TOOL
Fenton Growth Chart for Preemies
Plot your preemie's growth against the curves NICUs actually use.
Enter your baby's gestational age at birth and the plotter will automatically switch to Fenton mode and calculate corrected age for you.
Optional — lets us calculate age from checkup dates.
Your doctor may have called this “gestational age at birth.”
Tip: Add your baby's date of birth above and we'll calculate gestational age automatically from checkup dates.
Plotted on Fenton 2025 Preterm Growth Charts
For preterm infants, 22–50 gestational weeks
What Are Fenton Growth Charts?
Fenton growth charts are specialized percentile curves designed specifically for premature babies born between 22 and 36 weeks gestational age. They were developed by Dr. Tanis Fenton and colleagues by combining data from nearly 4 million preterm births across multiple countries.
Unlike WHO growth charts — which are based on healthy, full-term, breastfed babies — Fenton charts reflect how premature babies actually grow. They cover weight, length, and head circumference from 22 weeks gestational age through 50 weeks (about 10 weeks past a full-term due date), then smoothly transition to the WHO charts.
The most current version is the Fenton 2013 revision, which is used by NICUs and pediatricians around the world.
Who Needs a Fenton Growth Chart?
Fenton charts are used for babies born before 37 weeks gestational age. If your baby was born premature, their growth should be plotted on Fenton curves rather than standard WHO charts — at least until they reach 50 weeks corrected gestational age (roughly 10 weeks past their original due date).
After that, most pediatricians transition to WHO growth charts using corrected age. Our plotter handles this transition automatically — enter your baby's gestational age at birth and it will use the right chart for the right stage.
How to Read a Fenton Growth Chart
The curved lines on the chart are called percentile lines. Each one represents the percentage of babies at that measurement for a given age. For example, if your baby's weight falls on the 25th percentile, it means 25% of premature babies at the same gestational age weigh less and 75% weigh more.
What matters most is the trend, not a single point. Your baby's growth curve should generally follow along a percentile line over time. A baby who consistently tracks the 15th percentile is doing great — that's their growth pattern. What warrants attention is a sudden drop across two or more percentile lines, or growth that flattens when it should be rising.
Preemies often have a period of "catch-up growth" in the first 2–3 years where they move up percentile lines. This is normal and expected — your pediatrician will help you understand what's healthy for your specific baby.
What Is Corrected (Adjusted) Age?
Corrected age (sometimes called adjusted age) is your baby's age calculated from their original due date rather than their actual birth date. It accounts for the time they missed in the womb.
For example, a baby born at 32 weeks (8 weeks early) who is now 4 months old by birth date has a corrected age of about 2 months. Growth, development, and feeding expectations should be based on corrected age — not chronological age — for at least the first 2 years.
Our plotter calculates corrected age automatically when you enter your baby's gestational age at birth.
Fenton vs. WHO Growth Charts
| Fenton 2013 | WHO | |
|---|---|---|
| Designed for | Premature babies (22–36 weeks GA) | Full-term, breastfed babies |
| Age range | 22–50 weeks GA | 0–5 years |
| Data source | ~4 million preterm births (6 countries) | ~8,500 healthy infants (6 countries) |
| Measures | Weight, length, head circ. | Weight, length/height, head circ., BMI |
| Used by | NICUs, neonatologists | Pediatricians (well-child visits) |
If your baby was born premature, use Fenton charts until about 50 weeks corrected gestational age, then transition to WHO charts using corrected age. Our plotter handles this automatically.
When to Talk to Your Doctor
Growth charts are screening tools, not diagnoses. A single measurement outside the expected range is rarely cause for concern. Talk to your pediatrician or neonatologist if you notice:
- !Weight, length, or head circumference dropping across 2 or more percentile lines
- !Growth that has plateaued (flat line) for multiple measurements
- !Head circumference growing much faster or slower than weight and length
- !Measurements consistently below the 3rd percentile or above the 97th percentile
- !Any concerns about feeding, weight gain, or your baby's overall development
Remember: premature babies grow on their own timeline. Catch-up growth is common and expected — your pediatrician can help you understand what's normal for your baby's specific situation.
Sources
- Fenton, T. R., & Kim, J. H. (2013). A systematic review and meta-analysis to revise the Fenton growth chart for preterm infants. BMC Pediatrics, 13, 59.
- WHO Multicentre Growth Reference Study Group. (2006). WHO Child Growth Standards. World Health Organization.
- American Academy of Pediatrics. (2022). Monitoring Growth in Preterm Infants.
Related Tools & Guides
- WHO Growth Chart Plotter — For full-term babies using WHO standards
- Understanding Baby Growth Percentiles — What percentiles mean and when to worry
- Growth Tracking Guide — How to track your baby's growth at home
