What PMA means
Postmenstrual age (PMA) is the baby's gestational age at birth plus the time that has passed since birth. So if a baby was born at 30 weeks and is now 4 weeks old by the calendar, the PMA is 34 weeks.
PMA is the working clock for babies born before 37 completed weeks — the World Health Organization's definition of preterm birth — because in the NICU many clinical decisions are framed in gestational weeks rather than months since birth. Before the due date, corrected age is negative, while PMA still moves forward in a way that is easier for neonatal teams to use.
PMA vs corrected age vs chronological age
Chronological age is time since birth. Corrected age is chronological age minus the weeks of prematurity, so it counts from the due date. PMA is gestational age at birth plus chronological age, so it counts forward from conceptional maturity. Three numbers, three different starting points — the calculator on this page keeps them side by side so none of them gets swapped.
For the full four-term comparison, use the adjusted age vs chronological age guide.
These numbers answer different questions. PMA is common in early neonatal documentation. Corrected age becomes more intuitive after term when you are reading developmental milestones or discussing follow-up timing with parents.
When PMA matters most
PMA is most useful before term-equivalent age and in the earlier weeks after discharge. If your baby was born extremely or very preterm, you will often see PMA in clinic letters, scan timing, hearing follow-up and growth discussions, where size and growth standards such as INTERGROWTH-21st are quoted in gestational weeks rather than in months.
Once the baby is further past the due date, parents usually find corrected age easier to use for milestones and the milestone chart. The CDC's developmental milestone lists are published by age in months, which is exactly why they need re-indexing to corrected age for a baby born early.
If you want to see how PMA fits beside the other age labels, compare them on the adjusted age vs chronological age guide. If you are trying to understand where PMA appears in real follow-up, the NICU follow-up schedule puts it into a typical clinic timeline.
Common PMA questions
Is PMA the same as corrected age?
No. PMA and corrected age are linked, but they are not the same number. PMA looks forward from conceptional maturity; corrected age looks backward from the due date.
Why is corrected age negative before the due date?
Because corrected age is counting from term. If the baby has not yet reached the original due date, there are still weeks remaining before corrected age reaches zero.
Should parents track PMA at home?
Usually PMA matters most in earlier medical follow-up. For everyday developmental questions, corrected age is often the easier age to use once the due date has passed.
Use PMA with the rest of the follow-up toolkit
After you check PMA here, use the main corrected age calculator, read the premature baby milestones chart, and review the red flags that should always override the calendar.