I've been using my ball since 34 weeks after the midwife advised me to, my baby is back to back. It has helped as it moves him around, although he has turned back again! My midwife didn't say anything about preterm labour but, thinking about it, women are encouraged to use a ball to make contractions more effective. Sooo, now I really don't know. I'm 36 weeks now and have no signs that labour is near despite using the ball for an hour a day.