Effects of Patient-Controlled Epidural Analgesia on Uterine Electromyography During Spontaneous Onset of Labor in Term Nulliparous Women

Effects of epidural analgesia on intrapartum maternal fever and maternal outcomes: an updated systematic review and meta-analysis

OBJECTIVE

Epidural-related maternal fever in women is a common clinical phenomenon that leads to adverse consequences for mothers and neonates. The meta-analysis aimed to quantify the risk for intrapartum maternal fever after epidural analgesia (EA) stratified according to parity. The secondary objective was to investigate the association between EA and maternal outcomes.

METHODS

An electronic literature search of the Medline/PubMed, Embase, Cochrane Library, Wanfang Data, and China National Knowledge Infrastructure databases was performed to identify studies reporting the occurrence of intrapartum fever in parturients. Studies were reviewed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, and meta-analysis was performed using Review Manager version 5.3.

RESULTS

Seventeen randomized controlled trials (RCTs) (5959 parturients) were included. Odds ratios for maternal fever in the analysis were 4.17 (95% confidence interval (CI) 2.93-5.94) and 5.83 (95% CI 4.96-6.87), respectively. Results of subgroup analysis according to parity were consistent. EA significantly prolonged the length of the first stage of labor (MD 34.52 [95% CI 12.13-56.91]) and the second stage of labor (MD 9.10 [95% CI 4.51-13.68]). Parturients who received EA were more likely to undergo instrumental delivery (OR 2.03 [95% CI 1.44-2.86]) and oxytocin augmentation (OR 1.45 [95% CI 1.12-1.88]). There were no differences in cesarean delivery rates between the EA and non-EA groups.

CONCLUSIONS

Parturients who received EA exhibited a higher incidence of intrapartum fever. Credibility of the subgroup analyses was low because the mixed group did not effectively represent multiparas.

Use of External Uterine Electromyography Across Stage I Labor

INTRODUCTION

Highly sensitive, external uterine electromyography (EMG) measures myometrial electrical activity and is noninvasive compared with the clinical intrauterine pressure catheter. Most experimental studies have measured EMG in 30-minute epochs, limiting the utility of this instrumentation in intrapartum clinical practice. To test proof of concept, surface uterine EMG contraction activity was continuously collected throughout the first stage of labor from healthy women at term gestation with (n = 3) and without (n = 1) epidural or combined spinal-epidural analgesia for a maximal length of 11 hours and 24 minutes.

METHODS

EMG activity was recorded concurrently with tocodynamometer (toco) signals, using a pair of electrodes on the left and right sides of the maternal umbilicus with grounds attached to both hips of the reclining woman in labor. The preamplifier cutoff frequency settings were appropriate to monitor smooth muscle contraction in labor, with the analog high-pass filter set at 0.05 Hz and the low-pass filter at 1.50 Hz. Signals were sampled at 100 Hz, transmitted to a computer, and visualized by Chart 4.2 software. EMG data from epochs at baseline, during the pre-epidural fluid bolus and at the 60-minute post-epidural test dose, and at 3, 5, 6, and 8 cm dilatation were analyzed for burst power spectrum peak frequency (Hz), burst power spectrum amplitude (mV2 ), and burst duration (seconds).

RESULTS

Uterine EMG contractile bursts were preceded and followed by a stable baseline and coincided with toco contractions. Movement artifacts were negligible, and large movement artifacts were easily distinguishable. The EMG bursts and toco contractions remained clearly identifiable, even when one woman without epidural analgesia stood beside the bed laboring for approximately 10 minutes. Burst spectral components fell within the expected 0.34-to-1.00 Hz range for term labor.

DISCUSSION

High-quality data demonstrate that EMG instrumentation effectively and accurately measures uterine contraction parameters across the first stage of term labor.

Quantitative analysis for grading uterine electromyography activities during labor

BACKGROUND

The strength of uterine contraction is one of the decisive factors for labor progression and parturition. Clinicians usually encounter difficulties in early identification of inadequate contractions and in oxytocin treatment. Electromyography-an emerging technology for uterine contraction monitoring-can quantify the intensity of myoelectric activity of uterine contraction. Therefore, grading patients with different uterine contraction intensities by electromyography is of great significance to the clinical intensive management of uterine contraction and labor process.

OBJECTIVE

This study aimed to quantify and grade electromyography activity during the latent phase of the first stage of labor and explore its relationship with oxytocin treatment and length of labor.

