[Seasonal and daily rhythms of labor in women. Relation of some complications in labor to the daily rhythm of labor activity].
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Early first-stage labor pain is primarily visceral in origin. Increasing pain intensity and transition to somatic nociceptive input characterizes late first- and second-stage labor pain. The effect of this change in nociceptive input on the duration of intrathecal labor analgesia has not been well studied. This prospective cohort observational study compares the duration of intrathecal labor analgesia after intrathecal injections made in early labor (3- to 5-cm cervical dilation) and those made in more advanced labor (7- to 10-cm cervical dilation). Forty-one parturients (18 in early labor and 23 in advanced labor) received intrathecal sufentanil (10 micrograms) and bupivacaine (2.5 mg) as part of a combined spinal-epidural technique. Patients rated their pain using a 0-10 verbal pain scale prior to intrathecal injection and every 20 min thereafter. Duration of analgesia was defined as the lesser of time until the pain score exceeded 5 or until a request for supplemental epidural analgesia was made. The duration of spinal analgesia was significantly less when intrathecal injection was made in advanced labor (120 +/- 26 min) compared with early labor (163 +/- 57 min, P < 0.01). We conclude that cervical dilation and stage of labor significantly impact the effective duration of intrathecal sufentanil/ bupivacaine labor analgesia.
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.
The management of labor is based on a sound understanding of labor's biochemistry and physiology. The interaction between prostaglandin synthesis and other mechanisms postulated to control the initiation of labor shows promise, but the definitive explanation for the initiation of labor awaits further research. The procedures associated with the management of routine labor, including perineal preparation and the use of enemas, intravenous fluids, and analgesics and anesthetics, are generally best applied on the basis of individual need rather than protocol. The Friedman labor curve and intrapartum risk scoring have proved to be useful indices in the evaluation of the course of labor. Oxytocin and prostaglandin are two clinically useful agents in the induction and augmentation of labor. Currently, prostaglandin is used generally in the induction of preterm labors with oxytocin reserved for the induction of labor at term. The effects and side effects of the medications may be controlled by careful use and monitoring. A protocol for the successful use of oxytocin includes careful fetal monitoring and control of intravenous infusion with careful incremental increases in the dose of oxytocin based on uterine response.
An analysis was performed of 5187 intra-amniotically measured labor pressure curves in 40 births with spontaneous labour (20 primiparae and 20 multiparae) and 40 births births in which labor was induced with oxytocin (20 primiparae and 20 multiparae). The dilatation of the os uteri was divided into three phases--Phase 1, dilatation of the cervix to 2 cm; Phase 2, dilatation of the cervix from 2 to 4 cm, and Phase 3, dilatation from 4 cm onwards until complete. During the active phase, from 2 cm until dilatation of the os uteri was complete, no differences were observed between induced and spontaneous labor with regard to frequency and amplitude of contractions. In the induced-labor cases, the parameters for uterine activity, maximum contraction and dilatation speed were higher in all three phases of labor, and those for total duration of labor lower than in the spontaneous labor cases. The contraction/dilatation speed is an important parameter for monitoring the effect of drug-induced stimulation of labor. In the latency phase in spontaneous labor, more contractions were observed in multiparae than in primiparae. This fact which should be reason enough to intensify monitoring of both mother and fetus during this phase. In light of these results it would appear advisable, in the absence of progress in labor, to make a clear distinction between the goals of cervical maturity and promotion of uterine activity, and to institute different drug therapy accordingly.
"This paper constructs a dynamic, general equilibrium framework to study the relationship between international labor migration and domestic labor supply. The general equilibrium nature of the model enables us to endogenize the pattern of labor migration. The effect of labor migration on domestic wage rates and labor supply is shown to depend on the pattern of labor migration. If the substitution effect dominates the income effect in labor supply, the domestic supply of labor necessarily decreases in response to an inflow of migrants....Similarly, if the dominant effect is the income effect, the immigration of labor necessarily increases the domestic supply of labor."
