The postpartum systemic resistance to infection is reduced, and milk is a nutrient-rich petri dish for bacteria, and the stagnant milk is conducive to the growth and reproduction of invading bacteria. The following is an explanation of the causes of mastitis formation during lactation, what diseases it causes after formation and prevention. Causes of mastitis formation: ① the nipple is underdeveloped (too small or invaginated) to prevent breastfeeding; ② too much milk or the baby sucking less milk, so that the milk can not be completely emptied; ③ the milk ducts are not open, affecting the discharge of milk. Causes of cell invasion: Nipple breakage allowing bacteria to invade along the lymphatic vessels is the main way of infection. Infants sleeping with nipples in their mouths â⒬“ or infants with stomatitis â⒬“ also facilitate direct invasion of bacteria into the milk ducts. The causative organisms are mainly Staphylococcus aureus. At the beginning of the disease, the affected breast is full and enlarged, accompanied by swelling and pain, local hardening and formation of hard masses, and sometimes “worm-like” varicose milk ducts can be seen around the masses. If the abscess is not treated in time, there will be fluctuating sensation and swollen and painful lymph in the axilla on the affected side. It may cause loss of appetite, increase in body temperature and chills. At this point, an abscess may have formed and needs to be ruled out by breast ultrasound. Surgical incision and drainage is required when an abscess is formed, but conservative treatment may be attempted in rare mild cases. The clinical manifestations of abscesses are related to the depth of their location; in shallow locations, there is local redness, swelling, heat and pain in the early stages, while in deep abscesses the local manifestations are often not obvious in the early stages, and local pain and systemic symptoms are the main symptoms. Abscesses can be single or multiple; they can be formed successively or simultaneously; sometimes they break on their own or are discharged through the nipple, or they can invade the loose tissue in the posterior space of the breast and form posterior breast abscesses. Most Chinese people have the habit of “sitting on the moon” after giving birth, and this period is also the most prone to breast abscesses, which are formed by the following reasons in addition to the appeal: 1. The old habit of not bathing during the “menstruation” period, which decreases personal hygiene and causes the increase of bacteria on the skin surface; 2. Even the artificial formation of breast abscess or delayed treatment time. Once an abscess is formed, the old treatment principles are: 1. incision and drainage 2. stop breast milk 3. anti-infection. Nowadays, it is not necessary to stop breastfeeding for patients who have the will to continue breastfeeding after incision and drainage, except for the influence of drugs. The prevention of mastitis during breastfeeding is more important than the treatment, and lactation is the most crucial for both prevention and treatment. Different lactation techniques are used at different times, and the correct lactation technique can quickly reduce the patient’s symptoms and promptly exclude the petri dish for bacterial reproduction; incorrect techniques can aggravate local symptoms and cause systemic infection by introducing bacteria into the bloodstream. ”I hope this insight will show the way for confused mothers.