Preterm Low Birth Weight Baby Growth Charts

The Fenton 2025 Preterm Growth Chart (Girls)

Definitions: Preterm & LBW

Key Growth Charts - Comparison

1. Fenton Preterm Growth Chart (2013 / 2025)

• Most widely used in North America and globally for preterm monitoring
• Based on a 15-country meta-analysis; latest version is Fenton 2025 (3rd generation)
• Covers gestational age 22 to 50 weeks (i.e., through to term-equivalent age)
• Plots 3 parameters: Weight (kg), Length/Height (cm), Head Circumference (cm)
• Percentile lines: 3rd, 10th, 25th, 50th, 75th, 90th, 97th
• Bridges seamlessly to the WHO Child Growth Standards at 50 weeks (term-equivalent)
• Uses actual gestational age (not completed weeks) for more precise plotting
• Free download at ucalgary.ca/fenton
• Latest citation: Fenton TR, Elmrayed S, Alshaikh BN. Paediatr Perinat Epidemiol. 2025. PMID: 40534585

2. INTERGROWTH-21st Preterm Postnatal Growth Standards

• Developed by WHO/University of Oxford (2016 onward)
• Prescriptive standards (how babies should grow under optimal conditions) vs. Fenton's descriptive approach
• Covers gestational ages 26-64 weeks post-menstrual age
• Plots weight, length, and head circumference
• Based on 8 geographically diverse low-risk populations across 5 continents (~60,000 women)
• Endorsed by WHO as international standards
• Studies comparing Fenton vs. INTERGROWTH-21st in Indian preterm NICUs show INTERGROWTH-21st identifies more IUGR babies and predicts morbidity better in very preterm infants ≤32 weeks

3. WHO Child Growth Standards (2006)

• For term infants from birth to 5 years
• Not appropriate for preterm infants unless corrected age is used after discharge
• Used after term-equivalent age (40 weeks) with corrected/adjusted age for preterms

What the Chart Plots (3 Parameters)

Niklasson-Albertsson-Wikland Chart

How to Use the Fenton Chart

Step-by-step

1. Determine gestational age at birth (by dates or early ultrasound)
2. Plot measurements (weight, length, HC) against post-menstrual age (gestational age + postnatal days/weeks)
3. Classify at birth:
   • SGA = < 10th percentile
   • AGA = 10th-90th percentile
   • LGA = > 90th percentile
4. Monitor postnatal growth: Plot serial measurements; expect weight loss of 10-15% in first week, then regain birth weight by ~2 weeks, followed by ~15-20 g/kg/day weight gain
5. At 40 weeks corrected age: Transition to WHO growth charts using corrected age until 24-36 months (2 years corrected for extremely preterm, 1 year for moderate-to-late preterm)

Expected Growth Velocity in Preterm Infants (NICU)

Corrected (Adjusted) Age

• Weeks premature = 40-28 = 12 weeks = 3 months
• Corrected age = 6 - 3 = 3 months (plot on WHO chart at 3 months)

• 2 years for very preterm (< 32 weeks)
• 1.5 years for moderate preterm (32-34 weeks)
• 1 year for late preterm (34-37 weeks)

Growth Failure / Extrauterine Growth Restriction (EUGR)

• Defined as weight < 10th percentile at 36 weeks corrected age (or at discharge)
• Very common in VLBW infants (up to 90% in some studies)
• Causes: inadequate caloric intake, illness, NEC, chronic lung disease
• EUGR is associated with poor neurodevelopmental outcomes - early recognition using growth charts is key

Summary: Which Chart to Use?

• Fenton 2025 Girls Chart | Fenton 2025 Boys Chart
• INTERGROWTH-21st standards

• Sex: Girl
• Birth GA: 32-34 weeks (moderate preterm) - using 33 weeks as midpoint
• Chronological age: 13 months
• Corrected age: 13 months - 7 weeks premature = 13 - 1.75 = ~11.25 months corrected (approx. 11 months corrected)
• Birth weight: 1.5 kg
• Current weight: 5.2 kg
• Current height: 65 cm

Growth Assessment - 13-Month Girl (Born ~33 weeks, LBW 1.5 kg)

Step 1: Corrected Age Calculation

For a moderate preterm (32-34 wks), age correction is used until 18 months corrected age.

Step 2: Weight Assessment (WHO Girls, Weight-for-Age)

• 50th percentile = 8.7 kg, SD ~1.0 kg
• Z-score = (5.2 - 8.7) / 1.0 ≈ -3.5 SD (severe undernutrition range)

Step 3: Height/Length Assessment (WHO Girls, Length-for-Age)

• 3rd percentile: ~68.7 cm
• 10th percentile: ~70.0 cm
• 50th percentile: ~72.8 cm

Step 4: Weight-for-Height (WFH) / Wasting Assessment

• 50th percentile weight-for-height ~7.5 kg
• 3rd percentile ~6.5 kg
• 5.2 kg at 65 cm = well below 3rd percentile - indicates acute malnutrition / wasting ⚠️

Step 5: Birth Weight Trajectory

Summary Assessment

• Stunting (height-for-age < -2 SD): Borderline/mild
• Wasting (weight-for-height < -2 SD): Likely severe acute malnutrition (SAM) if < -3 SD
• Underweight (weight-for-age < -2 SD): Severe (z-score ~-3.5)

Clinical Recommendations

1. Urgent nutritional assessment - calculate caloric intake, assess feeding adequacy
2. MUAC measurement - mid-upper arm circumference (< 11.5 cm = SAM in children > 6 months)
3. Rule out underlying causes - chronic illness, recurrent infections, malabsorption
4. Extrauterine growth restriction (EUGR) - this baby likely had EUGR from NICU and has not fully caught up
5. Catch-up growth program: Target 150-200 kcal/kg/day with enriched feeds or therapeutic food
6. Developmental assessment - preterm infants with poor growth are at risk for neurodevelopmental delay
7. Refer to pediatric nutritionist and consider SAM protocol if MUAC confirms

⚠️ This child's growth pattern requires prompt clinical evaluation. The weight of 5.2 kg at 13 months chronological (11 months corrected) is significantly below expected for a preterm girl, even accounting for prematurity. Do not delay specialist review.