What is Sudden Infant Death Syndrome (SIDS)?

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The syndrome which is commonly referred to as cot death, is medically termed the Sudden Infant Death Syndrome (SIDS). It is the name given to the sudden death of a child less than 12 months old without a clear cause. In order to be diagnosed as SIDS, a thorough investigation of the death with an autopsy and other methods must have been unsuccessful in revealing the cause of death.

The incidence of SIDS varies considerably within developed nations, from 1 in 1000 to 1 in 10 000. On a worldwide basis, 15,000 infant deaths were diagnosed as SIDS in 2013, which is over 30% less than in 1990. In the United Kingdom, 300 infants die from sudden and unexpected causes annually.

The vast majority of cases of SIDS occur before the infant is six months old. It is more common in boys than girls. In most cases, the infant dies between midnight and 9 am, and there are absolutely no signs of any turmoil or distress in the environment where the baby slept.


By definition, the cause of SIDS is unknown. However, there are several factors that have been suggested to contribute to the occurrence of SIDS, including:

  • Genetic susceptibility
  • Sleeping on the belly or on the side
  • Keeping the baby too warm
  • Sleeping in an environment of tobacco smoke
  • The presence of soft objects on the bed during the baby’s sleep
  • Premature or low birth weight
  • Infection

It is estimated that in up to 5% of cases of SIDS, child abuse and intentional suffocation may be the real cause of the death of the infant, with a misdiagnosis of SIDS.


The most important factor in the prevention of SIDS is the position in which the infant sleeps. Sleeping on either the stomach or the side is associated with an increased risk of SIDS. It is therefore recommended that parents put young children to sleep on their back.

Other techniques that can help to prevent SIDS include:

  • The use of a firm mattress
  • Putting the infant to sleep close to parents or caregivers
  • Avoiding loose bedding
  • Keeping the sleeping environment cool
  • Using a pacifier
  • Avoiding smoking in the environment where infant sleeps
  • Breastfeeding
  • Making sure the infant receives appropriate immunizations

If parents make an effort to put their child to sleep on their back in a safe environment, there is a significant reduction in the risk of SIDS. However, it is not possible to eliminate the risk entirely.


It is important that families who have lost a child to SIDS have access to a strong support network and counseling if required.

As the infant death is sudden and unexpected, there is usually an in-depth investigation of the scene, which the parents and other members of the family can find upsetting.

Each individual grieves the sudden loss of the infant in a unique manner and usually needs time to process the death. It may often be helpful to talk with other people who have had similar experiences, which is why support groups can be very beneficial.

In the United Kingdom, the Lullaby Trust provides advice and support for families who have lost a child. The Babyloss and Sands websites also have useful information for families affected by SIDS.


  1. http://www.nhs.uk/Conditions/Sudden-infant-death-syndrome/Pages/Introduction.aspx
  2. http://www.babycentre.co.uk/a419/what-is-sudden-infant-death-syndrome-sids
  3. https://www.cdc.gov/
  4. http://www.chop.edu/conditions-diseases/sudden-infant-death-syndrome-sids
  5. http://www.babyloss.com/index.php
  6. https://www.sands.org.uk/

Further Reading

Last Updated: Aug 21, 2023

Yolanda Smith

Written by

Yolanda Smith

Yolanda graduated with a Bachelor of Pharmacy at the University of South Australia and has experience working in both Australia and Italy. She is passionate about how medicine, diet and lifestyle affect our health and enjoys helping people understand this. In her spare time she loves to explore the world and learn about new cultures and languages.


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