In the vast majority of women, after puberty, the ovaries begin to periodically secrete estrogen and progesterone. Under the effect of estrogen, the skin and mucous membrane of the vulva will become darker in color, relatively darker than other parts of the body, which is a normal phenomenon. After pregnancy, this situation will be aggravated, the color will be darker, mainly because of the thousands of times after pregnancy estrogen increase to cause. If the color of the vulva, in a local part of the darkening or blackening of the situation in the clinic should pay attention to, to understand whether it is due to the nevus, if the nevus in the vulva often friction, may cause lesions, so it is recommended that the clinic in a timely manner to deal with.