Global Developmental Delay

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Children typically gain skills in a stepwise progression, often called β€œmeeting their milestones”. There is a wide range of normal for the ages at which children acquire these skills, but if they are outside of this range, their development is considered β€œdelayed”.

Development can be assessed in four main categories: gross motor, fine motor (including vision), speech and language (including hearing) and social, emotional and behavioural. For more information, see our guide to developmental milestones.

If a child under five years old is found to be delayed (two or more standard deviations below the age appropriate mean) in two or more of these domains this is referred to as global developmental delay (GDD), alternatively called early developmental impairment (EDI).1 This affects 1-3% of children under five.2

In school age children, the term GDD is not used, with β€œlearning disability” being preferred. This refers to issues with intellectual and adaptive functioning, which begin in early childhood.3 Learning disability can be classified as mild, moderate, severe or profound based on IQ or by assessment of adaptive functioning.3 The underlying causes are generally the same as those for GDD.

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There are many causes of global developmental delay, and these can be thought of under the main headings of β€œwhen” i.e. prenatal, perinatal and postnatal; and β€œwhy” i.e. intrinsic or extrinsic.

The most common causes of GDD are genetic and structural brain abnormalities.4

If only motor domains are affected, consider cerebral palsy (a static insult to the developing brain affecting movement and posture).

If only speech and social communication are affected, especially if associated with rigid, repetitive behaviours, consider autism spectrum disorder.

Clinical features

Some children with global developmental delay will present to a healthcare setting due to parental concern about not meeting their milestones, but these children can also be picked up incidentally or by targeted screening by health visitors.

Generally, the more severe delays and those involving gross motor skills will present earlier than those which are less severe or involve speech and language or social skills (as these skills are acquired later).

Red flags

There are certain β€œred flag” features which should prompt urgent assessment, some of which are listed below (note the ages listed can differ slightly by resource used):

  • No social smile by 8 weeks
  • Not sitting by 9 months
  • Not walking by 18 months (need to exclude muscular dystrophy)
  • No words by 2 years
  • Developmental regression (loss of previously acquired skills) at any time

Differential diagnoses

As mentioned above, there are many different underlying causes of global developmental delay. This is not an exhaustive list but demonstrates the broad variety of aetiologies.

Table 1. Differential diagnoses to consider in the context of global developmental delay.Β 

Category Causes

Prenatal intrinsic

  • Chromosomal (i.e. Trisomy 21- Down’s Syndrome)
  • Single gene disorders (i.e. Rett Syndrome, Fragile X Syndrome)
  • Metabolic (i.e. congenital hypothyroidism, homocystinuria)
  • Congenital brain malformations
  • Other (i.e. autism spectrum disorder)

Prenatal extrinsic

  • Intrauterine infections (i.e. rubella, CMV, toxoplasmosis)
  • Teratogens (i.e. alcohol, valproate)


  • Prematurity
  • Asphyxia/ischaemia (hypoxic ischaemic encephalopathy)
  • Kernicterus (acute bilirubin encephalopathy)
  • Intracranial haemorrhage (often leads to cerebral palsy)


  • Hypoglycaemia
  • Infection (meningitis, encephalitis)
  • Traumatic brain injury
  • Toxins (i.e. lead)
  • Chronic illness (especially if extended hospital admissions)
  • Psychosocial (neglect)


It is important to undertake a detailed history and assessment to establish global developmental delay and to look for evidence of the varied potential causes.

These children are generally referred to their local community paediatrics service for assessment and ongoing management.


Important areas to cover in the history include:

  • Pregnancy: scans, maternal health/medications/drugs and alcohol
  • Birth: gestation, weight, mode of delivery, complications
  • Past medical history: early neonatal life (admission to NICU, infections, hypoglycaemia, jaundice), chronic illnesses, admissions to hospital, injuries, seizures, abnormal movements, medications, allergies, immunisations
  • Family and social history: family tree, who lives at home, history of consanguinity, any history of learning problems in the family
  • Developmental history: what milestones were achieved in each domain and when, any regression (loss of skills)

Clinical examination

Clinical examination should include assessment of:

  • Growth (weight, height, head circumference)
  • Dysmorphic features or neurocutaneous markers/birth marks
  • Systemic examination (respiratory, cardiovascular, abdominal, neurological)
  • Developmental assessment: there are formal tools for this i.e. SOGS (Schedule of Growing Skills assessment), but you can gather lots of information from observation of and playing with a child. Repeated assessments over time give more information than a one-off assessment


Note that guidelines for the investigation of GDD vary across locations.

