First, pull it manually. Girls' puberty is an important period for breast development and correction of nipple inversion. Often pulling the nipple can make the breast protrude, increase the supporting force of the surrounding skin, and play the role of "shaping". After a long time, the nipple naturally protrudes outward. If you can't pull it out, you can push the skin near the nipple outward first. Second, suction therapy. Breast pumps should be used every day after pregnancy.