***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: Background Reports indicate that the administration of epidural analgesia for pain relief during labor interferes with labor and increases cesarean deliveries . However , only a few controlled trials have assessed the effect of epidural analgesia on the incidence of cesarean delivery . The authors ' primary purpose in this r and omized study was to evaluate the effects of epidural analgesia on the rate of cesarean deliveries by providing a suitable alternative : patient-controlled intravenous analgesia . Methods Seven hundred fifteen women of mixed parity in spontaneous labor at full term were r and omly assigned to receive either epidural analgesia or patient-controlled intravenous meperidine analgesia . Epidural analgesia was maintained with a continuous epidural infusion of 0.125 % bupivacaine with 2 micro gram/ml fentanyl . Patient-controlled analgesia was maintained with 10 - 15 mg meperidine given every 10 min as needed using a patient-controlled pump . Procedures recorded in a manual that prescribed the intrapartum management were followed for each woman r and omized in the study . Results A total of 358 women were r and omized to receive epidural analgesia , and 243 ( 68 % ) of these women complied with the epidural analgesia protocol . Similarly , 357 women were r and omized to receive patient-controlled intravenous meperidine analgesia , and 259 ( 73 % ) of these women complied with the patient-controlled intravenous analgesia protocol . Only five women who were r and omized and received patient-controlled intravenous meperidine analgesia according to the protocol crossed over to epidural analgesia due to inadequate pain relief . There was no difference in the rate of cesarean deliveries between the two analgesia groups using intention-to-treat analysis based on the original r and omization ( epidural analgesia , 4 % [ 95 % CI : 1.9 - 6.2 % ] compared with patient-controlled intravenous analgesia , 5 % [ 95 % CI : 2.6 - 7.2 % ] ) . Similar results were observed for the analysis of the protocol -compliant groups ( epidural analgesia , 5 % [ 95 % CI : 2.6 - 8.5 % ] compared with patient-controlled intravenous analgesia , 6 % [ 95 % CI : 3 - 8.9 % ] ) . Women who received epidural analgesia reported lower pain scores during labor and delivery compared with women who received patient-controlled intravenous analgesia . Conclusions Epidural analgesia was not associated with increased numbers of cesarean delivery when compared with a suitable alternative method of analgesia OBJECTIVE This study was undertaken to determine whether a policy of  delayed pushing  for nulliparous women with continuous-infusion epidural analgesia reduces the risk of difficult delivery ( cesarean delivery , operative delivery from a midpelvic position , low-pelvic procedures with rotation > 45 degrees ) . STUDY DESIGN In this multicenter , r and omized , controlled trial women in the delayed pushing group ( n = 936 ) were advised to wait > or = 2 hours after full dilatation before commencement of pushing .  Women in the early pushing group ( n = 926 ) were advised to commence pushing as soon as they had been r and omly assigned . RESULTS Difficult delivery was reduced with delayed pushing ( relative risk , 0.79 ; 95 % confidence interval , 0.66 - 0.95 ) . The greatest effect was on midpelvic procedures ( relative risk , 0.72 ; 95 % confidence interval , 0.55 - 0.93 ) . Although there was little evidence for an effect on low-pelvic procedures , spontaneous delivery was more frequent among women who practice d delayed pushing ( relative risk , 1.09 ; 95 % confidence interval , 1.00 - 1.18 ) . Abnormal umbilical cord blood pH ( < 7.15 venous value or < 7.10 arterial value ) was more frequent in the delayed pushing group ( relative risk , 2.45 , 95 % confidence interval , 1.35 - 4 . 43 ) . However , scores for a summary indicator , the Neonatal Morbidity Index , were similarly distributed in the 2 groups . CONCLUSION Delayed pushing is an effective strategy to reduce difficult deliveries among nulliparous women We compared the incidence of Caesarean delivery in nulliparous women r and omized to receive epidural analgesia with those r and omized to intramuscular ( i.m . ) pethidine .  