The first cause is milk stasis, which occurs when, due to incorrect positioning during nursing or breastfeeding, a child inadvertently causes the milk ducts to close, leading to a significant accumulation of milk within these ducts. The milk inside the ducts provides an excellent medium for bacterial growth. The second cause is bacterial invasion, mainly through cracks and fissures in the nipple. Bacteria enter the milk ducts through these fissures or breaks, causing inflammation. The third cause is a decrease in the body's immune function, for example due to severe mental stress or lack of sleep. All of these are the primary causes of acute mastitis.