Association of epidural analgesia with cesarean delivery in nulliparas

Epidural analgesia: effects on labor progress and maternal and neonatal outcome

The intended and unintended effects of epidural labor analgesia are reviewed. Mothers randomized to epidural rather than parenteral opioid analgesia have better pain relief. Fetal oxygenation is not affected by analgesic method; however, neonates whose mothers received intravenous or intramuscular opioids rather than epidural analgesia require more naloxone and have lower Apgar scores. Epidural analgesia does not affect the rates of cesarean delivery, obstetrically indicated instrumented vaginal delivery, neonatal sepsis, or new-onset back pain. Epidural analgesia is associated with longer second labor stages, more frequent oxytocin augmentation, and maternal fever (particularly among women who shiver and women receiving epidural analgesia for > 5 hours) but not with longer first labor stages. Epidural analgesia has no affect but intrapartum opioids decrease lactation success. Epidural use and urinary incontinence are weakly, but probably not causally, associated. Epidural labor analgesia would improve if the mechanisms of these unintended effects could be determined.

Economic considerations related to providing adequate pain relief for women in labour: comparison of epidural and intravenous analgesia

Epidural analgesia and intravenous analgesia with opioids are two techniques for providing pain relief for women in labour. Labour pain is comparable to surgical pain in its severity, and epidural analgesia provides better relief from this pain than intravenous analgesia; a meta-analysis quantified this improvement to be 40 mm on a 100mm pain scale during the first stage of labour. Epidural analgesia also has fewer adverse effects. However, providing epidural analgesia for labour pain costs more. The full cost of providing epidural analgesia can be divided into two components: a baseline-cost component, which captures the costs of hospital care to parturients receiving intravenous analgesia for labour pain; and an incremental-cost component, which estimates the costs arising from incremental care specific to epidural analgesia. The baseline component may be constructed using hospital cost-accounting data pertaining to actual obstetric patients. The incremental component is constructed from a set of recognised complications of epidural and intravenous analgesia, associated incidence rates and estimates of the costs involved, from society's perspective. The incremental expected cost per patient to society of providing epidural analgesia was calculated to be approximately $US338 (1998 values). This cost difference results primarily from increased professional costs (and is particularly sensitive to the method used to estimate the cost of anaesthesia professional services) and increased complication costs associated with epidural analgesia. A rational social policy for providing labour analgesia must weigh the value of improved pain relief from epidural analgesia against the increased cost of epidural analgesia.

Reduced disability at five years with early treatment of inflammatory polyarthritis: results from a large observational cohort, using propensity models to adjust for disease severity

OBJECTIVE

To determine the effect of treatment with disease-modifying antirheumatic drugs (DMARDs) and/or steroids on 5-year disability outcome in patients with inflammatory polyarthritis.

METHODS

Three hundred eighty-four patients registered by the Norfolk Arthritis Register (a primary care-based observational cohort) were followed up for 5 years. Treatment details and Health Assessment Questionnaire (HAQ) scores were recorded annually. Logistic regression was used to model differences in baseline factors associated with the start of DMARDs and/or steroids within 12 months of baseline. Based on this model, each subject was given a probability of starting treatment ("propensity score"). A second model compared the odds of disability (HAQ score > or =1.00) in treated and untreated patients, adjusting for differences in disease severity using the propensity score.

RESULTS

Unadjusted analysis suggested that patients who received treatment had an increased odds of a worse outcome compared with those who did not receive treatment. When adjusted for differences in disease severity, using the propensity score, early treatment (within 6 months of symptom onset) was associated with a similar odds of disability at 5 years compared with those not treated (odds ratio 0.71; 95% confidence interval 0.34, 1.44). In contrast, starting treatment later (> or =6 months) was associated with a 2-fold increased odds of having a HAQ score > or =1.00 at 5 years.

CONCLUSION

The propensity score was a useful method of adjusting for "confounding by indication" in observational studies. Furthermore, this study showed that early treatment with DMARDs/steroids (within 6 months of symptom onset) reduced the odds of disability 5 years later to a level comparable with that of patients judged clinically as not requiring treatment.

