Hardness and pain in the chest after giving birth may be caused by breast milk stagnation, breast abscess, breast hyperplasia and other reasons. 1. Breast milk stagnation: If you don’t master the correct way of breastfeeding after giving birth, the milk on both sides is not emptied in time, and too much milk may block the milk ducts, thus forming a painful lump, and the chest will be hard and painful. 2. Breast abscess: After the milk is stagnant and leads to breast congestion or the blockage of the milk ducts further aggravates, inflammation and infection of the mammary glands may occur. Mastitis further develops, and the milk forms an abscess in the breast, which will also have the symptom of hardness and pain in the chest. 3. Mammary gland hyperplasia: If a woman has mammary gland hyperplasia after giving birth, the breast tissue will appear nodular or lumpy, accompanied by pain, which will also show hardness and pain in the chest. There are many reasons for postpartum hardness and pain in the breasts, and we recommend that you consult a doctor if it is serious.