Increased oxidative stress in human fetal membranes overlying the cervix from term non-labouring and post labour deliveries

Enzymatic breakdown of the collagen-rich extracellular matrix (ECM) that connects the amnion and chorion layers of the fetal membranes is one of the key events leading to rupture of membranes. Oxidant stress caused by increased formation of reactive oxygen species and/or reduced antioxidant capacity may predispose to membrane rupture, a major cause of preterm birth. The aim of this study was to determine the effect of human labour and supracervical (SC) apposition on antioxidant enzymes and 8-isoprostane (a marker of lipid peroxidation). To determine the effect of human labour on oxidative stress status, fetal membranes from the SC site (SCS) were collected from women at term Caesarean section (no labour), and from the site of membrane rupture (SOR) after spontaneous labour onset and delivery (post labour). To determine the effect of SC apposition on oxidative stress status, amnion was collected from the SCS and a distal site (DS) in women at term Caesarean section in the absence of labour. The release of 8-isoprostane was significantly higher in amnion from the SCS compared to DS, and in fetal membranes from the SOR compared to the SCS. Glutathione peroxidase (GPx) and superoxide dismutase (SOD) activity were lower in amnion from the SC compared to DS. SOD gene expression and enzyme activity were lower in fetal membranes after labour. There was no difference in expression or activity in catalase, GPx and glutathione reductase (GSR) between no labour and post labour fetal membranes. In primary amnion cells, SOD supplementation significantly augmented IL-1β induced MMP-9 expression and activity. In summary, non-labouring SC fetal membranes are characterised by reduced antioxidant enzyme activity when compared to distal membranes, and, as such, may be more susceptible to oxidative damage and thus membrane rupture.     

MAPK and AP-1 proteins are increased in term pre-labour fetal membranes overlying the cervix: regulation of enzymes involved in the degradation of fetal membranes

Fetal membranes overlying the cervix (i.e. supracervical site, SCS) are characterised by increased extracellular matrix (ECM) degradation. In non-gestational tissues, the mitogen activated protein kinase (MAPK) and activator protein (AP)-1 family are involved in the regulation of the ECM degrading enzyme metalloproteinase (MMP)-9. The aims of this study were (i) to compare the expression of AP-1 proteins in fetal membranes from the SCS and a distal site (DS), and (ii) determine if the MAPK/AP-1 pathway is involved in the regulation of MMP-9. Fetal membranes overlying the cervix were identified in situ in women undergoing term elective Caesarean section. Immunohistochemistry (n = 6) was used to localise the expression of the MAPK proteins ERK (total and phosphorylated), JNK (total and phosphorylated) and p38 MAPK (total and phosphorylated), and the AP-1 proteins JunB, cJun (total and phosphorylated), JunD, cFos and FosD. There was no difference in JNK, p38 MAPK, FosB, cJun and JunD protein expression between SC and distal fetal membranes. However, when compared to DS, the intensity and/or extent of staining of ERK, p-ERK, p-JNK, p-p38 MAPK, cFos, JunB and p-cJun were greater in amnion and chorion obtained from the SCS. In order to elucidate a role for these proteins in ECM degradation, pharmacological inhibitors of MAPK protein activation were utilised in primary amnion cells. The ERK inhibitor U0126, JNK inhibitor SP600125 and p38 MAPK inhibitor SB202190 all significantly decreased IL-β-induced MMP-9 gene expression and pro MMP-9 in human primary amnion cells. In summary, at term, non laboured SC fetal membranes are characterised by increased expression of MAPK and AP-1 proteins. MMP-9 expression and production was significantly suppressed by inhibitors of three key enzymes in the signalling cascades leading to AP-1 formation, ERK 1/2, JNK and p38 MAPK. Thus, the MAPK/AP-1 pathway may play a role in the degradation of the ECM at the SCS making it more susceptible to membrane rupture.     

Mapping of zones of altered morphology and chorionic connective tissue cellular phenotype in human fetal membranes (amniochorion and decidua) overlying the lower uterine pole and cervix before labor at term

