ABSTRACT
A retrospective study assessing the effect of epidural analgesia in labor on the incidence
of cesarean section was performed. The first 500 consecutive nulliparas meeting the
following criteria were included in this study: term (37 weeks or longer) and singleton
gestation, cephalic presentation, spontaneous onset of labor, and 5 cm or less of
cervical dilation on admission. Patients were grouped according to their rate of cervical
dilation in early labor (≥ 1 cm/hr, and < 1 cm/hr) and the timing of epidural placement
(none, early, or late). There was no effect of epidural analgesia on the incidence
of cesarean section for fetal distress. The incidence of cesarean section for dystocia
was significantly greater (p >0.000001) in the epidural group (15.6%) than in the
nonepidural group (2.4%). The greatest effect of epidural analgesia on the incidence
of cesarean section for dystocia was observed in nulliparas who dilated at slower
rates (<1 cm/hr) in early labor and who had epidural analgesia placed at 5 cm or less
of cervical dilation (20.6% versus 3.4%, relative risk of 6, p <0.0005). The increase
of cesarean section for dystocia associated with epidural analgesia could not be accounted
for when other possibly confounding variables were studied. Both the dilation rate
prior to epidural placement and the cervical dilation at epidural placement were significantly
correlated to frequency of cesarean section for dystocia (p <0.01). This study suggests
that epidural analgesia in labor may increase the incidence of cesarean section for
dystocia in nulliparas.
