Tiny Milestones guides

Adjusted age for babies born early

If your baby was born more than 3 weeks early, doctors judge development by adjusted age, also called corrected age: your baby's age counted from the due date instead of the birthday. Take the weeks since birth and subtract the weeks born early. The American Academy of Pediatrics advises using adjusted age for the first 2 years, by which time most children born early have caught up.

Two dates on the calendar

A baby born early has two dates that matter: the birthday and the due date. Milestone ages describe term babies, so the AAP suggests looking at both dates and using the gap between them to adjust your baby's age¹. The adjustment applies to babies born more than 3 weeks early².

How to work it out

Start with your baby's actual age in weeks, then subtract the number of weeks your baby was born early. That is the adjusted age¹². To get the weeks early, subtract the week of pregnancy your baby was born at from 40¹.

• Born at 34 weeks: 6 weeks early. At 20 weeks old, the adjusted age is 14 weeks, a little over 3 months.
• Born at 30 weeks: 10 weeks early. At 9 months old (about 39 weeks), the adjusted age is 29 weeks, about 6 and a half months.

The AAP's own example: a baby born at 32 weeks was 8 weeks early, so at 4 months old the adjusted age is 2 months¹.

Why it changes what to expect

In that example, the 4-month-old would be expected to do what a 2-month-old does, such as beginning to hold the head up and smile, rather than rolling from stomach to back, a skill term babies often show around 4 months¹. Family and friends sometimes worry that a baby born early is behind, when the baby is right on track for their adjusted age¹. The CDC's checklists ask the same thing from the other side: among the things to share with the doctor at each age is whether your baby was born prematurely³.

Until when

The AAP advises using adjusted age when following development until 2 years of age. By then, most children born early have caught up to the typical range; a child who hasn't may need extra support for longer². Ask your pediatrician how they plot your baby's growth chart, since that is a separate question.

Watching progress, not just ages

Even with an adjusted age, what matters most is forward movement: from pulling up, to standing, to walking, in your baby's own time². Keep the well-child visits, where the doctor checks progress and asks what you've seen². If anything worries you, you don't have to wait: talk with your baby's doctor and ask about developmental screening⁴. Ask too about early intervention, the services and supports for babies and young children with delays and the families caring for them; every state and territory has a program, free or at reduced cost for children who qualify²⁵.

In Tiny Milestones

Tiny Milestones asks for your baby's due date and counts age from it for a baby born early, so the milestones for "your baby's age" are the right ones. Our guide to when babies roll, sit, crawl, and walk explains where those ages come from.

This is general information, not medical advice. Ask your baby's doctor about your own baby.