According to statistics, 20-30% of children in China are suffering from rickets, chondromalacia, osteoarthritis and other bone diseases. In the clinic, we often meet parents to consult their children about calcium supplementation, which we often say is to prevent rickets. So how should we give it to our children? What are the conditions that require supplementation? When to supplement? How to supplement? These are the concerns of our parents. Generally speaking, premature babies and twins should start supplementing VitD about 2 weeks after birth, and normal full-term babies should start supplementing about 4 weeks after birth. 400 IU per day for infants under 6 months old and 400-600 IU per day for infants over 6 months old. Sunlight exposure is an important measure to prevent rickets. Don’t go through glass windows when sunbathing; the ultraviolet rays of the sun rarely penetrate glass windows. Also, try to expose as much skin as possible to increase skin synthesis of VitD. Summer outdoor activities are more, 1 year old baby temporarily can not take VitD, so as not to accumulate in the body caused by poisoning. Breastfed babies can get 225-250 mg of calcium per day from breast milk within 1 year of age, so for breastfed babies within 6 months, there is no emphasis on extra calcium supplementation when the daily cod liver oil needs are met; and breastfed babies from 6 months to 1 year of age also need only a little extra calcium supplementation to be sufficient, and these are basically enough by adding supplementary foods such as rice flour containing calcium. In this case, if the child has no obvious symptoms of calcium deficiency, there is no need for calcium supplements. If the mother takes sufficient calcium supplements during breastfeeding, the baby can get more calcium through breast milk and it is absorbed well. For babies who are mixed or artificially fed, the amount of calcium a baby gets from food throughout the day should generally be determined by the type of food. babies under 6 months of age who are mixed or artificially fed should get about 150 mg of extra calcium per day, and those over 6 months of age should get an extra 200 mg of calcium per day, and generally these can be obtained adequately from formula, fresh milk and other foods. After weaning, it is necessary to give your baby some choice of chewable tablets containing calcium carbonate to supplement calcium because the amount of milk consumed is greatly reduced. VitD and calcium supplementation should be continued until 2 to 2 1/2 years of age. Toddlers do not need VitD and calcium supplements after 2 1/2 years of age when outdoor activities increase and the variety of diet gradually diversifies. However, if your baby has obvious symptoms of calcium deficiency such as night terrors, excessive sweating, and irritability you should bring him/her to the hospital for a consultation.