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PubMed1977

The effect of normal labor on the renin-angiotensin system in mother and fetus.

Plasma renin activity (PRA) and angiotensin I concentration (AI) in mother, umbilical vessels, and amniotic fluid were measured during 11 elective cesarean sections and after 12 normal labors. During cesarean section, PRA and AI were significantly lower in umbilical vessels than in mother or in amniotic fluid. This finding reflects the steady state in the late pregnancy. PRA and AI were significantly higher in the umbilical vessels after normal labor in comparison to the levels of cesarean section. In the mother there was no difference in PRA after normal labor and during cesarean section, but AI was significantly higher after normal labor. After normal labor no difference of PRA between mother, umbilical vessels, and amniotic fluid was found. The rise of fetal PRA and AI as a reaction to uterine contractions may be of great importance in ensuring the fetoplacental circulation during the labor.

Amniotic Fluid↗
PubMed1979

Infant outcome following labor induction.

A matched control study was undertaken in which 156 children were examined between ages 23 and 62 months after births associated with spontaneous labor, oxytocin-induced labor, or prostaglandin E2 (PGE2)--induced labor. Physical development was not adversely affected by labor induction based on height and weight percentiles. The frequency of neurologic or developmental abnormalities not attributable to postdelivery events was the same overall in induced and spontaneous labors (19.2 per 1,000), but those abnormalities occurring after labor induction all followed use of oxytocin. None followed PGE2 despite case-selection criteria which specifically chose PGE2 cases from among those with documented adverse drug-related reactions.

Abnormalities, Drug-Induced↗
PubMed1981

Randomized trial of ambulation versus oxytocin for labor enhancement: a preliminary report.

Published reports imply that intrapartum ambulation may improve labor. This suggests the possible efficacy of ambulation in labors requiring augmentation, provided that adequate monitoring surveillance is maintained. Fourteen patients who failed to progress in active-phase labor, and who required augmentation for "inadequate" contractions were randomized into ambulation (eight) and oxytocin (six) groups. Internal fetal monitoring was used in all patients for 30 minute baseline and 2 hour study periods, with two-channel telemetry used in ambulating patients. Oxytocin was administered by infusion pump. Study parameters included changes in cervical dilation and station, contraction frequency, intensity and baseline tonus, and uterine activity. Labor progress was slightly but not significantly better in the ambulatory group. A mean increase in uterine activity units (UAU) in the ambulatory group was immediate to ranges not reached in the oxytocin group for 2 hours. Increase in Montevideo units was slightly greater in the ambulatory group during the first hour, but was exceeded by the oxytocin group during the second hour. These initial observations seem to indicate that, in terms of labor progress and initial effects on uterine activity, ambulation is as effective as oxytocin for the enhancement of labor and warrants further investigation.

Cervix Uteri↗
PubMed1986

Assessment of uterine activity in ambulatory patients at high risk of preterm labor and delivery.

With use of an ambulatory tocodynamometer, prelabor uterine activity was recorded daily during pregnancy in 34 patients at increased risk of preterm labor and delivery. The data indicate that the frequency of contractions was significantly greater among women who subsequently developed preterm labor when compared to that observed among women who labored at term. This difference was present up to several weeks before the onset of labor. An additional significant rise in frequency of contractions could be observed within the last 24 hours before the development of clinically apparent preterm labor, as evidenced by progressive cervical dilation and effacement. If these results can be reproduced in a larger sample, intermittent ambulatory monitoring may offer an effective way to better identify patients at risk of preterm labor as well as enhance the early diagnosis of this event.

Adult↗
PubMed1989

Umbilical cord is the major source of prostaglandin E2 in the gestational sac during term labor.

