I have endometriotic cyst and the size was 3 cm during my csection. what precautions should be taken to stop the cyst growing?

Endometriosis: If is a true endometrial cyst it will continue to enlarge slowly (most likely) and will need surgery to remove it. After menopause it might shrink some, but that may be many years off. Medical suppression with hormonal agents might help any pain but will not usually benefit what is going on with the cyst. Surgery is probably the best option for you.