Premature mothers often compare their babies with those full-term babies whose birth dates are about the same size, they feel that their babies are not growing as well as those born at full term, in fact, these parents ignore the problem that their babies are born early and need some time to catch up, for example, a baby born 2 months premature, when he is 4 months old, is actually only equivalent to a 2-month-old baby The growth and development of the baby, so the application of the corrective age can avoid unnecessary anxiety and worry of parents. Corrected age (in months) = actual age (in months) – months of prematurity, or age in months according to the due date. The assessment of the length and weight of preterm babies and the timing of complementary feeding should be calculated according to the corrective age (age of months), especially the motor and intellectual development, including intelligence tests and neuromotor examinations should be judged according to the corrective age. However, by the age of 2 years, the age should be calculated according to the date of birth, and it would be better if the physical and intelligence reach the birth age earlier.