First line tests

First line blood tests include FBC, U&E, LFT, TFT, CK and ferritin.

With the easy availability of genetic testing, microarray/array CGH (which picks up significant deletions and duplications)Β is now included in first line testing.2,5 This has a diagnostic yield of 10-20% in GDD.5

A formal assessment of vision and hearing should be arranged if there are concerns.

Autism assessment (if the delay is in speech, language and social communication, with typical features suggestive of autism). Autism can also cause an apparent regression in speech ability.6

Second line tests

Second line tests depend on the likely aetiologies.

This may include a metabolic screen (i.e. ammonia, lactate, amino acids). Many other tests are included in a metabolic screen (e.g. homocysteine for homocystinuria, very long chain fatty acids for adrenoleukodystrophy and urine glycosaminoglycans for mucopolysaccharidoses). These are beyond the scope of this article.

Further genetic testing (including single gene tests i.e. Fragile X) can be performed.7

An MRI brain may be required, especially if microcephaly, focal neurology, epilepsy or developmental regression.2,6

Case example 1

Theo is an 18 month old child who was born at 28 weeks, and unfortunately had a significant right sided intracranial haemorrhage. Even using corrected gestational age, he is delayed in gross motor (not yet walking, sat at 13 months), and fine motor (able to make a pincer grip with right but not left hand), and is quite stiff on the left side of his body.

The likely diagnosis here is hemiplegic cerebral palsy secondary to prematurity and intracranial haemorrhage. Theo would likely have an abnormal MRI with right sided abnormalities.

Case example 2

Chloe is a 22 month old child who was developing normally until six months ago, when she started to have difficulty feeding and lost some words she had known previously. She can no longer walk steadily and has reduced tone, unusual hand movements and has recently started to have seizures.

This is a concerning history as there is developmental regression and seizures. The likely diagnosis is Rett Syndrome, but Chloe would require an MRI and extensive blood tests and genetics to establish the diagnosis urgently.

Case example 3

Sam is a 4 year old boy whose mother had an uneventful pregnancy and delivery. He has normal gross and fine motor skills but is delayed in speech and language (only uses a few words) and social communication (plays alongside but not with other children). He likes to line up his toys, makes minimal eye contact and gets upset if his normal routine is not followed.

This is a common way that autism spectrum disorder presents in preschool children, and Sam would require a formal autism assessment.


The aim of investigating global developmental delay is to identify children who have an underlying medical condition that would require/benefit from treatment and to provide an explanation for families.

Genetic conditions also have potential implications for other family members, including siblings (who might be carriers or asymptomatic) and any future children.

Children with GDD require multidisciplinary assessment and support, including education, speech and language, physiotherapy, occupational therapy and community paediatrics. This should be β€œneeds-led” and focus on the child’s strengths and areas of difficulty rather than the specific diagnosis, if there is one.

Key points

  • Global developmental delay refers to delays in two or more of the four developmental domains in children under five
  • It affects 1-3% of children and has many and varied causes, which can often be suggested by a thorough history and examination
  • There are first and second line tests in the investigation of GDD, which include blood tests, genetics and imaging


Dr Chris Jefferies


  1. Shevell MI, Majnemer A, Rosenbaum P, et al. Etiologic yield of subspecialists’ evaluation of young children with global developmental delay. J Pediatr 2000;136:593–8.
  2. Mithyantha R, Kneen R, McCann E, et al. Current evidence-based recommendations on investigating children with global developmental delayΒ  Arch Dis Child 2017;102:1071–1076.
  3. PRAM Network. Fifteen minute consultation: Approach to a school age child with suspected learning disability. Arch Dis Child Educ Pract Ed Epub ahead of print: [Nov 2023]. doi:10.1136/archdischild-2022-324224
  4. Majnemer A, Shevell MI. Diagnostic yield of the neurologic assessment of the developmentally delayed child. J Pediatr 1995;127:193–9.
  5. Miller DT, Adam MP, Aradhya S, et al. Consensus statement: chromosomal microarray is a first-tier clinical diagnostic test for individuals with developmental disabilities or congenital anomalies. Am J Hum Genet 2010;86:749–64
  6. Smith T, Ram D. Fifteen-minute consultation: A practical approach to developmental regression in childrenΒ  Arch Dis Child Educ Pract Ed 2019;104:173–177.
  7. Coysh T, Hogg SL, Parker APJ. Fifteen-minute consultation: Efficient investigation of the child with early developmental impairment in the era of genomic sequencing. Arch Dis Child Educ Pract Ed 2020;105:13-18.


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