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PubMed2005

Prediction of spontaneous onset of labor at term: the role of cervical length measurement and funneling of internal cervical os detected by transvaginal ultrasonography.

The objective of this study was to examine the values of the cervical length measurement and detection of internal cervical os funneling by transvaginal ultrasonography in the prediction of spontaneous labor within a 7-day period at term. Ninety-three pregnant women were enrolled into this study. All patients were evaluated by transvaginal ultrasonography first at the 37th completed week of gestation and weekly thereafter. Endocervical canal length was measured and the presence of funneling was recorded. The end points were the percentage of patients with a spontaneous onset of labor in the week after these data were recorded. The optimal cutoff values for predicting the onset of spontaneous labor within 7 days were 29.5 mm for cervical length at 37 weeks, 27.5 mm at 38 weeks, 25.5 mm at 39 weeks, and 24.5 mm at 40 weeks of gestation. There was also statistically significant agreement between the presence of the funneling and spontaneous labor within 7 days. Measurement of cervical length and detection of funneling at the internal cervical os by transvaginal ultrasonography might help us to predict the spontaneous onset of labor in a 7-day period, and help clinicians to decide about the time of labor induction in certain complicated pregnancies.

Adult↗
PubMed2005

Rho A/Rho kinase mRNA and protein levels in human myometrium during pregnancy and labor.

OBJECTIVE: To quantify mRNA levels of Rho A, and rho-associated coil-forming kinases I and II (ROCK I and ROCK II) in human pregnant (before and after labor onset) and nonpregnant myometrium, and to investigate protein expression of Rho A, ROCK I, and ROCK II in these three tissue types. METHODS: Real-time fluorescence reverse transcriptase-polymerase chain reaction (RT-PCR) using primers for Rho A, ROCK I, and ROCK II was performed on total RNA isolated from the three tissue types under investigation. Western blot analysis using antibodies specific to Rho A, ROCK I, and ROCK II was performed on protein isolated from the three tissue types. RESULTS: Real-time fluorescence RT-PCR, using primers for Rho A, ROCK I, and ROCK II, revealed Rho A mRNA expression was significantly greater in human pregnant myometrium after labor onset, in comparison to pregnant myometrium before labor onset (P < .05), or nonpregnant myometrium (P < .01). ROCK I and ROCK II mRNA expression levels were similar in the three tissue types (P > .05). With Western blot analysis, using antibodies specific to Rho A, ROCK I, and ROCK II, Rho A protein levels were significantly lower in pregnant (before and after labor onset) in comparison to nonpregnant myometrium (P < .01). ROCK I protein levels were similar in the three tissue types (P > .05). No signal for ROCK II was detected in myometrial tissue. CONCLUSIONS: These results outline the presence of the Rho A/Rho kinase system in modulating contractility of human myometrium. Total Rho A protein expression is down-regulated in the third trimester of pregnancy while up-regulation of Rho A mRNA occurs with labor onset.

Adult↗
PubMed2002

Influence of low- and high-molecular-weight plasminogen activators on the onset of labor and on the hemostatic system.

Measurement of activities of urinary (u-PA) and tissue plasminogen activator (t-PA) and analysis of euglobulin lysis times (ELTs) and prekallikrein were performed simultaneously using the plasma of normal pregnant women and nonpregnant women. The activities of plasminogen activators were determined by the method of electrophoretic zymography. The activity of low-molecular-weight (LMW) u-PA was significantly decreased at the onset of labor (p = 0.05) compared with that during the latter half of pregnancy. The same tendency was observed in the analysis of prekallikrein. On the contrary, no significance was shown in activities of high-molecular-weight (HMW) u-PA or t-PA. It is suggested that the action of kallikrein on low-molecular-weight u-PA causes it to change into plasmin at the onset of labor.

Case-Control Studies↗
PubMed2006

Sexual intercourse at term and onset of labor.

OBJECTIVE: To determine whether sexual intercourse at term hastens the onset of labor and to observe its effect on cervical status. METHODS: Women with low-risk pregnancies at term were asked at each of their term prenatal visits whether they had engaged in penile-vaginal intercourse during the previous week. Delivery outcomes were compared between those women who were sexually active at term and those who were not. A Bishop score was assigned to each cervical examination at term, and the weekly results of the cervical examination were compared between women who were sexually active in the previous week and those who were not. RESULTS: Forty-seven (50.5%) of 93 women reported having had sexual intercourse at term. The gestational age at delivery of those women who were sexually active at term was greater than those who were not (39.9 weeks versus 39.3 weeks; P = .001). There was no difference in Bishop score between women who had sex in the previous week and those who had not. After adjusting for the effect of time, those who were sexually active the previous week had Bishop scores that were, on average, lower by 0.26 (95% confidence interval -1.26 to 0.74, P = .61) compared with those who abstained. CONCLUSION: Sexual intercourse at term is not associated with ripening of the cervix and does not hasten labor. LEVEL OF EVIDENCE: II-3.

