I have a cyst in my uterus and i'm 9 weeks pg.my doc said the cyst will shrink but what if it doesn't. is this cyst going to harm pg?

Trust your OBG/Doc: The cyst you mentioned is very unlikely to harm or enlarge and your doc will be monitoring it with us to assure it is not. Sometimes this will occur due to the surgery on the uterus, so you might ask if it is located in the previous incision area on the lower anterior wall of the uterus at your next prenatal visit. Don't obsess over this, but do keep your appointments and be observant.