It is normal for preterm babies to eat 40ml of milk sometimes and 80ml of milk sometimes. Preterm babies are generally advocated to be breastfed on demand in the early stage of their life, 40ml of milk means that the baby may not be very hungry; 80ml of milk means that the baby is hungry. The amount of breastfeeding per day for preterm babies depends on the gestational age and weight, the smaller the gestational age, the more water is needed in the body, and the more milk is needed per kilogram of body weight. Usually, when a preterm baby is in a stable feeding state, the lower the weight, the lower the amount of breastfeeding, and the higher the amount of breastfeeding. Since the weight and age of the preterm infant are not known, it is not possible to estimate the normal daily milk intake. However, since breastfeeding on demand is generally advocated for preterm infants in the early stages, it is normal for both 40 ml and 80 ml of milk to be consumed. The consumption of 40 ml of milk indicates that the infant’s time from the previous feeding was too short, and the child may not be too hungry, so he or she eats less. Eating 80 ml of milk means that it has been too long since the previous feeding and the baby may be hungry. However, as long as there is no other abnormality in the baby, it is usually normal. Parents are advised not to be overly anxious, to carefully observe the baby’s condition, and once abnormalities occur, to seek timely and complete the relevant examinations and standardized treatment.