The main manifestations of breast cancer during pregnancy are as follows: 1) the most common manifestation is breast lumps; 2) nipple discharge, especially bloody nipple discharge; 3) breast redness and swelling, similar to inflammation; 4) enlarged axillary lymph nodes, which is a manifestation of axillary lumps. During pregnancy and lactation these manifestations sometimes coexist or appear separately. For example, if a breast lump appears and there is no redness or swelling, nipple overflow, or swollen axillary lymph nodes, a breast lump that is not painful or itchy in this case may be breast cancer. There are often patients in the clinic who neglect the mother’s own health because they focus on the child during pregnancy. By the time they are more than 30 weeks pregnant, they come to the clinic because the lump is gradually increasing in size. In this case, it is easy to have more advanced axillary lymph node enlargement, and the disease enters the middle and advanced stage, which is relatively more complicated to treat. Therefore, women need to be aware that if they have painless breast lumps during pregnancy or breastfeeding, or if they have bloody overflow from the nipples or milk mixed with blood during pregnancy and breastfeeding, they must go to the hospital in time to rule out breast cancer during pregnancy and breastfeeding.