I've also read that pushes during natural birth tend to be shorter (less than 10 seconds each) than when coached through an epidural, and it's long pushes that increase the odds of pelvic dysfunction afterwards.

I actually ran that experiment myself during my last birth. While coached, I watched the clock behind my doctor and deliberately did not go over 10 seconds per push. It made a difference!

After a previous birth, I fainted. But after this one, I still had enough energy to be hungry and demolish a cheeseburger from hospital room service. After another previous birth, I had hemmeroids that felt like continuous contractions. But this time when the epidural wore off, I was just sore like I'd overdone squats at the gym.

Were there other factors? Maybe. And I admit that this is anecdotal. But I do believe that shorter pushes made the difference between fainting from exhaustion and screaming in pain, to being merely worn out and sore.

And up until the advent of the epidural (which I love overall, don't get me wrong), shorter pushes were the norm.