The umbilical cord is an amniotic structure histologically resembling amnion lining the basal plate and reflected chorion. Prostaglandin E2 is secreted by amnion and is present in amniotic fluid. This study measured prostaglandin E2 production by amnion from all three locations to determine the relative contributions of prostaglandin E2 to amniotic fluid at term. Total surface areas and weights of umbilical cord, basal placental plate, and reflected chorionic amnion were measured in afterbirths from 20 normal patients delivered at term by elective repeat cesarean section before the onset of labor or vaginally after spontaneous onset of labor. Subsequently, 2 cm lengths of umbilical cord and 8 cm2 disks of basal placental plate and reflected chorionic amnion were incubated in perfusion chambers, and prostaglandin E2 production was measured by radioimmunoassay. Umbilical cord accounted for the least surface area (16% to 17%) but greatest tissue mass (75% to 76%). Both basal placental plate and reflected chorionic amnion increased prostaglandin E2 production 2.3-fold and 4.1-fold, respectively, after labor versus before labor, whereas umbilical cord prostaglandin E2 output was unchanged. However, umbilical cord accounted for 66% and 44% of the total prostaglandin E2 output before labor (697 +/- 169 ng/hr) versus (1201 +/- 380 ng/hr) after labor. Thus, of the three amniotic locations, umbilical cord represents the principal site of prostaglandin E2 production within the gestational sac.

Amnion↗
PubMed1990

Symptoms that precede preterm labor and preterm premature rupture of the membranes.

Great emphasis has been placed on recognition of the early warning symptoms of preterm labor by both pregnant women and health care providers. In addition to the expected increase in both painless and painful uterine contractions, several symptoms have been commonly cited in textbooks and patient educational materials as preceding preterm labor including menstrual-like cramps, backache, pelvic pressure, and an increased amount of vaginal discharge. We interviewed 107 women with preterm labor, 102 women with preterm prematurely ruptured membranes, and 106 ambulatory normal pregnant women to ascertain the frequency of each of eight putative warning symptoms of preterm labor in each group. Preterm labor patients were distinguished as expected from both normal women and amniorrhexis patients by a greater frequency of painful and painless contractions. Menstrual cramps, backache, and increased vaginal discharge, symptoms often said to be normally present in pregnancy, were also significantly more common in preterm labor patients than in women with preterm membrane rupture and in normal subjects.

Adolescent↗
PubMed1991

The enhanced production of placental interleukin-1 during labor and intrauterine infection.

The purpose of this study was to determine the effect of labor and chorioamnionitis in interleukin-1 production by human placenta. We studied the activity of the placenta to produce interleukin-1 with an enzyme immunoassay by culturing tissue blocks. The placental tissue obtained after labor produced a larger amount of interleukin-1 than placental tissue obtained before labor. All the placental tissues produced more interleukin-1 beta than interleukin-1 alpha. The placentas with labor and chorioamnionitis produced about seventeenfold more interleukin-1 than placentas with labor only. We immunohistochemically identified interleukin-1--producing cells in the placenta and found that syncytiotrophoblasts produced both interleukin-1 alpha and interleukin-1 beta, while Hofbauer cells produced only interleukin-1 beta. In vitro analysis of the trophoblast activities to produce interleukin-1 revealed that microbial byproducts enhanced interleukin-1 production, possibly inducing accumulation of interleukin-1 receptor-positive cells at the sites of inflammation. In addition to stimulation of prostaglandin biosynthesis and labor, the placental interleukin-1 may act as an inflammatory mediator, leading to systemic and local changes at fetomaternal interface and activating fetomaternal immune systems against intrauterine infection.

Chorioamnionitis↗
PubMed1991

Do catechol estrogens participate in the initiation of labor?

To assess the role of catechol estrogens in the initiation of labor, we compared the levels in amniotic fluid during the second and third trimesters and from women undergoing cesarean section at term not in labor and those with spontaneous labor at term. Catechol estrogen concentrations in amniotic fluid increased significantly with the progress of pregnancy. Further, concentrations (mean +/- SE) were significantly higher in spontaneous labor at term (468.6 +/- 29.5 pg/ml) compared with those obtained during cesarean section (242.6 +/- 22.3 pg/ml) at term not in labor. We suggest that catechol estrogens, through their stimulating effects on prostaglandin synthesis, participate in the initiation of labor.

