What causes evolution? Adaptations that give individuals better chance of breeding and passing on their genes.
Less painful/dangerous process probably would cause better chances of having more than one child, but probably wouldn't be a factor that would effect the choosing of a mate, or surviving to breeding age.
Also, we've pretty much stopped evolving, we no longer allow our external circumstances to affect us, we change them. And these days, with pain relief, caesarians etc. we aren't gonna be changing much in the future.
Also, most people these days have opportunity to have kids/pass on their genes. With most genes being passed on/surviving, evolution (by survival of the fittest) no longer really occurs.