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Oncofetal fibronectin: new insight into the physiology of implantation and labor.

Oncofetal fibronectin is a newly studied protein produced by the trophoblast and is present in plasma and cervicovaginal secretions of pregnant women as labor approaches or when they have certain complications of pregnancy. Alterations in levels of oncofetal fibronectin occur in preterm labor, postterm pregnancy, and pregnancy-induced hypertension. Determining the presence or absence of full-term and preterm labor often is difficult in the clinical setting, and decision-making sometimes is hindered by the lack of a specific biochemical marker for labor. Oncofetal fibronectin may become a clinical indicator or predictor of true labor, preterm labor, or some complications of pregnancy. Assay techniques that identify clinically meaningful levels of oncofetal fibronectin are being developed and investigated and soon may be available to screen and identify pregnant women at risk. Research findings suggest new paths for investigation that may lead to important interventions in health care directed at identifying and decreasing maternal and neonatal morbidity and mortality. This article reviews pertinent aspects of placentation and the rationale for using oncofetal fibronectin detection as a clinical marker for abnormal pregnancy states.

Adenosine Monophosphate↗

ERK1/2-mediated phosphorylation of myometrial caldesmon during pregnancy and labor.

We used a timed-pregnant rat model to track changes in myometrial contractility during pregnancy and labor and to correlate these changes with upstream signaling events. Myometrium was harvested from CO(2)-euthanized rats. Although contraction amplitudes increased at 16 and 20 days of pregnancy, contraction incidence and area under the force curve were inhibited, consistent with the myometrial quiescence of pregnancy. The Ca(2+) sensitivity of contraction was decreased at 20 days of pregnancy and this was partially reversed in labor. The protein content of h-caldesmon (h-CaD) was increased in pregnancy. A 40-fold increase in the signal from a phospho-CaD antibody specific for phosphorylation at an ERK1/2 site occurred during labor. ERK1/2 activation increased significantly at the onset of labor. Myosin light chain phosphorylation (LC20-P) increased significantly in labor compared with the nonpregnant state. Thus we conclude that the increase in CaD protein content during pregnancy may contribute to a suppression of the contractility of pregnant myometrium. Conversely, CaD phosphorylation, through an ERK1/2-mediated signaling pathway, as well as an increase in basal LC20-P, is suggested to contribute to the reversal of inhibition and promote contraction of the uterus during labor.

Animals↗

Changes in polymorphonuclear leukocytes in the vagina of patients with preterm labor.

To evaluate changes in vaginal polymorphonuclear leukocytes (vPMNL) in patients with preterm labor, we obtained vPMNL-rich suspensions from vaginal fluids of 77 women (21 with preterm labor and 56 control women with uncomplicated pregnancy). Total counts of vPMNL and % viability of vPMNL (viable vPMNL:total vPMNL) were significantly higher in patients with preterm labor (37 +/- 92 x 10(5), 23 +/- 29%) vs. controls (11 +/- 15 x 10(5), 6.9 +/- 8.3%). The concentration of granulocyte elastase in vaginal fluid diluted to 20 ml was also higher in patients with preterm labor than in controls (4,806 +/- 3,818 vs. 2,739 +/- 2,556 ng/ml). We conclude that PMNL and granulocyte elastase are abundant in the vagina in patients with preterm labor, which suggests that the PMNL may be involved in the pathogenesis of preterm labor.

Adult↗

Sonographic cervical length measurement before labor induction in term nulliparous women.

