The sudden and unexpected death of a baby is usually referred to by professionals as ‘sudden unexpected death in infancy’ (SUDI) or ‘sudden unexpected death in childhood’ (SUDC), if the baby was over 12 months old. The death of a baby which is unexpected is also sometimes referred to as ‘sudden infant death’.

Some sudden and unexpected deaths can be explained by the post-mortem examination, revealing, for example, an unforeseen infection or metabolic disorder. Deaths that remain unexplained after the post-mortem are usually registered as ‘sudden infant death syndrome’ (SIDS) or ‘sudden unexplained death in childhood’ (SUDC) in a child over 12 months. Sometimes other terms such as SUDI, SUDC or ‘unascertained’ may be used.

While SIDS is rare, it can still happen and there are steps you can take to help reduce the risk for your baby. 
A guide to Safer Sleep for babies - Lullaby Trust