The first consideration is the pigmentation, many women in the process of puberty development, sexual characteristics will gradually obvious, and the body hormone level changes, will also lead to the appearance of vulvar pigmentation and other performance, are normal body reaction, basically can not be treated. Secondly, consider the long-term sexual stimulation or inflammatory stimulation, when excessive friction will lead to local color changes in the pubic area, resulting in the lower body darkening. Third, there may be genetic factors and other issues caused by many women born with black skin, so the lower body skin darkening is a normal physiological reaction, if there are no other symptoms, you do not need to treat, basically there is no harm to the body, usually pay more attention to personal hygiene.