STUDY DESIGN

We performed a retrospective cohort study to identify electromyography parameters as a predictor for oxytocin treatment and length of labor among a cohort of term singleton primipara (n=508) during the latent phase who delivered in Guangzhou between August 2018 and December 2021. The electromyography parameters were graded according to the quartile method, and the significance of grading and delivery outcome was explored. Univariate and multivariate logistic regression were used to determine the predictors of oxytocin treatment.

RESULTS

Maternal gestational age (adjusted risk ratio, 1.2; 95% confidence interval, 1.0-1.5), root mean square (adjusted risk ratio, 0.01; 95% confidence interval, 0.004-0.03), and power (adjusted risk ratio, 0.02; 95% confidence interval, 0.01-0.05) were significant predictors of oxytocin argumentation. The low electromyography activity group had a longer first stage labor and total labor time and were more likely to use oxytocin.

CONCLUSION

Electromyography parameters root mean square and power had high predictive values for later oxytocin treatment among patients with spontaneous labor. Patients with low-grade electromyography were more likely need oxytocin treatment. Electromyography grading is very important for its clinical promotion and use, and it could lead to more reliable analyses of oxytocin treatments and eventually to more effective interventions to prevent prolonged labor.

The Effect of Epidural Analgesia on Labour and Neonatal and Maternal Outcomes in 1, 2a, 3, and 4a Robson's Classes: A Propensity Score-Matched Analysis

Background: Lumbar epidural analgesia (EA) is the most commonly used method for reducing labour pain, but its impact on the duration of the second stage of labour and on neonatal and maternal outcomes remains a matter of debate. Our aim was to examine whether EA affected the course and the outcomes of labour among patients divided according to the Robson-10 group classification system. Methods: Patients of Robson’s classes 1, 2a, 3, and 4a were divided into either the EA group or the non-epidural analgesia (NEA) group. A propensity score-matching analysis was performed to balance the intergroup differences. The primary goal was to analyse the duration of the second stage of labour. The secondary goals were to evaluate neonatal and maternal outcomes. Results: In total, 21,808 cases were analysed. The second stage of labour for all groups was prolonged using EA (p < 0.05) without statistically significant differences in neonatal outcomes. EA resulted in a lower rate of episiotomies in nulliparous patients, with a higher rate of operative vaginal deliveries (OVD) (p < 0.05) and Caesarean sections (CS) (p < 0.05) in some classes. Conclusions: EA prolonged the duration of labour without affecting neonatal outcomes and reduced the rate of episiotomies, but also increased the rate of OVDs.

A study of uterine inertia on the spontaneous of labor using uterine electromyography

OBJECTIVE

The purpose of this study is to analyze uterine electromyography burst patterns in patients with spontaneous labor and patients with uterine inertia.

MATERIALS AND METHODS

Uterine electromyography was recorded using 4 silver/silver chloride electrodes placed periumbilical. Thirty women in the spontaneous labor were enrolled. Uterine electromyography was also recorded from patients with uterine inertia before and after oxytocin treatment. EMG bursts were characterized by analysis of multiple variables including burst frequency, duration, root mean squared, amplitude, and total power.

RESULTS

There were significant reductions (P < .01) in all EMG burst characteristics. In addition, uterine electromyography parameters were all increased after oxytocin treatment and were comparable (P > .05) to patients in spontaneous labor.

CONCLUSIONS

Uterine electromyography can be used effectively to distinguish patients progressing with spontaneous labor from patients that develop uterine inertia. Uterine inertia is characterized by reduced EMG activity and failure of cervical dilation. Uterine electromyography is a quantitative, non-invasive assessment tool that contributes to the diagnosis, evaluation and management of patients with spontaneous labor and uterine inertia.

Intrauterine contraction parameters at baseline and following epidural and combined spinal-epidural analgesia: A repeated measures comparison

OBJECTIVE

The effects of epidural and combined spinal-epidural analgesia on uterine contraction parameters are unclear, although as many as 80% of laboring women use neuraxial analgesia. We explored the effects of epidural and combined spinal-epidural analgesia on all uterine contraction parameters using a retrospective analysis of selected parturients, who required Intrauterine Pressure Catheter (IUPC) instrumentation for clinical management. Additionally, we analyzed the effects of parity, Pitocin dose, and mode of neuraxial anesthesia, i.e. epidural verses combined spinal-epidural on uterine contractility.

