I remember seeing an emergency room with a baby who was not yet full term and had a breast abscess up to the back, which was unbearable to see and really heartbreaking. When I asked about the medical history, it was said that the breast was artificially squeezed in order to pass milk later. The newborn’s breast cannot be squeezed. In late pregnancy, high levels of corpus luteum and placenta in the mother’s blood rush through the placenta into the fetal circulation and thus stimulate the fetal mammary glands. This causes the primitive fetal terminal vesicles to produce milk in a form similar to that of the adult female mammary gland in late gestation. The birth of the infant causes a separation of maternal and fetal circulation, resulting in a rapid decrease in the level of sex hormones in the infant’s circulating blood, followed by the maintenance of prolactin secretion by the infant’s pituitary gland. These conditions again create a state similar to that of the pregnant woman, allowing the nipples of the breast to secrete milk in 80-90% of newborn infants, both male and female. Prolactin levels in newborns then decrease and lactation can cease after the next few weeks. Therefore, lactation and breast swelling in newborns are normal physiological phenomena and are only considered to be of disease origin if they persist. When a newborn is born, it is inevitable that he or she will be a little uncomfortable when he or she is suddenly transferred from the quietness of the womb to the complexity of life outside. The newborn has low immunoglobulin, poor phagocytosis of white blood cells and other immune functions, and very low defenses against bacteria. If parents squeeze the breast, bacteria may often enter the body from the nipple squeeze rupture, thus causing redness, swelling and heat in the breast, and even septic mastitis, which can develop into sepsis in severe cases, bringing great harm to the newborn’s body. Therefore, parents should not squeeze the swollen breast of the newborn.