OBJECTIVE: To define factors causing prolonged labor in nulliparous women undergoing active management of labor. METHODS: We included all nulliparas delivered during 1990-1994 with spontaneous onset of labor lasting more than 12 hours, singleton gestation, cephalic presentation, and labor at greater than 37 weeks. Each patient was matched with the next nulliparous woman who delivered with a labor lasting less than 12 hours and who fulfilled the same inclusion criteria. Subjects were managed according to the previously described active management of labor protocol from The National Maternity Hospital, Dublin. RESULTS: In the 5-year period, 9018 nulliparas met inclusion criteria, with 147 (1.6%) having prolonged labor. Prolonged labor was due to inefficient uterine action in 65%, persistent occipitoposterior position in 24%, and cephalopelvic disproportion in 11% of cases. Univariate analysis showed statistically significant (P < .05) differences in maternal body mass index, cervical dilation on admission, oxytocin use, epidural use, placement of epidural at less than 2 cm of dilation, and birth weight between these study groups. On multivariate conditional logistic regression analysis, the following were significant independent predictors for having a prolonged labor (odds ratios with 95% confidence intervals presented): 3.1 (1.3-7.3) for cervical dilation less than 2 cm on admission, 42.7 (7.5-242.0) for early epidural placement, 5.1 (1.9-13.7) for epidural placement at greater than or equal to 2 cm, and 10.2 (3.6-29.4) for birth weight greater than 4000 g. CONCLUSION: Less-advanced cervical dilation on admission and epidural use, especially when placed early, are strongly associated with prolonged labor.
BACKGROUND: The aim of this prospective, double-blind, sequential allocation study was to compare the effects of spontaneous and prostaglandin-induced labor on the minimum analgesic dose of epidural sufentanil in the first stage of labor. METHODS: Seventy healthy, nulliparous women, at more than 37 weeks' gestation with cervical dilatation from 2 to 4 cm, requesting epidural pain relief in labor were enrolled. The subjects were assigned to two different groups according to whether labor was spontaneous or induced with dinoprostone 0.5 mg. Parturients received 10 ml of the study solution through a lumbar epidural catheter. The initial dose was sufentanil 25 microg, and subsequent doses were determined by the response of the previous patient in the same group using up-down sequential allocation. The analgesic effectiveness was assessed using 100-mm visual analog pain scores. The up-down sequences were analyzed using the method of independent paired reversals and probit regression. RESULTS: The minimum analgesic dose of sufentanil in spontaneous labor was 22.2 microg (95% CI: 19.6, 22.8) and 27.3 microg (95% CI: 23.8, 30.9) in induced labor. The minimum analgesic dose of sufentanil in induced labor was significantly greater (P = 0.0014) than that in spontaneous labor (95% CI difference: 2.9, 9.3) by a factor of 1.3 (95% CI: 1.1, 1.5). CONCLUSION: Prostaglandin induction of labor produces a significantly greater analgesic requirement than does spontaneous labor.
To obtain data on the immunologic events during labor, we investigated cytotoxic activity, progesterone-prostaglandin F2 alpha and prostaglandin E2 sensitivity of the lymphocytes in late pregnancy at early and late stages of labor and in the puerperium. In an attempt to investigate common determinants between the behavior of lymphocytes during labor and threatened preterm delivery, the same parameters of lymphocytes obtained from women with threatened preterm delivery were tested in parallel. At the beginning of labor, cytotoxic activity of the lymphocytes significantly increased and remained at a high level till the end of labor. A negative correlation (r = -0.803) was found between the increase of cytotoxicity and the duration of labor. High progesterone sensitivity of pregnancy lymphocytes decreased while low sensitivity to prostaglandin E2 increased during labor. Sensitivity of the lymphocytes to prostaglandin F2 alpha was similar in all of the groups examined. Except for prostaglandin E2 sensitivity all parameters of the lymphocytes obtained from women with threatened preterm delivery were similar to those of lymphocytes obtained during labor.
