I chose an epidural for my first one after 8 hours in labor and it was a good thing. I needed an emergency C-section and it took 5 minutes for the baby to come out from the moment the decision was made. If I had chosen not to have one they would have had to either knock me out of give me the epidural, wait for it to work, and then do the C-section. If I had not have it, I may not have a beautiful 23 year old daughter today. For my second one I asked for it the second I walked into the hospital and had an emergency c-section again. To me it was more of a preventive measure.
They say that there are too many c-sections done, but in my case I couldn't give birth naturally because of the shape of my bones. The third one was a c-section immediately.