Adult↗
PubMed1999

Interleukin-8 release from human gestational tissue explants: effects of gestation, labor, and chorioamnionitis.

Interleukin-8 (IL-8) is a chemotactic cytokine that has been implicated in the process of human parturition, including the processes of cervical ripening and rupture of fetal membranes. In this study, the in vitro release of IL-8 from human amnion, choriodecidua, and placenta tissues obtained before and after spontaneous labor onset both at term and preterm, was assessed. The effect of chorioamnionitis on IL-8 release was also established. All tissue explants examined released IL-8; however, IL-8 release from choriodecidual explants was significantly (p < 0.02) greater than that observed from amnion and placenta. Furthermore, choriodecidual IL-8 release was significantly (p < 0.001) greater from term tissues (850 +/- 134.4 ng/mg DNA, n = 18) than from preterm tissues (458 +/- 68.8 ng/mg DNA, n = 17). Spontaneous onset of labor, irrespective of the eventual mode of delivery, was not associated with any significant changes in IL-8 release from human gestational tissues compared to not-in-labor tissues, both at term and preterm. IL-8 release from gestational tissues was not significantly different in the absence or presence of chorioamnionitis. These data are in contrast to the previously reported stimulatory effects of bacterial endotoxin on IL-8 release from human gestational tissues. The data are consistent, however, with the suggestion that IL-8 release is an early event in chorioamnionitis that precedes the appearance of clinically overt symptoms.

Amnion↗
PubMed1988

Changes in plasma cyclic AMP and cyclic GMP during spontaneous labor and labor induced by oxytocin, prostaglandin F2 alpha and prostaglandin E2.

To investigate the response of cyclic nucleotides to the oxytocic agents administered for induction of labor, plasma concentrations of cyclic AMP (cAMP) and cyclic GMP (cGMP) were determined by radioimmunoassay during spontaneous labor and labor induced by oxytocin (OT), prostaglandin F2 alpha (PGF2 alpha), or PGE2 (PGE2). Subjects were 7 Japanese women in each labor group. Plasma cAMP levels significantly rose at the time of crowning of the fetal head in all 4 groups. They did not increase until that time in the 3 labor groups (spontaneous, OT-induced, and PGF2 alpha-induced labor groups). In the PGE2-induced labor group, plasma cAMP levels were significantly higher at labor onset (mean +/- SEM = 16.5 +/- 1.3 pg/ml) when compared to the pretreatment values (13.7 +/- 1.0 pg/ml), and increased thereafter gradually toward the time of crowning of the head (26.3 +/- 2.0 pg/ml). Plasma cGMP levels in the OT-induced group significantly rose after the onset of labor and remained at a high level until expulsion of the fetus. Plasma cGMP levels in the other groups did not change significantly throughout labor. These results suggest that cAMP may be involved in the labor process induced by PGE2, and that cGMP may be in that induced by OT.

Cyclic AMP↗
PubMed1990

Apheresis of low molecular weight protein fraction and the onset of labor.

In our study, we subjected six (6) pregnant goats of known gestational age to whole blood ultrapheresis using an extracorporeal circuit. The serum fraction removed was replaced with equal volume of the same material prepared from non-gravid goats. The serum fraction removed was identified as to content of clinically measurable parameters and plotted as permeability coefficient compared with molecular weight. The goats were observed to enter the first stage of labor as a consequence of this form of apheresis and to deliver normal products of conception. No clinically significant deleterious effects on the goats were observed. There was no evidence of complement activation, nonspecific heparin effect, or endotoxin effect. We consider the possibility that soluble mediators of immune suppression may play a role in the maintenance of pregnancy and that the onset of the first stage of labor may be an immunologic event.

Animals↗
PubMedDate not supplied

Prostaglandin endoperoxide synthase kinetics in human amnion before and after labor at term and following preterm labor.