OBJECTIVE: The purpose of this study was to determine the location, frequency, and extent of altered fetal membrane morphology before term labor and its relation to myofibroblast activation in their connective tissue layers. STUDY DESIGN: Fetal membranes that were obtained from 10 women who underwent prelabor cesarean delivery at 38 to 39 weeks of gestation underwent biopsy examination with respect to the internal os of the cervix. The thickness of their constituent layers was measured, and the numbers of alpha-smooth muscle actin immunoreactive cells (ie, marker of myofibroblast activation) within the reticular layer were counted. RESULTS: A region that measured 119+/-21cm(2), that exhibited altered morphology of the fetal membranes from the lower uterine pole, and that was characterized by increased connective tissue thickness and decreased thickness of the cellular layers was demonstrated in all patients. In 8 of 10 patients, this region was centered on the location of the Babcock tissue forceps. Within this region was an area of fetal membranes that exhibited alpha-smooth muscle actin immunoreactivity in the cells of the reticular layer and whose number correlated with parameters of altered morphology. CONCLUSION: All patients before labor at term possess an area of fetal membranes that are located in the lower uterine pole that exhibit altered morphology that is associated with myofibroblastic activation in the chorionic connective tissue.     

Increased apoptosis of human fetal membranes in rupture of the membranes and chorioamnionitis

Apoptosis is thought to participate pathophysiologically in the rupture of human fetal membranes (ROM). The aim of this study was to assess apoptosis of the amnion and the chorion in relation to ROM and chorioamnionitis (CAM). The amnion and chorion at the position of the cervical os and fundus of the uterus were obtained from 44 patients. Apoptotic DNA fragmentation was densitometrically determined, and the relative ratio was used for the quantitative evaluation. Among patients without CAM, the relative ratios of apoptosis in the amnion from patients with ROM were higher than those in patients without ROM (P< 0.05). Among patients without ROM, the apoptotic levels in the amnion from patients with CAM were higher than those in patients without CAM (P< 0.05). These were the cases with the amnion at the position of cervical os and fundus, but not with the chorion. The highest ratio of apoptosis was seen in the amnion from patients with CAM and ROM. Among patients with ROM and no CAM, the apoptotic levels at the cervical os in the amnion (P=0.059) and chorion (P< 0.05) was higher than those at the fundus. The increased apoptosis of human fetal membranes was related to ROM and CAM. Apoptosis plays a role in the pathophysiology of ROM.     

Management of premature rupture of membranes and unfavorable cervix in term pregnancy

One hundred thirty-four indigent patients at term who had premature rupture of membranes and a cervix unfavorable for induction of labor (80% effacement or less, 2 cm dilation or less) were randomized to compare expectant with intervention management. Women with any medical or obstetric condition warranting immediate intervention were excluded from the study. Patients treated expectantly were placed at bed rest and observed for labor or infection. Patients managed by intervention were given oxytocin if labor did not ensue within 12 hours of rupture of the membranes. Patients in the intervention protocol had longer labor (P less than .02) and a higher incidence of both cesarean delivery (P less than .05) and intraamniotic infection (P less than .05). There was only one case of proven neonatal sepsis, and this occurred in a patient managed by induction of labor. There was no statistically significant difference between groups in mean length of maternal hospitalization.     

Misoprostol for labor induction in women with term premature rupture of membranes: a meta-analysis

OBJECTIVE: To systematically review published data evaluating the comparative use of misoprostol with placebo/expectant management or oxytocin for labor induction in women with term (> or = 36 weeks of gestation) premature rupture of membranes. DATA SOURCES: PubMed (1966-2005), Ovid (1966-2005), CINAHL, The Cochrane Library, ACP Journal Club, OCLC, abstracts from scientific forums, and bibliographies of published articles were searched using the following keywords: premature rupture of membranes, misoprostol, labor induction, and cervical ripening. Primary authors were contacted directly if the data sought were unavailable or only published in abstract form. METHODS OF STUDY SELECTION: Only randomized controlled trials evaluating the efficacy and safety of misoprostol in comparison with placebo or expectant management (n = 6) and oxytocin (n = 9) published in either article or abstract form were analyzed and included in the meta-analysis. TABULATION, INTEGRATION, AND RESULTS: Studies were reviewed independently by all authors. Meta-analysis was performed, and the relative risks (RRs) were calculated and pooled for each study outcome. Misoprostol, compared with placebo, significantly increased vaginal delivery less than 12 hours (RR 2.71, 95% confidence interval [CI] 1.87-3.92, P < .001). Misoprostol was similar to oxytocin with respect to vaginal delivery less than 24 hours (RR 1.07, 95% CI 0.88-1.31, P = .50) and less than 12 hours (RR 0.98, 95% CI 0.71-1.35, P = .90). Misoprostol was not associated with an increased risk of tachysystole, hypertonus, or hyperstimulation syndrome when compared with oxytocin and had similar risks for adverse neonatal and maternal outcomes. CONCLUSION: Misoprostol is an effective and safe agent for induction of labor in women with term premature rupture of membranes. When compared with oxytocin, the risk of contraction abnormalities and the rate of maternal and neonatal complications were similar among the 2 groups.     

