Sudden infant death syndrome (also known as SIDS or ‘cot death’) is the sudden and expected death of a baby younger than 12 months of age, which usually happens during sleep, and cannot be explained even after a thorough investigation. SIDS is a tragic event and is the subject of much ongoing research.

While SIDS can happen anytime in the first 12 months of life, the majority of deaths happen in babies aged under 6 months of age, with a peak around 3 to 4 months of age.

You may also hear the term ‘sudden unexpected death in infancy’ or SUDI – this is sometimes used to describe all cases of sudden and unexpected deaths in infancy, not just those due to SIDS. For example, other causes of SUDI may include the death of an infant due to an illness that was not thought to be life-threatening or death from an accident or trauma.

What causes SIDS?

SIDS is an unexplained death, and experts are not sure why it occurs. However, it is most likely that some babies have a subtle underlying issue such as a genetic defect or brain abnormality (e.g. in the part of the brain that controls arousal from sleep and breathing). These babies are then exposed to a trigger (or several triggers) that may lead to SIDS.

Triggers may include:

  • Sleeping on the tummy or side
  • Sleeping on a soft surface
  • Co-sleeping in bed with an adult
  • Respiratory infection
  • Exposure to secondhand smoke (e.g. by one or both parents or another caregiver).

Vaccinations do not cause SIDS. There is no evidence that childhood vaccinations increase the risk of SIDS. These provide important protection against serious infections and should not be missed or delayed unless there are strong medical reasons to do so.

What are the risk factors for SIDS?

There are several risk factors for SIDS, including parent and baby factors.

Parent factors include:

  • Smoking by the mother during pregnancy
  • Parental smoking around the baby
  • Young maternal age (mother less than 20 years of age)
  • Co-sleeping with a baby in the same bed.

Baby factors include:

  • Gender: Boys are more likely to have SIDS than girls
  • Low birth weight: Babies born prematurely or who are small for their age have a higher risk of SIDS
  • Family history: Babies with a brother, sister or cousin who died of SIDS have a greater risk of SIDS.

Can SIDS be prevented?

Although there is no guaranteed way to prevent SIDS, there are things you can do to reduce the risks of it happening. These include:

  • Sleep your baby on their back from birth, not on their tummy or side. The rates of SIDS have gone down by over 50% since parents have been advised to put babies to sleep on their backs
  • Make sure your baby sleeps with their head and face uncovered at all times
  • Avoid overheating your baby
  • Keep your baby a smoke-free environment – both before birth and after they have been born. Parents and other caregivers should quit smoking if possible and should never smoke around a baby or in a baby’s home
  • Provide a safe sleeping environment for all sleeps during the day and night (see below)
  • Sleep your baby in their own safe sleeping place in the same room (but not the same bed) as an adult caregiver for the first 6 to 12 months of life
  • Breastfeed your baby if possible
  • Let other caregivers and babysitters know about sleeping your baby on their back at all times.

What is a safe sleeping environment?

A safe sleeping environment means:

  • Choose a safe cot which meets Australian Standard AS2172
  • Give your baby a safe mattress which is firm, clean, flat and the right size for the cot
  • Tuck blankets in firmly or use a safe baby sleeping bag (a bag in which the baby cannot slip inside and become completely covered)
  • Do not use a pillow, cot bumper, lamb’s wool, soft toys or doona in the cot at anytime, day or night
  • Do not let your baby sleep on a soft mattress, sofa, couch, chair, beanbag or waterbed in any circumstances
  • Do not share a bed with your baby: While it’s a great idea to sleep in the same room as your baby, babies should never share a bed with an adult
  • Make sure the cot is not near any dangling cords e.g. from blinds, curtains or electrical appliances
  • Keep all heaters and electrical appliances away from the cot.

There is some evidence that using a dummy (pacifier) when a baby goes to sleep may help to reduce the risk of SIDS. While some countries recommend using a dummy in this way, Australian guidelines currently make no recommendations about using dummies in the prevention of SIDS. This is because Australian authorities believe that the evidence is not yet firm enough to encourage dummies as part of a SIDS prevention strategy.

Can babies be put on their tummy to play?

Yes. It is important that babies have time on their tummies, but only when they are awake and an adult is with them. Tummy time helps babies to develop the muscles in their neck, back and arms and prepares them for crawling. However, you should never put a baby on their tummy for sleeping.

How do I know it was SIDS?

The only way to find out why a baby died suddenly and unexpectedly is perform a thorough investigation. This includes reviewing the history, doing an autopsy and investigating the circumstances of death, including where the baby died. When no cause can be found for the death it is called SIDS.

Parents who have experienced this devastating event often feel guilty that they could have prevented it. This is understandable but is not correct. It is just not possible to watch a baby for every moment of its life.

Talk to you GP about any questions you have about SIDS, or if you are having trouble coping. Your GP will be able to provide support and help you find other local support services. You may also find it comforting to talk to other parents who have experienced SIDS.

Last Reviewed: 26/05/2016

myDr


References

1. SIDS and Kids. Safe sleeping FAQ (updated May 2015). http://www.sidsandkids.org/wp-content/uploads/SIDS066-H-SIDS-Safe-Sleeping-FAQ-V7-web.pdf (Accessed May 2016).
2. Up to Date.com. Patient information: Sudden infant death syndrome (SIDS): Beyond the Basics (updated July 2015). http://www.uptodate.com/contents/sudden-infant-death-syndrome-sids-beyond-the-basics?source=search_result&search=sids&selectedTitle=3~52 (Accessed May 2016).
3. Mayo Clinic.com. Sudden infant death syndrome (SIDS) (updated May 2014). http://www.mayoclinic.org/diseases-conditions/sudden-infant-death-syndrome/basics/definition/con-20020269 (Accessed May 2016).