Corrected Age & Milestone Dates
Corrected (adjusted) age accounts for prematurity when assessing developmental milestones. It is calculated by subtracting the weeks of prematurity from the chronological age. This calculator also provides the exact calendar dates when key PMA milestones — 34, 36, and 40 weeks — are reached.
Key concepts
Corrected age = chronological age − weeks of prematurity (40 − GA at birth)
PMA (postmenstrual age) = GA at birth + postnatal age in weeks
Use corrected age for all developmental assessments until approximately 2–3 years of chronological age.
Best estimate from antenatal ultrasound (range 22–42 weeks)
References: AAP Committee on Fetus and Newborn. Hospital discharge of the high-risk neonate. Pediatrics. 2008;122(5):1119–1126. Engle WA, et al. Late-preterm infants. Pediatrics. 2007;120(6):1390–1401.
Frequently asked questions
When should corrected age be used?
For assessing growth and development in former preterm infants, generally until about 2–3 years of age.
From when does corrected age apply?
From 40 weeks 0 days postmenstrual age (the estimated date of delivery). Before then, use postmenstrual age.
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