Nipple is a normal physiological structure of the human body, for women is more important sex organs, have the function of feeding children, in various stages of women, especially the color and shape of the nipple will change. After women enter puberty, with the increase of estrogen level in the body, breasts begin to develop, nipples gradually grow, pink color is normal. Most women who are pregnant with areola coloring and gradually growing breasts may deepen the color of the nipple to dark brown or brown, in preparation for breastfeeding in the future. The normal nipple is a cylindrical protuberance with holes, about 1cm in diameter and 1.5-2cm in height, dark in color. Usually nipples without pain, itching, cracking, depression, etc., are normal, usually keep a happy mood, eat more fruits and vegetables, pay attention to breast hygiene and cleanliness.