Newborns’ weight will decrease physiologically in the first 10 days, and their weight may increase by 1~1.7kg in the first month. After birth, due to insufficient milk intake, water loss, meconium discharge and other reasons, there can be a temporary weight loss, the range of decline is 3%~9% of the newborn’s weight, usually in the 7th~10th day can gradually restore the weight at birth. According to our statistics, the weight of a newborn can increase by 1~1.7kg, i.e. 2~3.4 pounds in the first month. Newborn weight gain is only a reference range, the specific situation varies from person to person, acquired feeding, exercise, sleep, disease and other factors have an impact on the weight, can not be assessed only through the weight of the newborn’s development.