What are developmental milestones? 

Developmental milestones are things most children can do by a certain age. When your baby is born early (prematurely) you need to know both your baby’s due date and how many weeks premature your baby was to determine your baby’s corrected age. Your baby’s corrected age should be used to track developmental milestones. 

To calculate your baby’s corrected age: 

• Begin with baby’s age in weeks (number of weeks since birth). 
• Subtract the number of weeks old your baby was at birth from 40. This is the number of weeks your baby was premature. 
• Subtract the number of weeks your baby was premature from your baby’s age in weeks. This is your baby’s corrected age. (A full-term pregnancy is 40 weeks.) 

 
(Baby’s current age in weeks) – (Number of weeks premature) = Baby’s corrected age 

For example: Andrew is 6 months old (24 weeks since birth). He was born at 28 weeks. So he was 12 weeks premature (40 weeks – 28 weeks = 12 weeks). 

Andrew’s corrected age is 12 weeks or 3 months. (24 weeks – 12 weeks = 12 weeks.) 

What to expect: corrected age 

For Andrew, even though he is 6 months old, his parents should expect him to act and meet the developmental milestones of a 3-month-old. 

People may think Andrew is delayed for a 6-month-old, when in fact he is doing great and meeting milestones ahead of his corrected age of 3 months old.