The possible causes of yellow fluid flow from the breast are breast fluid during pregnancy, breast inflammation, papilloma in the milk ducts, etc., and you should consult a doctor in time to find out the cause of the disease. 1. Breasts overflow during pregnancy: during pregnancy, due to the hormone secretion of pregnant women’s body increased significantly, the mammary glands caused a certain impact, thus the secretion of milk, which can be manifested as a yellow liquid outflow, which may be a normal physiological phenomenon during pregnancy, don’t worry about it, it is recommended to keep the breasts localized clean, and don’t use your hands to squeeze the breasts. 2. Breast inflammation: If the breast is infected by bacteria, causing inflammation, the mammary gland may flow yellow liquid, in this case it is best to timely anti-infection treatment. 3. Intraductal papilloma: Generally speaking, intraductal papilloma is mostly seen in menstruating mothers, clinically speaking, patients usually have no obvious conscious symptoms, often due to the flow of yellow or dark brown liquid from the mammary glands to contaminate the underwear and draw the attention of patients. In general, the tumor of intraductal papilloma is usually small and often nonpalpable, and occasionally a larger mass may be present, which usually needs to be treated by surgery. There may also be other causes of yellow fluid in the breast, such as cystic hyperplasia of the breast, breast tumor, etc. If physiological causes are ruled out, the patient should consult a doctor in time to clarify the specific cause and treat accordingly.