Most studies, including the ive from Parkland Hospital, report that epidural analgesia prolongs labor and increases the use of oxytocin stimulation (Table 25-8). Alexander and associates (2002) examined the efects of epidural analgesia on the Friedman (1955) labor curve described in Chapter 22 (p. 432). Compared with original Friedman criteria, epidural analgesia prolonged the active phase of labor by 1 hour. As further shown in Table 25-8, epidural analgesia also increased the need for operative vaginal delivery because of prolonged second-stage labor. But importantly, this led to no greater rates of adverse neonatal efects.
This association among epidural analgesia and prolonged second-stage labor and operative vaginal delivery has been attributed to anesthesia-induced motor blockade and resultant impaired matenal expulsive eforts. Craig and colleagues (2015) randomized 310 nulliparous women with labor epidural analgesia to bupivacaine plus fentanyl or fentanyl alone during second-stage labor. Epidural bupivacaine analgesia did cause motor blockade during the second stage, however, the duration of the second stage was not increased.
TABLE 25-8. Selected Labor Events in 2703 Nulliparous Women Randomized to Epidural Analgesia
First-stage duration 8.1 ± 5 7.5 ± 5 0.01s1 (hr)b
Second-stage 60 ± 56 47 ± 57 <0.001 duration (min) Oxytocin ater 641 (48) 546 (40) <0.001
Type of delivery
SVD 1027 (77) 11s22 (82) <0.001 Forceps 172 (l3) 101 (7) <0.001 Cesarean 140 (10.5) 141 (10.3) 0.92 aData are presented as n (%) or mean ± SD.
bFirst stage = initiation of analgesia to complete cervical dilatation.
SVD = spontaneous vaginal delivery.
Adapted with permission from Sharma SK, Mcintire DD,
Wiley J, et al: Labor analgesia and cesarean delivery. An individual patient meta-analysis of nulliparous women,
Anesthesiology. 2004 Jan;l 00(1 ):142-148.
Fetal Heart Rate. Hill and associates (2003) examined the efects of epidural analgesia with 0.25-percent bupivacaine on fetal heart rate patterns. Compared with intravenous meperidine, no deleterious efects were identified. Reduced beat-co-beat variability and fewer accelerations were more frequent sequelae in fetuses whose mothers received meperidine (Chap. 24, p. 462). Based on their systematic review, Reynolds and coworkers (2002) reported that epidural analgesia was associated with improved neonatal acid-base status compared with meperidine.
Cesarean Delivery Rates. A contentious issue in the past was whether epidural analgesia increased the risk for cesarean delivery. Supporting evidence for this view came from the era when dense blocks of local anesthetic agents were used that impaired motor function and therefore likely did contribute to higher cesarean delivery rates. As techniques were refined, however, many investigators came to believe that epidural administration of dilute anesthetic solutions did not increase cesarean delivery rates.