Key takeaways
- A girl born at 32 weeks is classified SGA below 1,501 g and LGA above 2,199 g, showing how Fenton cutoffs apply to a single week and sex.
- SGA (small for gestational age) is defined as birth weight below the 10th percentile (p3-p10 range shown for extremes).
- AGA (appropriate for gestational age) spans birth weight between the 10th and 90th percentiles.
- LGA (large for gestational age) is birth weight above the 90th percentile, with p90-p97 shown for the upper extreme.
- Fenton percentile cutoffs change every week of gestation and differ by sex, making bedside eyeballing of the chart slow and error-prone.
References
- Fenton TR. 2025 meta-analysis for size for gestational age (small, large and appropriate) assignment at birth, V2. University of Calgary.
- Fenton TR, Kim JH. BMC Pediatr. 2013;13:59.
Fenton chart at birth: SGA, AGA or LGA in seconds
NEONATOLOGY · GROWTH
Fenton chart at birth: SGA, AGA or LGA in seconds
Sex, gestational age and birth weight. NeoFast does the rest — no plotting, no ruler, no guesswork.
- SGA — small for gestational age — < p10
- AGA — appropriate for gestational age — p10 – p90
- LGA — large for gestational age — > p90
Birth weight percentile, for gestational age and sex
THE RULE
Birth weight percentile, for gestational age and sex
The 3rd and 97th percentiles are shown alongside to locate the extremes.
| SGA | AGA | LGA |
|---|---|---|
| below p10 | p10 to p90 | above p90 |
p3 p10 … p90 p97
- Same baby, same week, different weights. A girl born at 32 weeks is SGA below 1,501 g and LGA above 2,199 g.
- Cutoffs change every week and differ by sex — that is why reading the chart by eye at the bedside is slow and error-prone.
Example 1 · SGA
EXAMPLE 1 · SGA
1,420 g at 32 weeks
Below the 10th percentile. The app also guides the next step: subclassify by head circumference.
- Female — sex
- 32 wk — gestational age
- 1420 g — birth weight
- → SGA — p3 – p10
App screen: Fenton chart – size at birth – SGA, AGA and LGA classification by weight.
- Sex: Male / Female (Female selected)
- Gestational age at birth (completed weeks): 32 — From 22 to 42 weeks, the extent of the table.
- Birth weight (g): 1420 — From 200 to 6000 g.
SGA – small for gestational age — p3 – p10
SGA – small for gestational age: Weight below the 10th percentile for gestational age.
Example 2 · AGA
EXAMPLE 2 · AGA
1,850 g at 32 weeks
Between p10 and p90 — with a reminder to follow the trajectory, not just the starting point.
- Female — sex
- 32 wk — gestational age
- 1850 g — birth weight
- → AGA — p10 – p90
App screen: Fenton chart – size at birth – SGA, AGA and LGA classification by weight.
- Sex: Male / Female (Female selected)
- Gestational age at birth (completed weeks): 32 — From 22 to 42 weeks, the extent of the table.
- Birth weight (g): 1850 — From 200 to 6000 g.
AGA – appropriate for gestational age — p10 – p90
AGA – appropriate for gestational age: Weight between the 10th and 90th percentiles for gestational age.
Example 3 · LGA
EXAMPLE 3 · LGA
2,300 g at 32 weeks
Above the 90th percentile, with what to investigate and monitor right after birth.
- Female — sex
- 32 wk — gestational age
- 2300 g — birth weight
- → LGA — p90 – p97
App screen: Fenton chart – size at birth – SGA, AGA and LGA classification by weight.
- Sex: Male / Female (Female selected)
- Gestational age at birth (completed weeks): 32 — From 22 to 42 weeks, the extent of the table.
- Birth weight (g): 2300 — From 200 to 6000 g.
LGA – large for gestational age — p90 – p97
LGA – large for gestational age: Weight above the 90th percentile for gestational age.
Why it’s practical
WHY IT’S PRACTICAL
Three inputs. One instant answer.
- Tap the sex — Male or female — cutoffs are sex-specific
- Type gestational age — Completed weeks, from 22 to 42
- Type birth weight — In grams, from 200 to 6,000
- SGA, AGA or LGA + percentile band — Plus clinical guidance for each result, as you type
| PAPER CHART | NEOFAST |
|---|---|
| Find the week, find the weight, plot the point, estimate the line. | Fenton 2025 cutoff table built in. Result updates as you type. |
Classify at birth in seconds
Growth and Development ›
Fenton chart – size at birth
Available on iOS and Android, in English, Portuguese and Spanish.
Frequently asked questions
What birth weight is considered SGA at 32 weeks for a female infant?
At 32 weeks, a female infant is SGA (small for gestational age) if birth weight is below 1,501 g, corresponding to below the 10th percentile.
What is the LGA cutoff at 32 weeks for a female infant?
At 32 weeks, a female infant is LGA (large for gestational age) if birth weight is above 2,199 g, corresponding to above the 90th percentile.
How is AGA defined using the Fenton chart?
AGA (appropriate for gestational age) is defined as birth weight between the 10th and 90th percentiles (p10-p90) for a given gestational age and sex.
What inputs are needed to classify a newborn’s size using this tool?
Three inputs are needed: sex (male or female), gestational age in completed weeks (22 to 42), and birth weight in grams (200 to 6,000). The result (SGA, AGA, or LGA plus percentile band) updates as you type.
Why can’t the Fenton chart be reliably read by eye at the bedside?
Because the percentile cutoffs change every week of gestation and differ by sex, reading the chart by eye at the bedside is slow and error-prone.
