Same here - my labour was augmented with the drip, but was pain relief free. I just did some reading, but really it came down to me not wanting anything passed through to the baby (even gas). I'd avoided caffeine and alcohol and all those other yummyy things for 9 months coz I was looking after my baby.. why would I suddenly allow painkillers through?! DH was a wonderful support and reminded me of why I didn't want drugs, and told the midwives to stop offering me pain relief.

I guess my 2 tips would be:

Tell the midwives straightup that you don't want anything, and if you do, you'll ask for it (even then it can be something you scream out and not really mean! LOL) Get them to help with positions and being upright.

And BEWARE OF TRANSITION! This is where you're most likely to cave and want drugs (it's the last 1/2 hr or so of the 1st stage). Make sure your support partner knows what transition is and get them to keep telling you that it means you're nearly there! The pushing stage wasn't painful at all for me, just tiring, but it was a bit of a buzz getting through to then without any pain relief, so maybe that helped. hehe.

All the best with your research