Intensity of Labor Pain and Cesarean Delivery

Some authors have suggested that the intensity of labor pain may be related to labor dystocia. We performed a secondary analysis of a previously published randomized investigation of the effects of epidural analgesia during labor compared with patient-controlled IV meperidine on cesarean delivery. Two-hundred-fifty-nine women who received patient-controlled IV meperidine were identified for analysis. All women were in spontaneous labor with a singleton, term gestation. Women requiring 50 mg or more of meperidine per hour during labor were compared with those who required <50 mg/h. In addition, their pain scores (visual analog scale) were compared before and after analgesia administration. Pain scores were significantly higher in women requiring 50 mg/h of meperidine (8.7 vs 8.0, P = 0.05), and their labors tended to be longer (9 vs 5 h, P = 0.09). More cesarean deliveries for obstructed labor were performed in women requiring >50 mg/h of meperidine (14% vs 1.4%, P = 0.001). Neonatal outcomes were similar in the two groups.

Labor epidurals improve outcomes for babies of mothers at high risk for unscheduled cesarean section

CONTEXT

Epidural placement for labor in the general population of laboring women is associated with increased incidence of operative deliveries, prolongation of labor, and may be associated with an increased cesarean section rate. The risks and benefits associated with epidural placement for labor in the subpopulation of mothers at high risk for cesarean section have not been studied.

OBJECTIVE

To determine if a population of mothers and babies at high risk for cesarean section will have improved outcomes with labor epidural placement.

DESIGN

A decision and cost analysis examining epidural placement for labor on a population of women who are at high risk for unscheduled cesarean section and may benefit from scheduled cesarean section as determined by threshold analysis was performed. Outcomes and probabilities were determined through analysis of the Department of Defense's 1996 National Quality Management Program (NQMP) Birth Product Line data set containing more than 7000 deliveries. Outcomes were defined using variables comprised of all documented conditions that occurred during the peripartum and neonatal hospitalizations. The 1997 NQMP data set was used to validate the results.

SETTING

Military Treatment Facilities throughout the United States and abroad and civilian facilities in the United States providing care to military dependents.

PATIENT POPULATION

Active duty and dependent pregnant women and babies.

RESULTS

About 8% of mothers in this patient population were found to be at high risk for cesarean section. The decision and cost analyses showed that babies of the high risk mothers who received epidurals for labor had better clinical outcomes (p<0.05) and the procedure was cost neutral (p=0.23). The procedure did not increase the frequency of cesarean section, and there was no effect on maternal outcomes scores. These results were confirmed by the validation study.

CONCLUSIONS

There is a sizable subpopulation of women at high risk for cesarean section whose babies may have better outcomes with epidural placement with no sacrifice in maternal outcomes or costs.

Validating recommendations for coronary angiography following acute myocardial infarction in the elderly: a matched analysis using propensity scores

We determined whether adherence to recommendations for coronary angiography more than 12 h after symptom onset but prior to hospital discharge after acute myocardial infarction (AMI) resulted in better survival. Using propensity scores, we created a matched retrospective sample of 19,568 Medicare patients hospitalized with AMI during 1994-1995 in the United States. Twenty-nine percent, 36%, and 34% of patients were judged necessary, appropriate, or uncertain, respectively, for angiography while 60% of those judged necessary received the procedure during the hospitalization. The 3-year survival benefit was largest for patients rated necessary [mean survival difference (95% CI): 17.6% (15.1, 20.1)] and smallest for those rated uncertain [8.8% (6.8, 10.7)]. Angiography recommendations appear to select patients who are likely to benefit from the procedure and the consequent interventions. Because of the magnitude of the benefit and of the number of patients involved, steps should be taken to replicate these findings.

The effect of the obstetrician group and epidural analgesia on the risk for cesarean delivery in nulliparous women

BACKGROUND

The effects of regional anesthesia and of the obstetrician on the risk of cesarean delivery remain controversial. The purpose of this study was to determine whether epidural analgesia or the obstetrician group is associated with an increase in the risk for cesarean delivery in nulliparous women.

METHODS

Data were collected for a two-year period from the medical records of all nulliparous women who had a private obstetrician who delivered >20 babies per year, and who presented with a singleton gestation in the vertex presentation for a trial of labor.

