Skip to content

Failure to thrive



Luke is a 2-month-old boy who presents with poor weight gain since birth.

He was born at term via emergency c-section due to failure to progress and foetal distress. Antenatal history was unremarkable.

His birth weight was 2.72 kg (3rd centile), length 49 cm (18th centile) and head circumference 33 cm (5th centile).

‘Failure to thrive’ is common

“Failure to thrive” occurs when a child has slow weight gain. It is commonly seen in the first couple of years of life and accounts for 1-5% of paediatric hospital admissions for those under two. The term. ‘failure to thrive’, describes a slow growth pattern. It is not a diagnosis.

There has been a shift in terminology to more neutral or descriptive terms such as “faltering growth,” “poor growth,” and “slow weight gain” to avoid the negative connotation associated with the word “failure”. The prevalence of failure to thrive is between 1.3% to 20.9%. Infants who are slow to gain weight require early treatment as they are at risk for having a short stature, behavioural and emotional problems, and developmental delays.

‘Failure to thrive’ has many definitions

We use standardized charts to document infant growth. WHO growth charts are commonly used for children less than two years old. These growth charts need to be adjusted for infants born prematurely until they are two years old. CDC growth charts are commonly used for children two years or older.

Infants with developmental conditions such as Down and Turner Syndrome also need different growth charts

There are many different definitions of “failure to thrive”:

Weight below the 3rd percentile

Weight for length less than 10th percentile

Weight 20% below the ideal weight for length

Weight dropped two major percentile lines

The best growth assessment requires plotting serial measurements on the appropriate charts. The trend is much more important than any individual number.

Normal growth variants can present as presumed ‘failure to thrive’

For many reasons, an infant may present with presumed ‘failure to thrive’. It is important to consider whether this is a normal variant of growth. Four main patterns exist:

  • Genetic short stature
  • Ex-premature infant
  • Constitutional
  • ‘Catch down’ growth

Normal variants of growth presenting as ‘failure to thrive’

Expected weight gain

What causes failure to thrive?

As with many diagnoses, “failure to thrive” is descriptive. Identifying the underlying cause can be challenging. It can help to divide your thought process into the following:

Inadequate caloric intake

Excessive caloric demand

  • Does the child have a congenital cardiac condition?
  • Is there an underlying endocrinological condition that is undiagnosed and untreated? E.g. Diabetes mellitus, hyperthyroidism
  • Is there an underlying chronic infection that is undiagnosed and untreated? E.g. urinary tract infections, osteomyelitis
  • Is there an underlying chronic inflammatory condition that is undiagnosed and untreated? E.g. Cystic fibrosis
  • Is there an underlying malignancy?


  • Does the child have a cow’s milk protein allergy?
  • Does the child have coeliac disease?
  • Does the child have chronic diarrhoea?
  • Is there an underlying inflammatory bowel disease?


  • Is there a syndrome known to cause poor growth? E.g. Russell-Silver Syndrome



  • Food security
  • Family safety
  • Parental capability for feeding
  • Child behaviour around feeding and mealtime

Medical Child Abuse

  • Most commonly presents as “failure to thrive” with unclear aetiology and is ultimately due to parental food restriction.


Start with a thorough history, focusing on input and output. Obtain as many growth measurements as possible. Start with the antenatal history and review maternal health, growth and morphology scans, medication exposure, smoking or recreational substances.

  • What were the growth parameters at birth (measurements and centiles)?
  • How has the baby been feeding? Are they breast or bottle-fed (with expressed milk or formula)? If formula-fed, are the bottles being made appropriately?
  • What is the feeding pattern (frequency and volume)?
  • What is the baby’s output with regard to vomits, urine and stools?

You sit down with Luke’s parents, Susan and David, to take a history.

Luke is exclusively breastfeeding, demanding feeds every 2-3 hours during the day and 3-4 hours at night. Susan had issues initially with ensuring the correct latch, but after a review with a lactation consultant, feeding is going well. He feeds for about 40-60 minutes, often falls asleep on the breast, and must be woken.

At the 6-week check, Luke is 3.54 kg (1st centile), with a length of 53 cm (20th centile) and a head circumference of 36cm (12th centile). 

He has 5-8 wet and 4-6 dirty nappies daily. His stools are liquid mustard brown, with no mucous or blood.

He has the occasional posit post-feed but no high volume or forceful vomits. They note that he quickly tires at the breast with a very slow suck. Occasionally, he looks pale and sweaty when he feeds, but they think that might be due to the weather.

  • Is there a family history of medical, cardiac, gastrointestinal, genetic, or metabolic disorders?
  • Are the parents consanguineous, increasing their risk of a genetic or metabolic disorder?

Luke’s parents are of Lebanese and Australian background and are non-consanguineous. There is no family history of significance.

Now, take a thorough social history, considering possible psychosocial contributors to poor growth.

Luke is their first child.

Though it has been hard, they have been coping well and enjoying parenthood. There are no red flags for postnatal anxiety or depression in either parent. They have no financial stressors. They have supportive parents who live nearby and a good friend network.

Once you have completed your history, it’s time to examine the child. First and foremost, do they look well or unwell? Are there signs of significant dehydration or malnutrition? Take accurate growth measurements and plot them against previous measurements. Don’t forget to take the parents’ heights to calculate mid-parental height!

For girls: (maternal height in cm + paternal height minus 13cm) divided by 2.

For boys: (maternal height in cm + paternal height plus 13cm) divided by 2.

Look at the muscle bulk and subcutaneous fat stores. Look at the health of skin, hair, eyes, gums, and nails for indications of micronutrient deficiencies. Look for syndromic features, neurocutaneous stigmata, and congenital defects. Look for any red flags suggesting abuse or neglect.

