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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↗
PubMed1999

Amniotic fluid volume and onset of labor in physiological pregnancy.

We measure, by means of ultrasound, the amniotic fluid volume (expressed as maximal vertical pocket or MVP) in 646 normal pregnancies at the 39th gestational week. Our aim is to evaluate the possible correlation between MVP and onset of the labor. In a 2-week follow-up, the onset of the labor is considered the "event" variable in a time-dependent statistical analysis. Univariate analysis (Kaplan-Meier algorithm) describes a different trend in predicting the onset of labor when a stratification of MVP < 50 and > or = 50 mm was performed (chi2 = 7.91 p < 0.0049 with 1 df, Breslow-Gehan test). The first category was comprised of 496 fetuses with a median (min-max) MVP of 39 mm (25-49), the second category of 150 fetuses with a MVP of 57 mm (50-100). The results suggest that lower levels of MVP are associated to a higher percentage of the onset of labor. Furthermore, in our measurement, performed at the 39th gestational week, the correlation with the events is higher within the 40th gestational week. In fact, at 7 days from the amniotic fluid measurement, the onset of labor and the subsequent delivery is observed in 80.65 and 73.00% of the cases when they are stratified according to MVP < 50 and > or = 50 mm. At the end of the follow-up, instead, the percentage of "events" is similar, 88.10 and 86.67%, respectively. Adjustment for covariates (Cox analysis), as well as maternal age, neonatal weight, and obstetrics history, show an odds ratio (95% C.I.) of 2.08 (1.61-2.69) for MVP, using the above cutoff level. In physiological pregnancy, lower levels of amniotic fluid at term correlated to a higher probability of the onset of labor.

Adolescent↗
PubMed1998

Characterization and prognostic significance of variable decelerations in the second stage of labor.

The characteristics of variable decelerations (VD) in the second stage of labor and the relationship between the number, frequency, or severity and neonatal outcome have not been studied. We have analyzed the characteristics of VD in the second stage of labor and their prognostic significance in the prediction of Apgar scores. In this descriptive study, fetal heart tracings containing VD from 250 singleton, vaginal deliveries between June 1994 and July 1996 were reviewed blinded to outcome information. Excluded were: (1) deliveries at <36 weeks, (2) uninterpretable tracing, (3) absence of VD in second stage of labor, and (4) absence of exam establishing beginning of second stage of labor. VD characteristics evaluated: shape (U, V, W); anterior and posterior "shoulders"; slow return to baseline (< or = 30-degree curve); cumulative depth of VD per 10 min, second stage oxytocin dose. Outcome information collected: method of delivery, birth weight and Apgar scores. Statistical analysis included regression and analysis of variance (ANOVA). The mean maternal age was 32+/-5 years and gestational age 39+/-1.3 week. In the second stage of labor, the mean oxytocin dose was 3+/-5 mu/min, length of the second stage 65+/-57 min, total number of VD averaged 21+/-17 and uterine contractions 26+/-22 per patient. The percentage of VD <100 bpm was 50+/-27%, VD <70 bpm 13+/-20%, anterior shoulders 76+/-30%, posterior shoulders 75+/-30% and slow return to baseline 12+/-17%. The number of VD significantly increased with the length of the second stage of labor (r=0.85, p <0.001). The total number and percentage of VD <70 bpm were inversely correlated with 5-min Apgar score (p=0.038, 0.015 respectively). The sum of the depth of VD/length of second stage as well as the percentage of VD with anterior and/or posterior shoulders and slow return to baseline were not significantly related to Apgar scores (p=0.08, 0.72, 0.73, 0.99, respectively). Patients with a higher percentage of decelerations with slow return to baseline had a higher rate of operative vaginal deliveries (20 vs. 11 %, p=0.002); but no significant differences in Apgar scores compared with those with spontaneous delivery (p=0.9). Second stage VD <70 bpm were significantly associated with lower 5-min Apgar scores. Although the presence of VD with a slow return to baseline was significantly associated with operative delivery, there was no difference in 5-min Apgar scores.

