Corrected age, also known as adjusted age, is a measurement used to accurately track the growth and development of babies born prematurely. This metric accounts for the time a baby missed developing in the womb by calculating their age from their original due date instead of their birth date. The concept acknowledges that a premature baby’s body and nervous system have had less time to mature compared to a full-term infant. Using this specialized age helps set realistic expectations for when a preemie will achieve developmental milestones and provides reassurance to parents who may worry about delays.
Chronological Age Versus Corrected Age
A premature baby has two different ages tracked during their early years. Chronological age is the time elapsed since the baby’s birth, measured in days, weeks, or months.
The second measurement, corrected age, provides a better picture of the baby’s biological maturity. This figure represents the age the baby would be if they had been born at the typical 40-week gestation period. Using corrected age is important because a baby born early has not completed the full period of neurological and physical development.
How to Calculate Corrected Age
Calculating a premature baby’s corrected age requires a simple two-step process focused on weeks. First, determine the number of weeks the baby was born prematurely by subtracting their gestational age at birth from 40 weeks (full-term pregnancy). For instance, a baby born at 32 weeks’ gestation was 8 weeks premature (40 weeks minus 32 weeks).
Next, subtract those weeks of prematurity from the baby’s current chronological age (total weeks since birth). If that same baby is now 16 weeks old chronologically, subtracting the 8 weeks of prematurity yields a corrected age of 8 weeks. This calculation shows that while the baby has been alive for four months, their developmental expectations align with a two-month-old full-term infant.
Using Corrected Age for Developmental Milestones
Pediatricians rely on corrected age to accurately assess a preemie’s development, as comparing them to a full-term peer by chronological age would lead to an expectation of delays. Developmental milestones like sitting up, rolling over, and beginning to speak are typically reached closer to a preemie’s corrected age. When a six-month-old preemie is not yet sitting unassisted, a doctor will check their corrected age, and if it is only three months, the lack of that milestone is viewed as typical.
Corrected age is also used when plotting a preemie’s physical growth on specialized charts. These charts track metrics like weight, height, and head circumference against the corrected age to assess the rate of “catch-up growth.” By adjusting for prematurity, medical teams can monitor if the infant is growing along a healthy curve, ensuring expectations for the baby’s body and brain function align with their biological readiness.
When to Transition Away from Corrected Age
The use of corrected age is generally temporary because most premature infants eventually catch up to their full-term peers developmentally. Health professionals typically recommend using corrected age until the child reaches 24 months of chronological age. For infants born extremely prematurely, this adjustment may be extended slightly longer, sometimes up to three years.
By two years old, the neurological and physical differences attributable to being born early have largely resolved for the majority of children. Once this developmental convergence occurs, doctors begin to track all growth and milestones using the child’s chronological age. The transition signifies that the child is now functioning and developing within the expected range for their actual birth date.