Complete a thorough cardiovascular, respiratory, gastrointestinal, and neurological examination, looking for signs of systemic illness.

Lastly, observe a feed or mealtime if you can. Assess the child’s development and behaviour and child-caregiver interactions.

Luke is awake and alert.

He does not have any dysmorphic features. He looks a little pale but has warm peripheries and a cap refill of 2 seconds. His measurements today are 3.54 kg (1st centile), length 55 cm (22nd centile) and head circumference 37cm (15th centile). He has a soft fontanelle and moist mucous membranes. He does not have significant muscle bulk or subcutaneous fat stores.

You note a soft systolic murmur at the left sternal base. It is difficult to hear with Luke squirming and crying. His lungs otherwise sound clear. His abdomen is soft with no organomegaly. His femoral pulses are symmetrical and strong. His oropharynx appears normal. His central and peripheral tone is normal, and his neonatal reflexes are all present.

Luke is given to Susan for a feed. He starts sucking quickly, but after a few minutes, slows down and looks very sleepy.

You re-listen to his chest and clearly hear a pan-systolic murmur at the left sternal base. There are no associated thrills or heaves.

Investigations are guided by your history and clinical examination. Most children will require baseline bloods, which include full blood count, iron studies, electrolytes, glucose, liver function tests and thyroid function studies. For infants under 12 months, a urine specimen to exclude UTI and another sample for a metabolic screen. For children with malabsorptive signs, a stool specimen looking at microscopy, fat globules, fatty acid crystals and possibly faecal calprotectin. If the child is on solids, consider coeliac serology with total IgA levels and micronutrients e.g. Vitamin B12 and folate.

Additional investigations for genetic or inborn errors of metabolism can be done if clinically indicated.

Given your examination findings, you opt to organise baseline bloods for Luke, including FBC, urea and electrolytes, LFT and TFTs and an echo.

The sonographer happens to be available. They find a VSD, which is impacting his feeding and growth.

You refer him to cardiology for guidance on management, potential surgical correction, and the feeding clinic. Luke may require fortified supplemental feeds in the interim to optimise his growth.


Clinical management will depend on your aetiology but will involve a multi-disciplinary team of general paediatricians, dietitians, speech therapists and the family’s GP or child family health nurse. If severely dehydrated or malnourished, then they require admission for close monitoring with rehydration and refeeding. If available at your hospital, a referral to a feeding clinic to facilitate outpatient management will ensure all the relevant healthcare workers are involved. Occasionally, paediatric subspecialties such as gastroenterology, genetics, metabolic or neurology may also need to be involved.

Regardless of the underlying aetiology, optimising caloric, macronutrient and micronutrient intake will be necessary. If we go back to our categories in aetiology, additional management strategies include the following:

Inadequate caloric intake

  • Optimise breast or bottle-feeding
  • Surgical correction of any oropharyngeal or gastrointestinal defects
  • Supportive allied health and psychological therapy for oral aversion, sensory processing difficulties or eating disorders
  • Treat underlying reflux or vomiting

Excessive caloric demand

  • Medical and surgical management of congenital cardiac conditions
  • Medical management of endocrinological conditions, chronic infections, or chronic inflammatory conditions
  • Medical and surgical management of underlying malignancy


  • Avoidance of allergens, e.g. cow’s milk protein, gluten
  • Medical management of chronic diarrhoea
  • Medical management of inflammatory bowel disease


  • Adjust expectations of growth depending on genetic condition


  • Adjust expectations of growth depending on genetic condition


  • Social support and use of charitable organisations to increase access to food
  • Social support for parents
  • Psychological support for children with behavioural difficulties around meals

Medical Child Abuse

  • If suspected, notify the appropriate child protective services.
  • Children require hospital admission to observe feeding and growth

Key points

A thorough history is required to determine if the caloric intake is adequate.

Obtain as many serial growth measurements as you can to plot percentiles. The trend over time tells more than a single measure.

A complete history and examination will guide you towards which investigations are necessary.

Management involves a multidisciplinary team optimising caloric, macronutrient and micronutrient intake and diagnosis-specific treatment.


Correia Martins L, Lourenço R, Cordeiro S, Carvalho N, Mendes I, Loureiro M, Patrício M, Anjos R. Catch-up growth in term and preterm infants after surgical closure of ventricular septal defect in the first year of life. Eur J Pediatr. 2016 Apr;175(4):573-9. doi: 10.1007/s00431-015-2676-4. Epub 2015 Dec 9. PMID: 26646145.,emotional%20problems%20and%20developmental%20delays.

International Journal of Epidemiology, Volume 33, Issue 4, August 2004, Pages 847–848,

Vademacum Metabolicum, Diagnosis and Treatment of Inborn Errors of Metabolism, J. Zschocke, G. Hoffman,




Management of Button Battery Ingestion

, ,

Cervical Spine Imaging in Kids – the PECARN rule

, , ,

The ‘Hidden C’


Necrotising Enterocolitis

Copy of Trial (1)

Bubble Wrap PLUS – June 2024

Copy of Trial (1)

The 81st Bubble Wrap


Persistent Pulmonary Hypertension of the Newborn


Diagnosing acute post-streptococcal glomerulonephritis

Not a fever HEADER

When is a fever not ‘just a fever’?

Copy of Trial (1)

Bubble Wrap PLUS – May 2024

Copy of Trial (1)

The 80th Bubble wrap x DFTB MSc in PEM


SVT in infants




Paediatric acute respiratory distress syndrome (PARDS)

, ,

The Oxy-PICU trial

, , ,

Leave a Reply

Your email address will not be published. Required fields are marked *