When a previously healthy baby or child dies suddenly and unexpectedly, the term “Sudden Unexpected Death in Infancy” (often abbreviated to SUDI), may be used by the medical professionals to explain the death. In the past the terms “cot death” or “SIDS” may also have been used.

Sudden Infant Death Syndrome (SIDS) was defined in 1969 as “the sudden death of an infant or young child which is unexpected by history and in which a thorough post mortem examination fails to demonstrate an adequate cause for death”. SIDS is very rarely used to describe the cause of death on death certificates in Scotland. Terms such as “Sudden Unexpected Death in Infancy” and “Unascertained” are now much more likely to be used.