If children younger than fetal age are fed properly after birth, if they do not get sick or are less sick, and if they live a regular and happy life, most children younger than fetal age can catch up with the height level of normal children. The growth rate of less-than-gestational-age children accelerates in the first 2-3 years after birth, especially in the first 6 months, which is very important for their final height. How many of them can catch up to normal height? According to the study, 25% of them can catch up with the normal height of children in the first 6 months, and another 20% can catch up with the normal height of children after 3 years of age, but about 15% of the younger-than-gestational-age children still grow up to be short. Some studies have concluded that most children younger 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 is 162 cm for boys and 147 cm for girls when they reach adulthood. The Swedish study concluded that 80% of the smaller-than-normal gestational age children whose length at birth was below normal were below normal height at age 18, so being short at birth is more important than being low weight. The Department of Pediatrics of Peking Union Medical College Hospital in China observed 121 cases of less-than-normal children born from 1986 to 1989, who grew 20-22 cm on average from birth to 6 months of age, growing faster than normal children (16-18 cm), with 64% reaching the normal range (above the 10th percentile) by 6 months of age, and 85% reaching the normal range by 2 years of age, but their average length was at the low to moderate level (25th percentile).