I was adamant not having it and I ended up requiring for stitching up. I still wouldn't want it out of choice because the not being able to move and the catheter drove me senile and I don't know what it was, I think it was the diamorphine painkiller that made me really itchy and that peeped me right off! I couldn't wash after birth and I had blood under my nails and stuff till the day after it was gross!
Just saying that sometimes it's out of your hands. Happy hormones that our body make, do their very best but for some people it just doesn't even cut the edge and theoretically speaking you'd be dragging the anaesthetist in by its throat to come give you one. You don't really know what you're game for once your actually in labour. Just know that you're always allowed to change your mind and choose a pain reliever if you wish to when you initially didn't want to when the time comes!