Breastfeeding breast swelling and pain may be caused by milk stagnation, mastitis, breast hyperplasia and other factors, it is recommended to consult a doctor in time to identify the cause of treatment. 1. Breast milk stagnation: During the breastfeeding period, due to excessive milk secretion and untimely breastfeeding, the milk will be stagnated in the breast, which will cause edema and pain in the long run. Thus, the situation of breast swelling and pain during breastfeeding occurs. You can massage the area, apply hot compresses, or use a breast pump to encourage the breasts to empty. 2. Mastitis: Long-term breast milk is not timely cleaned up, will breed bacteria, bacteria invasion easy to produce mastitis, breast pain is significantly worse, may even be accompanied by symptoms of fever. This can lead to breast swelling and pain during breastfeeding. 3. Mammary gland hyperplasia: The level of estrogen in the body will increase during the breastfeeding period. This can lead to breast enlargement, which in turn can lead to breastfeeding breast swelling and pain. If the situation is not serious, you can relieve it by applying hot compresses. If the situation is serious, you should stop breastfeeding in time and take treatment under the guidance of the doctor. In addition, breast trauma, breast fibroma, breast malignant tumors may also appear similar manifestations of breast swelling and pain during breastfeeding, it is recommended to go to the hospital in a timely manner to conduct relevant examinations, under the guidance of the doctor for treatment.