The most important thing that newborns need to supplement after birth is vitamin A and vitamin D. Vitamin A is to prevent night blindness, and vitamin D is to prevent the occurrence of vitamin D deficiency rickets, which is often referred to as calcium deficiency. The reason why you need to supplement vitamin A and vitamin D so early is because early newborns, especially inside the full moon, do not see sunlight, and vitamin D is synthesized in the body through sunlight on the skin, so if there is no sunlight, the baby will be deficient in vitamin D. Therefore, newborns should be supplemented with vitamin D to prevent the occurrence of vitamin D deficiency rickets, and if vitamin D deficiency rickets occurs, it should be If vitamin D deficiency rickets occurs, it should be treated early.