I used a TENS machine for my VBAC with DD. It was brilliant! I had never used one before but the physio (I hired it from the maternity hospital physio) showed me how to use it effectively. I started using it when my contractions were about 10 minutes apart and used it all the way into the end of transition where I felt like it wasn't working anymore. At one point I had it maxxed out and shouted at DH that it was broken LOL...Anyway, it was really good. The tingling sensation and the fact that I had buttons to push was a great distraction as well as a pain reliever. The only downside was that I could not take it in the bath or shower obviously. But, yes, very effective tool and I'd use it again next time.