Formula for preterm infants is generally eaten until the weight can be greater than or equal to 5kg, correcting the gestational age at about 48-52 weeks, but the specific situation should be analyzed. If the child’s gestational week is particularly small, less than 28 weeks, or the birth weight is particularly small, less than 1kg, or if the child’s weight gain is slow after birth, it is recommended to use preterm formula again for a period of time. This is because preemie formula contains higher levels of energy, DHA and ARA. It is important to note that because preterm formula is low in vitamin A and vitamin D, etc., it needs to be supplemented. If the child is gaining weight satisfactorily, eating and pooping well, can meet a weight greater than 5kg, and corrects a gestational age greater than or equal to 48-52 weeks, you can gradually replace the preterm formula with regular formula.