Corrected Age for Premature Babies: Why the Math Matters for Every Milestone

When a baby is born at 28 weeks instead of 40, their developmental clock does not start at birth. It starts at their due date. This concept, called corrected age or adjusted age, is critical for properly tracking milestones, and misunderstanding it causes unnecessary anxiety for thousands of parents every year. What corrected age means Corrected age is calculated by subtracting the number of weeks of prematurity from the baby's chronological age (actual age since birth). A baby born at 32 weeks is 8 weeks premature (40 - 32 = 8 weeks). When that baby is chronologically 6 months old, their corrected age is approximately 4 months (6 months minus 8 weeks). Developmental milestones should be evaluated against the corrected age, not the chronological age. A 6-month-old preemie with a corrected age of 4 months should be hitting 4-month milestones, not 6-month milestones. Why this matters for development tracking The milestone charts that pediatricians use assume full-term birth. When a preem