Adjusted Age in Premature Infants

Newborn baby sleeping in incubator
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Adjusted age, also called corrected age, is the age a preemie would be if they had been born on their due date. Doctors use adjusted age when evaluating a preemie's size and development.

For example, if your baby was born early, your child's doctor will use their adjusted age to determine when they should reach certain milestones.

Chronological age is not used as a benchmark for preemies because these infants may not have developed functions that babies born at term typically have, such as breathing on their own and maintaining their body heat.

Calculating Adjusted Age of a Preemie

To determine your baby's adjusted age, start by figuring out how many weeks or months early your baby was born. Then, subtract that number from their actual age.

For example:

  • A baby who is 8 months old but was born a month early would have a corrected age of 7 months old.
  • A baby who is 5 months old but was born 6 weeks early would have a corrected age of 3 1/2 months old.

Subtracting the months early an infant was born provides the baby with a more appropriate timeline for reaching certain milestones.

An infant who is 4 months old but was born 2 months early may be at a weight and stage of development that is closer to that of a 2-month-old infant. Therefore, the baby's corrected age is 2 months old.

Preemies may exceed expectations and skew closer to their actual birth date or fall behind even their adjusted age projections.

How Long to Use Adjusted Age

There isn't any hard and fast rule about how long you should use your preemie's corrected age. When gauging your child's development, most doctor's recommend using your baby's adjusted age instead of their actual age until they turn 2 years old, or until their size and development catch up to what they should be if they had been born at term.

If your preemie is doing everything that a full-term baby the same age can do, then it's probably safe to stop using their corrected age.

If your preemie is older than 2 years old but still seems younger, then it would make sense to continue using their corrected age.

Your child may experience a growth spurt or developmental push between the ages of 1 and 2 that catches them up to normal numbers for their actual birth age.

If your baby is still behind after they turn 2, doctors will no longer chart your baby according to normal infant development. Instead, they'll focus on the rate of growth expected for your child.

Explaining Adjusted Age to Loved Ones

Your friends and family may not understand adjusted age. If you choose to share this information, be prepared to explain the difference between corrected age and chronological (actual) age.

People may be confused and question you about the importance of adjusted age. You can address any misunderstandings by explaining the number is used to help monitor your baby's growth.

Just as it is with babies born on their due date, there is no guarantee that a baby who was born prematurely will follow the adjusted age growth chart.

The most important thing you can do is stay attentive to your preemie. Even if they seem too small to do certain things, allowing them to play and interact with you will help move them toward normal development.

1 Source
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  1. American Academy of Pediatrics. Corrected Age For Preemies.

By Cheryl Bird, RN, BSN
Cheryl Bird, RN, BSN, is a registered nurse in a tertiary level neonatal intensive care unit at Mary Washington Hospital in Fredericksburg, Virginia.