If you have no nipples at the age of 18, you should undergo surgery early if you have contracture of the breast ducts due to hereditary factors and nipple invagination. If the nipple invagination is caused by pressure from wearing too tight underwear for a long time, the nipple can be lifted intermittently, and if necessary, the nipple can be sucked out with a breast pump and moderate breast expansion exercises to enhance the elasticity of the nipple support structure. If you do not have nipples at the age of 18, you should go to a regular hospital for breast surgery or plastic surgery after ruling out physiological factors, and decide whether to undergo surgery after a full assessment by a specialist, otherwise it may affect breastfeeding or even cause acute mastitis later. In daily life, you should avoid wearing too tight underwear, and moderate breast massage to promote the development of nipples.