The effect of a birth companion on duration of labor was examined in a sample of 66 nulliparous women in Michigan. Two-thirds of the sample were single, 66% received Medicaid, and 88% were white. Using simple linear regression, support during labor explained a significant amount of variance in duration of labor. Duration of labor for 8 unsupported mothers was significantly longer (965 +/- 206 min) than that for 58 supported mothers. Using hierarchic regression and including maternal education, marital status, race, amniotomy, and labor induction in the model before support, support during labor continued to explain a significant amount of variance in duration of labor. These findings are similar to those reported from earlier randomized trials of social support during labor. Evidence continues to accumulate that confirms the proposition that labor duration is affected by environmental as well as biologic factors.
OBJECTIVE: To determine whether cervical dilatation at the time of placement of patient-requested epidural affects cesarean rates or lengths of labors in actively managed parturients. METHODS: The charts of 255 women randomized to active management of labor (n = 125) or control protocols (n = 130) were reviewed and stratified to early epidural placement (up to 4 cm cervical dilatation) versus late placement (more than 4 cm). RESULTS: Women with early epidural placement had shorter labors than those with late placement (11.6 +/- 4.6 versus 13.2 +/- 5.6 hours; P = .02). Active management reduced the length of labor compared with controls regardless of epidural timing, with a reduction of 1.4 hours in early epidural placement (10.9 +/- 4.7 versus 12.3 +/- 4.3 hours; P = .04) and 3.6 hours in those with later placement (11.0 +/- 3.6 versus 14.6 +/- 6.2 hours; P = .004). Cesarean rates did not vary significantly (early 14.5% versus late 7.9%; P = .21). Early epidural placement did not lengthen the second stage of labor or increase operative vaginal delivery rates. CONCLUSION: Early epidural placement did not affect lengths of labor or cesarean rates and was actually associated with shorter labor compared with late epidural placement. Women managed actively in labor, regardless of timing of epidural placement, had shorter labors than controls.
This correlational study was conducted to examine the relationship between maternal sleep during the nights prior to the onset of labor and labor outcomes of length, type of delivery, and maternal perceptions of labor. Subjects (N = 99) were drawn from childbirth education classes at a women's hospital in the southeastern United States. Subjects completed the Visual Analog Sleep Scale each morning, beginning two weeks prior to their due dates. Following delivery, subjects completed the Perception of Labor and Delivery Scale, and researchers gathered data about their labors. These women reported poor sleep effectiveness coupled with high sleep disturbance; however, there were no significant correlations between sleep quality and length of labor or maternal perceptions of labor for either the night, or the week, prior to the onset of labor. This finding leads us to question the view that disturbed prenatal sleep will interfere with the progress of labor and lead to more cesarean sections.
INTRODUCTION: A strong rise in the use of induced labor has been observed in France. The aim of this work was to analyze the different methods used for achieving induction of labor and their implications. METHODS: One out of four French obstetricians were randomly selected to answer a questionnaire on their practice for achieving induction of labor. Four hundred of the 997 obstetricians answered the questionnaire. Univariate and multivariate analysis was applied. RESULTS: A high rate of induced labor was correlated with some areas of the country and with private practice. Certain methods were used in spite of opposing advice by experts in the field: elective induction of labor with unfavorable cervix, use of prostaglandins in elective induction of labor, induction of labor in cases of scarred uterus or breech presentation, use of misoprostol. Some methods were still used in spite of their poor efficacy: intravenous oxytocin used with unfavorable cervix, use of intravensou PGE2. CONCLUSION: This study would show that theory and practice are often distinctly different. Induction of labor is currently used on a far wider scale than ever before. We obviously need studies for careful assessment of the circumstances in which induction of labor is used in order to improve methods and indications of such a clinical practice.
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