The premature infant: How old is my baby?

Babies who are born prematurely often have two ages:

  • Chronological age is the age of the baby from the day of birth—the number of days, weeks or years old the baby is.
  • Adjusted age is the age of the baby based on his due date. Health care providers may use this age when they evaluate the baby's growth and development. So, if a baby is 6 months old, but was born two months early, his adjusted age is 4 months.

What to say when someone asks

This is up to you.

  • You can say, "He's 6 months old, but he was born two months early. That's why he looks like a 4-month-old."
  • Or you can say, "He's 6 months old" and leave it at that.

 Remember: When people ask about your baby, they usually are being kind, not nosy.

Calculating your baby's adjusted age

Here's how to calculate your baby's adjusted age:

  • Chronological age: 20 weeks
  • The number of weeks your baby was premature: 6 weeks
  • Subtract the number of weeks premature from the chronological age (this is your baby's adjusted age): 20 weeks minus 6 weeks equal 14 weeks.
  • Divide your baby's adjusted age in weeks by 4 to determine your baby's adjusted age in months: 14 divided by 4 equals 3 ½ months.

See also
: Share your story

Last reviewed: August, 2014