To determine whether the kinetics of prostaglandin endoperoxide synthase (PGHS, commonly known as cyclooxygenase) in human amnion change with labor onset or between preterm and term labor, a specific enzyme assay was developed and characterized. The assay was linear for time (0-8 min) and protein concentration (5-30 micrograms/250 microliters incubation volume). The optimum pH was 8.0-8.5, and the enzyme reaction reached saturation at 10-20 microM arachidonic acid. Flufenamic acid was more efficacious than ibuprofen in the presence of 1 mM tryptophan in inhibiting enzyme activity. The Km and Vmax of PGHS were determined in 10 amnions obtained at elective caesarean section before labor onset (CS) at 39.3 +/- 0.8 wk gestational age (mean +/- SD, range = 38.5-41 wk) and 9 amnions obtained following spontaneous labor and vaginal delivery (SL) at 39.6 +/- 0.8 wk (range = 38.5-41 wk). The Km values were 1.4 +/- 1.2 mumol/l (CS) and 2.2 +/- 1.5 mumol/l (SL) (not different). However, the Vmax increased significantly (p < 0.05) from 11 +/- 8 (CS) to 19 +/- 4 (SL) pg PGE2/micrograms protein/min. In eight preterm amnions obtained following spontaneous labor and delivery at 32.9 +/- 2.1 wk (range = 29-36 wk), the Km and Vmax were 2.0 +/- 1.2 mumol/l and 17 +/- 9 pg PGE2/micrograms protein/min, respectively. Neither of these values was different from those of CS or SL amnions. None of the preterm pregnancies displayed histological evidence of infection. These results suggest that an increase in the mean amnion PGHS maximum velocity occurs in association with the onset of labor at term. The mean Vmax of PGHS in amnions obtained from idiopathic preterm spontaneous deliveries is between the CS and SL term values, reflecting, perhaps, multiple etiologies for preterm delivery.

Amnion↗
PubMed1987

The relationship between fetal biophysical profile and cord pH in patients undergoing cesarean section before the onset of labor.

In a prospective study of 124 patients undergoing cesarean section before the onset of labor, the fetal biophysical profile was found to have a significant relationship with umbilical cord blood pH (artery and vein). Using cord arterial pH less than 7.20 as a standard for the diagnosis of fetal acidosis, the sensitivity, specificity, and positive and negative predictive values of the fetal biophysical profile score were 90, 96, 82, and 98%, respectively. When the combination of nonreactive nonstress test and absent fetal breathing was used as the "abnormal test," the sensitivity, specificity, and positive and negative predictive values were 100, 92, 71, and 100%, respectively. The first manifestations of fetal acidosis are nonreactive nonstress testing and loss of fetal breathing; in advanced acidemia, fetal movements and fetal tone are compromised. A protocol of antepartum fetal evaluation is suggested based upon the individual biophysical components rather than the score alone.

Acidosis↗
PubMed1980

[Control of labor in swine with dexamethasone of various injection frequencies on the onset of labor and other selected parameters in farrowing sows and piglets].

Included in experiments with 185 sows with synchronised oestrus and ovulation were 52 untreated animals (K), while the others received intramuscular injections of daily doses of 75 mg of dexamethasone (DXMS), between the 109th and 111th days of pregnancy (V1) or 200 mg on the 110th day (V2) or on the 111th day (V3). While DXMS failed to have any substantive effect on mean pregnancy time or duration of labour, the variance of farrowing dates was reduced with significance. The average intervals which passed from the injections to delivery were 58.8 hours (V1), 82.2 hours (V2) or 54.8 hours (V3). No major difference was found to exist between K, V1, V2, and V3 regarding stillbirths or piglets with underweight, weights at birth and on the 21st day of age, loss in the course of raising, and percentual frequency of sows with normal or increased rectal temperature during the first three days after farrowing.

Animals↗
PubMed1983

Phagocytosis and onset of human labor.

An in vitro experimental model has been developed which allows the study of amnion lysosomal enzyme release under controlled conditions. Briefly, a layer of human amnion membrane mounted on a specially designed reaction vessel serves as the reaction surface. We have noted that the addition of particulate material to these membranes incubating in pseudoamniotic fluid results in an increased release of the lysosomal marker enzyme N-acetylglucosaminidase when compared to the release in the absence of particles. This release is completely inhibited by iodoacetate and slightly by azide. A similar increased release is also noted with the use of term amniotic fluid as incubation medium when compared to centrifuged (30,000 g/20 min) amniotic fluid. Lecithin and lysolecithin were effective in releasing increasing amounts of enzyme. This increased release was noted only from membranes of placentas collected from subjects who had undergone cesarean section prior to labor. Membranes collected from vaginal deliveries after labor showed a baseline increased release but no further stimulation upon the addition of any of the substances. These results suggest that the release of lysosomal enzymes from amnion membranes is brought about by substance(s) present in amniotic fluid. Very probably, these are surfactants. The interaction of these substances with amnion cells would eventually result in an exponential burst of prostaglandin synthesis, which would result in labor.