RESULTS

Data were collected for 3699 women of whom 1832 were nulliparous. Of the 1832 nulliparous women, data were analyzed for the 1278 women who met our study criteria, representing 14 separate obstetrician groups. Excluding the 50 women whose babies were delivered for fetal distress (leaving 1228 women for analysis), the epidural rate was 93%, range 81-98%, and the cesarean delivery rate was 14%, range 8-34%. Logistic regression analyses revealed that (odds ratio, 95% confidence interval) patient age (1.7, 1.2-2.4), birth weight (1.001, 1.001-1.002), induction of labor (1.9, 1.3-2.7), non-Caucasian (1.9, 1.2-2.9) and the obstetrician group, (P=0.002), were independently associated with the risk of cesarean delivery, but epidural analgesia was not (1.6, 0.7-3.6).

CONCLUSIONS

The obstetrician group is independently associated with the risk of cesarean delivery in nulliparous women, but we could not demonstrate this association with epidural analgesia. We suggest that in future studies regarding epidural analgesia and cesarean delivery, the obstetrician group should be included as a variable.

Evidence-based care and the breastfeeding couple: key concerns

Optimal health care is based on evidence that a) no harm is done when that care is provided and that b) the care provided assists in the prevention of further problems or the resolution of the presenting problem. Too often, care provided to lactating mothers and their breastfeeding offspring lacks evidence supportive of the techniques used or care provided. This article addresses 10 common hospital-based practices and reviews documented evidence related to their effect on breastfeeding success. Concepts pertaining to the breasts and breastfeeding that require incorporation into the educational offerings of current and future health care providers are also identified.

An association between severe labor pain and cesarean delivery

The relationship between epidural analgesia and cesarean delivery remains controversial. Several studies have documented an association, although others have not. This inconsistency may result from an association between severe labor pain and dystocia. We hypothesized that dystocia causes severe labor pain, such that more epidural medication is required to maintain comfort. We examined the relationship between labor outcome and severe pain, defined by the number of supplemental epidural boluses. We retrospectively reviewed the anesthesia records of 4493 parturients who received small-dose labor epidural analgesia. An independent association was found between operative delivery and maternal age, body mass index, nulliparity, fetal weight, induction of labor, and the number of boluses required during labor. By using multivariate analysis, the odds ratio of cesarean delivery among women who required at least three boluses was 2.3 compared with those who required two boluses or less. No association was found between the concentration of bupivacaine in the epidural infusion and operative delivery. Because women with cesarean deliveries appeared to have more pain, degree of labor pain may be a confounding factor in studies examining epidural analgesia and outcome.

IMPLICATIONS

This is a retrospective observational study demonstrating an association between labor pain and cesarean delivery. Our results provide an alternative explanation of why epidural analgesia is associated with cesarean delivery.

Obstetric analgesia

Several analgesic options are available for patients during labor. Selection of the appropriate technique must be individualized. Education and preparation begins during prenatal care. If medications are to be used, the risks and benefits to the mother and infant must be considered. Continued patient-doctor communication throughout labor is essential. Patient preferences, tempered by sound medical judgement, should guide the selection of the optimal modality for pain control during labor.

Epidural analgesia need not increase operative delivery rates

OBJECTIVE

We sought to examine the relationship between epidural analgesia and cesarean and instrumental vaginal delivery rates.

STUDY DESIGN

This is a retrospective analysis of the first 1000 nulliparous pregnancies in women with a cephalic presentation in spontaneous labor at term in each of 3 different years, over which the epidural rate increased from 10% to 57%.

RESULTS

Cesarean and instrumental vaginal delivery rates were similar in all 3 years. Demographic characteristics remained unchanged or altered in a manner that has previously been associated with an increase in intervention. Electronic fetal monitoring and first-stage oxytocin use remained unchanged, but oxytocin use in the second stage increased considerably.

CONCLUSIONS

Increased use of epidural analgesia had no effect on cesarean delivery rates. Although randomized trials have suggested that it increases instrumental vaginal delivery rates, this might be overcome by active management of labor or judicious use of oxytocin in the second stage.

Factors predicting cesarean delivery for American Indian women in New Mexico

BACKGROUND

American Indian women have one of the lowest cesarean delivery rates among all ethnic groups evaluated in the United States. Our objective was to identify risk factors for cesarean delivery among American Indian women in New Mexico.

METHODS

Live birth certificate data (1994) from the New Mexico Bureau of Vital Records and Health statistics were used to compare American Indian women who had a cesarean delivery with those who had a vaginal delivery. We examined demographic, prenatal, and intrapartum factors to determine risk factors for cesarean delivery.

