You kno hose ones that you strap over a normal chair and plug in, and they've got rollers in them. I've got one sat in the cupboard but from googling it says they can bring on prem labour.
Any ideas on if that's true? I'm 30 weeks and have a co stand ache in my back now. Entirely self inflicted due to excesses chip/cake consumption and huge weight gain.
It's horrible though and I can't get comfy.