As an OB, I think epidurals can both interfere with labor and aid it.  The
patient who could really benefit from ambulating, squatting, etc. finds it
impossible to do (unless she has a "walking" epidural), and I'm sure some of
these patients have ended up with sections because the baby wouldn't come down
the vaginal canal because it was occiput posterior or transverse.  Some
movement would have helped the baby change its position.

On the other hand, I have seen women who were very tired, scared, or were
blessed with a low pain threshold who benefitted from the relief and sleep
they were able to get with an epidural.  We often let the epidural wear off
around here when mother begins to push, and I think that prevents a lot of
sections.  Personally, I don't encourage epidurals in most instances.....VNJ