A 4-month-old infant should be fed 800-1000 ml of milk a day, with each dose being about 150-180 ml. Therefore, the infant can be fed 5-6 times a day, about once every 3-4 hours, and at night the interval can be extended to once every 4-5 hours. Infants before 3 months of age need to be nursed on demand, while infants between 3 and 4 months of age gradually begin to be fed regularly, with the number of meals related to their age, the amount of food they eat at each meal, their stomach capacity, etc. Usually, they are nursed 5-6 times a day, about once every 3-4 hours, and the interval between feedings can be extended at night. After full-term infants are more than 5-6 months old, their digestive system is relatively mature, their hand and mouth movements are coordinated, their heads are erect and stable, and their backs are well supported, so they can consider adding complementary foods, i.e. iron-fortified rice flour, and gradually increase the amount instead of a meal of milk. The main source of nutrition for infants younger than 6 months of age is breast milk or formula, after 5-6 months of age, complementary foods should be added gradually to meet the nutritional needs of babies.