On admission to the delivery suite in established labour , 802 nulliparae had already agreed to be r and omized with respect to their first analgesia . One hundred and eighty-eight women required either no analgesia or 50 % nitrous oxide in oxygen ( Entonox ) only . Of the remaining 614 women , 310 were r and omly allocated to receive i.m . pethidine up to 300 mg and 304 to receive epidural bupivacaine . Labour management was st and ardized according to the criteria for active management of labour . The intention-to-treat analysis showed similar Caesarean section rates in those r and omized to epidural ( 12 % ) or pethidine analgesia ( 13 % ) . The difference in Caesarean rate was -1.1 % with 95 % confidence intervals from -6.3 % to + 4.1 % . The normal vaginal delivery rates were similar ( epidural , 59 % ; pethidine , 61 % ) The aim of this quasi‐experimental study was to examine the effects of maternal pethidine during labour on the developing breast feeding behaviour in infants in the first 2 h after birth compared with infants not exposed to pethidine . Forty‐four healthy infants were observed immediately after birth . They were placed skin‐to‐skin on their mothers ' chests . The development of mouth and sucking movements as well as rooting behaviour and state of sleep/wakefulness were noted . The observer was blind as to the pain relief the mother had received during labour . Of the 44 mothers 18 had received pethidine .  The main findings were that infants exposed to pethidine had delayed and depressed sucking and rooting behaviour . In addition , a smaller proportion of infants exposed to pethidine started to suckle the breast . Rooting movements which are expected to be vigorous at 30 min after birth were affected both by administration of pethidine and a longer second stage of labour . It is suggested that the differences found in sucking behaviour may be a central effect of pethidine . Depression of rooting movements in the pethidine group may be caused by exhaustion due to a longer second stage of labour and administration of pethidine . It is recommended that pethidine‐exposed mother‐infant couples stay together after birth long enough to enable the infant to make the choice to attach or not to attach to the nipple without the forceful helping h and of the health staff Background Some studies suggest that epidural analgesia prolongs labor and increases the incidence of cesarean section , especially if it is administered before 5 cm cervical dilation . The purpose of the current study was to determine whether early administration of epidural analgesia affects obstetric outcome in nulliparous women who are receiving intravenous oxytocin .  Methods Informed consent was obtained from healthy nulliparous women with a singleton fetus in a vertex presentation , who requested epidural analgesia while receiving intravenous oxytocin at at least 36 weeks ' gestation . Each patient was r and omized to receive either early or late epidural analgesia . R and omization occurred only after the following conditions were met : ( 1 ) the patient requested pain relief at that moment , ( 2 ) a lumbar epidural catheter had been placed , and ( 3 ) the cervix was at least 3 but less than 5 cm dilated . Patients in the early group immediately received epidural bupivacaine analgesia . Patients in the late group received 10 mg nalbuphlne intravenously . Late-group patients did not receive epidural analgesia until they achieved a cervical dilation of at least 5 cm or until at least 1 h had elapsed after a second dose of nalbuphine . Results Early administration of epidural analgesia did not prolong the interval between r and omization and the diagnosis of complete cervical dilation , and it did not increase the incidence of malposition of the vertex at delivery . Also , early administration of epidural analgesia did not result in an increased incidence of cesarean section or instrumental vaginal delivery . Thirteen ( 18 % ) of 74 women In the early group and 14 ( 19 % ) of 75 women in the late group underwent cesarean section ( relative risk for the early group 0.94 ; 95 % confidence interval 0.48–1.84 ) . Patients in the early group had lower pain scores between 30 and 120 min after r and omization , and were more likely to experience transient hypotension . Infants in the late group had lower umbilical arterial and venous blood pH and higher umbilical arterial and venous blood carbon dioxide tension measurements at delivery . Conclusions Early administration of epidural analgesia did not prolong labor or increase the incidence of operative delivery , when compared with intravenous nalbuphine followed by late administration of epidural analgesia , in nulliparous women who were receiving intravenous oxytocin Background : In 1981 , with support from the American Society of Anesthesiologists and the American College of Obstetricians and Gynecologists , anesthesia and obstetric providers were surveyed to identify the personnel and methods used to provide  obstetric anesthesia in the United States . The survey