I have had 3 children and am pregnant with number 4!  I was given birthing ball in the maternity unit when I was in labour and it was fantastic - speeded up labour and I managed to get through whole thing without any pain relief.  I felt it definitely helped and I am going out to buy a gym ball for the early stages for baby number 4

PS for first timer's if you are in an upright position sitting on birthing ball and then on your knees staying fairly upright during labour I felt it really helped with the pain and I ended up giving birth to my last one from that position and it was so much better than the other 2 labours I had 

I would definitely recommend one. I bought a cheap gym ball in argos (like the person below). I used it at home in the few weeks up to giving birth to encourage the baby into a good position. In the end, I was induced at 38 weeks so I did non of my labour at home but as I already knew I liked the ball, I used the birthing ball in the hospital throughout the first stage of labour. It was brilliant. It just gives you another option. Whatever positions you like, you will need several up your sleeve as you just need to change what you're doing every half hour or so. I think you need three or four positions that you like. I spent hours on the ball and leaning against the back of the bed and standing up all in a rotation. If I had done my early labour at home, I would definitely have used the ball.

We didnt buy a birthing ball but did go out and buy a "space hopper" - wonderful dose of retro sillyness - my other half found it helped a lot and also had handles! Bonus we still can use it now to play with the kids!