I gave birth laying down in theatre with my feet in stirrups (ventouse). But, I laboured in the pool on all fours rocking backwards and forwards for the most part. I pretty much changed positions as much as possible until I could find something that felt comfortable (well, as comfortable as can be).

I think you will just find something that feels the best for you at the time, it may not be what you thought you'd do but if it works just go with it.

Stella was born standing right beside the toilet because I was convinced I needed to wee.  Because I was only an hour into labour none of us had any inkling that it was her!!  I had time to stand up, open the door and yell before she was out in one push.  Very attractive with trackpants and knickers around the ankles . 

Flissty wrote: My MW said she can do her checks pretty much whenever, whereever and I can just do what I need to do (though she'd prefer I wasn't sitting on the toilet!)

I came so close to having my 1st baby on the toilet.  I was only 4cms when I got to hospital but a little over an hour later I was telling my midwife I wanted to push.  She thought I was in transition and because I'd not been wees in nearly 8 hrs she convinced me to go to the toilet before she checked how far dilated I was.  In the labour room ensuite with DH holding me I had several contractions and it was taking all my might and willpower not to let my body push. We went back into the room because I was sure if I didn't I'd have the baby in the toilet but before I got back up on the bed again I had another contraction, I was on my tippee toes squeezing my pelvic floor muscles together crying "I have to push, I can't not push" when the midwife looked between my legs and said "Jo, you can't push... you have to get on the bed.  Your babies coming... she's brunette".

First time I was on my knees leaning my arms against the sofa and second I was standing (though that was because I had no choice but to stop where I was and let her out because she was in such a hurry!).  I got the impression that standing isn't quite so fabulous as a newborn can be slippery and so they have further to fall if someone fails to catch them but other than that I would highly recommend both (and if they are warned whoever is doing the catching presumably has pillows etc just in case baby needs somewhere to fall).  Great from a gravity and pelvic space perspective.  My understanding about more upright positions is that the baby isn't putting all their pressure on the nerves that go through your pelvis too - the one contraction I had on my back certainly hurt a whole pile worse than any other.

Both times I was sitting up while pushing and lying against the mattress (which was raised) for a rest inbetween contractions.  I think the idea is that by sitting it reduces the space in your abdomen thereby helping to push the baby out.

You can change positions if you find the one you've chosen doesn't work for you, 2nd time I started out on hands and knees but turned over because I found sitting far more comfortable.