Why does my baby keep spitting up milk?

It is a common phenomenon for infants to spit up milk, mainly due to the following reasons: 1. Gastrointestinal system abnormalities: An infant's gastrointestinal system is not fully developed and may have characteristics such as a small stomach volume, a horizontally positioned stomach, and a relatively relaxed cardiac sphincter. 2. Improper feeding: The infant's stomach is in a horizontal position and in an unstable state, while the esophagus and the entrance of the stomach are also in a relaxed state. The infant's stomach cannot contract effectively, and incorrect feeding posture can easily cause milk to flow back into the esophagus, resulting in vomiting. 3. Milk allergy: If an infant is allergic to formula milk, frequent spitting up may occur. Allergic reactions generally accompany symptoms such as diarrhea and rashes. If such symptoms appear, the type of formula milk should be adjusted. 4. Pathological causes: If a baby is infected by bacteria or viruses and develops an upper respiratory tract infection, typical symptoms may include coughing and phlegm production. Coughing can increase abdominal pressure and accelerate breathing rate, which may lead to spitting up during feeding.