The causes of babies sleeping on their stomachs are categorized as physiological and pathological. Physiological may be related to the baby’s sense of security when sleeping. Pathological may be related to the baby’s abdomen cold, gastrointestinal dysfunction or upper respiratory tract infection. 1. physiological: the baby before birth, in the mother’s body posture is the back outward, the body curled up, so the baby will like to sleep on his back after birth, sleep on his back position for the baby has a greater sense of security, the most stable sleep. 2. Pathological: (1) abdominal cold: when the baby’s abdomen is cold, the baby will naturally want to warm the cold parts, the baby lying on his back position, can make the abdomen feel warm. (2) gastrointestinal dysfunction: when the baby gastrointestinal dysfunction, there will be indigestion, food accumulation and other symptoms, the baby lying on his back to promote gastrointestinal peristalsis, can relieve the baby’s discomfort. (3) upper respiratory tract infection: when the baby upper respiratory tract infection, there may be symptoms of nasal congestion, the baby by lying on the posture to relieve the symptoms of nasal congestion. Babies sleeping on their stomachs may also have other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.