RESULTS

In 1994 American Indian women in New Mexico had a cesarean delivery rate of 12 percent. Risk factors for cesarean delivery included age equal to or over 35 years (OR = 1.8, 1.3-2.5) and nulliparity (OR = 1.9, 1.5-2.5). Obstetric risk factors included prematurity (OR = 2.3, 1.5-3.6), low birthweight (OR = 2.6, 1.7-4.2), diabetes (OR = 1.7, 1.1-2.5), pregnancy-induced hypertension (OR = 2.6, 1.8-3.8), and labor and delivery complications (OR = 9.5, 7.5-12.1). Age less than 20 years was negatively associated with cesarean delivery (OR = 0.5, 0.3-0.7).

CONCLUSION

American Indian women have risk factors for cesarean delivery that are similar to those reported in other populations. Future prospective research evaluating intrapartum management may help identify reasons for the low cesarean birth rate.

Nulliparas' preferences for epidural analgesia: their effects on actual use in labor

BACKGROUND

Few studies have directly examined the reasons for choices of pain relief during labor. The purpose of this study was to investigate if women's preferences for epidural analgesia in labor have an impact on the use of intrapartum epidural analgesia.

METHODS

Nulliparous women attending childbirth classes completed questionnaires about their antenatal preferences for the use of intrapartum epidural analgesia. Data on actual use of analgesia was obtained by chart review. The analysis included 303 women with either spontaneous or induced labor at term.

RESULTS

The 185 women who planned to receive epidural analgesia had a markedly higher rate of epidural use (91%) than the 110 women who hoped to avoid it (57%) (p = 0.001). Of 237 epidurals administered, 169 (71%) were planned during the antenatal period. Among women receiving epidural analgesia, those planning to receive it tended to have more frequent early administration (< or = 3 cm cervical dilation) than women who unsuccessfully tried to avoid epidural use (54% vs. 24%, p = 0.003).

CONCLUSION

In our population of nulliparas, a woman's antenatal plan to receive epidural analgesia is strongly associated with her likelihood of receiving it. Women who plan to receive epidural analgesia have earlier administration.

Active management of labor

The active management of labor may be one approach to achieving lower rates of intervention. Numerous institutions have reported lower CS rates since initiating this labor management scheme, and concurrent decreases in the length of labor and infectious morbidity have been demonstrated. Sufficient data now exist to conclude that such programs can be instituted without deleterious effects on neonatal outcomes. Nevertheless, success in decreasing CS rates has not been uniform and may be confined to certain settings. Other approaches to labor management may be as good or better at achieving low rates of intervention with minimum morbidity. Any approach that emphasizes advocacy for vaginal birth is likely to produce some success and should receive support.

Epidural analgesia in association with duration of labor and mode of delivery: a quantitative review

OBJECTIVE

This study was undertaken to quantitatively summarize previous literature on the effects of epidural analgesia in labor on the duration of labor and mode of delivery.

STUDY DESIGN

Original studies published in English from 1965 through December 1997 were reviewed and assigned a quality score independently by 2 of the authors. Studies that met the minimal requirements were evaluated further. Data syntheses were performed separately according to study design and outcome measurements, including cesarean delivery, instrumental delivery, oxytocin augmentation, and durations of the first and second stages of labor.

RESULTS

Seven randomized clinical trials and 5 observational studies met the minimal requirements. Among them 4 studies of each sort were included in the data synthesis. Both types of studies showed that epidural analgesia increased risk of oxytocin augmentation 2-fold. Clinical trials suggested that epidural analgesia did not increase the risk of cesarean delivery either overall or for dystocia, nor did it significantly increase the risk of instrumental vaginal delivery; however, observational studies reported a more than 4-fold increased risk of cesarean and instrumental deliveries. Although most studies showed a longer labor among women with epidural analgesia than without it, especially during the second stage, most of the studies used inappropriate statistical analysis.

CONCLUSION

Epidural analgesia with low-dose bupivacaine may increase the risk of oxytocin augmentation but not that of cesarean delivery.

Maternal intrapartum temperature elevation as a risk factor for cesarean delivery and assisted vaginal delivery

OBJECTIVES

This study investigated the association of intrapartum temperature elevation with cesarean delivery and assisted vaginal delivery.

