It helps in lots of ways. Strengthens your muscles for carrying baby, helps your pelvis prepare for labor, helps with pack pain, also if your baby is head down but in sunny side up(their spine to yours) it can help turning them by sorting straight on one to prevent back labor. And yes it is suppose to help induce labor to bounce on one towards the end its safe and slight bouncing doesn't help you have to bounce pretty good on one. I just watched a video of a girl bouncing trying to induce labor it's what heridwife said to do. But also you can bring your ball for labor and it will help relive pressure and make it less painful.
I was just thinking to myself.. does it help to break your water or something? Ive heard of bouncing on them is that safe?