Women are supposed to show chest swelling around 40 days of pregnancy. This situation is related to endocrine, after pregnancy, estrogen and progesterone increase, showing the phenomenon of breast swelling and pain, nausea, vomiting, loss of appetite, drowsiness or weakness, these are physiological pregnancy reactions, this situation is not too worried. Chest pain starts from 40 days of pregnancy and should last until the end of pregnancy, and this phenomenon can be relieved after the birth of the baby. However, after the baby is born, there will be milk secretion and a slight tingling or swelling sensation. As long as the pain is not particularly severe and there are no hard lumps in the breast, no special treatment is needed. During this period, if the pain is unbearable and there is a swollen lump, it is considered to be a disease such as breast enlargement or lobular hyperplasia.