Randomized comparison of oral misoprostol and oxytocin for labor induction in term prelabor membrane rupture

OBJECTIVES: To compare labor induction intervals between oral misoprostol and intravenous oxytocin in women who present at term with premature rupture of membranes. METHODS: One hundred eight women were randomly assigned to misoprostol 50 microg orally every 4 hours as needed or intravenous oxytocin. The primary outcome measure was time from induction to vaginal delivery. Sample size was calculated using a two-tailed alpha of 0.05 and power of 80%. RESULTS: Baseline demographic data, including maternal age, gestation, parity, Bishop score, birth weight, and group B streptococcal status, were similar. The mean time +/-standard deviation to vaginal birth with oral misoprostol was 720+/-382 minutes compared with 501+/-389 minutes with oxytocin (P = .007). The durations of the first, second, and third stages of labor were similar. There were no differences in maternal secondary outcomes, including cesarean birth (eight and seven, respectively), infection, maternal satisfaction with labor, epidural use, perineal trauma, manual placental removal, or gastrointestinal side effects. Neonatal outcomes including cord pH, Apgar scores, infection, and admission to neonatal intensive care unit were not different. CONCLUSION: Although labor induction with oral misoprostol was effective, oxytocin resulted in a shorter induction-to-delivery interval. Active labor intervals and other maternal and neonatal outcomes were similar.     

Induction of labor with oral misoprostol for premature rupture of membranes at term in women with unfavorable cervix: a randomized, double-blind, placebo-controlled trial

AIM: To evaluate the efficacy and safety of oral misoprostol for labor induction in women with term premature rupture of membranes (PROM) and an unfavorable cervix. METHODS: We randomized 130 women with PROM of < or =4 h to either oral misoprostol, 50 microg, or a placebo given every 4 h for up to three doses. Intravenous oxytocin was initiated if active labor did not begin within 12 h. RESULTS: Sixty-four women received oral misoprostol and 66 received placebo. The PROM-to-delivery interval was shorter with misoprostol than with placebo (13.7+/-5.8 vs. 20.3+/-6.8 h, respectively, P<0.05). Misoprostol significantly reduced the need for oxytocin (28.1 vs. 72.7%, P<0.001) and antibiotics (25 vs. 69.7%, P<0.001). No significant differences in cesarean section or hyperstimulation rate were noted. CONCLUSION: Oral misoprostol given to women with unfavorable cervix soon after term PROM significantly reduces the induction-to-delivery time and the need for oxytocin and antibiotics.     

Management of term patients with premature rupture of membranes and an unfavorable cervix.

The purpose of this prospective investigation was to evaluate a protocol for management of term patients with premature rupture of membranes (PROM) and a cervix unfavorable for induction of labor (Bishop score 4 or less). Patients initially were observed for 24 to 36 hours for the spontaneous onset of labor. If spontaneous contractions did not commence, labor was induced with oxytocin. Patients subsequently were divided into three groups: 44 who had spontaneous labor, 29 who had spontaneous labor but required oxytocin augmentation, and 39 women who had oxytocin induction. Patients who entered labor spontaneously had a significantly shorter mean latent period between rupture of membranes and onset of labor (16.0 versus 26.8 and 40.7 hours), shorter mean duration of labor (7.6 versus 12.1 and 13.1 hours), and shorter mean duration of rupture of membranes (23.6 versus 39.0 and 53.8 hours). These women also had a significant decrease in the frequency of chorioamnionitis (7 versus 14 and 33%), and their infants had fewer evaluations for sepsis (25.0 versus 34.5 and 53.8%). We conclude that term patients with PROM and an unfavorable cervix who require oxytocin augmentation or induction of labor are at increased risk for intrapartum and neonatal infection compared with those who progress through labor spontaneously.     