DESIGN

Using a retrospective within and between repeated measure design we compared uterine contraction parameters at 4 time points (epochs): (1) baseline, (2) pre-epidural fluid bolus, (3) immediate and (4) secondary post-epidural/combined spinal-epidural analgesia to detect differences in contractility over time comparing two types of epidural interventions.

METHODS

Eighteen healthy parturients at term gestation were admitted to the labor unit for induction, augmentation, or spontaneous labor. Contraction parameters including frequency, duration, peak intensity, resting intensity and duration, and Montevideo Units (MVUs) were collected using fetal monitor strip data with intrauterine pressure catheter (IUPC) instrumentation.

FINDINGS

Parametric and non-parametric tests showed no significant differences within or between the two Epidural intervention groups for frequency, duration, peak intensity, resting intensity and duration, and MVUs at all epochs at the .05 alpha level. Compared with Nulliparous women, multiparous women had significantly lower contraction intensity and longer contraction duration. Based on multilevel modeling (MLM), neither Pitocin dose nor type of epidural intervention revealed significant differences on any contraction parameters.

CONCLUSIONS

When parity, other demographic variables and Pitocin dose were statistically controlled, no uterine contraction parameter changed from baseline through 90 min following either epidural or combined spinal-epidural analgesia. Obstetrical care providers should consider the preciseness their contraction monitoring instrumentation and their clinical management preferences as well parity as before prescribing Pitocin after neuraxial analgesia intervention.

The effects of epidural analgesia using low-concentration local anesthetic during the entire labor on maternal and neonatal outcomes: a prospective group study

PURPOSE

The purpose of this study was to study the impact of epidural analgesia using low-concentration local anesthetic during the entire labor on maternal and neonatal outcomes.

METHODS

The authors enrolled 2310 parturient mothers who underwent vaginal delivery at their hospital since January 1, 2019. The parturients were allocated either into the analgesia or into the non-analgesia groups based on whether they received analgesia during the delivery process. To investigate the effects of epidural analgesia using low-concentration local anesthetic on maternal and neonatal outcomes, the authors assessed between-group differences in the labor duration, newborn Apgar score, and maternal and neonatal outcomes.

RESULTS

Compared to the non-analgesia group, the first and second labor stage durations in the analgesia group were significantly longer. Similarly, the analgesia group had a higher frequency of oxytocin injections, Category II and III fetal heart rate tracing during labor, and intrapartum fever development. Further, the need for episiotomy and assisted vaginal delivery was higher in the analgesia group than that in the non-analgesia group. Regarding neonatal outcomes, the neonatal hospitalization rate and incidence rate of umbilical cord blood pH < 7.2 were higher in the analgesia group than those in the non-analgesia group. However, there were no significant between-group differences in the incidence rates of stained amniotic fluid, mild neonatal asphyxia, and severe perinatal asphyxia.

CONCLUSION

Patient-controlled epidural analgesia using low-concentration local anesthetic during the entire labor did not increase the incidence rate of severe adverse outcomes in neonates born through vaginal delivery; however, it increased the delivery duration, and thus, the chance of possible perinatal interventions.

Dexmedetomidine versus sufentanil with high- or low-concentration ropivacaine for labor epidural analgesia: A randomized trial

AIM

To study analgesic effects of dexmedetomidine or sufentanil, both combined with ropivacaine, in epidural analgesia during labor.

METHODS

We recruited 160 primigravidae with full-term pregnancy who received epidural anesthesia during labor and randomized them into four groups to receive epidural administration of ropivacaine combined with sufentanil (RS₁ and RS₂ groups) or with dexmedetomidine (RD₁ and RD₂ groups). Systolic blood pressure, diastolic blood pressure and heart rate before anesthesia (T₁ ), 15 min after anesthesia induction (T₂ ), on delivery (T₃ ) and 2 h postpartum (T₄ ), together with visual analogue scale scores, Bromage scores, Ramsay scores, adverse reactions during analgesia and urinary retention at 6 and 24 h postpartum were recorded; the pH, PCO₂ and PO₂ of umbilical cord arterial blood and Apgar scores at 1, 5 and 10 min after childbirth were assessed.

