Vitamin AD drops are best taken from 7:30-8:30 am. Vitamin AD is cod liver oil, which can promote bone growth as well as calcium absorption. When used with calcium supplements, it can play a synergistic role, thus reducing and avoiding rickets in children. In most cases in the morning, when the baby has just finished breast milk or formula, taking vitamin AD drops after meals can promote the absorption of the drops. During this period, the child sleeps less and is more active, which helps the gastrointestinal tract to digest and absorb and utilize vitamin D more. If the weather is sunny at this time, parents can take their baby outdoors in the sun, which is good for the transformation of vitamin D and better promote the absorption of calcium in the baby’s body. It is best to take calcium orally at night, when growth hormone secretion is high, which helps children to grow and develop better. Generally children can take daily vitamin AD drops about 2 weeks after birth, but when consuming, the blood level of vitamin AD should be reviewed regularly so as to guide the adjustment of dosage.