METHODS

Participants were 1233 nulliparous women with singleton, term pregnancies in vertex presentations who had spontaneous labors and were afebrile (temperature: 99.5 degrees F [37.5 degrees C]) at admission for delivery. Rates of cesarean and assisted vaginal deliveries according to highest intrapartum temperature were examined by epidural status.

RESULTS

Women with maximum intrapartum temperatures higher than 99.5 degrees F were 3 times as likely to experience cesarean (25.2% vs 7.2%) or assisted vaginal delivery (25.2% vs 8.5%). The association was present in epidural users and nonusers and persisted after birthweight, epidural use, and labor length had been controlled. In adjusted analyses, temperature elevation was associated with a doubling in the risk of cesarean delivery (odds ratio [OR] = 2.3, 95% confidence interval [CI] = 1.5, 3.4) and assisted vaginal delivery (OR = 2.1, 95% CI = 1.4, 3.1).

CONCLUSIONS

Modest temperature elevation developing during labor was associated with higher rates of cesarean and assisted vaginal deliveries. More frequent temperature elevation among women with epidural analgesia may explain in part the higher rates of cesarean and assisted vaginal deliveries observed with epidural use.

Observations on labor epidural analgesia and operative delivery rates

OBJECTIVE

Our purpose was to compare operative vaginal and abdominal delivery rates in a large population before and after on-demand labor epidural analgesia became available.

STUDY DESIGN

We retrospectively compared patients who gave birth during a 20-month period immediately before the introduction of an on-demand labor epidural analgesia service with those who gave birth during a 20-month period after the epidural usage rate had reached a plateau at approximately 60%. Operative vaginal and cesarean delivery rates were stratified according to parity and history of prior cesarean delivery.

RESULTS

A total of 4859 women gave birth during the study period when on-demand epidural analgesia was available, and 4778 women gave birth in the study period before the availability of on-demand epidural analgesia. Comparisons between the women with and those without on-demand availability of epidural analgesia demonstrated no statistically significant differences in the rate of spontaneous vaginal delivery (69.5% vs 68.3%), the overall cesarean delivery rate (19.0% vs 19.4%), the primary cesarean delivery rate (13.2% vs 13.4%), or the operative vaginal delivery rate (11.1% vs 11.9%) between the 2 periods. There were no statistically significant differences in mean gestational age at the time of delivery between the 2 groups, whereas there were statistically significant increases in the proportion of nulliparous women and in mean birth weight during the on-demand epidural period. Analysis after substratification of the study groups according to parity also revealed no statistically significant differences in the primary cesarean delivery rate or the proportion of women undergoing vaginal delivery. The sample size was adequate to exclude a 2% increase in the primary cesarean delivery rate between the 2 periods with 80% power. Subgroup analysis of the population of women who gave birth while epidural analgesia was available on request demonstrated that nulliparous parturient women who requested epidural analgesia were almost twice as likely to require operative vaginal or cesarean delivery as women who did not request epidural analgesia, a finding suggesting that women who request labor epidural analgesia have an inherent propensity toward operative delivery.

CONCLUSION

The introduction of an on-demand labor epidural analgesia service does not increase the rate of cesarean delivery or operative vaginal delivery.

The effects of epidural analgesia on the course and outcome of labour

The potential effects of epidural analgesia on the progress and outcome of labour have been the subject of lasting controversy. Retrospective reviews indicate that epidurals are associated with longer labours and/or an increase in the incidence of instrumental or operative delivery. Similar results were obtained in non-randomized prospective studies. None of them established a causal relationship, because without randomization the selection bias cannot be ruled out. Other factors, such as premature rupture of membranes and maternal socioeconomic status, may affect the outcome of labour. It was also reported that introduction of the on-demand epidural service did not increase the primary caesarean section rate. The few prospective randomized studies are contradictory and not very reliable owing to small patient populations and high cross-over rates. There is, however, unanimity among the authors regarding the superiority of pain relief provided by epidural blocks over systemically administered opioids.

