What is meant by corrected age in premature infants?

Corrected Age in Premature Infants

Corrected age (also called adjusted age) is the age a premature infant would be if calculated from their expected due date rather than their actual birth date, and it is essential for accurately assessing growth and development in preterm infants. 1, 2

How to Calculate Corrected Age

• Subtract the number of weeks born early from the infant's chronological age 1
• For example, an infant born at 28 weeks gestation (12 weeks early) who is now 16 weeks old chronologically would have a corrected age of 4 weeks (16 weeks - 12 weeks = 4 weeks) 1
• This adjustment accounts for the developmental time the infant missed in utero 1, 3

Why Corrected Age Matters

• Preterm infants' brains are developmentally delayed compared to term infants - even full-term neonates with congenital heart disease show brain maturation averaging only 35 weeks' gestation 4
• Using chronological age instead of corrected age systematically underestimates preterm infants' development and growth, leading to misdiagnosis of delays and inappropriate interventions 3, 5
• Without age correction, up to 72.9% of preterm children can be misclassified as stunted and 89.8% as underweight 5

When to Use Corrected Age

For Growth Assessment

• Corrected age must be used for all growth parameters (weight, height, head circumference) through 36 months of corrected age in extremely preterm (<28 weeks) and very preterm (28 to <32 weeks) infants 5
• The American Academy of Pediatrics recommends plotting growth on appropriate charts with gestational age correction, typically until age 2-3 years 2

For Developmental Assessment

• Full correction should be applied during the first year to avoid over-referral for developmental services 6
• Correction remains necessary through 3 years of age for cognitive, language, and motor assessments in most preterm infants 7
• At 2 years, very premature children (<32 weeks) show development equal to or better than term children without correction, though correction may still be appropriate depending on degree of prematurity 6
• Even late and moderately preterm infants (32-36 weeks) show significantly higher developmental test scores when corrected age is used - mean differences of 2.1 points for cognitive and 2.5 points for language scores 3

For Clinical Decision-Making

• Corrected gestational age is critical when assessing postoperative apnea risk - former preterm infants <46 weeks' corrected gestational age require at least 12 hours of postoperative monitoring after general anesthesia 1
• Younger corrected gestational age correlates with higher perioperative complications - infants ≤43 weeks' corrected age have higher surgical complication rates 1
• Corrected age helps identify high-risk periods for cerebral palsy diagnosis, which can be made before 6 months' corrected age using appropriate tools 1

Common Pitfalls

• Not correcting leads to systematic underestimation of abilities - chronological age results in scores up to 5.2 z-scores lower than corrected age for length measurements at term 5
• The impact varies by degree of prematurity - greater prematurity (more weeks early) creates larger discrepancies between corrected and chronological age assessments 8, 7
• The effect is most pronounced at younger ages - the absolute difference between corrected and chronological scores decreases as children get older but remains clinically significant through age 3 years 8, 7
• Higher baseline functioning shows greater score reductions when uncorrected - children performing at average levels show more dramatic drops in scores when chronological rather than corrected age is used 8, 7