Birth · Newborn
Fenton Preterm Growth Chart
Fenton 2013 preterm growth chart (BMC Pediatrics 2013) — weight-for-PMA percentile and z-score for ages 22-50 weeks postmenstrual age. AAP / Canadian Paediatric Society / WHO endorsed standard.
Last reviewed 25 May 2026
Fenton 2013 preterm growth chart
Preterm weight-for-PMA percentile
Sex
wk
kg
Enter PMA (22-50 weeks) and weight in kg.
Educational tool only — not medical advice. Fenton 2013 is the AAP / CPS / WHO-aligned preterm growth chart for 22-50 weeks PMA. Tracks to WHO 0-24 mo standards at 50 weeks PMA. The 2025 third-generation Fenton charts (Paed Perinat Epidemiol 2025) further refine the LMS values. This widget uses median values from the 2013 publication.
What does this mean?
For preterm babies the right comparator is postmenstrual age (PMA), not chronological age or term reference charts. The Fenton 2013 chart is the AAP/CPS preferred growth reference from 22–50 weeks PMA, smoothly transitioning to the WHO 0–24 mo standards. NICU goals for stable preterms aim for ~15–20 g/kg/day weight gain in the early growth phase, with target percentile tracking parallel to the in-utero curve. SGA (small for gestational age, < 10th pct at birth) and EUGR (extrauterine growth restriction — falling off the curve postnatally) are common and matter long- term: better neurodevelopmental outcomes correlate with quality of growth (lean mass, head circumference) more than raw weight gain. Use corrected age (chronological − weeks early) for at least the first 2 years when assessing developmental milestones too.
Introduction
The Fenton growth chart is the standard preterm growth reference for NICU monitoring. Revised by Fenton and Kim (BMC Pediatrics 2013) from earlier 2003 charts using pooled data from ~4 million infants across 6 countries, it covers 22-50 weeks postmenstrual age (PMA) and tracks seamlessly into the WHO 0-24 mo standards.
What is PMA?
Postmenstrual age = gestational age at birth + chronological age in weeks. A baby born at 28 weeks GA who is now 8 weeks old is at 36 weeks PMA. The Fenton chart uses PMA to compare a preterm infant's size to where the same infant would have been if still in utero.
Interpretation
- 3rd-97th percentile — typical range.
- < 10th percentile — Small for Gestational Age (SGA). Higher risk of complications.
- < 3rd percentile — Severely SGA. Increased morbidity / mortality.
- 10th-90th percentile — Appropriate for Gestational Age (AGA).
- > 90th percentile — Large for Gestational Age (LGA). Maternal diabetes consideration.
- > 97th percentile — Macrosomia. Birth-injury risk in vaginal delivery.
NICU growth goals
The goal during NICU stay is to track ALONG the percentile curve the baby was born on, not necessarily to catch up to 50th. For most preterm infants this means:
- 15-20 g/kg/day weight gain during 28-36 weeks PMA.
- 0.9-1.1 cm/week length gain.
- 0.5-0.8 cm/week head circumference gain.
Drops in percentile over weeks suggest extrauterine growth restriction — associated with worse neurodevelopmental outcomes. Nutrition adjustment (fortified breast milk, increased caloric density, micronutrient supplementation) is the typical response.
Comparison of preterm growth charts
- Fenton 2013 / 2025 — pooled international meta-analysis. AAP / CPS / WHO endorsed. This widget uses Fenton 2013.
- Olsen 2010 — US-specific reference, 257,000 births. Some US NICUs use Olsen.
- INTERGROWTH-21st 2014 — prescriptive (healthy-population) standard. Higher 50th percentile than descriptive references. Used in research and increasingly in clinical practice.
Limitations
- This widget uses Fenton 2013 median values; full LMS table allows half-week precision.
- Length and head circumference percentiles are critical complements to weight — included in the full Fenton chart but not this widget (educational simplification).
- Above 50 weeks PMA, switch to WHO 0-24 mo standards.
- Educational only; NICU growth monitoring is by trained staff with appropriate chart selection.