Adult↗
PubMed1991

Serum magnesium levels in pregnancy and preterm labor.

Pregnancy is marked by a state of hypomagnesemia. The serum magnesium level shows no gestational dependence (mean, 1.79 +/- 0.44 mg/dl) until 33 weeks, at which point it continuously declines. Serum magnesium is not depressed further with the onset of labor at term. Patients in preterm labor have a significantly depressed serum magnesium level (mean, 1.60 +/- 0.46 mg/dl; 21 to 33 weeks; p less than 0.0005). This level was not dependent on whether the etiology for the preterm labor was premature rupture of the membranes (PROM), twin gestation, abruption, placenta previa with bleeding, or chorioamnionitis. With PROM, the serum magnesium level was not depressed prior to the initiation of preterm labor. However, observation of hypomagnesemia for this and other etiologies just prior to the initiation of preterm labor were not available. Possible mechanisms by which hypomagnesemia induces uterine irritability are explored, including inhibition of adenyl cyclase with resultant increase in cytoplasmic calcium levels. Patients with diabetes mellitus appeared to have slightly reduced serum magnesium levels, but the results were not statistically significant. Magnesium levels in patients with preeclampsia were not significantly different from controls. Hypomagnesemia (magnesium 1.4 mg/dl or less) may be a marker for true preterm labor.

Calcium↗
PubMed1985

Effect of Lamaze childbirth preparation on maternal plasma beta-endorphin immunoreactivity in active labor.

Previous studies have documented a reduction in plasma beta-endorphin levels with the use of various analgesic techniques in labor, such as segmental epidural anesthesia or intrathecal morphine. The Lamaze method of childbirth preparation, which has been found to reduce the need for medication during childbirth and to decrease the subjective perception of pain during labor and delivery, has not been studied in this regard. In this study plasma beta-endorphin immunoreactivity levels were measured during the active phase of labor in 26 patients who had Lamaze classes and in 28 patients who did not have Lamaze classes. The Lamaze group had significantly lower plasma beta-endorphin immunoreactivity (37.2 vs. 68.5 pg/ml; P less than 0.001) and significantly shorter first stages of labor (8.28 hrs. vs. 9.86 hrs; P less than 0.02). It can be theorized that both lower beta-endorphin immunoreactivity and shorter labor in patients in the Lamaze group were related to the reduction of fear, tension, and the emotional stress of labor.

Adult↗
PubMed2000

The prevalence of thromboembolic events among women with extended bed rest prescribed as part of the treatment for premature labor or preterm premature rupture of membranes.

OBJECTIVE: This study was undertaken to determine the prevalence of thromboembolic events among women with extended bed rest prescribed as part of the treatment of premature labor or preterm premature rupture of membranes. STUDY DESIGN: A retrospective chart review was undertaken of all women who had bed rest of >/=3 days' duration prescribed as part of the treatment of premature labor or preterm premature rupture of membranes in the Akron General Medical Center Perinatal Unit during the period January 1, 1997-December 31, 1998. The prevalence of thromboembolic events in this population was determined. The charts of all additional gravid women with antepartum or postpartum deep vein thrombosis or pulmonary embolism diagnosed during the study period were also reviewed. The prevalence of these disorders among the pregnant population for whom extended bed rest was not prescribed as part of the treatment of premature labor or preterm premature rupture of membranes was also calculated. Statistical comparison of the prevalences in the 2 populations was undertaken by means of the chi(2) analysis with the Fisher exact test. RESULTS: There were 192 patients admitted during the study period who had extended bed rest prescribed as part of the treatment of premature labor or preterm premature rupture of membranes. Three of these women had thromboembolic events, for a prevalence of 15.6 cases per 1000 women. Five additional gravid women were admitted for the treatment of deep vein thrombosis or pulmonary embolism. There were 6164 deliveries among women not treated with extended bed rest for premature labor or preterm premature rupture of membranes during this period. Thus the prevalence of these phenomena among the remaining pregnant women was 0.8 cases per 1000 women. The prevalences of these disorders in the 2 populations were highly significantly different. CONCLUSION: The prevalence of thromboembolic events among women for whom extended bed rest is prescribed as part of the treatment of premature labor or preterm premature rupture of membranes is significantly increased with respect to that among gravid women who do not receive this therapy and is substantially higher than previously reported. If this finding is confirmed in other populations, it may be prudent to undertake further studies to determine whether this prevalence can be reduced.

