Baby nipple inversion may belong to the normal physiological phenomenon, there may be breast disease, it is recommended to go to the hospital in time for examination, after a clear diagnosis for treatment. 1. Physiological phenomenon: it may be due to the baby’s own sex hormone level secretion is not high, thus the phenomenon of nipple inversion will occur, generally with the growth of age, the body’s glandular hormone secretion will increase, will gradually return to normal. 2. Underdevelopment: It may be due to the baby’s nipple itself is underdeveloped, resulting in the deep buried in the breast tissue, thus leading to the baby nipple depression, this situation will generally with the growth of age, the degree of depression will become more and more obvious. 3. Mastitis: It may be due to a bacterial infection that causes an inflammatory reaction in the nipple, resulting in nipple inversion. Inflammation can cause fibrosis and spasm in the breast tissue, thus showing the symptom of inversion. In daily life, if you find that your baby’s nipples are inverted, be careful not to often squeeze or knead with your hands, so as not to cause inflammation or infection, and you should consult a doctor for diagnosis in time.