Sources
- Fenton TR, Kim JH. A systematic review and meta-analysis to revise the Fenton growth chart for preterm infants. BMC Pediatrics 2013;13:59.
- Fenton TR, et al. Third-generation Fenton charts for preterm growth monitoring. Paediatric & Perinatal Epidemiology 2025.
- Olsen IE, et al. New intrauterine growth curves based on United States data. Pediatrics 2010;125:e214-24.
- Villar J, et al. International standards for newborn weight, length, and head circumference by gestational age and sex: the Newborn Cross-Sectional Study of the INTERGROWTH-21st Project. Lancet 2014;384:857-68.
- AAP Committee on Nutrition. Pediatric Nutrition, 8th ed.
Frequently asked questions
What is the Fenton 2013 growth chart?
A preterm growth reference for ages 22-50 weeks postmenstrual age (PMA), revised by Fenton and Kim (BMC Pediatrics 2013) from earlier 2003 charts. Adopted by AAP, Canadian Paediatric Society, and WHO for preterm infant growth monitoring. The chart's design is unique — it tracks seamlessly into the WHO 0-24 mo growth standards at 50 weeks PMA (which corresponds to ~12 weeks corrected post-term age), giving a continuous reference from extreme preterm through 2 years.
What is PMA (postmenstrual age)?
Postmenstrual age = gestational age at birth + chronological age in weeks. So a baby born at 28 weeks GA now 8 weeks old is at 36 weeks PMA. Used preferentially for preterm growth charts because growth references are based on time since the start of the last menstrual period, regardless of when the baby was actually born. Once the baby reaches 40 weeks PMA (term-equivalent), the WHO growth charts take over for chronological age.
What does SGA mean for a preterm baby?
Small for Gestational Age — weight below the 10th percentile at birth for gestational age. Causes: placental insufficiency (most common), maternal medical conditions, infections (TORCH), genetic factors, multiple gestation, chromosomal abnormalities. SGA preterm infants have higher risk of perinatal mortality, hypoglycaemia, thermoregulation issues, respiratory distress, NEC, retinopathy of prematurity, and long-term developmental challenges than their AGA peers.
When is the 2013 chart preferred over 2003 or 2025?
The 2013 update reanalysed pooled data from 4 million infants across 6 countries — a substantially larger dataset than the 2003 version. The 2025 third-generation update (Fenton et al., Paediatric & Perinatal Epidemiology 2025) adds further refinement and accounts for population-level trends. For day-to-day NICU growth monitoring, both 2013 and 2025 versions are clinically equivalent — but newer NICUs increasingly use the 2025 update.
How is growth tracked over the NICU stay?
Daily weight measurements plotted weekly on the chart. The goal is to track ALONG the curve, not necessarily catch up to the 50th percentile (which is unrealistic for most preterm infants). Expected weight gain: ~15-20 g/kg/day during the rapid-growth phase (28-36 weeks PMA). Slower gain or weight loss after physiological postnatal weight loss is concerning and warrants nutrition review. Falling more than 1 SD over weeks is concerning.
What about Olsen / Fenton / INTERGROWTH-21st?
Three main preterm growth references. Olsen (US, 2010) — based on 257,000 US births, 22-42 weeks. Fenton (international, 2013, 2025) — pooled meta-analysis across 6 countries. INTERGROWTH-21st (international, 2014) — prescriptive (healthy-population) standard. AAP recommends Fenton; some centres use Olsen; INTERGROWTH-21st is increasingly used in research. All three give similar results for routine clinical monitoring; INTERGROWTH-21st sets a higher 50th percentile (reflecting healthy growth potential, not actual NICU growth).
What do AGA, SGA, and LGA mean for outcomes?
AGA (appropriate for gestational age, 10th-90th percentile) — best outcomes. SGA (< 10th) — higher mortality, hypoglycaemia, thermoregulation issues. LGA (> 90th) — large infants of diabetic mothers, increased birth-injury risk. Severe SGA (< 3rd) and macrosomia (> 97th) have higher complication rates. Growth trajectory after birth matters too — extrauterine growth restriction (drop in percentiles in NICU) is associated with worse neurodevelopmental outcomes.