The role of vitamin D is to promote the absorption of calcium and phosphorus, and premature babies have insufficient calcium and phosphorus reserves. According to China’s “Recommendations for the Prevention and Treatment of Vitamin D Deficiency Rickets”, premature babies should receive vitamin D supplementation of 800 to 1000 U/day immediately after birth, changing to 400 U/d after 3 months until 2 years of age. Premature babies have low iron reserves and are very prone to anemia, which directly affects physical and neurological development. According to the recommendations of domestic and foreign experts, preterm babies need to start supplementation with elemental iron at 24 mg per kg body weight per day 2 weeks after birth until the corrected age of 1 year. This supplementation includes iron in iron-fortified formulas, breast milk fortification, food and iron preparations.