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.