Terminology Explained


Sudden Unexpected Death in Infancy (SUDI) is the term used to refer to all cases of sudden and unexpected death in infancy and includes deaths from the Sudden Infant Death Syndrome (SIDS) and fatal sleeping accidents.

Deaths are classified within SUDI if they occur between 7 and 365 days of life and fulfil the following criteria:

  • deaths that were unexpected and unexplained at autopsy
  • deaths during acute illness that was not recognised as life threatening
  • deaths due to an acute illness of less than 24 hours duration in a previously healthy infant (or death after this if life had only been prolonged by intensive care)
  • deaths from a pre-existing occult condition, and
  • deaths from any form of accident, trauma or poisoning

CESDI SUDI studies 1993-19961

Sudden Infant Death Syndrome (SIDS)

Sudden Infant Death Syndrome (SIDS) “is defined as the sudden unexpected death of an infant <1 year of age, with onset of the fatal episode apparently occurring during sleep, that remains unexplained after a thorough investigation, including performance of a complete autopsy and review of the circumstances of death and the clinical history.”2

For information and support, contact Red Nose Grief and Loss on 1300 308 307.

Sudden Unexpected Death in Childhood (SUDC)

“Sudden Unexplained Death In Childhood (SUDC) is the sudden and unexpected death of a child over the age of 12 months, which remains unexplained after a thorough case investigation is conducted.”3

For information and support, contact Red Nose Grief and Loss on 1300 308 307.

Last reviewed: 20/7/24