RESULTS

RS₁ group had significantly lower systolic blood pressure, diastolic blood pressure and heart rate than RD₁ group at T₂ and T₃ (all P < 0.05), but not at T1. At T₂ and T₃ , the other three groups were lower than RS₂ group in visual analogue scale and Ramsay scores (all P < 0.05). After childbirth, RD₂ group had significantly higher PO₂ result than other three groups (P < 0.05). At 6 h postpartum, RD₂ group had significantly fewer cases of urinary retention than RD₁ and RS₁ groups (both P < 0.05).

CONCLUSION

A relatively low concentration of ropivacaine, combined with dexmedetomidine, is better in analgesia during labor.

Potential use of electrohysterography in obstetrics: a review article

Monitoring the uterine contraction during pregnancy is necessary to monitor labor progress, fetal and maternal well-being, and uterine activity. The aim of this review was to evaluate the performance of electrohysterography and to analyze the nature of uterine contraction. A search was undertaken using PubMed, Embase, and ClinicalTrials.gov database from 1 January 1950 to 1 November 2018. Search terms include: "Uterine" or "Uterus" or "Labor" or "Labour" and "electrical activity" or "electrohysterogram" or "electrohysterograph". Reviewing the literature, electrohysterography showed a higher sensitivity for uterine contraction detection and was independent of body mass index, abdominal wall thickness, or maternal position enabling monitoring obese patients as well. Electrohysterography can enhance uterine monitoring throughout labor because of its noninvasiveness, adhesive properties, and reduced obesity sensitiveness. Electrohysterography should be available to safely improve intrapartum monitoring instead of the invasive intrauterine pressure catheter.

Factors that affect ultrasound-determined labor progress in women undergoing induction of labor

BACKGROUND

The traditional approach to the assessment of labor progress is by digital vaginal examination; however, it is subjective and imprecise. Recent studies have investigated the role of transperineal ultrasonographic assessment of fetal head descent by measuring the angle of progression and head-perineum distance.

OBJECTIVE

The objective of this study was to evaluate factors that affected labor progress, which were defined by the transperineal ultrasonographic parameters, in women who achieved vaginal delivery.

STUDY DESIGN

This was a prospective longitudinal study performed in 315 women with singleton pregnancy who underwent labor induction at term between December 2016 and December 2017. Paired assessment of cervical dilation and fetal head station by vaginal examination and transperineal ultrasonographic assessment of fetal head descent (parasagittal angle of progression and head-perineum distance) were made serially after the commencement of labor induction until full cervical dilation. The researchers were blinded to the findings of the clinical team's vaginal examination and vice versa. The repeated measure data were analyzed by mixed effect models to identify the significant factors (age ≥35 years, obesity, parity, methods of labor induction, and epidural anesthesia) that affected the relationship between parasagittal angle of progression and head-perineum distance against fetal head station and cervical dilation.

RESULTS

The total number of paired vaginal examination and transperineal ultrasonographic assessments among the 261 women (82.9%) with vaginal delivery was 945, with a median of 3 per woman. The median assessment-to-assessment interval was 4.6 hours (interquartile range, 4.3-5.2). Multiparity and mechanical methods of labor induction were associated with a faster rate of fetal head descent, which was determined by head-perineum distance against fetal head station, than nulliparity and the use of a slow-release vaginal pessary, respectively. An additional increase of 0.10 cm in head-perineum distance was observed, for an unit increase in fetal head station in nulliparous women (P=.03) and women who had a slow-release vaginal pessary (P=.02), compared with multiparous women and those who had mechanical methods for labor induction. The use of epidural anesthesia was associated with a slower rate of fetal head descent, which was determined by both parasagittal angle of progression and head-perineum distance, against fetal head station. An additional decrease of 3.66 degrees in parasagittal angle of progression (P=.04) and an additional increase in 0.33 cm in head-perineum distance (P≤.001) were observed for a unit increase in fetal head station in women with the use of epidural anesthesia, compared with those without. Obese women had higher head-perineum distance overall, compared with normal weight women; at different cross-sections of time periods, obesity appeared to be associated with a slower rate of change between head-perineum distance and cervical dilation. Advanced maternal age did not affect transperineal ultrasound-determined labor progress (P>.05).

CONCLUSION

Parity, methods of labor induction, the use of epidural anesthesia, and obesity affect labor progress, which has been illustrated objectively by serial transperineal ultrasonographic assessment of fetal head descent.

