Nine-month-old babies shaking their heads can be seen in physiological phenomena, pathological conditions (such as vitamin D deficiency, eczema, etc.), the specific need to combine with the baby’s situation to determine the specific. 1. Physiological phenomenon: for this age group of babies can appear in the process of play, or imitation of people around such actions, usually the baby no abnormal symptoms, mental reaction are good. Or the environment temperature is too high, the baby sweats more to stimulate the scalp can also appear the above behavior, is a normal physiological phenomenon, need to be closely observed. 2. Pathology (1) Vitamin D deficiency: in the early stage of the disease, the baby may have increased sweating and other neurological excitatory phenomena, which can stimulate the scalp to produce discomfort, the baby may appear shaking the head phenomenon, especially at night can be obvious, and some babies may be accompanied by skeletal changes such as square skull. (2) eczema: if the baby has a more serious scalp or facial eczema, resulting in obvious itching, the baby can relieve the discomfort through the above behavior. Nine-month-old baby shaking his head may also have other reasons, it is recommended to go to the hospital in time to improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.