Corrected Age For Premature Infants

Premature babies are infants born before 37 weeks of pregnancy are completed. A full-term pregnancy is 40 weeks.1

The gestational age of a baby is the time elapsed between the first day of the last menstrual period and the day that your baby was born.2

Corrected age is a premature baby’s chronological age, minus the number of weeks or months they were born early.3

Chronological age is the age of an individual as measured from birth to a specific date.4

Understanding your correct age may be helpful if you are trying to work out whether your premature baby’s development is tracking in a typical way. For example, if your child is six months old but not sitting up yet, his/her corrected age will explain that he/she is only three months old when it is generally not expected for a child to sit up. Corrected age is especially relevant during a child’s early years, as it might explain things that may appear as developmental lags.3

Corrected Age Calculator



It may be good idea to tell anyone who cares for or works with your child that he/ she was born prematurely such as health professionals and teachers. They may also want to know how many weeks early your child was born.

There is no set age when one should stop correcting a child’s age for prematurity, but most health professionals recommend continuing until your child is at least two years old.3


Generally, children start preschool and school based on their chronological age, not their corrected age. But a few months in age can make a difference to what a child can do and what is expected of them. For this reason, some parents of children who are born prematurely, decide to delay school for a year, if their child’s corrected age is just below school entry age. This may give children extra time to catch up in growth and develop the social skills needed for preschool and school.3


Premature babies are generally vaccinated at the same chronological age as full-term babies. This is because they need the protection of immunisation as they are more likely to get certain infections. Sometimes, an extra dose of some vaccines are required if infants are older. It is best to consult with your healthcare provider about your child’s immunisation needs.3


[1] MedlinePlus, National Library of Medicine, “Premature Babies,” MedlinePlus, National Library of Medicine, 12 April 2021. [Online]. Available: MedlinePlus, National Library of Medicine. [Accessed 15 May 2021].

[2] Albertha Health Services, “Nutrition Guideline healthy infants and young children: Post-discharge preterm formula (PDPF),” AlberthaHealth Services, 2014.

[3] Raising Children Network (Australia) Limited, “Corrected age: how old is your premature baby?,” Raising Children Network (Australia) Limited, 2021. [Online]. Available: [Accessed 15 May 2021].

[4] Merriam-Webster, “Chronological age,” [Online]. Available: [Accessed 15 May 2021].SAN-000208 05/21

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