Three-month-old baby hands and feet keep moving, if overheating, hungry, etc. is a normal phenomenon; if eczema, prickly heat and other itchy skin caused by the lack of vitamin D, etc., then belong to the cause of disease. 1. Physiological phenomenon: three-month-old babies neurological, motor system development is not perfect, often appear unconscious limb activity, in addition to excessive clothing, hunger, urination and defecation may occur when the hands and feet activities increased, accompanied by crying, etc., is a normal phenomenon. 2. Skin diseases: baby eczema, prickly heat and other skin diseases, accompanied by rashes, itching, tingling and other discomforts, may cause the baby’s limbs activities scratching, rubbing to help relieve. 3. Vitamin D deficiency: Vitamin D deficiency can lead to increased neural excitability in babies, frequent hand and foot activity, accompanied by growth retardation, excessive sweating and other symptoms. Three-month-old baby hands and feet keep moving, there may be other causes, 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.