Whether the weight loss of newborn babies is normal depends on the time, if it occurs within 10 days after birth, it can be considered normal. Because generally 2-3 days after birth, meconium excretion, fetal fat absorption, coupled with water loss and less milk for newborn children, a transient weight loss can occur, which is clinically called physiological weight loss. The weight loss is not a lot, but generally 6%-9% lower than the birth weight, for example, the birth weight is 3000g, if the weight drops to 2700g, it is normal, if it drops to 2500g, it is too much, possibly due to insufficient feeding. If the weight is more than 10% of the birth weight, or if the weight drops to a minimum during the first week after birth, i.e., 6-7 days, and then slowly rises, but does not return to the birth level by the 10th day, this is an abnormal weight loss and should be looked at to see if the child is not fed enough, does not have enough milk, or is sick. Especially for breastfed children, when there is not enough breast milk, the child can not eat and let go. Secondly, not all children will look for milk, and some will not look for milk when they are half full. Therefore, if they are not fed enough and are not hydrated enough, they will lose weight more quickly. In addition, if a child has pneumonia or is born prematurely, as in the case of premature children, many times the weight has not returned to the birth weight in 3 weeks, so this situation is caused by a disease, as long as the disease is removed, the weight will rise.