OBJECTIVE: The purpose of the study was to determine if transvaginal sonographic measurement of the cervical length is a useful method to predict successful labor induction in nulliparas. METHODS: 137 women who were scheduled for medically indicated induction of labor had a transvaginal sonographic measurement of the cervical length before labor induction. Inclusion criteria were: (1) singleton pregnancy; (2) gestational age between 37-42 weeks; (3) live fetus in cephalic presentation; (4) intact membranes; (5) no vaginal bleeding; (6) no previous history of uterine surgery; (7) nulliparous women, and (8) no allergy or asthma in response to prostaglandins. Induction of labor was performed within 6 h of the ultrasonographic examination, by inserting 2 mg of dinoprostone in the posterior vaginal fornix, repeated if needed every 6 h for up to three doses. When the cervix became favorable and no regular contractions were observed, amniotomy and oxytocin augmentation, starting at 1 mIU/min and increasing 1 mIU every 30 min as necessary, was performed. RESULTS: All women were Caucasians and the mean age was 24.3 years (range 19-37 years). The mean cervical length was 28 mm (range 11-39 mm). The Bishop score was < or =5 in 101 women and >5 in the 36 others. Vaginal delivery occurred in 92 women (67.1%), and the vast majority of them (89 women; 96.7%) gave birth within 24 h of induction. Forty-five women (32.8%) had a cesarean section. The Bishop score was not predictive of the mode of delivery. Thirty-six of 101 women (35.6%) with a Bishop score < or =5 delivered by cesarean section, compared to 9 of 36 women with a Bishop score >5 (25%) (p = NS). Women with a cervical length <27 mm were more likely to deliver vaginally. Using this cutoff value the sensitivity of a successful labor induction was 76% and the specificity was 75.5%. CONCLUSIONS: Transvaginal sonographic measurement of cervical length is a good predictor of a successful labor induction at term in nulliparas.

Adult↗

Prostaglandin E2 induction of labor for isolated oligohydramnios in women with unfavorable cervix at term.

OBJECTIVE: To evaluate the maternal and neonatal outcomes of pregnancies complicated with isolated oligohydramnios at term, managed by induction of labor. METHODS: We conducted a retrospective case-control study. 138 women with uncomplicated oligohydramnios at term [amniotic fluid index (AFI) < or =5 cm] and a low Bishop score (< or =6) underwent induction of labor with prostaglandin E2. These women were compared to 67 women who underwent induction of labor at 42 weeks' gestation and 276 women at low-risk pregnancy and spontaneous onset of labor, matched for parity and race. RESULTS: Cesarean section (CS) rate was similar in the study and the post-date group (17.4 and 17.9%, respectively), but significantly higher than the spontaneous labor group (5.8%, OR 3.42, 95% CI 1.75-6.68). No differences were found with other outcomes. CONCLUSION: Pregnancies with isolated oligohydramnios at term apparently are not at higher risk of perinatal complications, but induction of labor is associated with increased rate of CS.

Case-Control Studies↗

Acupuncture before delivery: effect on labor.

Acupuncture treatment in the final weeks of pregnancy has been claimed to shorten the duration of labor in primiparous women. In the present study, the length of the various phases of labor was calculated for 56 primiparous women who were repeatedly treated with manual acupuncture during the month prior to parturition. In vaginally delivering women, the average lengths of the latent and active phase and the second stage of labor were 4.1, 3.4 and 1.4 h, respectively. In a nontreated control group of 112 primiparous women, the corresponding durations were 4.4, 3.5 and 1.1 h. Acupuncture treatment before delivery did not shorten the delivery time. Instead, acupuncture seemed to lengthen pregnancy and to prolong labor, for there was a positive correlation between the number of acupuncture treatments given and the length of gestation, second-stage labor and total delivery time. Based on the results of the present study, it appears possible that the effect of acupuncture is the opposite to that suggested by others, i.e. it lengthens the pregnancy as well as delivery time and does not reduce the duration of labor.

Acupuncture Therapy↗

The effect of unrestricted oral carbohydrate intake on labor progress.

OBJECTIVE: To determine if unrestricted oral carbohydrate intake during labor reduced the incidence of dystocia in low-risk nulliparous women. DESIGN AND SETTING: A randomized clinical trial at a university-affiliated hospital in southeastern Ontario. Low-risk nulliparous women were randomized between 30 and 40 weeks gestation to either an intervention or usual care group. INTERVENTION: Women in the intervention group received, prenatally, guidelines about food and fluid intake during labor and were encouraged to eat and drink as they pleased during labor. Women in the usual care group received no prelabor information and were restricted to ice chips and water during labor in the hospital. MAIN OUTCOME MEASURE: The incidence of dystocia, defined as a cervical dilatation rate of less than 0.5 cm/hr for a period of 4 hrs after a cervical dilatation of 3 cm. RESULTS: Three hundred twenty-eight women were randomized to the intervention (n = 163) or usual care (n = 165) groups. Women in the intervention group reported a significantly different pattern of oral intake during early labor in the hospital (chi(2) = 40.7, p < .001). The incidence of dystocia was 36% (n = 58) in the intervention group and 44% (n = 72) in the usual care group and was not significantly different (OR = 0.71, 95% CI = 0.46, 1.11). There were no significant differences in the other secondary outcomes or in the incidence of adverse maternal or neonatal complications. CONCLUSION: Eating and drinking early in labor had no significant impact on the incidence of dystocia and/or adverse maternal or neonatal outcomes.

