Colostrum is the milk produced by the breasts within 2-3 days after delivery, and most of them do not exceed 7 days, with some individual differences. During pregnancy, the estrogen, progesterone and placental lactogen increase in the pregnant woman’s body, promoting the development of the mammary glands and the secretion of colostrum. Colostrum can start to be secreted in the first 3 days after delivery and can be accompanied by symptoms such as breast engorgement, swelling and pain. Colostrum is yellowish in color, thick in texture, and contains more protein and secretory IgA, which is easily digested and absorbed, making it an ideal natural food for newborns in their early years. Generally, after 1 week, the amount of milk can gradually increase, and then it turns into white mature milk, the protein content in mature milk decreases, and the content of fat and lactose gradually increases. Because colostrum is rich in nutrients, it is usually recommended to be given to newborns to replenish a variety of antibodies needed in the newborn’s body and to improve the newborn’s immune resistance, etc.