Developmental delay: failure to attain appropriate developmental milestones for child's corrected chronological age

Patterns of abnormal development

Global developmental delay

• Affects 1-3% of under 5s
• Significant delay (<2SD) in 2+ of: gross/fine motor, speech/language, cognition, social/personal, ADL
• Termed learning or intellectual disability in school age
• Investigations vary widely between centres
• Gap between child with global developmental delay and their peers will increase with age - better to look at delay as a percentage (e.g. 25%) until ~16 years where development tends to plateau

Prenatal causes

• Genetic (e.g. Down's syndrome)
• Metabolic (e.g. PKU, hypothyroidism)
• CNS malformation (e.g. neuronal migration disorders)
• Infections (e.g. TORCH infections)
• Toxins (e.g. maternal substance misuse)

Perinatal causes

• Prematurity
• Asphyxia

Postnatal

• Infection (e.g. meningitis)
• Trauma (accidental and non-accidental)