Nipple reduction may be caused by abnormal development, mastitis, breast hyperplasia and so on. 1. Developmental abnormality: If the patient’s nipple local tissue structure has developmental abnormality, resulting in poor nipple support, making nipple inversion, thus causing nipple shrinkage. 2. Mastitis: Nipple shrinkage may be caused by mastitis, which may be caused by obstruction of milk ducts, infection, breast trauma, smoking, etc. It is mainly due to the proliferation of fibrous connective tissues, which causes nipple inversion by pulling on the nipple, thus leading to nipple shrinkage. 3. Mammary gland hyperplasia: It is possible that the ratio of estrogen and progesterone is out of proportion, which makes the breast parenchyma hyperplasia, resulting in nipple shrinkage of patients. If the patient’s symptoms are more serious, it is recommended to go to the hospital in time, under the diagnosis of the doctor, according to the patient’s specific condition, targeted treatment.