How is age adjusted for premature (premie) infants when assessing developmental milestones and determining treatment plans?

Age Adjustment for Premature Infants

Direct Answer

For premature infants, correct for gestational age when assessing developmental milestones for at least the first 24 months of life, and extend correction through 36 months for growth assessments in extremely and very preterm infants. 1, 2

Developmental Milestone Assessment

Correction Duration by Domain

Developmental milestones should be corrected for prematurity for at least the first 24 months of life. 1 This means you subtract the number of weeks the infant was born early from their chronological age to calculate their "corrected age" or "adjusted age."

• For infants born at less than 32 weeks gestation, full correction should be applied during the first year to avoid overreferral for developmental stimulation 3
• At 2 years of age, correction becomes less necessary for developmental assessment, as preterm children's development equals or exceeds term children without correction 3
• Using chronological age instead of corrected age significantly overestimates developmental delays and leads to misclassification 4

Practical Application

When evaluating a premature infant's development:

• Calculate corrected age: Subtract weeks premature from chronological age 1, 2
• Apply to all developmental domains: Motor, social, language, and cognitive functions should all be assessed using corrected age 1
• Document both ages: Record both chronological and corrected age in the medical record for clarity 4

For example, a 6-month-old infant born at 28 weeks gestation (12 weeks early) should be assessed against developmental milestones for a 3-month-old (6 months chronological - 3 months premature = 3 months corrected age).

Growth Assessment

Extended Correction for Growth Parameters

For extremely preterm (<28 weeks) and very preterm (28 to <32 weeks) infants, age correction is required for all growth measures (weight, length, head circumference) through 36 months of corrected age. 5

• Using chronological age instead of corrected age results in massive misclassification: up to 72.9% misdiagnosed as stunted and 89.8% misdiagnosed as underweight at term 5
• Growth parameters should be plotted on appropriate preterm growth charts (such as Fenton charts) that account for gestational age 6
• The difference between corrected and chronological age-based scores can be as large as -5.2 z-scores for length at term 5

Growth Chart Selection

• Use preterm-specific growth charts (Fenton or similar) from birth through term-equivalent age 6
• Transition to WHO growth standards at 50 weeks postmenstrual age, continuing to use corrected age 6
• Continue correction through 36 months for extremely and very preterm infants 5

Special Populations Requiring Heightened Surveillance

High-Risk Criteria for Brief Resolved Unexplained Events (BRUE)

For premature infants presenting with BRUE, only infants with gestational age ≥32 weeks AND postconceptional age ≥45 weeks qualify as lower-risk. 1 Infants born at less than 32 weeks gestation or those who have not reached 45 weeks postconceptional age are considered higher-risk regardless of other factors.

Congenital Heart Disease

Premature infants with congenital heart disease face compounded neurodevelopmental risk and require heightened developmental screening, including late-preterm infants (34-36 weeks). 1, 7 These infants should be categorized as high-risk and referred directly for comprehensive developmental evaluation rather than relying on screening alone 1

Common Pitfalls to Avoid

Critical Errors in Age Correction

• Failing to correct past 12 months: Many clinicians stop correcting too early, but correction should continue through at least 24 months for development and 36 months for growth in very preterm infants 1, 5
• Using chronological age for growth assessment: This leads to dramatic overdiagnosis of growth failure and unnecessary interventions 5
• Inconsistent correction: Some clinicians correct for some assessments but not others; correction should be applied uniformly across all developmental domains and growth parameters 4
• Forgetting to correct for late-preterm infants: Even infants born at 34-36 weeks benefit from age correction, particularly those with additional risk factors like congenital heart disease 1

Documentation Best Practices

• Always document both chronological age and corrected age in the medical record 4
• Specify which age was used for each assessment to avoid confusion among providers 4
• Educate families about the difference between chronological and corrected age to manage expectations appropriately 4

Treatment Planning Implications

Intervention Thresholds

When determining need for early intervention services, use corrected age to avoid unnecessary referrals in the first 24 months. 1, 3 However, maintain heightened surveillance as premature infants remain at elevated risk for developmental delays even when age-corrected.

• Infants showing delays based on corrected age warrant immediate referral 1
• Infants meeting milestones on corrected age but not chronological age should continue routine surveillance without intervention 3
• At 2 years corrected age, transition to using chronological age for most developmental assessments 3

Specific Milestone Concerns

When taking developmental history, ask parents: "Is there anything your child is not doing that you think he or she should be able to do?" while clarifying you are assessing based on corrected age, not chronological age 1, 2

Red flags requiring evaluation regardless of age correction include: 1

• Regression of previously acquired skills
• Asymmetric motor development (e.g., handedness before 18 months)
• Abnormal tone or posture
• Absent social smiling by 2 months corrected age