Girls labia black with several factors: 1, may be due to heredity. Many women are born with black skin, so there will be labia black symptoms is a normal reaction, you can not have to be treated. 2, may be and estrogen and progesterone levels increase, resulting in pigmentation. Women in the adolescent growth and development process, the body of female hormone levels continue to increase, in addition, high levels of estrogen and progesterone during pregnancy, will lead to melanin deposition, thus appearing labia black symptoms. 3, may be often walking friction or sex life is too frequent and lead to. 4, some endocrine diseases, such as polycystic, hyperadrenalism, and other diseases, leading to hormone level abnormalities, can also cause the labia black.