Smaller than gestational age infants (SGA for short) are also called intrauterine growth retardation, commonly known as “small-like infants”, and can be preterm, term or late term infants. Newborns with standard deviation. Simply put, this means a birth weight of less than 2,500 grams. SGA may lead to short stature, mental retardation, delayed sexual development, and other disorders in children in adulthood. Whether the growth rate of children younger than gestational age accelerates in the first 2 years of life, especially the first 6 months, is of great importance for their final height. So how many of these children will catch up to normal height among them? According to the study, 40% of the children catch up with the normal height in the first 6 months after birth, 25% catch up with the normal height before 3 years of age, and 20% catch up with the normal height after 3 years of age, but about 15% of the children younger than gestational age still grow up to be short. Some studies have also reported that most children less than gestational age catch up with normal infants within 6 to 12 months after birth, and 10% to 30% do not have accelerated growth after birth, and the average height of these children as adults is 162 cm for boys and 147 cm for girls. A Swedish study suggests that less-than-normal length at birth is less than normal for children of gestational age, and 80% are below normal height at age 18, so short stature at birth is more important than low weight. Our researchers reported 121 cases of less than fetal age children born in a hospital from 1986 to 1989, who grew an average of 20-22 cm from birth to 6 months, growing faster than normal children (16-18 cm), with 64% reaching the normal range in length by 6 months (above the 10th percentile), and 85% reaching the normal range in length by 2 years of age, but their average length was at However, their average length was in the low to moderate range (25th percentile). Some of the children with SGA may still grow slowly after birth, i.e., their height tends to remain below the third percentile and rarely exceeds the fiftieth percentile. Chatelain et al. reported that 49% of SGA (105 cases) had peak serum hGH below 10ug/ml after two growth hormone stimulation tests. This suggests that children with SGA have insufficient growth hormone secretion. In addition, some researchers measured the 24-hour growth hormone secretion profile of children with SGA and found that the spontaneous secretion of growth hormone was reduced by about half compared with normal children, and their serum insulin-like growth factor 1 levels were relatively low. children with SGA have inadequate or abnormal growth hormone secretion, resulting in a low final adult height. Alert parents to children with SGA!!! Most children younger than gestational age can catch up with the height level of normal children if they are fed properly after birth, do not have or have few illnesses, and if the child has a regular and happy life.