Growth Charts for Preterm Infants
For preterm infants, use specialized preterm growth charts (Fenton or INTERGROWTH-21st) from birth until term-equivalent age, then transition to WHO growth charts at term-corrected age through 24 months, followed by CDC growth charts from 24 months onward. 1, 2, 3
Recommended Chart Selection Algorithm
Birth Through Term-Equivalent Age (Preterm Infants)
Use Fenton preterm growth charts as the primary recommendation for monitoring preterm infant growth from 22-24 weeks gestational age through 50 weeks post-menstrual age 1, 2, 3. The recently updated Fenton third-generation charts (2025) demonstrate:
- Improved growth velocity curves across all percentiles with more uniform slopes 1
- Better alignment with fetal ultrasound estimates, representing the recommended growth goal (fetal growth pattern) 1, 2
- Sex-specific charts for weight, length, and head circumference 2, 3
- Harmonization with WHO growth standards at term-equivalent age, enabling smooth transition 2, 3
- Based on 4.8 million births from 15 countries, excluding infants with abnormal fetal growth 1
INTERGROWTH-21st Preterm Postnatal Follow-up Study (PPFS) charts are an alternative prescriptive standard based on optimal growth conditions 4, 5. However, these charts:
- Define fewer infants as having extrauterine growth restriction compared to Fenton charts 4
- May better categorize infants with adverse clinical courses 4
- Have similar predictive ability for adverse feeding outcomes as Fenton charts 5
Term-Corrected Age Through 24 Months
Transition to WHO growth charts once the preterm infant reaches term-equivalent age (approximately 40 weeks post-menstrual age) and continue through 24 months of corrected age 6, 2, 3. The WHO charts:
- Represent optimal growth standards based on healthy breastfed infants 6
- Are recommended by CDC, NIH, and AAP for all infants under 24 months 7, 6
- Use the 2.3rd and 97.7th percentiles (±2 standard deviations) as cutoffs for identifying abnormal growth 7, 6
24 Months Through Childhood
Switch to CDC growth charts at 24 months of age and continue through 19 years 7, 6. This transition is recommended because:
- Methods used to create WHO and CDC charts are similar after 24 months 7
- CDC charts allow continuous monitoring without further chart changes 6
- The 5th and 95th percentiles are typically used as cutoff points 6
Critical Implementation Points
Age Correction for Prematurity
- Always use corrected gestational age (not chronological age) when plotting preterm infants on growth charts until 24 months 2, 3
- The Fenton third-generation charts use exact gestational age (weeks and days) rather than completed weeks for more precise monitoring 1, 2
Identifying Growth Faltering
- Use z-score changes rather than single percentile measurements to identify extrauterine growth restriction 4, 5, 3
- A z-score change of ≥-1.5 to -2.0 from birth indicates clinically significant growth faltering 4, 5
- Serial measurements are essential—growth velocity over time is more informative than isolated measurements 8, 6
Common Pitfalls to Avoid
Do not use intrauterine/fetal growth charts to evaluate birthweight in clinical neonatal practice, as this creates inconsistency with postnatal charts used for ongoing monitoring 3. While obstetric information about fetal growth restriction should inform risk assessment, neonatal growth monitoring requires postnatal-specific charts 3.
Do not use standard term infant charts (WHO or CDC) for preterm infants before term-equivalent age, as these do not account for the unique growth patterns and nutritional needs of preterm infants 1, 2, 3.
Expect a slight disjunction when transitioning between chart types (Fenton to WHO at term, WHO to CDC at 24 months), which may temporarily reclassify a child's growth percentile 6. This is normal and should be interpreted in context of overall growth trajectory 6.