The female breast contains many hormone receptors that are easily regulated by endocrine hormones. The nipples are generally pink during puberty and before puberty, but with puberty, the breasts are affected by the hormones in the body, and pigmentation begins to appear causing the nipples to gradually deepen in color, which is a normal human reaction. The color of the nipple will deepen under the influence of progesterone, especially in late pregnancy and at the beginning of breastfeeding, the color of the nipple and areola will deepen and become larger. The main reason for this is to prepare for breastfeeding at a later stage, so the dark purple nipples are affected by the hormone levels in the body. It can also be seen in wearing rougher underwear and frequent friction stimulation can also lead to increased pigmentation. This situation is relatively minor, usually pay attention to good local cleanliness and hygiene wear breathable and comfortable underwear.