Bed Rest↗
PubMed2000

Maternal and neonatal outcomes after induction of labor without an identified indication.

OBJECTIVE: This study was undertaken to examine associations between induction of labor and maternal and neonatal outcomes among women without an identified indication for induction. STUDY DESIGN: This was a population-based cohort study of 2886 women with induced labor and 9648 women with spontaneous labor who were delivered at 37 to 41 weeks' gestation, all without identified medical and obstetric indications for induction. RESULTS: Among nulliparous women 19% of women with induced labor versus 10% of those with spontaneous labor underwent cesarean delivery (adjusted relative risk, 1.77; 95% confidence interval, 1.50-2.08). No association was seen in multiparous women (relative risk, 1.07; 95% confidence interval, 0. 81-1.39). Among all women induction was associated with modest increases in instrumental delivery (19% vs 15%; relative risk, 1.20; 95% confidence interval, 1.09-1.32) and shoulder dystocia (3.0% vs 1. 7%; relative risk, 1.32; 95% confidence interval, 1.02-1.69). CONCLUSION: Among women who lacked an identified indication for induction of labor, induction was associated with increased likelihood of cesarean delivery for nulliparous but not multiparous women and with modest increases in the risk of instrumental delivery and shoulder dystocia for all women.

Adult↗
PubMed2000

Effect of previous vaginal delivery on the risk of uterine rupture during a subsequent trial of labor.

OBJECTIVE: We examined the effect of prior vaginal delivery on the risk of uterine rupture in pregnant women undergoing a trial of labor after prior cesarean delivery. STUDY DESIGN: The medical records of all pregnant women with a history of cesarean delivery who attempted a trial of labor during a 12-year period at a single center were reviewed. For the current analysis, the study population was limited to term pregnancies. The effect of previous vaginal delivery on the risk of uterine rupture during a subsequent trial of labor was evaluated. Separate analyses were performed for women with a single previous cesarean delivery and for those with >1 prior cesarean delivery. For each of these subgroups, the rate of uterine rupture among women who had > or =1 prior vaginal delivery was compared with the rate among women with no prior vaginal delivery. Logistic regression analysis was used to examine the associations with control for confounding factors. RESULTS: Of 3783 women with 1 prior scar, 1021 (27.0%) also had > or =1 prior vaginal delivery. During a subsequent trial of labor, the rate of uterine rupture was 1.1% among pregnant women without prior vaginal delivery and 0.2% among pregnant women with prior vaginal delivery (P =.01). Logistic regression analysis controlling for duration of labor, induction, birth weight, maternal age, year of birth, epidural analgesia, and oxytocin augmentation indicated that, among women with a single scar, those with a prior vaginal delivery had a risk of uterine rupture that was one fifth that of women without a previous vaginal delivery (odds ratio, 0.2; 95% confidence interval, 0.04-0.8). In the group of 143 pregnant women with >1 previous cesarean delivery, women with a prior vaginal delivery had a somewhat lower risk of uterine rupture (3.9% vs 2.5%; adjusted odds ratio, 0.6; 95% confidence interval, 0.01-6.7). This difference was not statistically significant. CONCLUSION: Among women with 1 prior cesarean delivery undergoing a subsequent trial of labor, those with a prior vaginal delivery were at substantially lower risk of uterine rupture than women without a previous vaginal delivery.

Female↗
PubMed2001

Influence of labor on fetoplacental adrenomedullin concentrations.

