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Have you heard of “corrected age” or “adjusting for prematurity”? If you have a premature baby, you may see this on websites and content about infant development, including our own Pathways.org brochures and checklists. You may also notice that your premature baby is behind in meeting some of their milestones based on their actual age. This is why their corrected age is so important to calculate and use for tracking their milestones. Learn more below!

First, when is a baby considered premature? A baby is premature, also known as preterm, if they are born at or before 37 weeks. They are very preterm if they are born at 28 to 32 weeks, and extremely preterm if born before 28 weeks. If your child was born at or before 37 weeks, you’ll want to consider tracking their milestones based on a corrected age, rather than their actual age.

when-is-a-baby-considered-preterm

So, what does it mean to “adjust for prematurity”? This is also known as corrected age, and it means you are tracking your child’s milestones not by their actual age, but by the age that they would be if they had been born on their due date.

How do you adjust for prematurity? The adjustment is made by considering two important dates: baby’s due date, and the date baby was actually born. First, in terms of weeks, consider how old your baby actually is. Let’s say your baby was born on June 1 and today is September 1. Your baby’s actual age is about 3 months, or 13 weeks.

Then, consider how early your baby arrived in comparison to the mother’s due date. Let’s say the due date was August 1. If your baby was born June 1, they arrived about 2 months, or 9 weeks, early.

To find the corrected age for your baby, simply take the actual age and subtract the weeks preterm. In the above example, if your baby is actually 13 weeks old, but was born 9 weeks early, their corrected age is 4 weeks or about 1 month.

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Why is it important to adjust for prematurity? The corrected or adjusted age gives you a better idea of how your baby is tracking with their milestones. You don’t need to adjust for prematurity throughout their entire childhood, but it will give you a clearer picture of when they should be meeting their milestones for the first 2 years.

What does this mean for your baby’s milestones? It can mean that despite being behind their actual age, your baby is still on track. For example, if your child’s actual age is 3 months, but their corrected age is 1 month, then they should not be expected to meet all of their 3 month milestones just yet. They may not meet all of them until their corrected age is 3 months, and their actual age is around 5 months.

Of course, every baby is different. If you have any questions about your child’s age and their milestones, consult with a healthcare provider who can help you determine exactly where baby should be.