ABSTRACT
BACKGROUND: Epidural analgesia effectively relieves labor pain, but questions persist about possible adverse effects of epidurals on labor, the mother, and the neonate. This meta-analysis compared the impact of epidural analgesia with parenteral opioids on birth outcomes.
POPULATION STUDIED: A total of 4721 women from 16 studies were identified. The participants were nulliparous and multiparous women with uneventful pregnancies undergoing spontaneous and induced labor. Thus, the subjects are likely to be similar to those seen by many family physicians, although more detail about race, gestational age, and other obstetric risk factors would have been useful.
STUDY DESIGN AND VALIDITY: The authors searched MEDLINE, EMBASE, the Cochrane Library, and meeting abstracts and references of review articles for randomized controlled trials comparing epidural analgesia with parenteral opioids during labor. Prospective cohorts were used only if no randomized controlled trial was available for a particular outcome and articles met criteria for quality. The authors assessed methodological quality with the Jadad scale. Heterogeneity was assessed with a chi-square test; Cochrane software was used to combine the results using a random effects model on an intent-to-treat basis.
OUTCOMES MEASURED: Maternal outcomes included maternal pain; satisfaction with pain control; labor duration; oxytocin use; temperature of >38°C; incidence of cesarean and instrumental delivery, and incidence of postpartum urinary incontinence and low back pain. Neonatal outcomes included 1- and 5-minute Apgar scores, fetal heart rate abnormalities, umbilical artery pH, and lactation success. Spinal headaches, neonatal jaundice, and hypoglycemia as well as treatment costs were not addressed.
RESULTS: Available trials were of low to moderate quality, with none having blinded assessment of outcomes. The rate of cesarean delivery was similar for patients receiving epidural and parenteral opioid analgesia; analyzing only higher quality trials did not change this result. Compared with women receiving parenteral opioids, patients receiving epidural analgesia had significantly lower pain scores (mean weighted difference = –40 on 100-mm scale; 95% confidence interval [CI], –42 to –38) and greater satisfaction with pain relief (odds ratio [OR] = 0.27; 95% CI, 0.19–0.38; number needed to treat [NNT] = 5). Women receiving epidural analgesia also had a 15-minute longer second stage and more oxytocin use (OR = 2.80; 95% CI, 1.89–4.16; NNT = 5), fever (OR = 5.6; 95% CI, 4.0–7.8; NNT = 5), and instrumental delivery (18.9% vs 12.2%; OR = 2.08; 95% CI, 1.48–2.93; NNT = 14). The rate of instrument use for shoulder dystocia was similar. For patients given parenteral opioid analgesics, naloxone was used most frequently. No differences were noted in incidence of low umbilical pH, low 5-minute Apgar scores, or fetal heart rate abnormalities. Randomized controlled trials were unavailable for lactation and incontinence outcomes; 1 prospective cohort study for each outcome found no differences.
Epidural analgesia provides better pain control than parenteral opioids without increasing cesarean delivery rates. Clinicians should counsel women choosing epidural agents, however, to expect a small increase in second-stage labor and a higher rate of maternal fever, use of oxytocin, and instrumented delivery. Clinicians should keep in mind that this study did not compare epidural analgesia with nonpharmacologic interventions, such as social support, which are known to have potent influence on labor course. Further studies of the impact of analgesia choice on breast-feeding and maternal incontinence are important.