The causes of dark nipples are mainly related to sexual maturity, hormonal changes and melanoma. 1. After reaching sexual maturity, the color of nipples will be affected by estrogen and other hormones in the body. When sexually mature, nipple color will become darker, which is a normal physiological phenomenon, no need to worry. 2. After pregnancy, women are affected by the hormones in the body, which can also lead to breast enlargement and deepening of areola color, which is related to melanin deposition after pregnancy. This is related to melanin pigmentation after pregnancy, and this condition will not disappear after the end of the whole pregnancy period, and may be accompanied by lifelong. 3. It may be caused by melanoma, but in addition to darkening of nipples, melanoma is also accompanied by local pain and itching, which needs to be clarified by pathological examination. To summarize, there are many reasons for nipple blackening, and it is recommended to go to the hospital in time to avoid delaying the condition.