Epidural labor analgesia and the incidence of cesarean delivery for dystocia

We performed this retrospective study to examine the changes in cesarean delivery rates associated with the establishment of a labor epidural service. In April 1993, St. Louis Regional Medical Center established an on-demand labor epidural service. We obtained demographic data for all patients and reviewed the operative records of all patients undergoing cesarean section who delivered 12 mo before and 16 mo after the start of the labor epidural service. We compared labor epidural rates and total and nulliparous dystocia cesarean delivery rates before and after the epidural service started and among patients who did and did not receive labor epidural analgesia when it was available. Included were 3195 patients who delivered before and 3733 patients who delivered after epidural analgesia became available. Labor epidural rates were 1.2% vs 29.4% for the Before group versus the After group (P < 0.001). Total (9.1% vs 9.7%) and nulliparous dystocia (5.7% vs 6.4%) cesarean delivery rates did not significantly change with the availability of epidural analgesia. However, the total (11.6% vs 8.8%; P = 0.009) and dystocia (8.0% vs 1.0%; P = 0.001) cesarean delivery rates were higher among patients who received epidural analgesia when it was available. We conclude that epidural labor analgesia is associated with, but does not cause, cesarean delivery for dystocia.

IMPLICATIONS

Increased epidural analgesia use did not change the overall dystocia cesarean delivery rate, although dystocia was more common among women who chose an epidural analgesia. Consequently, limiting epidural availability will not affect cesarean delivery rates. The evidence does not support advising patients that epidural labor analgesia increases the risk of cesarean delivery.

Epidural analgesia compared with combined spinal-epidural analgesia during labor in nulliparous women

BACKGROUND

Among nulliparous women, there appears to be an association between the use of epidural analgesia during labor and an increased risk of dystocia. We tested the hypothesis that combined spinal-epidural analgesia, which permits ambulation during labor, is associated with a lower incidence of dystocia than continuous lumbar epidural analgesia.

METHODS

Between July 1995 and September 1996, we randomly assigned 761 nulliparous women in spontaneous labor at term who requested epidural analgesia to receive either continuous lumbar epidural analgesia or a combination of spinal and epidural analgesia. Among the women who received combined spinal-epidural analgesia, some were discouraged from walking and others were encouraged to walk. Maternal and neonatal outcomes, the incidence of dystocia necessitating cesarean section, and measures of patients' satisfaction were compared in the two groups.

RESULTS

There were no significant differences in the overall rate of cesarean section, the incidence of dystocia, the frequency of maternal or fetal complications, the patients' or nursing staff's assessment of the adequacy of analgesia, or the degree of overall satisfaction between the two groups. Significantly more women receiving combined spinal-epidural analgesia had pruritus (P<0.001) and requested additional epidural bolus doses of local anesthetic (P=0.01). For all the women, dystocia necessitating cesarean section was significantly more likely when analgesia was administered with the fetal vertex at a negative station (odds ratio, 2.5; P<0.001) or at less than 4 cm of cervical dilatation (odds ratio, 2.2; P<0.001).

CONCLUSIONS

As compared with continuous lumbar epidural analgesia, the combination of spinal and epidural analgesia is not associated with an overall decrease in the incidence of cesarean delivery.

Nulliparous active labor, epidural analgesia, and cesarean delivery for dystocia

OBJECTIVE

Our purpose was to examine the effect of epidural analgesia on dystocia-related cesarean delivery in actively laboring nulliparous women.

STUDY DESIGN

Active labor was confirmed in nulliparous women by uterine contractions, cervical dilatation of 4 cm, effacement of 80%, and fetopelvic engagement. Patients were randomized to one of two groups: epidural analgesia or narcotics. A strict protocol for labor management was in place. Patients recorded the level of pain at randomization and at hourly intervals on a visual analog scale. Elective outlet operative vaginal delivery was permitted.

RESULTS

One hundred women were randomized. No difference in the rate of cesarean delivery for dystocia was noted between the groups (epidural 8%, narcotic 6%; p = 0.71). No significant differences were noted in the lengths of the first (p = 0.54) or second (p = 0.55) stages of labor or in any other time variable. Women with epidural analgesia underwent operative vaginal delivery more frequently (p = 0.004). Pain scores were equivalent at randomization, but large differences existed at each hour thereafter. The number of patients randomized did not achieve prestudy estimates. A planned interim analysis of the results demonstrated that we were unlikely to find a statistically significant difference in cesarean delivery rates in a trial of reasonable duration.

CONCLUSIONS

With strict criteria for the diagnosis of labor and with use of a rigid protocol for labor management, there was no increase in dystocia-related cesarean delivery with epidural analgesia.