Me: 4 births, no epidurals, no intervention, and stitches only with DD1 who punched her way to freedom through my perineum (thanks, darling).
Friend 1: 3 births, no epidurals, no interventions.
Friend 2: 3 births, 3 epidurals, 2 sections (one including failed forceps)
Friend 3: 1 birth, induction, epidural, section
Friend 4: 4 births, no epidurals, no interventions
Cousin: 2 births, no epidurals, no interventions
SIL: 3 births, no epidurals, no interventions
Those are honestly the only ones where I can remember enough the details of the births. There's a definite pattern there, but as PP have said, what's not clear is that women have epidurals because they have more pain which indicates am more difficult lie etc. Though to my mind, it stands to reason that if you are immobile on your back, you will not labour as effectively as if you are walking around, on hands and knees, able to squat etc.