At present, the weather is getting colder and colder, the time of outdoor activities for infants and young children is reduced, some mothers are afraid of their children catching a cold, and even do not let their children go out in winter, there is no opportunity for sunshine, plus the children grow and develop faster, need more calcium, such as not timely calcium supplementation, it will lead to calcium deficiency. The main manifestations of calcium deficiency are: 1. More sweating, independent of temperature. Occipital bald circle appears behind the skull and hair is thinning. 2, mental irritability, sometimes crying, sleep disturbance, often suddenly awakened at night crying. 3, late teething, delayed closure of fontanelle, 1.5 years old still not closed, high forehead protrusion, the formation of square skull. 4, often have a beaded chest, chicken chest, funnel chest, sitting and walking weakness, such as standing too long or walking too early can form “X” leg, “O” leg. 5.Fat body, muscle flabbiness, easy to repeatedly cold. The performance of calcium deficiency in children varies, so parents should judge whether their children are deficient in calcium according to their own performance, so that they can make up calcium in time to reduce the symptoms. In terms of diet, give your child more calcium-rich foods, such as fish, shrimp, kelp, bone broth, etc. Also, eat foods rich in vitamin D, such as animal liver, to promote the absorption of calcium. It is also recommended that parents take their children outdoors and get more sunlight, around 10 a.m. and 3 or 4 p.m., for half an hour each time. The ultraviolet rays in sunlight can transform subcutaneous T-dehydrocholesterol into vitamin D3, which can promote the absorption of calcium in the body. If the symptoms of calcium deficiency are more serious you should go to the hospital for calcium supplementation under the guidance of a doctor.