OBJECTIVE: Circulating adrenomedullin is increased in pregnancy, and placental and fetal membranes participate significantly in its secretion. Recent studies have suggested a potential role for this peptide in the regulation of fetoplacental circulation and placental hormonal secretion. Because adrenomedullin acts also as a uterorelaxant in rats, this study was designed to investigate whether fetoplacental adrenomedullin production changes with human labor, either at term or preterm. STUDY DESIGN: Eighty pregnant women grouped according to gestational age and presence of labor were studied. Adrenomedullin concentrations in plasma, amniotic fluid, and placental tissue extracts were measured by means of radioimmunoassay and immunohistochemistry. In addition, the ability of amnion and chorion-decidua to secrete adrenomedullin was investigated in vitro. RESULTS: Adrenomedullin concentrations in amniotic fluid were higher in preterm labor, whereas no differences were found in adrenomedullin expression or concentrations in tissues or in maternal and fetal plasma between vaginal delivery or elective cesarean section, both at term and preterm. During term labor (8 patients), maternal plasma adrenomedullin concentration decreased with advancing cervical dilatation, being 173 pg/mL at the beginning of the active stage of labor and 57 pg/mL at the time of delivery. Adrenomedullin concentration in the medium of amnion- and chorion-decidua-cultured cells was higher after vaginal delivery. CONCLUSION: These results suggest that a decrease in adrenomedullin production is not involved in the onset of labor in human subjects but rather that it may play a role other than that of a myometrial relaxant in human parturition.

Adrenomedullin↗
PubMed2001

Outcomes of trial of labor following previous cesarean delivery among women with fetuses weighing >4000 g.

OBJECTIVE: To compare outcomes at term of a trial of labor in women with previous cesarean delivery who delivered neonates weighing > 4000 g versus women with those weighing < or = 4000 g. STUDY DESIGN: We reviewed medical records for all women undergoing a trial of labor after prior cesarean delivery during a 12-year period. The current analysis was limited to women at term with one prior cesarean and no other deliveries. The rates of cesarean delivery and symptomatic uterine rupture for women with infants weighing > 4000 g were compared to the rates for women with infants weighing < or = 4000 g. Logistic regression was used to control for the potential confounding by use of epidural, maternal age, labor induction, labor augmentation, indication for previous cesarean, type of uterine hysterotomy, year of delivery, receiving public assistance, and maternal race. Adjusted odds ratios and 95% confidence intervals were calculated. RESULTS: Of 2749 women, 13% (365) had infants with birth weights > 4000 g. Cesarean delivery rate associated with birth weights < or = 4000 g was 29% versus 40% for those with birth weights > 4000 g (P = .001). With use of logistic regression, we found that birth weight > 4000 g was associated with a 1.7-fold increase in risk of cesarean delivery (95% CI, 1.3-2.2). The rate of uterine rupture for women with infants weighing < or = 4000 g was 1.0% versus a 1.6% rate for those with infants weighing > 4000 g (P = .24). Although the logistic regression analysis revealed a somewhat higher rate of uterine rupture associated with birth weights of > 4000 g (adjusted OR, 1.6; 95% CI, 0.7-4.1), this difference was not statistically significant. The rate of uterine rupture was 2.4% for women with infants weighing > 4250 g, but this rate did not differ significantly from the rate of uterine rupture associated with birth weights < or = 4250 g (P = .1). CONCLUSION: A trial of labor after previous cesarean delivery may be a reasonable clinical option for pregnant women with suspected birth weights of > 4000 g, given that the rate of uterine rupture associated with these weights does not appear to be substantially increased when compared to lower birth weights. However, some caution may apply when considering a trial of labor in women with infants weighing > 4250 g. In these women with infants weighing > 4000 g, the likelihood of successful vaginal delivery, although lower than for neonates weighing < or = 4000 g, is still 60%.

Adult↗
PubMed2006

Performance of acupuncture as labor analgesia in the clinical setting.

