Babies born early often reach milestones on a timeline that reflects their due date, not their birthday. Corrected age (also called adjusted age) accounts for this.
How to calculate corrected age
Subtract the number of weeks your baby was born early from their age since birth.
Corrected age = age since birth minus (40 weeks minus weeks of pregnancy at birth)
Example: a baby born at 32 weeks was born 8 weeks (about 2 months) early. At 6 months old, their corrected age is about 4 months.
When is corrected age used?
- Growth: plotting weight, length and head size on growth charts
- Development: checking milestones such as smiling, sitting and walking
- Starting solid foods: often guided by corrected age and readiness signs
Doctors usually use corrected age until about 2 years, by which time most premature babies have caught up.
When is actual age used?
Vaccinations are given according to your baby’s actual age since birth, not corrected age, unless your doctor advises otherwise.
Talk to your care team
Every premature baby is different. Your baby’s doctor or health visitor will track growth and development and let you know if extra support is needed.
Enter your baby’s corrected age in our Baby Growth Percentile Calculator to check growth on WHO charts.