My mother sent me a fascinating article from the American Academy of Physician called "Spontaneous Vaginal Delivery." Only the abstract is online but if you happen to be near a library that carries it, it's an interesting read. I was particularly surprised to hear epidurals slow labor down (338). From the anecdotal stories I've heard, I had received the impression that epidurals sped up the process of labor, not slowed it down. I suppose this is yet another reason it's important to make decisions based on research rather than assumptions :)