BACKGROUND: Three randomized controlled trials have shown that acupuncture during labor can reduce the use of epidural analgesia and meperidine. To supplement these trials, we have designed an observational study to answer the research question: "Do laboring women in a normal hospital setting who receive acupuncture require less epidural analgesia than those who do not receive acupuncture?" METHODS SETTING: Delivery ward of a tertiary care University hospital in Norway. SUBJECTS: All attempted vaginal labors during the period 01.12.99-31.12.03 (n = 17,741). STATISTICAL ANALYSIS: Multivariate logistic regression analysis. RESULTS: The dependent variable in the regression analysis was use of epidural analgesia. The independent variables were: use of acupuncture, use of nitrous oxide, use of meperidine, parity, ethnicity, age, duration of pregnancy, type of labor (induced or not), and duration of first stage of labor. In the multivariate analysis the odds ratio for having an epidural was 0.6 (95% CI 0.5-0.7) for the patients having acupuncture compared to those not having acupuncture. CONCLUSIONS: Women having acupuncture as labor analgesia in the clinical setting have a reduced use of epidural analgesia.

Acupuncture Analgesia↗
PubMed1994

Magnesium sulfate loading: preeclampsia vs preterm labor (a clinical pearl).

OBJECTIVE: To measure the apparent volume of distribution (AVOD) for magnesium (Mg) in preeclampsia and preterm labor and determine if a standard 4 gm loading dose of magnesium sulfate (MgSO4) is sufficient to attain therapeutic levels. METHODS: Twenty-five patients with preeclampsia and 25 with preterm labor received 4 g of MgSO4 intravenously over 15 minutes. Serum Mg levels were determined before and one minute after loading and the AVOD for Mg was calculated. Stepwise linear regression with AVOD as the dependent variable was performed and comparisons between the groups were made. RESULTS: Preeclamptics were heavier, had greater surface areas, and presented at a later stage of pregnancy than did patients with preterm labor. Despite these differences AVOD did not differ between the groups. Predose magnesium levels were slightly higher in the preeclamptic group (p = .04). Post-loading levels were nearly identical due to similar AVOD's and, because of the lower levels required for seizure prevention as opposed to tocolysis, were therapeutic 88% of the time in preeclampsia but only 12% of the time in preterm labor (p < .001). Multivariate analysis revealed that only ideal body weight, degree of underweight, and current therapy with betamimetics were significantly related to AVOD. CONCLUSION: AVOD was found to be similar in preeclamptic and preterm labor patients. A 4 g loading dose of MgSO4 is usually adequate to achieve therapeutic levels in preeclampsia but not in preterm labor.

Female↗
PubMed1995

Maternal-fetal transfer of ionized serum magnesium during the stress of labor and delivery: a human study.

OBJECTIVE: The purpose of this study was to compare levels and fractions of ionized magnesium in maternal venous serum with those in umbilical venous and arterial serum and to determine whether the maternal levels and fractions change during the stress of labor. METHODS: Utilizing an ion-selective electrode, we determined levels and fractions of ionized magnesium (IMg2+) and levels of ionized calcium (ICa2+) in the maternal venous serum (MVS) of 12 parturients on admission and at the end of labor, as well as in the umbilical venous (UVS) and umbilical arterial serum (UAS) at delivery. A paired-sample study design was used. RESULTS: Whereas mean levels of ICa2+ did not change significantly (p > 0.05) during labor, the mean (+/- SE) MVS levels of IMg2+ and total magnesium (TMg) fell from 0.50 +/- 0.01 and 0.80 +/- 0.02 mmol/L, respectively, on admission to 0.46 +/- 0.01 and 0.68 +/- 0.01 mmol/L (p < 0.01 and p < 0.001, respectively) at delivery. The ionized fraction, expressed as a percent (IMg2+/TMg x 100), increased from 62.8 +/- 2.1% to 67.8 +/- 1.2% (p < 0.05). In the UVS, the mean IMg2+ level (0.52 +/- 0.02 mmol/L) and the mean ionized fraction (73.6 +/- 1.7%) were higher than in MVS on admission or at delivery (p < 0.05 for all comparisons). The mean IMg2+ level in UAS (0.50 +/- 0.02 mmol/L) was lower than in UVS (p < 0.05), but higher than in MVS at delivery (p < 0.01). Finally, there were significant positive correlations between levels of magnesium (Mg) in MVS and in the UAS or UVS. CONCLUSIONS: The observation that UAS levels of IMg2+ and TMg were similar to the MVS levels on admission despite the fall in maternal levels during labor points to the presence of homeostatic mechanisms in the fetus and placenta. It is possible that the presence of a higher fraction of unbound, free magnesium in UVS enhances magnesium transport to the fetus and thus homeostasis. Finally, we hypothesize that the fall in the levels of the biologically active form of Mg during labor may be yet another manifestation of the known stress responses to labor.

