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A baby born early is developmentally 'younger' than their birthday suggests. Corrected age (also called adjusted age) is the age the baby would be if born on the due date: actual age minus the weeks born early.
Doctors use corrected age for growth charts, developmental milestones and starting solids until about age 2, by which time most premature babies have caught up. Vaccinations follow actual age.
| Date of Birth | 1 Jun 2026 |
| Born at (weeks) | 32 weeks |
| + days | 0 days |
| Age on Date | 1 Oct 2026 |
| Corrected (adjusted) age | 9 weeks 3 days |
| Actual (chronological) age | 4 months 0 days |
| Born early by | 8 weeks 0 days |
| Original due date | Mon, 27 Jul 2026 |
| Prematurity category | Moderately preterm (32–33 weeks) |
| Use corrected age until | Thu, 27 Jul 2028 (age 2 corrected) |
Corrected age 9 weeks 3 days; actual age 4 months 0 days.
Try this example →| Date of Birth | 10 Mar 2026 |
| Born at (weeks) | 35 weeks |
| + days | 3 days |
| Age on Date | 1 Oct 2026 |
| Corrected (adjusted) age | 5 months 21 days |
| Actual (chronological) age | 6 months 22 days |
| Born early by | 4 weeks 4 days |
| Original due date | Sat, 11 Apr 2026 |
| Prematurity category | Late preterm (34–36 weeks) |
| Use corrected age until | Tue, 11 Apr 2028 (age 2 corrected) |
Corrected age 5 months 21 days.
Try this example →Subtract the weeks born early from the actual age. A baby born at 32 weeks (8 weeks early) who is 20 weeks old has a corrected age of 12 weeks.
Usually until 2 years (sometimes 3 for babies born before 28 weeks).
No — vaccines are given by actual (chronological) age.
Birth before 37 weeks: late preterm 34–36, moderately preterm 32–33, very preterm 28–31 and extremely preterm before 28 weeks.