I had it for my first. I breathed in too deeply and it made me feel really woozy and out of it. So the mw turned the mix down so it was more oxygen, but that had no effect on the pain.
Later I tried it again, and my DH suggested the mw turn it back up, because by then I had the idea of just breathing in a little as the contraction built and then stopping.
I used it for both my previous and will be using it again with this one. That's all I used and it doesn't do much for pain but it helps get you through the contractions
Re: Entonox or "laughing gas" as pain relief method
Elizabeth 5yrs old Jane 3yrs old