Background and objectives. Over 100 papers in the medical literature s
uggest pro or con that epidural analgesia is associated with an increa
se in the incidence of instrument delivery. This two-component study w
as performed to evaluate the influence of epidural labor analgesia on
the incidence of instrument delivery. Methods. Component 1 was a retro
spective analysis of the medical records of 14,804 mothers having a va
ginal delivery before and after implementation of an active epidural s
ervice. Component 2 was a case control study designed to determine fac
tors, in addition to epidural analgesia, associated with an increase i
n instrument delivery. In component 2 11 factors describing maternal,
fetal, anesthetic, and obstetric factors were analyzed for each of 609
consecutive patients having an instrument delivery and 246 controls h
aving a spontaneous vaginal delivery. Results. In component 1, despite
a tenfold increase in the use of epidural analgesia, there was a simi
lar association between epidural use and instrument delivery in both t
ime periods. Additionally, the epidural-forceps association was twice
as strong for parous patients as for nulliparous patients (odds-ratios
9.74 and 4.52, respectively). In component 2, five factors were signi
ficantly (P > .0001) associated with instrument delivery conclusions.
Conclusions. While epidural analgesia was one factor, the others were
gestational age > 41 weeks, a second stage of labor > 2 hours, an occi
put posterior or transverse fetal position, and previous cesarean sect
ion. These four factors are individually and independently associated
with an increase in the incidence of instrument delivery independent o
f epidural use.