A one-month-old baby who cries all the time is usually due to physiologic factors such as hunger, environmental discomfort or pathologic factors such as meningitis and intestinal cramps. 1. Physiological factors: (1) hunger: if feeding is not timely, one-month-old babies will keep crying if they are always hungry, and mothers should pay attention to whether it is time to feed. (2) environmental discomfort: such as the surrounding environment temperature environment appears too cold, too hot, can lead to infant discomfort, thus appear one-month-old baby has been crying. 2. Pathological factors: (1) meningitis: when a one-month-old baby has meningitis, he or she may cry all the time due to physical discomfort. (2) intestinal spasm: infants are more prone to intestinal spasm due to their fragile digestive system, which can lead to abdominal pain, thus causing them to cry all the time. There may be other reasons why a one-month-old baby keeps crying, so it is recommended to go to the hospital in time for a complete examination to clarify the cause of the disease and then give targeted treatment or therapy.