Correcting Age for Prematurity

Understanding why and how to correct for prematurity is so important for parents to know! If you have a preemie, you may be used to hearing things like, “she’s so tiny for a 6 month old!” or “he’s a year old, he should be walking already!”. Whether you decide to share this information with others is up to you, but understanding how to correct your baby’s age will hopefully relieve you of some worry if your baby is not quite doing what you expect they should for their age.

If your baby was born before 37 weeks, they are considered premature. You can correct their age in one of two ways:

  • Calculate their adjusted age from your due date to today, the day you expected your baby would be born. In other words, use your due date instead of their birth date when calculating their age.
  • Subtract how early they were born from their age since birth. Subtract the number of weeks at which they were born from 40 weeks. For example, if your baby was born at 32 weeks, they were born 8 weeks early (40-32=8), so you would subtract 8 weeks from their age.

The earlier your baby was born, the more this will matter. If your baby is born at 28 weeks, that’s 3 whole months! If your baby is 6 months old, 3 months is 50% of their age! The older your baby gets the less a few months make a difference, so we stop correcting for prematurity typically at age 2.

Use your baby’s adjusted age when considering what milestones they should be meeting, not their chronological age (age since birth). If your baby is meeting milestones for their adjusted age, we don’t consider them to be delayed and you shouldn’t either!

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