20-day-old babies can be seen in physiological phenomena, pathological conditions (such as gastrointestinal dysfunction), according to the baby’s specific situation to analyze and judge. 1. Physiological phenomenon: If the sleeping environment is too high in temperature or the blanket is too thick, making the baby feel uncomfortable, the above performance can occur, or some babies can also be shown as “grunting and making efforts” at the beginning of sleep, usually without abnormal discomfort, which is a normal physiological phenomenon. 2.Pathology (1) Gastrointestinal dysfunction: If the baby is not fed or cared for properly, the baby may have abdominal discomfort such as bloating, which may be accompanied by spitting up and vomiting, and the phenomenon of “grunting” may occur during sleep. (2) Constipation: When the baby has not defecated for a few days or the stools are obviously dry, the above situation may also occur, and is relieved by the use of corkscrew. In addition, there are other reasons for similar symptoms, such as increased nerve excitability due to vitamin D deficiency. It is recommended to consult a doctor as soon as possible for a definitive diagnosis and targeted treatment.