was exp and ed and repeated in 1992 with support from the same organizations . Methods : Comments and questions from the American Society of Anesthesiologists Committee on Obstetrical Anesthesia and the American College of Obstetricians and Gynecologists Committee on Obstetric Practice were added to the original survey instrument to include newer issues while allowing comparison with data from 1981 . Using the American Hospital Association registry of hospitals , hospitals were differentiated by number of births per year ( stratum I , > or= to 1,500 births ; stratum II , 500–1,499 births ; stratum III , < 500 births ) and by U.S. census region . A stratified r and om sample of hospitals was selected . Two copies of the survey were sent to the administrator of each hospital , one for the chief of obstetrics and one for the chief of anesthesiology . Results : Compared with 1981 data , there was an overall reduction in the number of hospitals providing obstetric care ( from 4,163 to 3,545 ) , with the decrease occurring in the smallest units ( 56 % of stratum III hospitals in 1981 compared with 45 % in 1992 ) . More women received some type of labor analgesia , and there was a 100 % increase in the use of epidural analgesia .  However , regional analgesia was unavailable in 20 % of the smallest hospitals . Spinal analgesia for labor was used in 4 % of parturients . In 1981 , obstetricians provided 30 % of epidural analgesia  for labor ; they provided only 2 % in 1992 . Regional anesthesia was used for 78–85 % ( depending on strata ) of patients undergoing cesarean section , result ing in a marked decrease in the use of general anesthesia . Anesthesia for cesarean section was provided by nurse anesthetists without the medical direction of an anesthesiologist in only 4 % of stratum I hospitals but in 59 % of stratum III hospitals . Anesthesia personnel provided neonatal resuscitation in 10 % of cesarean deliveries compared with 23 % in 1981 . Conclusions : Compared with 1981 , analgesia is more often used by parturients during labor , and general anesthesia is used less often in patients having cesarean section deliveries . In the smallest hospitals , regional analgesia for labor is still unavailable to many parturients , and more than one half of anesthetics for cesarean section are provided by nurse anesthetists without medical direction by an anesthesiologist . Obstetricians are less likely to personally provide epidural analgesia for their patients . Anesthesia personnel are less involved in newborn resuscitation OBJECTIVE Intrathecal narcotics ( ITNs ) are being used in some setting s as a sole labor analgesic . However , they have not been directly compared to epidural analgesia . STUDY DESIGN We used a prospect i ve observational design . POPULATION Eighty-two women with uncomplicated full-term pregnancies were enrolled upon analgesia request during spontaneous labor with cervical dilation 3 to 7 cm . Sixty-three chose ITNs ( morphine and fentanyl ) , and 19 chose epidural analgesia ( continuous infusion of bupivacaine and fentanyl ) . OUTCOMES MEASURED Pain scores were documented using a visual analog scale . Satisfaction and side effects were rated with Likert scales during a structured interview on the first postpartum day . Outcomes were analyzed with multivariate regression techniques . RESULTS Intrathecal narcotics were associated with significantly higher pain scores than was epidural analgesia during the first and second stages of labor and on an overall postpartum rating . The median effective duration of action for ITNs was between 60 and 120 minutes ; however , ITNs provided excellent analgesia for a subgroup of women who delivered within 2 to 3 hours of receiving them . Although women in both groups were satisfied with their pain management , women receiving ITNs had statistically lower overall satisfaction scores . CONCLUSIONS Within the limitations of a nonr and omized study , a single intrathecal injection of 
    Output:
    
Parenteral opioids provide modest pain relief in labor , and little evidence supports the use of one agent over another .
Although epidural analgesia is the most effective form of pain relief , its use is associated with a longer labor , an increased incidence of maternal fever , and increased rates of operative vaginal delivery .
The effect of epidural analgesia on rates of cesarean delivery is controversial .
Nitrous oxide provides a modest analgesic effect , but it is used less often in the United States than in other developed nations .
Paracervical block provides effective analgesia in the first stage of labor , but its use is limited by postblock bradycardia .