Faltered growth (the preferred term replacing "failure to thrive") is defined as weight consistently below the 2nd centile or crossing downwards through 2 or more centile spaces. NICE CG37 and RCPCH growth chart guidance emphasise that faltered growth is multifactorial — the majority (>80%) is due to inadequate caloric intake rather than underlying organic disease. However, the safeguarding dimension must be assessed in every case: faltered growth is one of the recognised presentations of child neglect, and the Working Together to Safeguard Children 2023 guidance requires GPs to apply threshold criteria for referral. Medical red flags requiring urgent paediatric assessment include: crossing 2+ centile lines, organomegaly, dysmorphic features, recurrent infections, significant developmental delay, and parental concern disproportionate to examination findings.

Measurement error is the most common cause of apparent faltered growth in primary care — up to 30% of weight measurements in primary care have significant errors due to inconsistent clothing, uncalibrated scales, or different measurement techniques. WHO growth charts (UK-WHO) are used from birth to 4 years because they represent optimal growth for breastfed infants in a supportive environment. UK90 charts are used from 4 years onwards. A single weight below a centile means nothing without context — serial measurements demonstrating sustained downward crossing of centile lines is the diagnostic criterion. Mid-parental height calculation is essential for any child with short stature — familial short stature is the most common cause of small stature and requires no investigation if growth velocity is normal and MPH centile is concordant.

Over 80% of faltered growth cases in the UK are due to inadequate caloric intake — the history must focus primarily on feeding before investigating for organic disease. Coeliac disease is the most commonly missed organic cause — it affects ~1% of the population and presents with faltered growth, steatorrhoea, and abdominal distension after gluten introduction. Cystic fibrosis should be considered in any child with recurrent chest infections and faltered growth — the newborn bloodspot screen (heel prick) screens for CF but false negatives occur. ARFID (Avoidant/Restrictive Food Intake Disorder) is increasingly recognised as a cause of inadequate intake in children — it requires specialist CAMHS and dietetic input and does not respond to standard feeding advice. Social history is not optional — food poverty affects 15–20% of UK children and is a primary driver of faltered growth that requires social care intervention, not medical treatment. Always ask about Healthy Start voucher entitlement.

The examination in faltered growth serves two purposes: to identify organic disease and to assess for signs of neglect or abuse. A child who is alert, interactive, and well-engaged with parents despite a low weight is very different from one who is withdrawn, apathetic, and showing poor parent-child interaction — the latter requires immediate safeguarding consideration. Dysmorphic features, cardiac murmurs, and organomegaly all require urgent secondary care assessment. Tongue tie (ankyloglossia) is a commonly missed cause of faltered growth in breastfed infants — it impairs latch and milk transfer, causing maternal nipple pain, poor infant satiety, and growth faltering. Assessment and division (frenotomy) by a trained practitioner resolves the problem. Tonsil size should always be assessed — Grade 3–4 tonsils can cause obstructive sleep apnoea, which dramatically increases basal metabolic rate and reduces appetite.

NICE guidance and paediatric consensus emphasise that investigation-driven approaches in faltered growth are ineffective — a focused history and examination identify the cause far more reliably than a "scatter-gun" blood panel. Coeliac serology is the one investigation that should be performed in almost all children with faltered growth and any GI symptoms — coeliac disease affects 1% of the population and is significantly underdiagnosed. The child must be on a gluten-containing diet for at least 6 weeks before testing — parents sometimes withdraw gluten before the diagnosis is confirmed, which invalidates the test. Total IgA must be checked alongside anti-TTG to exclude IgA deficiency (which gives false-negative anti-TTG in 2–3% of children). Sweat chloride testing for CF requires referral to specialist paediatric respiratory services — the test cannot be performed reliably in primary care.

Faltered growth is a quintessential MDT problem — no single professional can manage it effectively alone. The health visitor is the most important primary care professional in infant faltered growth — they have the frequency of contact, the home visiting capability, and the feeding expertise that GPs lack. The GP role is to exclude organic disease, identify safeguarding concerns, and coordinate the MDT. NICE CG37 recommends that paediatric referral should be made when there is: organic disease suspected, weight consistently below 0.4th centile, weight crossing ≥2 centile spaces, or concern about neglect. Safeguarding referral must be made where neglect is suspected — Section 17 (child in need) for support, Section 47 (child protection) where significant harm is suspected. GPs have a legal duty to refer under the Children Act 1989. Delay in safeguarding referral is a recurring finding in serious case reviews.

Caloric enrichment (adding fat and protein to existing foods) is more effective and better tolerated than volume increases for most children with faltered growth — it avoids overwhelming small appetites. The standard dietary target for catch-up growth is 120–150% of the estimated average requirement for chronological age, though this is guided by the dietitian based on the child's specific needs. Oral nutritional supplements can be prescribed on FP10 (NHS prescription) when a dietitian has confirmed inadequate intake — they should supplement, not replace, normal foods, as children who rely on supplements can develop feeding aversion. Pancreatic enzyme replacement (Creon) for CF must be given with every meal and snack — undertreatment causes malabsorption and persistent faltered growth despite adequate intake. For coeliac disease, strict gluten-free diet (not just low-gluten) is essential — even small amounts of gluten cause ongoing villous atrophy and malabsorption.

The "division of responsibility" in feeding (Ellyn Satter model) is evidence-based — parents control what food is offered, when, and where; the child controls whether and how much they eat. Pressure-based feeding strategies (coaxing, bribing, force) reliably worsen food refusal and increase mealtime anxiety, causing a negative cycle. Reducing pressure, even when a child is failing to thrive, produces better long-term outcomes than pressure-based approaches. Maternal postnatal depression affects feeding responsiveness — mothers with depression are less likely to recognise infant hunger cues, feed responsively, or persist with breastfeeding. Treating maternal mental health is a direct intervention for infant growth. Food poverty is a structural issue affecting 1 in 5 UK children — practical social support (food banks, Healthy Start vouchers, benefit entitlement checks) is a clinical intervention, not a social nicety. NICE CG37 explicitly recommends addressing social determinants of growth faltering as part of clinical management.

The frequency of monitoring should be tailored to severity and risk — NICE CG37 explicitly warns against over-frequent weighing, which creates parental anxiety and a medicalization of normal infant weight variation without improving outcomes. Catch-up growth (crossing centiles upward) typically begins 6–12 weeks after adequate nutritional intervention — do not expect immediate centile catches. Non-engagement with follow-up in the context of faltered growth is a safeguarding signal — it must be escalated rather than simply documented as "did not attend." Documenting safeguarding concerns contemporaneously (date, time, observations, who was present, what was said) is legally important and protects both the child and the clinician. The RCPCH Growth Chart guidelines recommend that growth monitoring should be part of a structured plan with clear escalation criteria documented at each review — "safety-netting" must be specific and recorded.