Slow weight gain

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  • See also

    Child abuse

    Key points

    1. Optimal growth assessment requires serial measurements plotted on appropriate growth charts
    2. Nutrition is the main driver of growth in children under 2 years of age. Most cases of slow weight gain are secondary to inadequate caloric intake
    3. Slow weight gain is commonly multifactorial in origin, with psychosocial stressors often a significant contributor
    4. Small and otherwise healthy babies following a growth percentile line may not need any investigations


    • Slow weight gain describes a child or infant whose current weight, or rate of weight gain is significantly below that expected for age and sex, or if weight has dropped ≥2 major percentile lines
    • Slow weight gain may indicate inadequate growth for health and development and should trigger a medical and psychosocial assessment
    • There is not always an underlying pathological cause for slow weight gain
    • Length and head circumference are often initially preserved in cases of slow weight gain, but may be affected if severe or prolonged insufficient nutrition



    • Intake:
      • breast/bottle, number and volume/duration of feeds per 24-hour period, breast milk supply, formula preparation
      • Solids - age commenced, composition, number and quantity of meals and snacks
      • Milk intake per 24hr period in toddlers
    • Output:
      • Vomiting, stool, urine output, other losses (eg stoma)
      • Any identified triggers to increased output (eg specific food)
    • Food behaviour and dietary practices:
      • acceptance of food (or parents feeling need to coerce/distract)
      • mealtime set-up and duration
      • dietary restrictions (see causes of slow weight gain table below)
    • Past history:
      • chronic and current illness, recurrent infections
    • Family growth:
      • pattern of weight gain and growth in other family members
      • mid parental height
    • Family psychosocial assessment:
      • Signs of family vulnerability (see causes of slow weight gain table below)


    • General: does the child appear in proportion and well, or do they look unwell? Significant malnutrition or illness
    • Hydration: significant dehydration
    • Signs of underlying systemic diagnosis
    • Pattern of growth:
      • plot serial measures of weight, height and head circumference
      • clarify circumstances at times where growth trajectory changed eg solids introduction
    • Mid-parental height
    • Muscle bulk (buttocks), subcutaneous fat stores (thighs), skin, hair, gums, eyes and nails
    • Developmental level, caregiver-child interactions, signs of abuse or neglect
    • Observe feed if able

    Growth charts

    • <2 years of age: WHO growth standards. Correct for prematurity (<37 weeks) until 2 years old
    • ≥2 years of age: CDC growth reference charts
    • Use specific growth charts (eg Down, Turner syndrome) where appropriate

    Growth chart interpretation

    In the first few months of life, a healthy baby who is gaining weight may cross and track along a lower centile than that of their birth weight.

    Children with isolated less than 3rd percentile weight-for-age, but with typical neurodevelopmental progress and no red flags on clinical assessment may still be within normal limits of growth

    • These children should be monitored over time and may not need extensive investigation

    A drop in percentiles may be observed when switching from WHO to CDC charts

    • This is usually due to differences in the charts rather than representing a true change in growth pattern


    A multi-disciplinary team approach is highly recommended. Professionals may include: 

    • Child health nurse and/or lactation consultant
    • General practitioner (GP), paediatrician
    • Dietician, speech pathologist, multidisciplinary feeding clinic
    • Psychologist, infant mental health clinician
    • Social worker or child protection services

    For an otherwise healthy and normally developing child with no suggestive features on history or examination, no investigations are necessary at first.
    If a particular diagnosis is suggested by the history or examination, investigate according to the features you have elicited

    Investigations to consider:

    All ages:

    • Urine: Urinalysis, microscopy and culture (especially infants <12 months of age, as occult UTI can present with slow weight gain)
    • Blood:
      • FBE, ferritin, UEC, TSH,  glucose, LFT
      • If on solids or feeds containing gluten - coeliac serology and total IgA
      • micronutrients – especially active B12 if suspicion of malabsorption or restricted dietary intake
    • Stool: Microscopy, fat globules, fatty acid crystals

    In children older than 12 months:

    • ESR, faecal calprotectin

    Specific investigations for underlying metabolic, immune or genetic cause should be performed in consultation with specialist services

    Causes of slow weight gain


    Inadequate caloric intake/retention

    Inadequate nutrition  (breastmilk, formula and/or food)
    Breast feeding difficulties
    Error in infant formula preparation
    Restricted diet eg restriction of food groups or macronutrients, vegan, sensory aversions
    Structural eg cleft palate
    Persistent vomiting
    Appetite loss due to chronic disease
    Early (<4 months) or delayed (>6 months) introduction of solids

