Do babies have calcium deficiency? Some of them are normal babies, some are late teething, and some have occipital baldness, night sweats or restless sleep and night crying. Are these problems related to calcium deficiency or not? Vitamin D insufficiency is the cause of calcium deficiency Normal babies in infancy and early childhood physical growth and development rate is rapid, such as the length of about 50 cm at birth, the average length of 25 cm at the age of one year, the second year and the third year of growth of 10 centimeters and 8 centimeters, respectively. With such rapid growth, babies need a lot of calcium and phosphorus in their bones to make them hard. When a baby’s body is deficient in calcium, it first shows up in a soft skull, a large fontanel, and a ping-pong feeling when the head is pressed. Later, the appearance of the chest bones is abnormal, such as the sternum protruding like a chicken breast and the lower edges of the two ribs turning out. If the bones of the lower limbs are soft, standing and weight-bearing cause ‘0’ legs or ‘x’ legs. In addition to skeletal changes, early manifestations include excessive night sweating, occipital baldness, restless sleep and easy to startle. The above manifestations are called vitamin D deficiency rickets. As the name suggests, this disease is caused by insufficient vitamin D intake. Vitamin D promotes the absorption of calcium and phosphorus in the small intestine, so that calcium is deposited from the blood into the fast-growing bones, making the bones hard. Therefore, calcium deficiency in infants and children is caused by vitamin D deficiency. Calcium deficiency is the ‘fruit’ while vitamin D deficiency is the ’cause’ of calcium deficiency.