Acetylglucosaminidase↗
PubMed1997

Epidermal growth factor receptors in uteroplacental tissues in term pregnancy before and after the onset of labor.

Using saturation binding assays and Scatchard analyses, we determined the concentrations and binding affinities of epidermal growth factor (EGF) receptors in human myometrium (n = 13) and decidua (n = 10) before and during labor and in placenta (n = 15), chorion (n = 17), and amnion (n = 17) before labor, during labor, and after vaginal delivery. Each tissue was individually assayed. In myometrium and chorion, EGF receptors increased significantly from 5.6 +/- 0.8 and 13.5 +/- 1.7 fmol/mg protein (mean +/- SEM) before labor to 11.1 +/- 2.8 and 26.7 +/- 3.0 fmol/mg protein, respectively, after the onset of labor (P < 0.05). In amnion, EGF receptors increased from 12.8 +/- 2.7 fmol/mg protein before labor to 33.0 +/- 2.3 fmol/mg protein during labor, but decreased significantly (5.9 +/- 1.2 fmol/mg protein) with vaginal delivery (P < 0.05). Decidual and placental concentrations of EGF receptors did not change significantly with labor. The binding affinity of EGF receptors in all tissues studied did not change significantly with labor, as reflected by their respective association and dissociation constants. Up-regulation of EGF receptors in myometrium, chorion, and amnion with spontaneous labor may enhance stimulation of prostanoid production and stimulate uterine activity.

Amnion↗
PubMed1984

[The onset of human labor].

The authors reviewed the literature in order to try to work out the different mechanisms that are responsible for labour starting. A role seems to be played by the decidua of the uterus, by the placenta and by the fetal membranes as well as the very important role of prostaglandin synthesis. It does seem as though there is no single factor that is important for starting labour. If we knew more about the physiology of human labour it would perhaps be easier to control premature labour.

Female↗
PubMed1978

[Attempts at control of parturition in swine with dexamethasone. 1. Effect of various treatment dates in late pregnancy on onset of labor, litter and rearing performance of the sows].

Studies were conducted with 66 gilts with synchronised ovulation, all kept in five separate experimental groups (I-V). Each of the animals received 75 mg Dexamethason (DXMS) per die over three consecutive days of pregnancy. Treatment of Groups I through V was started in this order on the 101st, 103rd, 105th, 107th or 109th days of pregnancy. The average intervals that elapsed between the last DXMS injection and onset of parturition were, in the same order, 174, 167, 133, 94 or 74 hours. Births were concentrated on two consecutive days in Group V. DXMS had no significant effect on the average duration and course of parturitions. The lowest average litter and piglet birth weights were recorded from those DXMS groups with shortest pregnancy. No significant mean differences in piglet weight were any longer established between the groups on the tenth day of age.

Animals↗
PubMed2000

Focal adhesion signaling in the rat myometrium is abruptly terminated with the onset of labor.

The dramatic increase in uterine growth during late pregnancy and the generation of labor contractions require dynamic remodeling of myometrial smooth muscle-ECM interactions. In many tissues, such interactions are provided by focal adhesions; however, there are no data as to the expression of focal adhesion proteins or of focal adhesion signaling in the myometrium. In this study, we show that tyrosine phosphorylation of myometrial FAK (FAK-P-Tyr) and of its downstream substrate, paxillin, exhibited a >10-fold increase during late pregnancy (days 15-22 of pregnancy) with each exhibiting a dramatic fall in P-Tyr on day 23 in association with the onset of labor. These changes in FAK-P-Tyr were paralleled by changes in FAK enzyme activity. Activated ERK1 and ERK2 expression remained relatively unchanged from day 15 to day 23, but decreased markedly 1 day post partum. Treatment of late pregnant rats with progesterone prevented the fall in FAK-P-Tyr/enzyme activity on day 23, and also blocked the onset of labor. These data suggest that progesterone (which decreases at term) modulates myometrial FAK activity/focal adhesion signaling and that these changes may underlie the tremendous remodeling that must occur in order for this muscle to develop optimal contractile activity during labor.

Animals↗