The impact of epidural analgesia on the duration of the second stage of labor

BACKGROUND

We aimed to describe the length of second stage of labor in a contemporary cohort. We calculated the 5th, 50th, and 95th percentiles for second-stage length stratified by parity and epidural analgesia use and evaluated the effect of labor induction and oxytocin augmentation in our cohort.

METHODS

We did a retrospective analysis of all live, singleton, term vaginal deliveries in one tertiary hospital. Multivariate linear regression was used to evaluate second-stage duration confounders. First, we calculated the second-stage length and presented it as 5th, 50th, and 95th percentiles stratified by epidural analgesia and parity. Second, we evaluated the effect of labor induction and oxytocin augmentation on second-stage length, and third, we determined the demographic and obstetrical confounders that affected second-stage length.

RESULTS

Overall, 15 500 deliveries were included. Nulliparity, oxytocin augmentation, epidural use, birthweight, labor induction, lower body mass index, and higher maternal age were found to be significantly associated with prolongation of the second stage. Epidural use was associated with an additional 82 minutes for the 95th percentile for both nulliparas and multiparas and tripled the rate of prolonged second stage for the entire cohort. Labor induction was associated with clinically significant prolongation of the second stage in nulliparas with epidural analgesia only. Oxytocin was associated with longer duration of the second stage for nulliparas, regardless of epidural use.

DISCUSSION

Our findings suggest a significant prolongation of the second stage in women receiving epidural analgesia. Recommendations for management of second stage should be reconsidered by contemporary data.

Effects of Ropivacaine in Patient-Controlled Epidural Analgesia on Uterine Electromyographic Activities during Labor

Epidural analgesia is effective in relieving pain during labor. However, concerns as to compromised labor progress and outcomes arise. This study aimed to assess the effect of patient-controlled epidural analgesia (PCEA) with ropivacaine on uterine electromyography (EMG) activities and outcomes in labor. A total of 213 pregnant women were divided into three groups: the PCEA with ropivacaine group (n = 78), the PCEA with levobupivacaine group (n = 66), and a control group that did not receive PCEA (n = 69). Uterine EMG activities were recorded during the first stage of labor. Maternal and fetal outcomes also were assessed. The primary outcomes of this study were EMG activities. No significant differences were observed in patient demographics or neonatal weight among the three groups. Compared to the PCEA with levobupivacaine group, the control and PCEA with ropivacaine groups had lower rates of oxytocin administration (P < 0.05) and shorter durations of the first stage of labor (P < 0.05). For the EMG activities, the PCEA with ropivacaine group showed a higher power (P < 0.01) and higher peak frequency (P < 0.05) than the PCEA with levobupivacaine group. With ropivacaine, the EMG activities remained stable 30–120 min. Compared with levobupivacaine, the use of ropivacaine in PCEA has no suppressive effect on uterine EMG activities during the first stage of labor. In addition, ropivacaine leads to labor progress and delivery outcomes similar to those in the control group, as well as similar and favorable analgesic satisfaction with the use of levobupivacaine.

Clinical Use of Electrohysterography During Term Labor: A Systematic Review on Diagnostic Value, Advantages, and Limitations

Importance

Real-time electrohysterography (EHG)-based technologies have recently become available for uterine monitoring during term labor. Therefore, obstetricians need to be familiar with the diagnostic value, advantages, and limitations of using EHG.

Objective

The aims of this study were to determine the diagnostic value of EHG in comparison to (1) the intrauterine pressure catheter (IUPC), (2) the external tocodynamometer (TOCO), and (3) in case of maternal obesity; (4) to evaluate EHG from users' and patients' perspectives; and (5) to assess whether EHG can predict labor outcome.

Evidence Acquisition

A systematic review was performed in the MEDLINE, EMBASE, and Cochrane library in October 2017 resulting in 209 eligible records, of which 20 were included.

Results

A high sensitivity for contraction detection was achieved by EHG (range, 86.0%-98.0%), which was significantly better than TOCO (range, 46.0%-73.6%). Electrohysterography also enhanced external monitoring in case of maternal obesity. The contraction frequency detected by EHG was on average 0.3 to 0.9 per 10 minutes higher compared with IUPC, which resulted in a positive predictive value of 78.7% to 92.0%. When comparing EHG tocograms with IUPC traces, an underestimation of the amplitude existed despite that patient-specific EHG amplitudes have been mitigated by amplitude normalization. Obstetricians evaluated EHG tocograms as better interpretable and more adequate than TOCO. Finally, potential EHG parameters that could predict a vaginal delivery were a predominant fundal direction and a lower peak frequency.