Adult↗

Adolescents' perceptions of pain during labor.

This descriptive study systematically described the quality and intensity of adolescents' pain during the progression of labor. The Gaston-Johansson Pain-o-Meter was administered to 33 adolescents during the three labor phases (2-4 cm, 5-7 cm, and 8-10 cm) following a contraction. The most frequently selected sensory words were cramping in Phase I and pressing in Phases II and III. Miserable and killing were the most commonly chosen affective words during the three labor phases. Using the Gaston-Johansson Pain-O-Meter and the Gaston-Johansson Pain-O-Meter Visual Analogue Scale, the total pain intensity scores were highest during phase III of labor and delivery. At-test of independent samples found that quality and intensity pain scores for primiparous and multiparous adolescent participants were not significantly different during the progression of labor. The findings of the study illustrate the value of using objective measures, such as the Gaston-Johansson Pain-O-Meter and the Gaston-Johansson Pain-O-Meter Visual Analogue Scale, to assess pain during labor. The study also demonstrated that nurses can use these tools with minimal training.

Adolescent↗

Labor-associated changes in Fas ligand expression and function in human placenta.

Fas ligand (FasL)-dependent apoptosis has been implicated in the control of tissue-damaging inflammatory responses in several immune privileged sites. Here, we present data demonstrating that FasL is expressed on human trophoblast cells throughout pregnancy and transduces growth inhibitory/death signals in cells bearing its receptor, Fas (CD95). Immunohistochemical analysis detected FasL-positive staining in the trophoblast layer of villi of first- and second-trimester and term (no labor) placental tissues, as well as in freshly isolated cytotrophoblasts representing these gestational ages. In contrast, term placental tissues and cytotrophoblasts from labor-associated deliveries exhibited significantly reduced FasL expression, suggesting that parturition altered the characteristics of trophoblast cells. FasL-specific immunoblotting of cytotrophoblast cell lysates further confirmed these results. To assess the functionality of FasL expressed on cytotrophoblasts, we co-cultured these cells with Fas-bearing Jurkat T cells. Cytotrophoblasts from early pregnancy, or term with no labor, significantly inhibited growth in Jurkat cells, evident even at a 1:1 effector:target cell ratio, as determined by the incorporation of [3H]thymidine. Similar results were obtained when a FasL-positive colon carcinoma cell line, SW620, was used in place of cytotrophoblasts. In contrast, term cytotrophoblasts from labor deliveries exhibited poor FasL expression and were quantitatively much less proficient in inhibiting [3H]thymidine incorporation in Jurkat cells. These data indicate that FasL could participate in modulating the inflammatory responses associated with labor and suggest intrinsic molecular differences in the placental microenvironment before and after labor .

Base Sequence↗

Labor promotes neonatal neutrophil survival and lipopolysaccharide responsiveness.

Labor is a mild proinflammatory state that is associated with fetal leukocytosis. Elective cesarean section has been linked with increased neonatal morbidity, which may be partially immune mediated. We hypothesized that labor may alter neutrophil phenotype and thereby decrease neonatal complications. We characterized neutrophil function and survival in normal neonates after either uncomplicated vaginal delivery (VD) or elective cesarean section (CS) without labor. Spontaneous neutrophil apoptosis is delayed in cord blood neutrophils of neonates after normal labor (VD) compared with CS, as assessed by propidium iodide DNA incorporation using flow cytometry. This demonstrates their ability to maintain an inflammatory response. CD11b expression on neonatal neutrophils after CS is decreased, providing further evidence of altered activation or priming. Lipopolysaccharide responsiveness, characterized by CD11b and apoptosis, is similar in VD and adults, but CS-derived neutrophils are unresponsive. Baseline TLR-4 levels are elevated in CS in contrast to the other groups, although expression is not up-regulated by lipopolysaccharide co-incubation. Neonatal neutrophil survival and function are altered by labor and may increase antibacterial function and neutrophilia. This suggests that labor of any duration may be immunologically beneficial to the normal term neonate.

