radical-trapping antioxidant potential in preterm versus term fetuses (umbilical arterial, 3.3 min/microL versus umbilical venous 5.4 min/microL; paired t test; P =.001; power, 0.98). Generally, maternal total radical-trapping antioxidant potential remained unchanged peripartum. CONCLUSION: Term labor triggers a compensatory up-regulation of nonenzymatic antioxidant reserve in the fetal red blood cell compartment that may act to protect against the relative hyperoxia that is experienced by the newborn infant at birth. In contrast, the decreased nonenzymatic antioxidant reserve in the fetal red blood cell and plasma compartments after preterm labor and delivery would enhance the vulnerability to free radical damage of the preterm neonate. These findings suggest that the two compartments of nonenzymatic antioxidant reserve have distinct physiologic roles in the peripartal defense against free radicals and that their development is, in some fashion, ontogenes, in some fashion, ontogenetically regulated.     

Identification of placental cytokine-producing cells in term and preterm labor

Objective: To determine if the production of proinflammatory cytokines by placentally derived macrophages changes with term and preterm labor and to examine if changes in antigen expression of these cytokines can be detected by immunohistologic methods.Methods: Enzymatically dispersed placental cell suspensions of the trophoblastic villi, obtained from 16 women with spontaneous term delivery, 16 women with elective cesarean delivery without any labor, and 22 preterm delivering women with labor unresponsive to tocolysis, were fractionated by magnetic-associated-cell-sorting, on the basis of CD11b-antigen expression. Positively and negatively sorted cell fractions were cultured and concentrations of interleukin-6, interleukin-1β, and tumor-necrosis-factor-α were measured in the culture supernatants. Immunohistologic staining was used for identification of cytokine-producing cells within placental tissues.Results: Positively sorted cells obtained from term (median 2027 pg/mL, P = .037) and preterm (median 3628 pg/mL, P = .001) laboring women produced significantly elevated amounts of tumor-necrosis-factor-α compared with non-laboring (median 1088 pg/mL) women at term. Negatively sorted cell fractions obtained from term (median interleukin-1β 162 pg/mL, P = .031, median interleukin-6 3134 pg/mL, P = .004) and preterm (median interleukin-1β 934 pg/mL, P = .003, median interleukin-6 5695 pg/mL, P = .001) laboring women produced significantly elevated amounts of interleukin-1β and interleukin-6 compared with nonlaboring (median interleukin-1β 29 pg/mL, median interleukin-6 135 pg/mL) women at term. Immunohistologic staining revealed that tumor-necrosis-factor-a activity was localized in isolated stromal cells, whereas interleukin-1β and interleukin-6 were predominantly found in endothelial cells within placental villi.Conclusion: The source of labor-associated release of tumor-necrosis-factor-α from placental tissues are macrophages, whereas interleukin-1β and interleukin-6 are released from placental endothelial cells.     

Association between raised serum relaxin levels during the eighteenth gestational week and very preterm delivery

OBJECTIVE: Our aim was to evaluate a possible association between serum relaxin levels in the 18th gestational week and preterm delivery. STUDY DESIGN: We conducted a nested case-control study that was based on serum samples obtained in the 18th week of gestation from 1545 unselected healthy primiparous women. Eleven case subjects were delivered very early (9 spontaneously, 2 by indicated cesarean delivery) and 42 moderately early (41 spontaneously, 1 by indicated cesarean delivery); 123 control subjects (121 having spontaneous labor, 2 undergoing indicated cesarean delivery) were randomly selected among the women with delivery at term. RESULTS: The serum relaxin concentration during the 18th gestational week was 63% higher among subjects with very preterm deliveries than among control subjects (P = .01, Mann-Whitney test). High relaxin levels during the 18th gestational week were associated with an increased risk of very preterm delivery (odds ratio, 11.3; 95% confidence interval, 2.14-59.1) and spontaneous very preterm delivery (odds ratio, 5.5; 95% confidence interval, 1.3-23). There was a negative correlation for case subjects and control subjects between serum relaxin concentrations during the 18th gestational week and gestational age at delivery (P < .05). CONCLUSION: Serum relaxin may be an independent predictor when identification of women at risk of very preterm delivery is attempted in the 18th gestational week.     

Monocyte chemotactic protein-1 in cervical and amniotic fluid: relationship to microbial invasion of the amniotic cavity, intra-amniotic inflammation, and preterm delivery

OBJECTIVE: The purpose of this study was to evaluate the role of monocyte chemotactic protein-1 in cervical and amniotic fluid in women in preterm labor and with preterm premature rupture of membranes. STUDY DESIGN: Women with singleton pregnancies (相似文献