Hi Kelly,
My cousin had this, she had her first baby at 20 weeks, which sadly died as she wasn't strong enough, Summer-leigh was born at 21 weeks, she has cerebral palsy which is affecting her legs but other than that she is a happy little girl and Miles her third was born at 27 weeks and he is as healthy as a full term baby.
She had a stitch put in her cervix but didn't seem to last long with her second but seemed to work better with her third.
I personally haven't been through it but i believe they take it out at around 36 weeks so if you do go into labour from then, it's fine.