Nipple fluid may be related to pregnancy, or it may be related to diseases such as ductal dilatation and breast cancer. 1. Pregnancy: Hormone levels in a woman’s body change when she becomes pregnant, and nipple fluid may occur during pregnancy. 2. Dilatation of mammary ducts: Dilatation of mammary ducts is a chronic breast disease with a long course and complex and diverse lesions. The common symptoms of ductal dilatation are nipple discharge, lump under the areola and so on. 3. Breast cancer: Breast cancer is a malignant tumor in which the epithelial cells of the breast proliferate out of control and become malignant. Symptoms of breast cancer include breast lump, breast skin abnormality, nipple discharge, nipple or areola abnormality and so on. In addition, breast hyperplasia and intraductal papilloma may also show similar symptoms, so it is said that once you find nipple fluid, you should seek medical treatment as soon as possible to clarify the diagnosis and carry out targeted treatment.