The birth weight of a normal full-term newborn is 2.5-4kg, while those less than 2.5kg are low birth weight babies and those greater than 4kg are huge babies. Some newborns born at normal gestational age weigh less than 2.5 kg, which is a small full-term baby, indicating intrauterine growth retardation. Most newborns born at a gestational age of less than 37 weeks are preterm, and most of them are born at a gestational age and weight that match. The weight growth during the newborn period is between 10-30g per day, with an average growth of about 20g per day. The weight growth of 600g or more in the first month is normal, and the first three months is a period of rapid weight gain, and the weight at three months is about twice the birth weight.