If you have a small breast during the breastfeeding period, it may be due to physiological factors, or it may be due to mastitis, breast hyperplasia and other diseases, which should be treated according to the specific situation. 1. Physiological factors: Many breastfeeding mothers are likely to have a problem with their breasts, mainly due to improper breastfeeding, such as breastfeeding without the two sides of the wheel of milk may form the breasts on one side of the side of the small, breastfeeding need to take turns on both sides of the wheel of milk, in order to improve the problem of breasts, a small one. If this situation is more obvious, you can consider looking for a professional breastfeeding teacher massage, can improve this problem, massage before the best do a hot compress. 2. Mastitis: Mastitis is an acute suppurative infection of the breast, most often caused by bacteria invading the breast tissue through the nipple cracks or the mouth of the milk ducts. The disease begins with swelling and pain in the breast, a lump that is painful to press, redness and swelling of the surface, and fever; the presence of mastitis on one side of the breast can lead to a large breast and a small one. It can be treated with antibiotics under the guidance of the doctor, such as penicillin, erythromycin, etc. When the condition is serious, surgery can be chosen. 3. Mammal hyperplasia: Mammal hyperplasia is a common breast disease in women, and its symptoms are mainly breast pain, breast lumps, nipple discharge, etc. When one side of the mammary gland is hyperplasia, there will be a big and small breast, and you can use medication under the guidance of the doctor, such as lactic acid elimination, or you can choose surgical treatment to remove the hyperplasia lumps. In addition, breast fibroadenoma, breast cancer, congenital factors may also appear similar clinical manifestations, breastfeeding chest a small, it is recommended to go to the hospital to avoid delays.