The correct use of breastmilk fortification is to refer to the instructions for use to add, it is generally recommended to transition from half the amount of breastmilk fortification to the full amount and then transition to individualized fortification, you can ask your pediatrician for more details on the specific use. If prolonged exclusive breastfeeding is unable to meet the needs of very low and ultra-low birth weight infants, and growth and development are lagging behind and malnutrition occurs, breastmilk fortification can be added under the guidance of the doctor to make up for the lack of nutrients and meet the growth needs of preterm infants. Refer to the instructions for different fortifiers and add them to breastmilk according to the doctor’s instruction. Generally, it is necessary to start with half amount of breastmilk fortification and gradually increase the amount to the full amount in 3-5 days, and slow down the rate of increase if intolerance symptoms such as frequent vomiting are observed in preterm infants, and if necessary, it is necessary to perform breastmilk composition analysis to add breastmilk fortification on an individualized basis. During the breastmilk fortification phase, the infant’s tolerance and growth should be evaluated regularly and the treatment should be adjusted according to the doctor’s instructions.