Apoptosis↗

Prostanoid concentrations in maternal/fetal plasma and amniotic fluid and intrauterine tissue prostanoid output in relation to myometrial contractility during the onset of adrenocorticotropin-induced preterm labor in sheep.

Prostanoid [prostaglandin (PG)] concentrations were measured in ovine maternal and fetal plasma and amniotic fluid during the onset of preterm labor induced by the administration of a pulsatile infusion of ACTH-(1-24) (P-ACTH; 66.7 ng/min for 15 min every 2 h) to the fetus and in saline-infused controls. P-ACTH administration stimulated a change in intra-uterine pressure from type A-activity, characterized by sustained increases of low amplitude, to type B labor-like activity of short duration, high amplitude (greater than or equal to 10 mm Hg) increases which occurred between 12 and 8 h before the onset of labor. PGF2 alpha and/or PGFM (13,14-dihydro-15-keto PGF2 alpha) concentrations increased consistently in all fluids 16 h or earlier before labor. All PGs increased in fetal carotid arterial plasma (PGE2 greater than PGF2 alpha) and amniotic fluid, and the relative increases in each PG were similar. However, PGF2 alpha and PGFM selectively increased in maternal vena caval and aortic plasma, whereas smaller or negligible increases in the prostacyclin hydrolysis metabolite 6-keto PGF1 alpha (6KF) and PGE2 were noted. The output of PGs E2 and F2 alpha (picograms per 10(5) cells/8 h) increased 1.6- and 1.7-fold, respectively, by cells dispersed from the chorioallantois of P-ACTH-treated animals compared to that in control animals infused with saline for 100 h. From fetal cotyledons, these increases were 2.4-fold (P less than 0.05) and 3.6-fold, respectively. No significant changes occurred in 6-keto PGF1 alpha output from any tissue or PGE2 or PGF2 alpha output from amnion or maternal cotyledons. We conclude 1) that PGs increase in all fluids before the increase in uterine mechanical activity during induced preterm labor, implying that PGs mediate this event and are not a result thereof; 2) that syntheses of PGs E2 and F2 alpha increase similarly in intrauterine tissues with the onset of labor; and 3) that a selective increase in PGF2 alpha, a myometrial stimulatory PG, occurs exclusively in maternal plasma, suggesting that endoperoxide conversion to PGF2 alpha is specifically enhanced during parturition or suggesting the existence of an intrauterine tissue source of 9-keto PG reductase.

6-Ketoprostaglandin F1 alpha↗

Prostaglandin endoperoxide-H synthase-1 and -2 messenger ribonucleic acid levels in human amnion with spontaneous labor onset.

Increased prostaglandin (PG) production within the uterine compartment has a pivotal role in the processes leading to labor onset in women. Two PG endoperoxide-H synthase (PGHS) isoenzymes have been identified in a number of cell types. PGHS-1 is constitutively expressed in most cases, whereas PGHS-2 expression is rapidly induced by several agonists. The aims of this study were to determine the levels of PGHS-1 and PGHS-2 expression before and after spontaneous labor (SL) onset in the amnion and to assess the contribution of PGHS-1 and PGHS-2 to enzyme activity. We established and validated ribonuclease protection assays to quantify PGHS-1 and PGHS-2 messenger ribonucleic acid (mRNA) levels in the amnion. PGHS enzyme activity was measured with an established assay. The antisense RNA probes used in the protection assays were generated using human PGHS-1 and PGHS-2 complementary DNAs. These probes specifically detected the 2.8-kilobase mRNA of PGHS-1 and the 4.8-kilobase mRNA of PGHS-2 in amnion RNA samples on Northern blots. We measured mRNA levels in amnion from patients after SL at term and from patients not in labor undergoing elective cesarean section (CS) at term. PGHS-2 mRNA levels were markedly higher after SL compared to levels in CS amnion [5.18 +/- 1.08 (n = 16) and 2.27 +/- 0.50 (n = 15), densitometric units, respectively; P < 0.02], whereas there was no difference in PGHS-1 mRNA levels after labor compared with CS samples. PGHS-2 mRNA levels were also positively correlated with PGHS enzyme activity in 4 separate assays with a total of 25 patients (r = 0.65-0.88; P < 0.05). There was no correlation between PGHS-1 mRNA levels and enzyme activity. We conclude that PGHS-2 mRNA is present in human amnion; its levels are elevated after SL onset, and they are correlated with enzyme activity. The stimulation of PGHS activity at labor onset probably involves increased expression of PGHS-2. The expression of PGHS-1 does not change in association with labor in human amnion.

