Babies start supplementing with vitamin A and vitamin D at fifteen days. Vitamin A is necessary to maintain the normal structure and function of the skin, conjunctiva and cornea. Dry eyes, periodontal overflow and night blindness can occur in case of deficiency. Supplementation is beneficial to eye development when started after 15 days of life. Vitamin D promotes the absorption of calcium and phosphorus by the mucous membrane of small intestine, the absorption of calcium and phosphorus by renal tubules, the metabolism of bone, and the balance of blood calcium and blood phosphorus. When deficient, children can suffer from rickets, deformity of bones, loose bones, excessive sweating and infantile hand and foot twitching and other symptoms; timely supplementation is conducive to bone development, improve resistance. It is recommended that you can take your baby to the hospital for a physical examination, and then supplement under the guidance of the doctor.