Its just early labour. It can go for 10 minutes or 10 days. When you are 4cms you are in active labour and thats when the contractions are constant and don't stop unless there is a reason. Relax, take it easy and sleep as much as you can before then. You could get some acupuncture to help, it doesn't mean you need a medical induction or C/S. Its all normal and will happen in its own time.