Adult↗
PubMed1993

The influence of elective amniotomy on fetal heart rate patterns and the course of labor in term patients: a randomized study.

OBJECTIVES: Our study was designed to evaluate the effects of routine elective amniotomy on the frequency and severity of abnormal fetal heart rate patterns and on the course of labor and the need for oxytocin augmentation. STUDY DESIGN: A randomized, controlled trial was conducted at term in patients in active labor who were randomly selected to undergo elective amniotomy (amniotomy group) or left intact with amniotomy reserved for specific indications (intact group). RESULTS: Four hundred fifty-nine patients were studied (235 in the amniotomy group vs 224 in the intact group). Average cervical dilatation at rupture was 5.5 cm in the amniotomy group and 8.1 cm in the intact group. Analysis of fetal heart rate revealed more mild and moderate variable decelerations in the active phase of labor in the amniotomy group but no difference in the frequency of more severe decelerations or operative deliveries. In the intact group the need for oxytocin was twice as common (76 in the intact group vs 36 in the amniotomy group, p = 0.000005), and the active phase of labor was considerably longer (5 hours 56 minutes in the intact group vs 4 hours 35 minutes in the amniotomy group). Neonatal outcome was similar in the two groups. CONCLUSIONS: Elective amniotomy appears to increase the likelihood of umbilical cord compression in the active phase of labor and results in more mild and moderate variable decelerations, but it does not result in more severe abnormal fetal heart rate patterns or more operative intervention. Elective amniotomy does, however, shorten the active phase of labor and decreases the need for oxytocin augmentation.

Amnion↗
PubMed1995

The effect of recent cocaine use on the progress of labor.

OBJECTIVE: This study was undertaken to determine whether peripartum cocaine use shortens labor. STUDY DESIGN: A total of 1220 gravidas delivering at an urban county hospital (November 1991 through April 1992) had urine specimens sent for toxicology studies. Cervical dilatation on admission and time intervals during the course of labor were recorded. Analysis of covariance and exact tests for multiple contingency tables were used to compare duration of labor by cocaine use after we adjusted for other factors. RESULTS: Compared with nonusers, women who had positive test results for cocaine were older, were of greater parity, and were admitted to the hospital at greater cervical dilatation (4.63 cm vs 3.96 cm, p < 0.05). The duration of labor from admission to birth was also shorter (336 vs 565 minutes, p < 0.001). After we controlled for type of delivery, parity, birth weight, and prenatal care, there was no significant difference in labor duration in any stage. CONCLUSIONS: There is no difference in duration of any stage of labor related to cocaine use after patients' obstetric characteristics are controlled for.

Adult↗
PubMed1995

Low-dose versus high-dose oxytocin augmentation of labor--a randomized trial.

OBJECTIVE: Our purpose was to compare the efficacy and safety of low-dose versus high-dose oxytocin regimens in the augmentation of labor. STUDY DESIGN: Three hundred ten term pregnancies requiring augmentation of labor underwent randomization to receive either a low-dose or high-dose oxytocin augmentation regimen. Maternal demographics, labor-delivery data, and neonatal outcome were compared. RESULTS: The high-dose oxytocin group had a significantly lower cesarean section rate, regardless of parity (10.4% vs 25.7%, p < 0.001), with no differences in maternal complications and neonatal outcomes. The time needed to correct the labor abnormality was also significantly decreased (1.24 +/- 1.4 hours vs 3.12 +/- 1.6 hours, p < 0.001) in the high-dose group. CONCLUSIONS: The use of high-dose oxytocin regimen benefits both nulliparous and multiparous women requiring labor augmentation by significantly lowering both the time necessary to correct the labor abnormality and the need for cesarean section.

Adolescent↗
PubMed1995

Fetal fibronectin as a selection criterion for induction of term labor.

