The five months of pregnancy belongs to the middle of pregnancy, pregnant women appear breast water, most of the body hormone secretion changes caused by the normal phenomenon, but also may be caused by mastitis, breast cancer, etc., need to be observed. The common clinical reasons are as follows: 1. Normal phenomenon: mid-pregnancy, lactogen content began to rise, stimulating the development of mammary gland ducts as well as follicles, the phenomenon of nipple outflow of milk for the delivery of lactation to prepare for the normal phenomenon, there will also be mammary ducts expansion, areola coloring, areola range increase, breast swelling and pain and other symptoms. Usually pay attention to maintain local dryness, cleanliness and hygiene, avoid squeezing the nipple by hand, wear loose cotton underwear to reduce local stimulation of the breast, which will help blood circulation and reduce breast discomfort; 2. Mastitis: In addition to breast water, it also manifests itself as a breast lump and breast pain, and when the above symptoms appear in the fifth month of pregnancy, it is recommended that you seek medical attention in time to choose medication or surgical treatment; 3. Breast Cancer: The symptoms of breast cancer in the early stages of life are often not obvious, but they may also appear in the early stages of life. It is not obvious, but there is a possibility of breast overflow, that is, the phenomenon of running water in the breast. If the diagnosis is confirmed after ultrasound and pathological examination, it is necessary to terminate the pregnancy at the right time and give surgical treatment, radiotherapy and chemotherapy adjuvant treatment. Simple breast water in the fifth month of pregnancy, without other symptoms, is generally a normal phenomenon, pay attention to keep the local clean. If it is accompanied by lumps, it is recommended to consult a doctor in time to clarify the cause of the disease and treat the cause.