Here's my experience to add to the mix :)
First: (12Hrs) Wasn't bothered at all about labour. It was painful, enough to make me throw up actually, but at the same time it wasn't frightening as I knew this was supposed to be happening. I did eventually have an epidural as they said I would be another 6 or 7 hours and I was reaching my limit - in the event I gave birth only 40 minutes later, and wished I hadn't bothered.
Second: (16Hrs) Based on previous birth, also wasn't worried. Unfortunately this one was really painful from start to finish - I think this was partly because I went in to the hospital too early and the midwife insisted on me being laid on the bed strapped to a monitor the whole flippin time, so I couldn't walk around and stretch etc.
Third: (slow mild labour 3 days, like pp's, then 3Hrs) Also not worried because although the 2nd was yuck, I reminded myself it was not going to go on forever and I knew I would get through it. Panicked briefly once labour actually started lol. In the end, I had a couple of paracetamol and gave birth two hours later almost painlessly, with midwife appearing at the door just in time to catch baby.
Fourth: As above, but with lovely African midwife in attendance and not interfering at all until I needed her.
Fifth: Due in May .... hoping for another easy one, but really not fretting at all.
Obviously, if you are very small, or the baby is big, or presents awkwardly it will probably hurt more - but every woman is different, as is every baby.
I am convinced though that more worry=more intervention=more pain=more drugs=more problems.
Focus instead on your poor baby who is being shoved face-first down a tunnel that is too tight - good job they don't have forums to worry on.... :)
xx
ann