OBJECTIVE: We examined whether the presence of fetal fibronectin in cervicovaginal secretions can be used as a selection criterion for induction of labor at term. STUDY DESIGN: Cervicovaginal secretions of 64 women who were scheduled for induction of labor were examined for fetal fibronectin and divided into group A (positive for fibronectin) and group B (negative for fibronectin). Both groups were examined for Bishop score, the number of prostaglandin tablets administered, and the interval between induction of labor and delivery. RESULTS: In group A the interval between induction of labor and delivery was significantly shorter (p < 0.0001) than in group B. The number of prostaglandin tablets administered to group A was likewise significantly lower (p < 0.0001). Unsuccessful induction of labor only occurred in women with fibronectin-negative cervicovaginal secretions. CONCLUSION: The assessment of the fibronectin content of cervicovaginal secretions constitutes a viable instrument in the decision-making process preceding induction of labor.

Biomarkers↗
PubMed1981

The effect of labor on surfactant secretion in newborn rabbit lung slices.

We have studied the rate of surfactant secretion in a newborn rabbit lung slice model. Newborn rabbits were injected with [Me-3H]choline and killed 4 h later. Secretion of phosphatidyl[Me-3H]choline was measured in washed slices from blood-free lungs. There was a developmental increase in the rate of secretion during the period 29 to 31 (full-term) days gestation. This was further increased by labor. Labor had no effect on the rate of incorporation of choline into phosphatidylcholine. Thus, the effect of labor was primarily on secretion rather than synthesis. The effect of labor on surfactant secretion could be mimicked by terbutaline and, as shown previously, by prostaglandin E2. It was abolished by indomethacin and beta-blocking agents. These data show that labor stimulates secretion of surfactant and suggest that this effect is, at least in part, mediated by prostaglandins and beta-adrenergic agents, both of which are known to increase physiologically during labor and birth.

Animals↗
PubMed1986

Induction of labor in postterm pregnant women.

We have studied the outcome of labor induction in 145 postterm pregnant women in whom gestational age was properly assessed by ultrasound scanning. The induction techniques were adapted to the cervical states of the patients. Seventy-five patients (32 nulliparous and 43 multiparous) with favorable cervical states were successfully induced with intravenous oxytocin. In this group the frequency of Caesarean section was 2%. Seventy patients (45 nulliparous and 25 multiparous) with unripe cervices received 0.5 mg PGE2 in viscous gel intracervically to prime the cervix and to induce labor; 38 (52%) were induced into labor after a single PGE2-gel application whereas 26 (48%) needed labor augmentation with intravenous oxytocin after PGE2-gel obtained cervical ripening. In 6 of the 20 patients the cervix did not ripen and the PGE2-gel application had then to be repeated. The frequency of cesarean sections was 11%. In 5 out of the 145 patients (4%) the fetuses had signs of intrauterine growth retardation (IUGR) as assessed by ultrasound scanning, and postmaturity as verified by pediatric examination at delivery. All these fetuses belonged to nulliparous women with unripe cervices and all had to be delivered instrumentally (3 by cesarean section and 2 by ventouse) indicating the fragility of these children. If postterm pregnancy is complicated by an unfavorable cervical state intracervical application of PGE2-gel seems to be an efficient method to prime the cervix and to induce labor. In most patients an uncomplicated vaginal delivery can be achieved by this procedure. However, nulliparous women with unfavorable cervices and signs of IUGR constitute a high risk group of patients at labor induction.

Adolescent↗
PubMed1991

A comparison of single prostaglandin E2 vaginal tablet with prostaglandin E2 vaginal pessaries for induction of labor at term.

This study represents the first of its kind in Kuwait. Two preparations of prostaglandin E2 (PGE2) have been compared as agents for induction of labor. In a randomized controlled study of 200 women of low parity and unfavorable cervical induction features induction of labor by means of a single vaginal tablets of PGE2 was compared with locally prepared PGE2 vaginal pessaries. The gradual increase of uterine contractions and the establishment of labor in a similar way to that observed during spontaneous labor was more apparent after PGE2 tablets. Labor induction was successful in 80% of patients in PGE2 tablet group compared with 59% in PGE2 pessaries group. The incidence of cesarean section was equal in both groups (4%), but none was performed due to uterine hyperactivity. The data presented indicate that the PGE2 vaginal tablet is safe and effective in induction of labor in healthy women at term.

