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Sudden Infant Death Syndrome

(Crib Death; SIDS)


Sudden infant death syndrome (SIDS) refers to the unexpected, unexplained death of a child less than 1 year old. SIDS is rare during the first month of life. It peaks at 2-4 months of age, then gradually decreases.


Experts do not know the exact cause of SIDS. Many theories exist. Potential causes include:

  • Abnormalities in a section of the brain that controls breathing during sleep and waking
  • Abnormalities in the control of heart rhythm
  • Changes in how serotonin, a neurotransmitter, functions in the brain
  • Changes in some components of the immune system
  • Inadequate arousal response to breathing obstruction or asphyxia—a lack of oxygen or excess carbon dioxide


Area of the brain involved in regulation of breathing.

Copyright © Nucleus Medical Media, Inc.

Risk Factors

SIDS is more common in infants less than 6 months old. Other factors that increase your infant's chance of SIDS include:

  • Low birth weight
  • Delayed fetal growth
  • History of SIDS death in a sibling
  • History of an acute life-threatening event
  • Previous incident of unexplained severe apnea—when breathing is repeatedly interrupted and requires resuscitation
  • Sleeping on the stomach or side rather than back
  • Co-sleeping in parents bed
  • Loose covers and blankets
  • Overheating
  • Other risk factors are more general and include:
    • Smoking during pregnancy or in a house where the baby is sleeping
    • Alcohol, excessive caffeine, opiate, or cocaine use during pregnancy
    • Mother's age—younger than 20 during first pregnancy
    • Poverty
    • Black, Native American, and Alaskan Native families
    • Sex: male
    • History of anemia or a urinary tract infection while pregnant
    • No or late prenatal care
    • Premature birth
    • Recent infection and/or fever
    • Cold weather in late fall or winter
    • Low socioeconomic status or low level of education


A baby that dies of SIDS typically appears healthy. The baby may have had a cold or gastrointestinal infection in the 2 weeks prior to death. There usually are no warning signs that a baby is about to have SIDS.


All possible illnesses and causes of death must be ruled out before a diagnosis of SIDS is made. A complete investigation will take place including:

  • Autopsy
  • Assessment of the death scene
  • Review of the baby and family's medical histories


Emergency medical personnel should be called as soon as the infant is discovered not breathing. Infant CPR should be started right away. Seek medical care right away even if the baby starts breathing again. The cause of the incident should be fully evaluated. Families may need grief counseling after the death. Some parents find support groups helpful.


There is no way to predict which infants will die of SIDS. Several actions may help you lower your child's chance of SIDS:

  • During pregnancy:
    • Get prenatal care early and regularly.
    • Do not smoke, drink alcohol, or use drugs while pregnant.
  • After birth:
    • Babies less than 1 year old should sleep on their back. Do not allow a young baby to sleep on their stomach or side. However, many babies roll over after 6 months of age and do not require constant monitoring of sleep position. Ask your doctor for more information about positioning your baby for sleep.
    • Other factors that may help reduce SIDS risk include:
      • Provide a firm crib mattress.
      • Breastfeed your baby.
      • Do not place blankets, a comforter, pillow, or sheepskin under your baby.
      • Do not let your baby sleep on a waterbed.
      • Remove soft, stuffed toys and loose bedding from the sleep area.
      • Do not cover your baby's head or face.
      • Have your baby sleep in the same room as you do for at least the first 6 months, but ideally for the whole year. However, do not share your bed.
      • Practice skin-to-skin contact with your baby as soon as possible after birth.
      • Keep the bedroom at a comfortable temperature (68-72°F [20-22.2°C]).
      • Avoid overheating. Do not overdress your baby.
      • While your baby is awake, place him on his stomach so that he can move his body.
      • If you smoke, do not smoke in the house or around your baby. Ask your doctor about ways you can quit.
      • Be sure that your baby gets routine medical care, including the recommended vaccines.
      • Do not use cardiorespiratory monitors or other commercial devices that claim to reduce the risk of SIDS. There is no evidence that these devices are useful.
      • Learn infant CPR.

    Make sure anyone else caring for your child is also aware of these recommendations.


Family Doctor—American Academy of Family Physicians

Healthy Children—American Academy of Pediatrics


About Kids Health—The Hospital for Sick Children

Caring for Kids—Canadian Paediatric Society


American Academy of Pediatrics SIDS Task Force. The changing concept of sudden infant death syndrome: diagnostic coding shifts, controversies regarding the sleeping environment, and new variables to consider in reducing risk. Pediatrics. 2005;116:1245-1255.

Galland BC, et al. Prone versus supine sleep position: a review of the physiological studies in SIDS research. J Paediatr Child Health. 2002;38:332-338.

Hunt CE, Hauck FR. Sudden infant death syndrome. CMAJ. 2006;174:1861-1869.

Sudden infant death syndrome (SIDS). EBSCO DynaMed Plus website. Available at: Updated September 15, 2017. Accessed March 20, 2018.

Sudden infant death syndrome (SIDS). Kid's Health—Nemours Foundation website. Available at: Updated February 2017. Accessed March 20, 2018.

10/23/2009 DynaMed Plus Systematic Literature Surveillance. Blair P, Sidebotham P, et al. Hazardous cosleeping environments and risk factors amenable to change: case-control study of SIDS in south west England. BMJ. 2009;339:b3666.

11/14/2011 DynaMed Plus Systematic Literature Surveillance. Task Force on Sudden Infant Death Syndrome. SIDS and other sleep-related infant deaths: expansion of recommendations for a safe infant sleeping environment. Pediatrics. 2011;128(5):1030-1039.

10/25/2016 DynaMed Plus Systematic Literature Surveillance. SIDS and Other Sleep-Related Infant Deaths: Evidence Base for 2016 Updated Recommendations for a Safe Infant Sleeping Environment Rachel Y. Moon, Task Force on Sudden Infant Death Syndrome. Pediatrics Oct 2016, e20162940; DOI: 10.1542/peds.2016-2940 .

9/26/2017 DynaMed Plus Systematic Literature Surveillance. Psaila K, Foster JP, et al. Infant pacifiers for reduction in risk of sudden infant death syndrome. Cochrane Database Syst Rev. 2017 Apr 5;4:CD011147.

Last reviewed March 2018 by EBSCO Medical Review Board Kari Kassir, MD  Last Updated: 9/26/2017