What is corrected age?
Corrected age (also called adjusted age) is a premature baby’s age counted from their original due date instead of their birth date. A baby born 8 weeks early who is now 6 months old has a corrected age of about 4 months. Health professionals commonly use corrected age to assess growth and developmental milestones, usually until around 2 years of age.
Corrected age = chronological age − (40 weeks − gestational age at birth)
Postmenstrual age
In the neonatal period, doctors often use postmenstrual age: gestational age at birth plus the time since birth. A baby born at 30 weeks who is now 6 weeks old has a postmenstrual age of 36 weeks. The calculator shows it alongside corrected and chronological age.
Examples
| Born at | Chronological age | Corrected age |
|---|---|---|
| 32 weeks | 12 weeks | 4 weeks |
| 28 weeks | 6 months (about 26 weeks) | about 14 weeks |
| 35 weeks | 10 weeks | 5 weeks |
Why corrected age matters
A baby born 10 weeks early has had 10 fewer weeks to develop before birth. Comparing them with babies born at term by birth date alone would make them look “behind” when they are developing normally for their true stage. Using corrected age when plotting growth and checking milestones such as smiling, sitting and walking gives a fairer picture, and the gap usually matters less and less as children grow.
Your baby’s healthcare team will tell you how corrected age applies to feeding, growth charts and milestones. To count the days between any two dates, use the Date to Date Calculator.