Long time MN lurker, first time poster.
However, I've had an idea that I must share- frozen foil pouch drinks for your hospital bag-They will stay cool for days and will keep other things (like snacks or water) cool in the process.
We currently do this for long journeys and camping- so I think it would work for being in labour too..
Sorry if this is already done already. However I thought of it so I'm claiming the credit 