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Section 7 — Fluid, Electrolyte & Nutrition Management Verify against local policy v1.0 · July 2026 Baylor Ed. 33 cross-checked Sept 2026

Chapter 7.5 — Growth Monitoring & Postnatal Growth Failure

Plotting weight, length, and head circumference on the right charts using corrected age, recognizing postnatal growth failure, and distinguishing inadequate nutrition from illness — built on West Midlands Neonatal Guidelines 2025–28, WHO/Fenton/INTERGROWTH-21st standards, and ESPGHAN nutrition guidance

Educational guideline — verify locally. Growth targets, chart choice, and fortification decisions must follow local policy and dietetic input. Avoid both under-nutrition (growth failure) and excessive/rapid catch-up. Does not replace attending or dietetic judgment.
BEDSIDE ACTION BOX

1. Overview

Overview

Growth is a vital sign of nutritional adequacy and health in the NICU. Preterm infants commonly accumulate a nutrient deficit and fall down the centiles (postnatal growth failure), which is associated with poorer neurodevelopment. Good practice means measuring the three growth parameters accurately, plotting them on the correct chart against corrected age, interpreting the trajectory, and responding to faltering growth by optimizing nutrition and excluding illness — while avoiding the opposite harm of excessive rapid weight gain.

Why This Topic Matters

Postnatal growth failure — particularly poor head growth — is linked to adverse neurodevelopmental outcomes, while over-rapid catch-up growth has metabolic risks. Careful monitoring and balanced nutrition optimize brain growth and long-term health.

2. Who This Guideline Applies To

Scope
  • All NICU infants, especially preterm/VLBW and growth-restricted infants, and those on PN/fortified feeds.
  • Infants with faltering growth or disproportionate growth parameters.
  • Cross-references: parenteral nutrition (7.2), enteral nutrition (7.3), metabolic bone disease (7.4), VLBW care (2.1), and discharge/follow-up (2.5).

3. Key Definitions

TermDefinition
Corrected ageChronological age minus weeks born preterm — used for growth assessment.
Postnatal growth failureGrowth (usually weight) crossing centiles downward relative to birth/expected.
Fenton / INTERGROWTH-21stPreterm growth charts/standards.
Catch-up growthAccelerated growth toward the expected trajectory (aim for steady, not excessive).
SGA / IUGRSmall for gestational age / intrauterine growth restriction (a distinct starting point).

4. Charts & Measurements

Measure Well, Plot Right
  • Measure weight (regularly), length (with a length board, not tape), and head circumference (weekly) accurately and consistently.
  • Plot on an appropriate chart: a preterm standard (e.g., Fenton or INTERGROWTH-21st) up to term-corrected, then WHO growth standards using corrected age.
  • Interpret the trend/trajectory across time, not one measurement; note proportionality of weight, length, and head.

5. Growth Targets (Principles — Verify Locally)

Steady, Proportionate Growth
  • Aim to approximate healthy intrauterine growth rates (weight gain of roughly ~15–20 g/kg/day is often quoted for stable growing preterm infants; verify locally), with steady length and head growth.
  • Track weight, length, and head together — head (brain) growth is especially important.
  • Avoid both faltering growth and excessive, rapid weight gain; individualize for SGA/IUGR infants.
Baylor Ed. 33 growth-rate guide (Table 14-13)

Use alongside the growth charts and the clinical picture, not instead of them. Baylor plots weight, weekly length and weekly head circumference electronically and calculates gain over the previous week.

GroupWeightLength (cm/week)Head circumference (cm/week)
Preterm <2000 g15–20 g/kg/day0.8–1.10.8–1
Preterm ≥2000 g20–30 g/dayVelocities not validated beyond 32–36 weeks — judge adequacy on the Fenton chart
Term (and preterm >4 months corrected), 0–4 months17–40 g/day0.6–10.3–0.5
4–8 months6–21 g/day0.3–0.50.1–0.2
8–12 months2–16 g/day0.2–0.40.1
Which laboratory markers actually help
  • The term rows come from ±2 SD on the WHO charts (4-month intervals divided into daily and weekly changes). PediTools (peditools.org) gives percentile and z-score calculators for the common charts.
  • Serum albumin is not a nutritional screen — do not order it routinely. Its half-life is about 21 days, and infection, liver disease, fluid shifts, rapid growth and prematurity all distort it.
  • Prealbumin (half-life 2–3 days) has the same confounders. Occasionally a trend helps in older infants with complex growth problems; discuss with the nutrition team first.
  • Alkaline phosphatase rises with poor bone mineralization, rapid bone growth and biliary disease — separate these with phosphorus, calcium and conjugated bilirubin. A low alkaline phosphatase is an insensitive marker of zinc deficiency; measure serum zinc if you suspect it. Bone screening thresholds are in chapter 7.4.

