Hello; It is caused by melanin precipitation. This is a normal phenomenon. If it is too dark, you can consider surgery at a beauty institution to improve it. If the labia is dark, you can use the labia bleaching method to improve the treatment. In addition, if you have dark labia, you can also choose an injection whitening method. Systemic whitening can also improve the darkening of the labia. For women with dark labia, gynecological plastic surgery includes labia bleaching surgery.