Slow weight gain

• 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
• Not a disease itself.

Typical Growth Expectations:

• Weight doubles in first 4-6 months.
• Weight triples by the first year.
  • Example: 6-pound newborn expected to weigh 12 pounds at 6 months and 18 pounds at 1 year.

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

When Slow Weight Gain is a Concern:

• Interferes with healthy development, especially in the first year.
• Indicators:
  • Newborn doesn’t regain birth weight within 10-14 days.
  • Baby <3 months gains <1 ounce/day.
  • Infant 3-6 months gains <0.67 ounces/day.
  • Child’s steady growth suddenly stops.

Less Concerning Situations:

• Newborn wakes up to feed 8-12 times a day.
• Baby growing at a steady rate.
• Baby has a normal number of wet/dirty diapers.

Symptoms of Slow Weight Gain:

• Size significantly smaller than peers (weight, height, head size).
• Lack of interest in surroundings.
• Extreme sleepiness.
• Frequent crying and fussiness.
• Missed physical milestones (e.g., rolling over, sitting up, walking).

Assessment

History

• 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)

Examination

• 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

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

Causes of Slow Weight Gain:

Medical Causes:

• Premature Birth: Difficulty feeding due to underdeveloped muscles.
• Down Syndrome: Issues with sucking and swallowing.
• Metabolic Disorders: Conditions like hypoglycemia, galactosemia, phenylketonuria.
• Cystic Fibrosis: Poor calorie absorption.
• Food Allergies/Intolerances: Limited diet due to illness.
• Gastroesophageal Reflux: Frequent vomiting.
• Chronic Diarrhea: Poor nutrient absorption.

Social and Financial Causes:

• Incorrect formula preparation.
• Misunderstanding feeding frequency.
• Household stress (e.g., divorce, death).
• Poverty impacting food availability.

Causes of slow weight gain	Examples
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 Hyperthyroidism
Other Medical Causes	Genetic syndromes Inborn errors of metabolism

Treatment:

A multi-disciplinary team approach is highly recommended

• Medical Conditions: Focus on treating underlying issues.
• Nutritional Deficiency: Nutritionist develops a balanced diet plan.
• Chewing/Swallowing Issues: Speech pathologist assistance.
• Behavioral Issues: Behavioral psychologist intervention.
• Nutritional Support: Temporary feeding tubes if necessary.
• 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 elicite

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