Amnion↗

Labor-associated changes in interleukin-10 production and its regulation by immunomodulators in human choriodecidua.

Parturition is associated with increased production of proinflammatory mediators by gestational tissues. Interleukin-10 (IL-10) is an antiinflammatory cytokine produced by human chorion, decidual, and trophoblast tissues. To study the effects of immunomodulators on IL-10, IL-6, and PGE2 production by human choriodecidua before and after labor, an organ explant system was established. Tissue disks (6 mm) were excised from choriodecidual membranes obtained at term by cesarean section before labor (n=6-7) or after spontaneous vaginal delivery (n=7-8). After 24-h equilibration in medium, the tissues were treated with IL-1beta (10 ng/mL), tumor necrosis factor-alpha (100 ng/mL), lipopolysaccharide (5 microg/mL), dexamethasone (1 micromol/ L), or an appropriate vehicle control (n=3 wells/treatment) for 24 h. Media were harvested, and IL-10, IL-6, and PGE2 concentrations were determined by immunoassay. Basal choriodecidual production rates of IL-10 were significantly decreased with labor (P < 0.001), whereas PGE2 and IL-6 production rates increased. The production of all three substances was increased by IL-1beta, tumor necrosis factor-alpha, and lipopolysaccharide, but inhibited by dexamethasone. In contrast to PGE2 and IL-6, there was significantly increased responsiveness of IL-10 production to inflammatory stimuli after labor, but decreased responsiveness to the inhibitory effects of dexamethasone. These data indicate that IL-10 could play a role in modulating or promoting resolution of the inflammatory processes associated with labor at term and with intrauterine infection-associated preterm labor.

Adjuvants, Immunologic↗

Seeking common ground: a history of labor and Blue Cross.

In recent years, voluntary health insurance costs have become a major source of friction in labor-management negotiations. What was once a "fringe" has led to job actions, strikes, and intensive bargaining. We examine the history of labor's participation in New York Blue Cross from the 1930s to the recent past and show that labor's participation in the plan was crucial to Blue Cross's success in the plan's early decades. By the late 1950s, serious tensions developed over rate increases and the participation of labor in Blue Cross governance. Ultimately, the issue was one of the control over what was provided by the plans and who would pay for the costs of care. We posit that labor was never able to achieve an important role in the control of the third-party payer, and in the antilabor environment of the 1980s this proved detrimental to labor's interests.

Blue Cross Blue Shield Insurance Plans↗

The missing millions: organized labor, business, and the defeat of Clinton's Health Security Act.

During the battle over comprehensive health care reform in the early 1990s, organized labor was not only unable to put together a winning coalition but also found itself divided and on the defensive as it struggled to prevent any further erosion of the private-sector safety net of the U.S. welfare state. Labor's relative ineffectiveness has deep institutional and political roots and was not merely a consequence of its dwindling membership base. Several key institutions of the private welfare state, notably the Taft-Hartley health and welfare funds and the Employment Retirement Income Security Act (ERISA) preemption, brought the interests of organized labor more closely in line with those of large employers and commercial insurers and aggravated divisions within organized labor and between unions and public interest groups. In addition, several political factors conspired to reinforce labor's tendency to stick to a policy path on health care issues that was predicated on an employer-mandate solution and that had been charted primarily by business and leading Democrats. As a result, organized labor did not emerge from the 1993-1994 struggle with its political base fortified nor with a viable long-term political strategy to achieve universal health care and to shift the political debate over health policy in a more desirable direction.

Attitude to Health↗

Prostaglandin F2alpha and E1 in plasma and amniotic fluid during human pregnancy and labor.

