When breasts are just developing, the main manifestations are breast enlargement, nipple enlargement, breast sensitivity and pain, as well as darkening of the areola color. 1. Breast enlargement: generally 12 or 13 years of age into puberty, due to changes in hormone levels in the body, will stimulate the development of breasts, breasts will gradually increase in size, at first mainly for the bulging similar to the steamed bread-shaped breasts. 2. Nipple enlargement: With the gradual enlargement of breasts, nipples will also be developed and enlarged, which is manifested as simple nipple bulge. 3. Sensitive and painful breasts: due to hormonal stimulation, the breasts will become sensitive, and pain and discomfort will occur. 4. Darkening of the areola: During this period, the color of the areola will gradually deepen, and the color will usually change to flesh pink. There may be other symptoms when the breasts start to develop, and if you have any discomfort, please consult the hospital in time. To avoid delays, please consult a doctor in time. Pay attention to increasing nutrition and breast hygiene.