6. Recognizing Growth Failure

Signals
  • Weight crossing centiles downward; inadequate weekly weight gain; poor length and (critically) head-circumference growth.
  • Disproportion (e.g., weight gain without head/length growth) may signal fluid retention or inadequate protein/energy quality.
  • Consider the starting point — SGA/IUGR infants follow a different trajectory.

7. Causes of Faltering Growth

CategoryExamples
Inadequate intakeInsufficient volume/energy/protein, under-fortification, feed intolerance, fluid restriction.
Increased lossesHigh stoma output, malabsorption, cholestasis, vomiting/reflux.
Increased demand/illnessBPD (high work of breathing), sepsis, NEC, cardiac disease, chronic inflammation.
Metabolic/endocrineMetabolic bone disease, hypothyroidism, inborn errors, electrolyte disturbance.

8. Assessment Algorithm

1
Measure & plot the trajectory
Weight, length, head on the right chart at corrected age; look at the trend and proportionality.
2
Growth faltering?
Crossing centiles down / poor head growth → investigate; confirm accurate measurements.
3
Is intake adequate?
Review actual volume, energy, protein, and fortification vs targets (7.2/7.3); optimize with the dietitian.
4
Any losses/illness?
Exclude/treat sepsis, NEC, cholestasis, high stoma output, reflux, metabolic bone disease, hypothyroidism.
5
Optimize & reassess
Increase/fortify nutrition and treat causes; monitor response; aim for steady, proportionate catch-up.
6
⚠ Do-not-miss
Poor head growth (neurodevelopmental risk); occult illness (sepsis/NEC/cholestasis); metabolic bone disease; and measurement error.

9. Management of Growth Failure

Optimize Nutrition, Treat Cause
  • Meet protein/energy targets; fortify human milk; optimize PN/enteral prescription with dietetic input (see 7.2/7.3).
  • Treat the underlying illness/loss (sepsis, NEC, cholestasis, high stoma output, reflux, metabolic bone disease, hypothyroidism).
  • Ensure adequate minerals/vitamins/iron; monitor phosphate/ALP for bone health (see 7.4).
  • Aim for steady, proportionate growth; avoid excessive rapid weight gain.

10. Monitoring

ParameterFrequencyAction
WeightRegularly (per unit)Plot; assess trend and adequacy of gain.
LengthWeekly (length board)Assess linear growth (protein quality).
Head circumferenceWeeklyBrain growth — key neurodevelopmental marker.
Intake vs targetsOngoingOptimize with dietitian.
Biochemistry (phosphate/ALP, etc.)As indicatedDetect MBD/deficiencies.

11. Precautions

Safety Cautions
  • Use the correct chart and corrected age; interpret trends, not single points.
  • Do not ignore poor head growth — it carries neurodevelopmental risk.
  • Confirm measurements (especially length) are accurate before acting.
  • Investigate faltering growth for illness/loss, not just intake.
  • Avoid excessive rapid catch-up weight gain (metabolic risk).

12. Escalation & Family Support

Family-Centered Communication
  • "We track your baby's weight, length, and head size on special charts to make sure they're growing well — head growth is especially important for the brain."
  • "If growth slows, we check the feeds and look for any illness, then adjust nutrition with our dietitian to get growth back on track steadily."

13. Key Pearls

High-Value Clinical Pearls
  • Plot weight, length, and head on the right chart at corrected age; interpret the trajectory.
  • Poor head growth is a red flag for neurodevelopment.
  • Faltering growth = ask about intake AND losses/illness.
  • Optimize protein/energy and fortify human milk; involve the dietitian.
  • Monitor phosphate/ALP for metabolic bone disease (7.4).
  • Aim for steady, proportionate growth — not excessive rapid catch-up.

14. Common Mistakes to Avoid

MistakeWhy it harmsBetter practice
Using uncorrected age/wrong chart.Misjudged growth.Corrected age; preterm then WHO charts.
Reacting to a single weight.Over/under-reaction.Interpret the trend.
Ignoring head circumference.Missed brain-growth failure.Measure head weekly; act on poor growth.
Only increasing volume.Misses protein/illness issues.Optimize energy/protein; exclude illness.
Pushing rapid catch-up.Metabolic risk.Steady, proportionate growth.

15. Board-Style High-Yield Summary

Key Takeaways
  • Measure weight, length, and head; plot on preterm charts (Fenton/INTERGROWTH-21st) then WHO, at corrected age.
  • Interpret the trajectory; postnatal growth failure = crossing centiles down (especially head).
  • Faltering growth: assess intake (volume/energy/protein/fortification) AND losses/illness (sepsis/NEC/cholestasis/MBD/hypothyroidism).
  • Optimize nutrition with the dietitian and treat the cause; aim for steady, proportionate growth.
  • Poor head growth is a neurodevelopmental red flag.
  • Avoid excessive rapid catch-up; monitor phosphate/ALP for bone health (7.4).

16. References

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