In order to elucidate the significance of PGs in human labor, PGE1 and F2alpha in biological fluid during human pregnancy and labor were measured by RIA newly developed. Analytical studies demonstrated that the levels of PGF2alpha in maternal plasma were 3.7 +/- 2.5 ng/ml a few days before parturition, 2.0 +/- 0.9 ng/ml in the first stage of labor and 1.9 +/- 1.4 ng/ml at delivery. Thus the concentrations of PGF2alpha in maternal plasma showed no significant changes around parturition. On the otherhand, the level of PGF2alpha in amniotic fluid represented a significant increase up to 44.27 +/- 32.81 ng/ml at delivery from 1.45 +/- 0.76 ng/ml before labor at 38-40 weeks of pregnancy (p less than 0.05), although it was uncertain whether this elevation was the cause or effect of uterine contraction. The concentration of PGE1 ranged from 2 to 14 ng/ml around parturition. This indicates that there was little remarkable difference between the levels of PGE1 in plasma and amniotic fluid during the last month of pregnancy and labor. Possible involvement of prostaglandins (PGs) in human labor has been discussed.

Amniotic Fluid↗

Randomized trial of administration of prostaglandin E2 gel for induction of labor in the morning or the evening.

OBJECTIVE: To compare the outcome of induction of labor and patient's preferences using a protocol with the first dose of prostaglandin E2 endocervical gel in the evening versus a protocol with the first dose in the morning. DESIGN: We performed a randomized trial comparing administration of prostaglandin E2 endocervical gel in the morning with administration of prostaglandin E2 gel in the evening, followed if necessary by a second dose being given after six hours if labor had not started or the cervix was still unripe. Formal induction of labor by amniotomy and oxytocin infusion was performed the morning after the initial prostaglandin E2 dose. Patients' preferences were assessed using a questionnaire that was completed after delivery. SETTING: Tertiary care hospital in the Netherlands with 1,600 deliveries per year. PARTICIPANTS: One-hundred and twenty-six women with viable singleton pregnancies at term who had induction of labor with prostaglandins. MAIN OUTCOME MEASURES: Time of delivery (daytime, evening or night) and patient's satisfaction. RESULTS: Fifty-eight women were allocated for administration of gel in the morning, whereas 68 had their gel in the evening. Administration of gel in the evening did not significantly reduce delivery between 23.00 hours and 08.00 hours, although there was a reduction in delivery between 23.00 hours and 08.00 hours in nulliparae. None of the multiparous women delivered between 18.00 hours and 23.00 hours after induction of labor in the evening. The relative risk for delivery by vacuum or forceps was increased after allocation of gel in the evening (4.2; 95% confidence limits 1.4 to 13). Patients' preferences favored administration of gel in the morning. CONCLUSIONS: There was no benefit in starting induction of labor with prostaglandin E2 in the evening, compared with starting in the morning.

Cervix Uteri↗

Fetal and maternal energy metabolism during labor in relation to the available caloric substrate.

AIM: To discuss maternal and fetal metabolic events during labor and the possible role of glucose administration. RESULTS: The oxidative pathway covers the largest part of the energy demand of labor, although in the second stage or, in polysystolic labor, the non-oxidative pathway becomes important as well. Glucose is the main maternal energy source, but the rise in ketobodies, even during normal labor, suggests a relative shortage. In the first stage of labor, a combination of a respiratory alkalosis, and to a lesser extent, a metabolic acidosis, result in a rise in the maternal pH. In the second stage of labor, the maternal pH decreases due to an increasing metabolic acidosis. Glucose is also the main fetal energetic fuel. In fetal hypoxia, lactate is produced, which in most cases is transferred to the maternal circulation. High maternal lactate concentrations, however, may interfere with this process. Furthermore, fetal hyperglycemia may lead to an increased fetal lactate production. CONCLUSIONS: Maternal hyperglycemia, may lead to an increase in maternal and fetal lactate production resulting in metabolic acidosis. Unlike high dosage intravenous glucose administration, it is not likely that oral intake of carbohydrates leads to maternal and fetal hyperglycemia and subsequently to metabolic acidosis, but studies are rare.

Acid-Base Equilibrium↗