Some parents often ask how to evaluate their children’s growth and development, while others ask whether their children are developing normally and so on. First of all, you have to be clear that the growth and development of children includes two major parts, one of which is physical development, and the other is neuropsychological development (commonly known as intellectual development), when both development is normal, it can be called a healthy child. Physical development includes weight, length, head circumference, chest circumference, and nearly 10 other items. Among them, weight and length are important indicators. And weight is the most sensitive indicator to observe the physical development of children. Every parent often weighs their children, but what is the practical significance of weight for children? How to evaluate it? Not many people really know. Guo Qinghua, Department of Endocrinology, Beijing 301 Hospital, Beijing, China Weight is the total weight of body organs, tissues, and body fluids. It can promptly reflect the recent nutritional status and disease of the pediatric population. Therefore, it is important to weigh children regularly. Generally speaking, it is best to measure the weight of children within 6 months once a month, 6 months to 1 year old every 3 months, more than 1 year old every half a year, more than 3 years old once a year. Measurement of weight is best to use a lever weighing, to check the zero point before measurement, should be removed from the pediatric outerwear, shoes and hats, older children try to empty urine, so that the value of the weighing is more accurate. Normal newborns weigh more than 2500 grams at birth, if less than 2500 grams for low birth weight, if equal to or more than 4000 grams for the giant. Newborns just born due to more sleep and less food, breathing, skin evaporation and urine and feces discharge lead to weight loss, this situation is known as physiological weight loss, 3-4 days after birth, the lowest point of weight loss, generally no more than 7% -8% of the birth weight, and then gradually increase, 25-30 grams per day, 7-10 days, and then gradually increase the weight of the baby. Afterwards, the weight gradually increases by 25-30 grams per day and returns to the birth weight in 7-10 days. At the end of the month, the baby should have gained 600-800 grams. The first year of life is the period of fastest weight gain. For example, a child with a birth weight of 3 kilograms will weigh twice as much as at birth at 3 months, about 6 kilograms, three times as much at 1 year, about 9 kilograms, and four times as much at 2 years of age, and after 2 years of age, he or she will gain an average of 2 kilograms per year. Length (height) is the distance from the top of the child’s head to the bottom of the foot. children under 3 years of age are measured in a prone position, so they are called length, and after 3 years of age, they are measured in an upright position, so they are called height. Hats, shoes, and socks should be removed when measuring length.There is a close relationship between length and nutrition and disease in children up to 3 years of age.After 3 years of age, height is more clearly influenced by race, genetics, and the environment.Short-term nutritional changes are not significantly associated with length, and short-term nutritional changes are not significantly associated with length. Length is not significantly related to short-term nutritional changes, but it is related to long-term nutritional status. Length also increases most rapidly during the first year of life. For example, a child’s length at birth is 50 cm, and grows about 25 cm in 1 year. at 1 year of age, the height is about 75 cm, and grows about 10 cm in the second year, and then increases by an average of 5-7 cm per year until puberty. if the child’s annual growth rate is less than 5 cm/year, it is important to go to the hospital for a systematic endocrine examination in a timely manner. If the infant’s weight and length increase regularly is one of the signs of health. When the child’s weight and length do not grow regularly, it means that the feeding method may be inappropriate, overfat may be over-nutrition, slow growth or no growth may be due to poor quality of food or diseases (such as pneumonia, diarrhea and other diseases) affecting the development of the child’s body, you should actively find out the causes and take measures.