What is SIDS?

SIDS is the sudden, unexplained death of a baby younger than 1 year of age that doesn’t have a known cause even after a complete investigation.

Each year in the United States, thousands of babies die suddenly and unexpectedly. These deaths are called SUID (pronounced SOO-idd), which stands for “Sudden Unexpected Infant Death.”

SUID includes all unexpected deaths: those without a clear cause, such as SIDS, and those from a known cause, such as suffocation. One-half of all SUID cases are SIDS. Many unexpected infant deaths are accidents, but a disease or something done on purpose can also cause a baby to die suddenly and unexpectedly.

Sleep-related causes of infant death are those linked to how or where a baby sleeps or slept. They are due to accidental causes, such as: suffocation; entrapment, when baby gets trapped between two objects, such as a mattress and wall, and can’t breathe; or strangulation, when something presses on or wraps around baby’s neck, blocking baby’s airway. These deaths are not SIDS.

SIDS is ...

  • the leading cause of death in infants from 1 month to 1 year of age, with most deaths occurring between 1 month and 4 months
  • sudden and silent—the infant was seemingly healthy
  • a death often associated with sleep and with no signs of suffering
  • a recognized medical disorder
  • determined only after an autopsy, an examination of the death scene, and a review of the infant's and family's clinical histories
  • a diagnosis of exclusion
  • an infant death that leaves unanswered questions, causing intense grief

SIDS is not ...

  • preventable, but the risk can be reduced by placing the baby on his or her back to sleep on a firm surface, by making sure the baby has a smoke-free environment, and by keeping the baby from being overheated
  • suffocation
  • caused by vomiting and choking or by minor illnesses such as colds or infection
  • caused by the diphtheria, pertussis, tetanus (DPT) vaccines or other immunizations
  • contagious
  • child abuse or neglect
  • the cause of every unexpected infant death

» Download PDF here