Oh just wanted to add... another reason the OB recommended it, is even if you just use it to learn to control the muscles down there.. he said there a lot of women who don't "let the baby out". So if you are aware of the muscles, you're able to be in more control, and then you're less inclined to hold the baby in! hehe. Once you get up to 8-10cm the instructions say to push the balloon out, so it simulates giving birth.. I didn't get that far.. but I can say that I struggled keeping the thing in there anyway! LOL. My body just wanted to push it out!