Why Growth Matters: Understanding Malnutrition and Growth Faltering

First published March 2014
Updated March 2026

As a pediatrician, some of the most important patterns I follow in clinic are those involving a child’s growth. When a child is not gaining weight or growing as expected, it can be confusing or worrying for parents and caregivers. Growth is a key sign of overall health, so when a child’s growth changes, we want to notice it early.

Let’s break down the new preferred terms of malnutrition and growth faltering—what these words mean, why they happen, and how we work together to support healthy growth in children.

Malnutrition

Malnutrition occurs when a child does not meet their body’s needs for calories, protein, or important nutrients. These shortages cause measurable changes in growth or body composition. Malnutrition is a medical diagnosis.

The Academy of Nutrition and Dietetics (AND) and the American Society for Parenteral and Enteral Nutrition (ASPEN) recommend using standardized, objective indicators.

Clinicians begin with single-point “z-scores,” such as:

• Weight-for-length (under age 2)
• BMI-for-age (ages 2-20)
• Length/height-for-age
• Mid-upper arm circumference

When we have repeated measurements over time, we can also look at:

• Weight-gain velocity (under age 2)
• Weight loss (ages 2-20)
• Declines in weight-for-length z-scores
• Documented inadequate intake

These trends also help determine the severity of malnutrition—mild, moderate, or severe.

Current guidelines also focus on why malnutrition occurs. It usually results from:

• Reduced nutrient intake
• Malabsorption
• Increased metabolic needs

Understanding the cause helps guide the right type of nutrition support.

Growth Faltering

Growth faltering (previously “failure to thrive”) means a child is not meeting expected patterns in weight, length/height, weight-for-length (under age 2), or BMI (ages 2 and older). Growth faltering is not a diagnosis. It is a descriptive term that signals a child’s intake, absorption, or needs may not be balanced.

In most cases, growth concerns are identified by:

• Plotting weight, height, and head circumference (when age-appropriate), along with either weight-for-length or BMI (depending on age).
  • The WHO growth chart is used for children under age 2, and the CDC growth chart is used for children age 2 and older.
• Watching for drops across percentiles
• Noting slow weight-gain velocity or significant weight loss
• Weight below the 2^nd percentile (WHO, under age 2) or the 3^rd percentile (CDC, age 2+)

Malnutrition and Growth Faltering Trends in Children

Most children fall into one or more of these categories:

1. Inadequate Caloric Intake

   This is the most common cause and may occur due to:

   • Feeding difficulties
   • Limited food availability
   • Restrictive eating behaviors
   • Improper formula mixing—even small changes in formula preparation can affect infants’ calorie intake.
2. Malabsorption

   This occurs when children take in enough calories but cannot absorb them well. Medical causes include:

   • Celiac disease
   • Cystic fibrosis
   • Gastrointestinal disorders
3. Increased Caloric Needs

   Some medical conditions increase energy use, such as:

   • Congenital heart disease
   • Chronic infections
   • Certain metabolic disorders
4. Psychosocial Factors

   Less commonly, growth concerns can be linked to family stress, inconsistent feeding routines, or neglect. Only a small proportion of growth faltering is due to neglect, but it remains an important part of a thorough evaluation.

Evaluating a Child with Malnutrition or Growth Faltering

A detailed assessment helps us understand why a child is not growing as expected. This includes:

1. Tracking Growth

   Plotting height, weight, head circumference (if appropriate), and weight-to-length/BMI (depending on age) over time remains our most sensitive tool.

2. History of:
   • Feeding routines
   • Formula preparation or direct breastfeeding patterns
   • Illness symptoms—vomiting, diarrhea, breathing difficulties
   • Developmental milestones
   • Social and family factors
3. Physical Exam

   We assess signs of nutrient deficiency, chronic illness, or developmental delays.

4. Diagnostic Testing

   Testing is only used when needed. Possibilities include:

   • Imaging: swallow studies, abdominal X-rays, endoscopy, or brain imaging
   • Bloodwork: complete blood cell count, electrolytes, kidney and liver tests, iron studies, thyroid function, and inflammatory markers

Treatment of Malnutrition or Growth Faltering

1. Optimizing Nutrition, which may involve:
   • Structured meals and snacks
   • Higher-calorie or higher-protein foods
   • Formula adjustments
   • Nutrition supplements
   • Modifying food textures
   • Addressing underlying health conditions
2. Team Support, which may include:
   • Medical provider
   • Feeding psychologist
   • Feeding therapist (occupational therapist or speech-language pathologist)
   • Dietitian
   • Social worker
3. Occasional Specialty Input from:
   • Gastroenterologists
   • Allergists
   • Pulmonologists
   • Cardiologists
   • Otolaryngologists (ENTs)

Early attention helps prevent long-term effects such as learning or developmental delays and shorter adult height. With timely support, children typically return to a healthy growth trajectory, and families feel empowered knowing they have a clear, manageable plan.

If you feel your child is not growing as expected, trust that instinct. You know your child best. Malnutrition and growth faltering do not mean you did something wrong—they mean we need to take a closer look together. These are signs that a child’s body may need more support, and early evaluation helps us understand what is happening.