Administration, Intravaginal↗
PubMed1993

Influence of labor and route of delivery on the frequency of respiratory morbidity in term neonates.

OBJECTIVES: The purpose of this study is to compare the frequency of respiratory morbidity (RDS-Type I, RDS-Type II and PFC) in term neonates relative to three different delivery modes (cesarean delivery without labor, cesarean in labor, vaginal delivery). METHODS: A case-control study was performed consisting of 692 maternal/neonate pairs at term gestation with either a documented mature lung profile at an obstetrical age > or = 37 weeks' gestation or a Dubowitz age > or = 38 weeks' gestation. RESULTS: Overall, the frequency of neonatal respiratory morbidity was 5.1%. Neonatal respiratory morbidity was observed in 23 (12.4%) of 186 cases when cesarean delivery was performed prior to the onset of labor; in 10 (5.6%) of 177 cases when the cesarean delivery was performed after labor had ensued; and in 2 (0.6%) of 329 cases when the fetus was delivered vaginally (P < 0.001). CONCLUSION: The frequency of respiratory morbidity in term neonates is influenced by labor and route of delivery, and it is highest when cesarean delivery is performed prior to the onset of labor.

Adult↗
PubMed1995

The partograph in the management of labor following cesarean section.

OBJECTIVE: To determine whether graphic labor record (partogram) can be used to predict the risk of uterine scar rupture in labor following lower segment cesarean section. METHODS: Between 1988 and 1991, 236 women had a trial of labor following cesarean section. After the onset of the active phase (3 cm cervical dilatation), a 1 cm/h line was used to indicate an alert line on the partogram. All the active phase partograms were divided into five time zones: A (area to the left of the alert line), B (0-1 h after the alert line), C (1-2 h after the alert line), D (2-3 h after the alert line), and E and F (> 3 h after the alert line). For the action line, different lag times after the alert line were defined according to the time zones. Sensitivity, specificity, cesarean section rates and rupture rates were calculated for the different lag times after the alert line, and a receiver-operating characteristic curve was constructed. RESULTS: Fifty-five (23.3%) trials of labor ended in a repeat emergency cesarean. There were seven (2.9%) cases of scar rupture. Of the 181 vaginal deliveries, 151 (83%) occurred within 2 h after the progress of labor had crossed the alert line (zones A-C). Five out of seven cases of scar rupture occurred more than 2 h after the alert line had been crossed (zones D-F). The 2- and 3-h lag time after the alert line had a sensitivity of 71% and 43%, respectively, and a specificity of 78% and 96%, respectively, in predicting uterine scar rupture. If cesarean sections were performed at 2 or 3 h after crossing the alert line, the projected cesarean rates would have been 36% and 27%, respectively. The scar rupture rates would in turn be 0.8% and 1.6%, respectively. CONCLUSION: In women undergoing a trial of labor following cesarean section, the partographic zone 2-3 h after the alert line represents a time of high risk of scar rupture. An action line in this time zone would probably help reduce the rupture rate without an unacceptable increase in the rate of cesarean section.

Adult↗
PubMed1992

The influence of labor on thrombotic and fibrinolytic systems.

Plasma fibrinopeptide A, thrombin-antithrombin III complexes, tissue-plasminogen activator and alpha 2-plasmin inhibitor-plasmin complexes were measured early in the first stage of labor, in the second stage of labor and at 15 min after placental separation. Fibrinopeptide A and thrombin-antithrombin III complex levels did not change from the first to the second stage of labor but increased significantly after placental separation. There was a significant increase of the tissue-plasminogen activator level between the early first stage of labor and the second stage of labor, and it remained high after placental separation. A significant increase in the level of plasma alpha 2-plasmin inhibitor-plasmin complexes was observed after placental separation. These findings suggest that activation of the thrombotic system occurs at the time of placental separation and that activation of the fibrinolytic system begins during labor before placental separation to compensate for the hypercoagulable state which develops at the time of delivery.

Adult↗