The symptoms of calcium deficiency in a two-and-a-half-year-old baby can be varied, such as a child who does not fall asleep easily, does not fall into a deep sleep easily, cries easily after falling asleep, wakes up easily, and shows excessive sweating after falling asleep. However, the above conditions can also be seen in normal babies. Some affected children can show symptoms such as X-shaped legs, O-shaped legs, chicken breasts, gray or whitish nails, anorexia, partiality, daytime irritability, fidgeting, delayed mental development, late talking, late walking, late teething, sparse, unevenly arranged and uncompacted teeth, thinning hair, poor health, easy to catch a cold, etc. When these symptoms are present, they need to go to the hospital for calcium checkup. If the degree is mild, foods high in calcium, such as fish, shrimp, and kelp, can be provided, while foods containing vitamin D should also be consumed more often to promote calcium absorption.