Gestational Age Classification

Q: What gestational age categories does this tool use?

Nine categories: extremely preterm, very preterm, moderately preterm, late preterm (all under the general 'preterm' umbrella), early term, full term, late term, and post term.

Q: How is 'day zero' defined?

The app follows conventional medical definitions where the day of birth counts as day zero when calculating postnatal gestational age in days.

Q: What is the difference between 'preterm' and a specific preterm subtype?

'Preterm' is a general umbrella label (under 37 weeks, under 260 days) that the app displays alongside a more specific subtype — extremely, very, moderately, or late preterm — rather than replacing it.

Q: What input range does the calculator accept?

Gestational age entries of 22 to 44 weeks and 0 to 6 days, per the app's own input validation.

Q: Does this tool also classify birthweight?

This specific screen classifies gestational age only, based on weeks and days entered; the app has a separate tool for absolute birthweight classification.

1 What is the Gestational Age Classification?

This tool classifies a newborn's postnatal gestational age, entered as weeks and days, into nine standard clinical categories spanning extremely preterm through post term, reproducing the app's own Table 6-2 reference ('Gestational Age and Birthweight Classification,' Chapter 6, page 51, as cited on-screen). Per the app's own note, definitions follow conventional medical convention where the day of birth counts as day zero. A live calculator matches an entered gestational age to its category and, when the result is preterm, displays both the specific subtype and the general 'preterm' umbrella label.

2 When to use it

Categorising a newborn's gestational age at birth for standardised documentation and handoff
Anticipating the general risk profile associated with the degree of prematurity
Distinguishing a specific preterm subtype (extremely, very, moderately, or late preterm) from the general preterm umbrella label
Distinguishing early term, full term, late term, and post term infants
Quick bedside or rounds lookup by entering gestational weeks and days

3 Formula & method

Classification runs on total postnatal age in days (gestational weeks × 7, plus additional days), matched against the app's nine defined ranges, taken verbatim from source: Extremely preterm (<28 weeks, <197 days), Very preterm (28 0/7–31 6/7 weeks, 197–224 days), Moderately preterm (32 0/7–33 6/7 weeks, 225–238 days), Late preterm (34 0/7–36 6/7 weeks, 239–259 days), Early term (37 0/7–38 6/7 weeks, 260–273 days), Full term (39 0/7–40 6/7 weeks, 274–287 days), Late term (41 0/7–41 6/7 weeks, 288–294 days), and Post term (42 0/7 weeks or more, ≥295 days). 'Preterm' (<37 weeks, <260 days) is treated as an umbrella label in the app rather than a mutually exclusive category, and is shown alongside the more specific subtype whenever the result is preterm. The in-app calculator accepts 22–44 weeks and 0–6 days as valid input.

4 Frequently asked questions

What gestational age categories does this tool use?

Nine categories: extremely preterm, very preterm, moderately preterm, late preterm (all under the general 'preterm' umbrella), early term, full term, late term, and post term.

How is 'day zero' defined?

The app follows conventional medical definitions where the day of birth counts as day zero when calculating postnatal gestational age in days.

What is the difference between 'preterm' and a specific preterm subtype?

'Preterm' is a general umbrella label (under 37 weeks, under 260 days) that the app displays alongside a more specific subtype — extremely, very, moderately, or late preterm — rather than replacing it.

What input range does the calculator accept?

Gestational age entries of 22 to 44 weeks and 0 to 6 days, per the app's own input validation.

Does this tool also classify birthweight?

This specific screen classifies gestational age only, based on weeks and days entered; the app has a separate tool for absolute birthweight classification.

5 Related tools

For qualified clinicians. This page and the PediAid app are a clinical aid only. Calculations and reference data must be verified against the patient's clinical context, the source guideline and your local protocols before any treatment decision is made.