    Psychosocial factors

    Parental mental illness, disability or chronic illness
    Poor carer understanding eg language barrier, intellectual disability, limited literacy
    Non-secure attachment patterns
    Behavioural disorders
    Difficulties at mealtimes
    Coercive feeding (including feeding child whilst asleep)
    Food insecurity
    Social isolation
    Failure to attend appointments
    Parental substance abuse
    Family violence
    Trauma or neglect
    Current or past child protection involvement

    Inadequate absorption

    Cow milk protein allergy
    Coeliac disease (if having gluten containing diet)
    Pancreatic insufficiency eg Cystic fibrosis
    Chronic diarrhoea
    Chronic liver disease

    Excessive caloric utilisation

    Urinary tract infection
    Chronic illness / inflammation
    Chronic Respiratory disease eg Cystic fibrosis
    Congenital heart disease
    Diabetes mellitus

    Other Medical Causes

    Genetic syndromes
    Inborn errors of metabolism


    • Specific management will be guided by underlying contributing factors
    • Most patients can be managed on an outpatient basis
    • Consider admission if red flag features are present

    Consider consultation with local paediatric team when

    • Significant malnutrition, illness or dehydration
    • Failed outpatient management
    • Concern about potential child abuse or neglect
    • Significant mental health concern in parent
    • For further assessment of feeding technique, parent–child interaction and involvement of a multidisciplinary team

    Consider transfer when

    • Severe malnutrition, underlying cause or contributing factors requiring specialist input
    • Child requiring care beyond comfort level of local services

    For emergency advice and paediatric or neonatal ICU transfers, see Retrieval Services.

    Consider discharge when

    A clear individualised plan is in place that clearly outlines the following:

    • Recommended feeding plan
    • Details of follow up, including any outstanding investigations

    Follow up

    • Frequency depends on the child's weight, age and psychosocial circumstances.  Weight monitoring every 1-4 weeks is usually sufficient in infants, depending on the level of concern.
    • One clinician should take responsibility for follow up and ensure that appointments are attended. This can often be a child health nurse and/or GP. Referral to a paediatrician may not be needed
    • If follow up appointments are not attended, action should be taken to ascertain the wellbeing of the child. Refer to Child Protection if considered to be at risk

    Parent information

    Growth charts

    Additional notes

    Average growth
    Although the use of a growth chart is the most accurate indication of overall growth the use of average weekly weight gain for children who are followed up at frequent intervals may be required

    The rate of weight gain per week is variable

    The table below is a guide to the expected average weight gain per week (it is not the minimally acceptable weight gain)

    0 to 3 months

    150–200 g/week

    3 to 6 months

    100–150 g/week

    6 to 12 months

    70–90 g/week

    Growth charts for Down syndrome and Turner syndrome are available at:

    More information on how to interpret child growth can be found at:
    Australian Paediatric Endocrine Group – Growth and Growth Charts
    Guidelines for healthy growth and development for children and young people

    Last updated March 2021

  • Reference List

    1. Homan, G 2016, Failure to thrive: A practical guide, Am Fam Physician,  vol. 94, no. 4, pp. 295-299
    2. Jaffe, C 2011, Failure to thrive: Current clinical concepts, Pediatrics in Review March , vol. 32, no. 3, pp. 100-108
    3. Nice guideline 2017, Faltering growth: Recognition and management of faltering growth in children. Nice guideline [NG75} Nice guideline, Viewed May 2020
    4. Marchand, V 2012, The toddler who is falling off the growth chart, Paediatr Child health, vol. 17, no. 8, pp 447-450
    5. McAlpine, J 2019, Growth Faltering: The New and the Old, Clin Pediatri, vol. 2, article 1012
    6. Motil KJ 2020, Poor weight gain in children younger than two years in resource-rich countries: Etiology and evaluation up to date, Up to date, Viewed May 2020 
    7. Queensland Government 2015, Chronic Conditions Manual: Prevention and management of chronic conditions in Australia, Queensland Government Publications, Viewed May 2020
    8. Starship clinical guidelines 2016, Faltering growth -failure to thrive, Starship, Viewed May 2020
    9. Standish, J 2020, Slow Growth, Paediatric Handbook 10th Ed, WILEY Blackwell, The Royal Children’s Hospital, Melbourne
    10. The Sydney children’s hospitals network, Common newborn concerns,  The Sydney Children’s hospitals network, Viewed May 2020
    11. Women’s and Children’s Hospital 2017, Tips for gaining weight for infants and toddlers factsheet, Women’s and Children’s Health network , Viewed May 2020