Calcium↗
PubMed2005

The effect of vaginal pH on labor induction with vaginal misoprostol.

OBJECTIVE: To estimate the association of vaginal pH on the induction to vaginal delivery interval in labor induction with vaginal misoprostol. METHODS: Women presenting at term with intact membranes for labor induction were recruited. The pH of the vagina was measured during a digital examination of the cervix to determine the Bishop Score. Labor was induced with 25 microg of vaginal misoprostol placed every 6 h until spontaneous rupture of membranes or active labor occurred. The primary outcome was the induction to vaginal delivery interval in the lower pH (< 5) versus higher pH (> or = 5) group. Secondary outcomes assessed maternal and neonatal morbidities. Sample size calculated a priori estimated 120 subjects were required for a power of 95% and a 2-tailed a of 0.05. RESULTS: 120 women met inclusion criteria and had available pH data. There was no difference in the induction to vaginal delivery interval in the lower pH (1455 min) versus higher pH group (1295 minutes, Mean difference 160 [- 147,468] P = .30). No difference was observed for operative delivery rates or neonatal outcomes. CONCLUSION: The pH of the vagina may not affect the length of the induction to vaginal delivery interval in women undergoing labor induction with vaginal misoprostol. Further research is required to determine factors that may influence the efficacy of vaginal misoprostol when used for labor induction.

Administration, Intravaginal↗
PubMed2001

Evaluation of fetal heart monitoring in the first stage of labor.

OBJECTIVE: To evaluate the usefulness of continuous electronic fetal heart rate (FHR) monitoring in the first stage of labor. METHODS: A total of 814 pregnant women in labor without identifiable risk factors was divided into two groups. In group A (468 cases), continuous FHR monitoring began in the earliest phase of the first stage of labor (cervical dilatation < or = 4 cm), while in group B (346 cases) it began when the cervical dilatation was > 4 cm. Initial FHR tracings were normal in all 814 cases. The fetal monitoring findings were analyzed at 10-min intervals, and comparisons were made between the two groups concerning FHR findings and their correlation with the state of the newborns. RESULTS: No significant difference was found between the two groups in the incidence of repetitive variable decelerations (1.9% and 1.7%, respectively); sporadic variable decelerations (9.2% and 8.7%, respectively); persistent repetitive late decelerations that resulted in Cesarean section (1.1% and 1.4%, respectively); or sporadic late decelerations (8.3% and 8.1%, respectively). One newborn from each group required intensive neonatal care. CONCLUSIONS: The same tracing sufficiency of fetal stress was observed in the two groups. However, the manner of labor supervision in group B seemed to be more beneficial, because of greater maternal comfort, a lower necessity for personnel, lower consumption of cardiotocographic materials and the possibility of labor induction for more women. Since fetal monitoring is widely used, it is preferable to start continuous FHR monitoring when the dilatation of the cervix approximates 4-5 cm (second phase of the first stage of labor) without risk of fetal loss.

Adolescent↗
PubMed2002

Activation of coagulation system in preterm labor and preterm premature rupture of membranes.

