A birth occurring before 37 full weeks of pregnancy is considered a premature birth. This early arrival interrupts the developing baby’s final stage of growth and maturation. The developmental trajectory of an infant born prematurely often begins on a different timeline than that of a full-term baby. The concern for developmental delays is common, and medical professionals use a specific calculation to accurately assess a preemie’s progress against their peers.
Understanding Adjusted Age
The concept of adjusted age provides a more accurate framework for assessing the growth and development of infants born before their due date. Adjusted age, sometimes called corrected age, calculates the child’s age by accounting for the weeks of gestation missed. This calculation is derived by subtracting the number of weeks the baby was born early from their chronological age, which is the time elapsed since their birth.
For instance, if a baby is six months old chronologically but was born two months early, their adjusted age is four months. Medical professionals rely on this adjusted age to evaluate whether a premature infant is meeting developmental benchmarks. This metric ensures that expectations for milestones are realistic, comparing the preemie’s development to what would be expected had they been born at full term.
Catch-Up Timeline for Physical Milestones
Physical development, encompassing gross motor skills, fine motor skills, and overall physical growth, is typically the first area where catch-up is observed. Gross motor milestones, such as lifting the head, rolling over, and sitting unsupported, are generally reached according to the adjusted age rather than the chronological age. For example, an infant born eight weeks early would likely begin to sit up eight weeks later than a full-term peer.
Physical growth, including weight, length, and head circumference, is monitored using specialized growth charts initially. Many premature infants experience a period of rapid “catch-up growth” during the first year of life. For most preemies without severe complications, physical growth and the achievement of major gross motor milestones, like walking, align with their full-term peers by 18 to 24 months of adjusted age. Fine motor skills, such as grasping and manipulating objects, also follow this adjusted timeline.
Catch-Up Timeline for Cognitive and Language Skills
Cognitive and language skills, involving complex brain functions like communication, problem-solving, and social interaction, often have a more varied catch-up timeline compared to physical skills. Initially, the development of these skills is assessed using the adjusted age. This means a child’s first words or their ability to solve simple problems is expected later than their chronological peers. Using the adjusted age during the first year helps avoid over-identifying developmental delays that are simply a product of biological immaturity.
While convergence occurs early on, some subtle differences in cognitive and language development may persist longer than physical ones. The gap in these areas often narrows considerably throughout the toddler and preschool years, generally between 24 and 36 months of adjusted age. Many children born prematurely become indistinguishable from their full-term peers in their language abilities by early school age. Consistent monitoring and early intervention services, if necessary, support the development of these less visible skills.
When Pediatricians Stop Tracking Adjusted Development
The practice of using adjusted age for routine developmental tracking is not indefinite, as the biological differences between preemies and full-term infants diminish over time. For the majority of children born prematurely without ongoing health complications, pediatricians typically stop using the adjusted age for developmental screening around 24 months of chronological age. By this time, the child’s development is generally expected to align closely enough with their chronological age peers that the adjustment is no longer necessary.
This two-year mark represents a point of convergence where most of the initial developmental gap has been resolved. The child is typically tracked against standard growth and development charts afterward. By the time children born prematurely reach three to five years of age, most are indistinguishable from their full-term peers in nearly all aspects of their growth and development.