for it to be effective you need to start using it from very early on in your labour so that the endorphins start building at the beginning when things aren't as painful. Apparently, if you first start using it when your contractions are painful it's not effective. HTH
Spot on, TENS is most effective if used right from the start. Unfortunately, if you begin using it later it is not only less effective but could actually be quite annoying!(Although everyone of course is different!)

What may work better for you if you want to focus on Hypnobirthing and meditation is a non-maternity TENS.
The ones designed for Labour have a button you can press to ramp up the TENS stimulation when you are having a contraction. It is foolproof to use as a Labouring woman cannot be mucking around with dials, buttons and switches. A regular TENS machine for pain relief is a unit which has two dials to increase intensity and frequency of stimulation. If you were to use one of these in Labour, (I did) all you need to do is set it to the intensity and frequency that suits you and let it do its thing. As things progress, you will become desensitised to the stimulation so will need to turn up the intensity, and this is as simple as turning up one dial. You would not necessarily do this for each contraction, just as you needed it over time. (Or get your support person to do it). In this way, it works as a background pain relief according to the 'pain gate' theory of pain relief - basically, flood the neural pathways with stimulation of a particular frequency and the nervous system prioritises this message over your pain messages from Labour (it can only pay attention to so many messages at once!!) hence you don't 'feel as much pain. Also, as someone alluded to earlier, it also works by stimulating the section of the brain responsible for the release of pain mediating hormones... hence, more feel good hormones floating round your body.

Every little bit helps!

If you use one this way, you can really focus on Meditation and breathing and just let the TENS do its thing in the background.
What a great idea! Any efforts to set yourself up with as much 'natural' or less invasive pain relief is a brilliant approach to your birth.

I used a sports TENS for my (loooong) Labour and made it a hell of a long way without any drugs for pain relief - as a matter of fact, the only reason I went for the gas in the end was because I was soooooooo damn tired and was falling asleep on my feet between contractions causing my midwife a big fright!

There have been a few threads from people asking for info about using TENS, I will try to locate a few recent ones for you as many people have responded.

HTH and let me know if what I have said here doesn't make any sense and you want any more details.