Four-month-old baby hair fall a lot, the first consideration is a normal phenomenon, the second is also considered to be caused by zinc deficiency, vitamin D deficiency rickets and other reasons. 1. Normal phenomenon: four months baby due to a long time in the sleep state, which will lead to a long time the head is compressed, hair is friction, easy to cause hair loss. This is a normal physiological phenomenon, generally in the baby grows up, often change the sleep position after the symptoms will improve. 2. Zinc deficiency: Zinc deficiency is caused by insufficient intake of zinc, absorption disorders and excessive loss of zinc. Patients will not only have different degrees of hair loss, but also anorexia, xerophagia, skin rashes, stomatitis and other manifestations. If a four-month-old baby has zinc deficiency, there will be a lot of hair loss symptoms. 3. Vitamin D deficiency rickets: Vitamin D deficiency rickets is due to insufficient sunlight, too fast growth rate and other factors. Patients will have symptoms such as occipital baldness, excessive sweating, irritability and irritability. If a four-month-old baby develops vitamin D deficiency rickets, he or she will show a lot of hair fall. Four-month-old baby hair fall a lot, there may be 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.