Sudden infant death syndrome (SIDS) is the sudden and unexplained death of an infant where no cause is found after detailed post mortem.

  • 182 unexplained infant deaths occurred in the entire UK in 2021, a rate of 0.26 deaths per 1,000 live births
  • 166 unexplained infant deaths occurred in England and Wales in 2021, a rate of 0.27 deaths per 1,000 live births: an increase from 0.26 deaths per 1,000 live births in 2020
  • Over half (63%) of all unexplained infant deaths were boys in 2021 (0.33 deaths per 1,000 live births)
  • In 2021, the unexplained infant mortality rate was highest for mothers aged under 20 years, at 0.95 deaths per 1,000 live births. This is almost 4 times higher than all other age groups

Credit: Office of National Statistics, National Records of Scotland and Northern Ireland Statistics and Research Agency 2021

*England and Wales data includes International Classification of Diseases (ICD) codes R95 (Sudden Infant Death Syndrome) and R99 (Ill Defined/Unknown), Northern Ireland data includes ICD code R95, R96 and R99 and Scotland data includes ICD code R95 only.*