The dark skin color of the inner thigh root of girls may be related to local friction, pregnancy, ringworm and other factors. 1. local friction: if daily exercise is more, the inner thigh skin is subjected to long-term friction, melanocyte hyperfunction, which can cause the skin color to deepen. 2. pregnancy: during pregnancy, due to the elevated level of estrogen and progesterone, it also affects the function of melanocytes in the thigh skin, causing melanocytes to synthesize melanin in large quantities, resulting in darker skin. 3. Ringworm: If the inner thigh is infected by fungus, it may cause ringworm, which can manifest as red spots, pimples, peeling and itching, etc. If it lasts for a longer period of time, the skin color will darken and become darker. If the girl’s inner thigh root skin becomes dark, and accompanied by other uncomfortable symptoms, should go to the hospital in time to check, symptomatic treatment.