...but midwives secretly work for drug companies so push their filth on you all the time.
Sorry, Ryn, but that's just not the case. Midwives (certainly in the public system, and most likely in the private system as well) don't work for drug companies - it's a gross conflict of interest, and it's not allowed. You should see the hoops I have to jump through just to lecture nursing students as a second job.

Ignore the stupid woman and kill the baby! We're midwives!
You know, I sympathise that you had a terrible birthing experience, and I really feel for you. But my wife is a midwife. I know an awful lot of midwives. I know some of them that believe in a woman's natural ability to birth their baby safely, and I know some who ascribe to the philosophy that every birth is potentially dangerous and should be managed with that in mind. But I do not know a single midwife who really thinks the way you are suggesting.

And on to the topic at hand, I use nitrous for pain relief in children, but have never used it in labour as I'm not a midwife. In my experience, it can make you feel a little giddy, and it should take the edge off the pain, but you shouldn't be "off your face" and you should remain conscious at all times. And yes, it can make you somewhat nauseous.