【Concept】： Small for gestational ageinfant (SGA) is a newborn whose birth weight is below the 10th percentile of the average weight of children of the same gestational age, or 2 standard deviations below the average weight. The incidence of SGA is 2.5% in developed countries in Europe and the United States and 6.39% in China. After birth, these children will have spontaneous catch-up growth, and most of them can catch up with their normal counterparts within 2 years of age. 10-15% of children younger than gestational age do not show adequate postnatal catch-up growth, and these children are short in stature during childhood, and nearly half of them are short in stature in adulthood. Special manifestations】 Neonatal period: malnutrition, wasting subcutaneous fat is obviously thin, dry skin. There is also hypoglycemia occurrence, because after birth, the tissue absorption and utilization of sugar is accelerated, and the glycogen storage in the liver is insufficient, so within 3 days still one third of SGA newborns will have hypoglycemia. Symptoms due to intrauterine hypoxia, such as amniotic fluid contamination, respiratory distress, acidosis, and hypotonia. There are also symptoms of intrauterine infection, hepatosplenomegaly, jaundice prolonged retinal chorioretinitis, hypoadrenocorticism, and weak stress response. Clinical manifestations: Proportional dwarfism, more peculiar facial features, triangular face, small jaw, abnormally wide forehead, small hands and feet and pelvis, relatively large ratio of hands and feet to body length, thin and slender body posture, fat accumulation in the abdomen. There may be clumsy stature, backward intelligence and encouragement, and high blood pressure (predominantly elevated systolic blood pressure). The risk of hyperlipidemia, type 2 diabetes mellitus and coronary heart disease increases in adulthood. [Causes of morbidity] Fetal factors: malformations, chromosomal abnormalities, viral or bacterial infections, multiple births, and other causes, as well as genetic mutations, inherited metabolic defects, and chromosomal abnormalities. Maternal factors: chronic hypertension, drug addiction, smoking, chronic poisoning, malnutrition, anemia, uterine malformation, certain drugs and alcoholism in the mother, or suffering from chronic systemic diseases such as diabetes, immune lupus erythematosus, kidney disease, infection, etc. Preventing mental retardation and short stature】 Children younger than gestational age are “high-risk” newborns and need to be given oxygen promptly when they have respiratory distress and bruising after resuscitation from asphyxia. Early adequate feeding can not only prevent hypoglycemia and help weight gain, but also help the proliferation of brain glial cells and prevent mental retardation. Proper feeding can make less-than-gestational-age children show accelerated growth within 6 months after birth, and most of them can catch up with normal children by the age of 2~3. Mental training is beneficial to promote the development of the nervous system and improve IQ, and early medical intervention and assistance are required. The child’s life should be regular, give more warmth to the child and keep the spirit happy, which helps to improve intelligence and height. 【Treatment of SGA】 If children with SGA do not show obvious catch-up growth after 2 weeks of age, and their height is still significantly behind that of their peers, treatment with growth hormone can be considered. It can enable the affected child to achieve catch-up growth in early childhood, maintain normal growth in childhood, and reach normal adult height. Studies have shown that some children with SGA have an increased risk of hyperlipidemia and coronary heart disease in adulthood, and growth hormone can improve lipid metabolism and reduce the occurrence of coronary heart disease. Growth hormone can also promote the development of brain function in these children, improve intelligence, and normalize cranial and facial growth. The growth in height is accompanied by an increase in hand length, foot length and hip width, resulting in a proportionate figure. The effectiveness of treatment depends on the start of growth hormone treatment, generally: the younger the age, the better the results. The recommended dose is 0.15~0.2IU/(kg・d), and its promotion of height of children is positively correlated with the dose; sufficient dose and course of treatment may make children with this type of dwarfism reach normal height and make lifelong height exceed the expected height. During the treatment, the relevant biochemical indicators and growth indicators should be monitored regularly to ensure the treatment effect!