Terminology

• SUDI: all infant deaths which happen suddenly, and for which there is no apparent reason, are unexpected
  • Initially, all such causes are 'unknown' (or unascertained) and therefore defined as SUDIs until more information is available
  • If the death is still unexplained following PM, the term SUDI may be given as a classification of death on the medical certificate of the cause of death
• SIDS: the term 'sudden infant death syndrome' is occasionally used where there is no pathology or risk factors present
  • The term is therefore a 'diagnosis of exclusion' rather than an actual cause of death itself
  • SIDS cases can therefore be regarded as a subset of all SUDIs investigated
• Cot death: popular description used for any of the above terminology

Epidemiology of SUDI

• Incidence 1:1 000 to 1: 4000 live births - varies between/within countries, ethnicity, social deprivation
• Largest cause of infant deaths in those 2-6 months; risk drops off after 12 months

SIDS risk factors

Triple risk model

• Critical development period
• Exogenous stress
  • Prone position
  • Overheating
  • Head covering
  • Co-sleeping
  • Infection
• Vulnerable infant
  • Preterm birth
  • Maternal smoking

Intrinsic risk factors

• Acute illness (e.g. UTRI/otitis media) with symptoms present at time of death but not significant as a cause of death
• Preterm birth before 37 weeks gestation
• Congenital anomaly causing death
• Multiple birth
• Previous unexplained infant death
• Small for gestational age
• Male infant