Amniotic fluid glucose concentration: a marker for infection in preterm labor and preterm premature rupture of membranes

Amniotic fluid Gram stain and culture have been utilized as laboratory tests of microbial invasion of the amniotic cavity. The Gram stain of amniotic fluid has a low sensitivity in the detection of clinical infection or microbial invasion of the amniotic cavity, and amniotic fluid culture results are not immediately available for management decisions. Glucose concentration is used to diagnose infection in other sites such as cerebrospinal fluid.Objective: The purpose of this study was to evaluate the usefulness of amniotic fluid glucose concentration in detecting microbial invasion of the amniotic cavity associated with preterm labor and preterm premature rupture of membranes.Methods: Amniocentesis was performed in 60 women with preterm labor and/or preterm premature rupture of membranes. Gram stain and culture for Mycoplasma hominis, Ureaplasma urealyticum, aerobic, and anaerobic bacteria were performed. Subjects were studied prospectively for the development of positive amniotic fluid cultures and the development of clinical chorioamnionitis.Results: The diagnosis of clinical chorioamnionitis was made in 25% (15/60) of women entered into the study. Low amniotic fluid glucose concentration Was considered < 15 mg/dl. The sensitivity, specificity, and positive predictive value of low amniotic, fluid glucose concentration to predict clinical chorioamnionitis were 73.3%, 88.1%, and 68.8% respectively, while positive amniotic fluid culture, hada sensitivity of 43.8%, specificity of 79.5%, and positive predictive value of 43.8%.Conclusions: Amniotic fluid glucose concentration was more sensitive in predicting chorioamnionitis than either Gram stain or culture. Amniotic fluid glucose concentration was better in predicting clinical chorioamnionitis than predicting positive amniotic fluid culture results. Gestational age-dependent normal ranges and pathologic conditions that may alter amniotic fluid glucose concentrations should be considered when interpreting amniotic fluid glucose values to diagnose microbial invasion of the amniotic cavity.     

Is the fibrinolytic activity involved in the mechanism of fetal membrane rupture? A clinical study of term and prematurely ruptured membranes

The fibrinolytic activity (FA) was determined in fetal membrane specimens obtained in 15 cases of premature rupture of the membranes (PROM) and from 15 control women who gave birth spontaneously at term. In each case two membrane specimens were obtained, one from the rupture margin and the other from the membranes close to the placental margin. No significant difference in FA was demonstrated between the two groups of patients. Nor could any significant difference be found on comparing the FA within the paired membrane specimens of each group. Furthermore, no obvious change in FA was demonstrated in relation to clinical signs of chorioamnionitis or microbiological findings. However, although the FAs observed in prematurely ruptured membranes were comparable to those found in term specimens, this does not exclude the possibility of an involvement of FA in the mechanism of membrane rupture.     

Programmed cell death (apoptosis) as a possible pathway to metalloproteinase activation and fetal membrane degradation in premature rupture of membranes

OBJECTIVE: Increased matrix metalloproteinase 2 expression and activity are associated with premature rupture of fetal membranes. A proapoptotic protein produced in response to deoxyribonucleic acid fragmentation, p53, can bind to the matrix metalloproteinase 2 gene promoter and cause increased gene expression. It promotes apoptosis by inducing the expression of the proapoptotic bax gene and inhibiting the antiapoptotic bcl-2 gene. This study was undertaken to investigate the expression pattern of apoptotic elements in pregnancy complications that may cause increased expression of the gene for matrix metalloproteinase 2. STUDY DESIGN: Amniochorial membranes were collected from the following groups of women: (1) women with premature rupture of fetal membranes, (2) women with preterm labor and intact membranes, and (3) women with term labor after vaginal delivery. Deoxyribonucleic acid fragmentation was tested with ligation-mediated polymerase chain reaction and the terminal deoxynucleotidyl transferase-mediated biotinylated deoxyribonucleoside triphosphate end-labeling assay. Matrix metalloproteinase 2, p53, bcl-2, and bax gene expression patterns were studied with quantitative competitive polymerase chain reaction. Statistical analysis was performed with the Tukey-Kramer multiple comparison test. RESULTS: Quantitative competitive polymerase chain reaction documented a 10-fold increase in the expression of the gene for matrix metalloproteinase 2 in premature rupture of fetal membranes with respect to term and preterm labor. This induction coincided with an increase in the expressions of the proapoptotic genes p53 and bax and a drop in the expression of the antiapoptotic gene bcl-2. Ligation-mediated polymerase chain reaction revealed deoxyribonucleic acid fragmentation in specimens from premature rupture of fetal membranes and not in those from preterm labor or labor at term. Histochemical analysis documented fragmented deoxyribonucleic acid in chorionic and amniotic cells. CONCLUSION: This study suggests that apoptosis is associated with premature rupture of fetal membranes. Deoxyribonucleic acid fragmentation, associated with elevations in the levels of the two proapoptotic gene products evaluated (p53 and bax ) and a drop in the level of the antiapoptotic bcl-2, was seen in premature rupture of the fetal membranes. Induction of matrix metalloproteinase 2 may be a function of p53 gene expression increase in premature rupture of fetal membranes.