Postnatal age minus the number of weeks born before the gestational age of 40 weeks. For example, an infant born at 30 weeks gestation and tested at 20 weeks after birth has a corrected age of 20 a (40-30) = 10 weeks. This preterm infant can then be compared to full term infants with a postnatal age of 10 weeks. The rationale for using corrected age is that development is a function of time since conception and not time from birth. Thus, corrected age matches preterm and full term infants in terms of ‘level of maturity’. There is still an outgoing debate as to how long corrected age should be used and for which functions in assessing the development of preterm infants.
See Chronological (or postnatal) age, Gestational age, Preterm infant