Sudden infant death syndrome

Alternative names 
Crib death; SIDS

Sudden infant death syndrome (SIDS) is the unexpected, sudden death of any infant or child under one year old, in which an autopsy does not show an explainable cause of death.

Causes, incidence, and risk factors

SIDS rates have dropped dramatically since 1992, when parents were first told to put babies to sleep on their backs or sides to reduce the likelihood of SIDS. Unfortunately, SIDS remains a significant cause of death in infants under one year old. Thousands of babies die of SIDS in the U.S. each year.

The cause of SIDS is unknown, although there are several theories. Many physicians and researchers now believe that SIDS is not a single condition that is always caused by the same medical problems, but infant death caused by several different factors.

These factors may include problems with sleep arousal or an inability to sense a build-up of carbon dioxide in the blood. Almost all SIDS deaths occur without any warning or symptoms when the infant is thought to be sleeping.

SIDS is most likely to occur between 2 and 4 months of age, and 90% occur by 6 months of age. It occurs more often in winter months, with the peak in January. There is also a greater incidence in Native Americans and African-Americans.

The following factors increase the risk of SIDS:

  • Babies who sleep on their stomachs  
  • Babies who have soft bedding in the crib  
  • Multiple birth babies  
  • Premature babies  
  • Babies with a sibling who had SIDS  
  • Mothers who smoke or use illegal drugs  
  • Teen mothers  
  • Short intervals between pregnancies  
  • Late or no prenatal care  
  • Situations of poverty

Boys are affected more than girls. While studies show that babies with these risk factors are more likely to be affected, the impact or importance of each factor is not well-defined or understood.

There are no symptoms. Babies who die of SIDS do not appear to suffer or struggle.

Signs and tests

Autopsy results are not able to confirm a cause of death, but may help add to the existing knowledge about SIDS. Autopsies may be required by state law in the event of unexplainable death.

Support Groups

Parents who have lost a child to SIDS are in tremendous need of emotional support. Because no cause is found for the infant’s death, many parents suffer from guilt feelings.

These feelings may be aggravated by investigations of police or others who, by law, must determine the cause of death. Timing of a subsequent pregnancy is a concern for many parents after experiencing SIDS.

A member of a local chapter of the National Foundation for Sudden Infant Death Syndrome may assist with counseling and reassurance to parents and family members. See SIDS support group.

Family counseling may be recommended to help siblings and all family members cope with the loss of an infant.

Calling your health care provider
If your baby is not moving or breathing, begin CPR and call 911. Parents and caregivers of all infants and children should be trained in CPR.


To reduce the chance of SIDS, put babies to sleep (naps included) on their backs. DO NOT put babies to sleep on their stomachs.

Also avoid soft bedding. The U.S. Consumer Product Safety Commission has stated that “as many as 900 infant deaths each year are still associated with suffocation in soft bedding.” They recommend babies be placed on a firm, tight-fitting mattress, with no comforter.

In the past, for homes in which there has been a previous sibling death from SIDS, home apnea (breathing) monitors were recommended. But research found that they had no effect, and the use of home monitors has largely stopped. Until the nature of the disease is fully understood, complete prevention will not be a reality.

Other recommendations include:

  • Do NOT let your baby become too hot.  
  • Do NOT lay your baby on pillows, bean bags, or sheepskin mattresses.  
  • Keep your baby in a smoke-free environment.  
  • Breastfeed your baby, if possible - breastfeeding reduces some upper respiratory infections that may influence the development of SIDS.  
  • NEVER give honey to a child less than 1 year old - honey in very young children may cause infant botulism, which may be associated with SIDS.


Johns Hopkins patient information

Last revised: December 3, 2012
by Martin A. Harms, M.D.

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