Conclusions and Relevance

Electrohysterography enhances external uterine monitoring of both nonobese and obese women. Obstetricians consider EHG as better interpretable; however, they need to be aware of the higher contraction frequency detected by EHG and of the amplitude mismatch with intrauterine pressure measurements.

Effects of combined spinal-epidural analgesia on first stage of labor: a cohort study

Background: Neuraxial anesthesia is considered as the gold standard in the control labor of pain. Its variants are epidural analgesia and combined spinal-epidural analgesia. Few studies, as yet, have investigated the duration of labor as a primary outcome. Some authors have suggested that combined spinal-epidural analgesia may reduce labor duration but at the moment the benefit of shortening labor is uncertain. The main aim of this study was to compare combined spinal-epidural with epidural analgesia in terms of their effect on duration of stage I labor, maternal, and neonatal outcomes. Methods: A prospective cohort study was conducted. Parturients who requested analgesia at cervical dilatation <6 cm were included. Analgesia was either epidural with low concentration levobupivacaine or combined spinal epidural with subarachnoid sufentanil. The primary outcome was the length of stage I labor. Onset and quality of analgesia, mode of delivery, effects on uterine activity and use of oxytocin, fetal heart rate abnormalities and uterine hyperkinesia, maternal, and neonatal complications were also considered. Results: We enrolled 400 patients: 176 in the combined spinal-epidural group and 224 in the epidural group. Patients in the two treatment groups were similar with regard to demographic characteristics, parity, and incidence of obstetric comorbidities, labor induction, oxytocin infusion, Bishop score, and Visual Analogue Score (VAS) at analgesia request. Duration of stage I labor did not differ, at 195 (120-300) minutes for both the groups (p = .7). Combined spinal-epidural was associated with less reduction in uterine contractility after initial administration: 15.34 versus 39.73%, (p < .001) and with delayed need for oxytocin, at dilations of 7 ± 2.5 cm versus 6. ± 2.7, (p = .002). Onset of analgesia was quicker for combined spinal-epidural analgesia: 31 versus 20%, with VAS <4 after 5 minutes, (p < .001); and lower VAS scores after initial analgesia administration. No differences were found in the other outcomes. Conclusions: Combined spinal-epidural with subarachnoid sufentanil may not reduce the duration of stage I labor, but in our study it appeared to affect uterine contractility less. It also had a more rapid onset and was more effective, without any concomitant increase in maternal or neonatal complications.

Uterine and Abdominal Muscle Electromyographic Activities in Control and PCEA-Treated Nulliparous Women During the Second Stage of Labor

OBJECTIVE

Patient-controlled epidural analgesia (PCEA), used to relieve pain during delivery, delays labor but the mechanism is unknown. The aim was to investigate the effects of PCEA on uterine and abdominal muscles electromyographic (EMG) activity during the second stage of labor.

METHODS

This study included 45 nulliparous pregnant women without PCEA, 42 women with standard PCEA treatment given during the first stage of labor and stopped near the end of the first stage, and 22 women with standard PCEA treatment with continued use throughout the first and second stages of labor. The EMG signals were recorded from the abdominal surface using PowerLab hardware and LabChart software (ADInstruments, New South Wales, Australia) and filtered to separate uterine and abdominal EMG. Various EMG burst parameters were obtained.

RESULTS

There are no differences ( P > .05) in the age, body mass index, fetal weight, and Apgar scores between the patients from the various groups. PCEA (both stopped and continued) inhibits ( P < .05) duration, number of bursts, and root mean square of uterine EMG. PCEA also produces statistically significant ( P < .001) reductions in abdominal EMG. The decrease in EMG activity is accompanied by a significant ( P < .001) prolongation of the second stage duration (PCEA continued = 95.08 ± 8.60 minutes, PCEA stopped = 79.39 ± 6.25 minutes, no PCEA = 61.00 ± 7.23 minutes).

CONCLUSION

PCEA suppresses uterine and abdominal muscle EMG during the second stage of labor but inhibition depends upon the treatment schedule. PCEA prolongs the duration of labor by inhibition of uterine and abdominal muscle and neural activity.