Newborns can take cod liver oil 1-2 weeks after birth, as appropriate, until 2 years of age. Cod liver oil mainly contains vitamin A and vitamin D, which helps infants and children grow and develop. Newborns grow and develop rapidly, and with insufficient light, they are prone to vitamin D deficiency and vitamin D deficiency rickets. In addition, vitamin A deficiency can appear dry skin mucosa, reduced resistance, pediatric night blindness, etc.. Therefore, full-term newborns should take prophylactic oral cod liver oil at 400 units per day until 2 years of age. Premature babies, low birth weight babies or twins should take cod liver oil orally one week in advance until 3 months after delivery at 800 units per day; after 3 months, they should be supplemented with 400 units per day until 2 years of age. In addition, increased outdoor exercise is also beneficial to the production of endogenous vitamin D. Therefore, the dosage of cod liver oil can be reduced at the discretion of infants and children with greater outdoor exercise.