OBJECTIVE: Thrombin, originally discovered as a coagulation factor, is a multifunctional protease capable of inducing myometrial contractions in vitro and in vivo. This enzyme has been implicated in the mechanisms of premature labor. Plasma concentrations of thrombin-antithrombin (TAT) complexes are an index of in vivo thrombin generation. The purpose of this study was to determine whether patients with premature labor and preterm premature rupture of membranes (PROM) have evidence of increased thrombin generation in maternal blood, as determined by the TAT complex concentrations. METHODS: A cross-sectional study was designed to determine plasma concentrations of TAT complexes in 110 women in the following groups: non-pregnant women (n = 20); normal pregnant women (n = 30); women in preterm labor with intact membranes (n = 30); and women with preterm PROM (n = 30). TAT complex concentrations were determined with a sensitive and specific immunoassay. Statistical analysis was conducted with non-parametric statistics. RESULTS: Patients with preterm labor and intact membranes had a significantly higher median plasma TAT complex concentration than normal pregnant women (women in preterm labor, median 19.1 microg/l; range 7.4-406 vs. normal pregnant women, median 15 microg/l; range 6.8-32.5; p = 0.03). Patients with preterm PROM had a higher median TAT complex concentration than normal pregnant women (preterm PROM, median 19.1 microg/l; range 4.7-738.6 vs. normal pregnant women, median 15 microg/l; range 6.8-32.5; p = 0.03). Normal pregnancy was associated with a higher median plasma TAT complex concentration than the non-pregnant state (normal pregnant women, median 15 microg/l; range 6.8-32.5 vs. non-pregnant women, median 2.7 microg/l; range 0.9-14.2; p < 0.001). CONCLUSION: Preterm labor and preterm PROM are associated with an excess generation of thrombin.

Adolescent↗
PubMed2002

The effects of labor on infant mortality among small-for-gestational-age infants in the USA.

OBJECTIVE: To determine whether the presence of labor affects infant mortality among small-for-gestational-age (SGA) infants. METHODS: Data were derived from the United States national linked birth/infant death data sets for 1995-97. Singleton SGA live births in cephalic presentation delivered at 24-42 weeks' gestation were included. Mortality rates for SGA infants exposed and unexposed to labor were compared, and relative risks (RR) were derived using multivariable logistic regression models, after adjusting for potential confounding factors. RESULTS: Of 986 405 SGA infants, 87.4% were exposed to labor. Infants exposed to labor at 24-31 weeks had greater risks of dying during the early neonatal period (RR 1.79-1.86). Decreased risks of late and postneonatal death were observed at all gestational ages in the presence of labor. CONCLUSIONS: Exposure to labor is associated with an increased risk of early neonatal death among SGA infants, especially at gestational ages below 32 weeks. Future randomized trials are warranted to determine the optimal obstetric management of these high-risk infants.

Female↗
PubMed2000

Oxytocin receptors in guinea pig myometrium near term and during labor.

Oxytocin receptors in myometrium of women, rats, and rabbits rise markedly before the onset of labor, suggesting a role in the initiation of labor. In guinea pigs, a previous study reported no such rise by one-point determination of oxytocin binding. The purpose of this study was to use a more rigorous method to determine whether the binding characteristics of myometrial oxytocin receptors change in relation to labor in guinea pigs. Competitive binding studies were carried out in microsomes from inner and outer myometrium between 42 days of gestation and labor. Binding to analogs was also tested. Data were analyzed with affinity spectra and LIGAND. Oxytocin bound to one site with a dissociation constant of 6.3 +/- 0.65 x 10(-9) M. Binding capacity was 1.0 +/- 0.1 x 10(-12) mol/mg protein. The Hill coefficient was near unity. No significant changes occurred with gestation or labor in dissociation constant, binding capacity, or Hill coefficient (all P >/= 0.2, nested ANOVA). Binding capacity was higher in the outer than in the inner layer (1.2 +/- 0.2 vs. 0.8 +/- 0.1 x 10(-12) mol/mg protein, P = 0.02), but the dissociation constants were similar. Differences existed in the dissociation constants of the analogs tested. The main conclusion is that oxytocin receptors are unlikely to have a regulatory role in the initiation of labor in guinea pigs.

Animals↗