Corrected age for premature babies

Key facts

  • Babies born before 37 weeks pregnancy are considered premature.
  • 'Chronological age' is your baby's age since birth.
  • Your baby's 'corrected age' takes into account how many weeks or months premature they were.
  • 'Corrected age' is used to check your baby's growth and development.
  • The timing of routine vaccinations is usually the same for premature babies.

    • What is a premature baby?

    In Australia, less than 1 in 10 babies are premature (born early).

    Premature babies can face more challenges than babies born at full-term (after 37 weeks). They may need to stay in hospital longer.

    Babies born before 32 weeks of pregnancy can face additional health problems.

    What is chronological age?

    Your baby's chronological age is the age of your baby since birth. You may celebrate this with birthdays.

    Chronological age doesn't take into account how many weeks premature your baby was.

    What is corrected age?

    Your baby's corrected age is the age your baby would be if they had been born on their due date.

    This is important as your premature baby's growth and development is measured against their corrected age.

    How do I work out my baby's corrected age?

    You can work out your baby's corrected age. Subtract how many weeks premature they were born from their actual age.

    Corrected age = chronological age – how many weeks premature

    For example, if your baby is 16 weeks old and they were born 8 weeks premature, their corrected age is 8 weeks.

    16 weeks – 8 weeks = 8 weeks corrected age

    Or you can use this online calculator to work out your baby's corrected age.

    If your baby hasn't yet reached their due date, their corrected age is worked out differently. You add their current age to the gestational age they were born at.

    Corrected age (before due date) = gestational age + chronological age

    For example, if your baby was born at 32 weeks of pregnancy and they are now 3 weeks old, they have a corrected age of 35 weeks.

    32 weeks + 3 weeks = 35 weeks corrected age

    During your baby's time in the special care nursery (SCN), the staff will calculate your baby's corrected age each day.

    Why is my baby's age corrected?

    Your premature baby may look and behave differently from a full-term baby.

    For example, a 3 month old baby born at 28 weeks is not expected to be at the same developmental stage as a 3 month old baby born on its due date.

    Corrected age takes this into account. It is used to help your health team check your baby's growth and development.

    Learn more about your premature baby's growth and development.

    Premature babies may need some extra time to catch up.

    When does corrected age stop being used?

    Your baby's corrected age is useful until at least 2 to 3 years of age.

    When should I see a doctor?

    If you are concerned about your baby's growth or development, talk to your doctor or child health nurse.

    Your baby should have their vaccinations according to the National Immunisation Program schedule for their chronological age.

    Whenever you take your baby to a health professional, let them know that your baby was premature. Your baby will be assessed in a way that takes this into consideration.

    Resources and support

    The Miracle Babies Foundation has online resources and a 24 hour support line — call NurtureLine on 1300 622 243.

    The Life's Little Treasures Foundation also has information and support — you can call them on 1300 697 736.

    You can also call the Preterm Infants Parents Association on 1300 773 672.

    The Royal Women's Hospital has information on premature babies, including in languages other than English.

    The Australian Breastfeeding Association can offer advice and support on feeding your premature baby on 1800 686 268.

    Speak to a maternal child health nurse

    Call Pregnancy, Birth and Baby to speak to a maternal child health nurse on 1800 882 436 or video call. Available 7am to midnight (AET), 7 days a week.

    Last reviewed: May 2025