The darkening of the vulva is mainly due to physiological pigmentation during pregnancy, too frequent sex or excessive local friction and genetic factors. 1. Vulvar congestion during pregnancy, skin thickening, labia major and minor pigmentation, increased blood vessels and connective tissue in the labia major, soft, stretch increase, facilitate the delivery of the fetus through, this time for the physiological vulvar darkening, after delivery will be better. 2. Sexual life is too frequent or localized excessive friction: If girls have sex too often, it will cause repeated friction on the vulva, which will help melanin deposition, which will cause blackening of the vulva. Women usually wear especially tight underwear, resulting in excessive friction on the vulva may also be accelerated by vulvar hyperpigmentation. 3. Genetic factors: some girls are born with darker skin color, mainly due to genetic factors, which can cause melanin deposition in the vulva area, so it can also cause darkening of the vulva in girls. There may be other reasons for the darkening of the vulva, if the pigmentation is obviously accelerated, it is recommended to consult a doctor in a timely manner to rule out abnormalities, so as not to delay the condition.