What is sudden infant death syndrome (SIDS)?

SIDS is the term used to describe the unexpected death of a baby when the cause is unknown. It was previously known as ‘cot death’.

SIDS causes more deaths of babies aged between one month and one year than any other cause.

SIDS is one of the main causes of Sudden Unexpected Death in Infancy (SUDI).

What is sudden unexpected death in infancy (SUDI)?

Sudden unexpected death in infancy (SUDI) is a term used to describe the sudden and unexpected death of a baby under 12 months of age. It is used when the cause of death is not immediately obvious.

Investigations can sometimes identify the cause of death, for example, those due to:

• accidents
• smothering by bedclothes
• infections
• metabolic disorders
• genetic disorders
• non-accidental injury

Sometimes, death occurs if a baby is suffocated or trapped by items in their sleep environment. This is called a fatal sleeping accident.

When no cause for the death can be found after a thorough investigation, the cause of death is called sudden infant death syndrome (SIDS).

What causes SIDS?

The cause of SIDS is still not known. Research suggests that a few different physiological (body) and environmental factors are involved.

Despite this, there are things you can do to reduce the risk of SIDS.

SIDS is more common in babies who are premature or born small.

How often does SIDS occur?

SIDS and SUDI are rare. The risk of your baby dying suddenly and unexpectedly is very low.

The rate of SIDS deaths has declined in Australia since safe sleeping campaigns were introduced in 1991.

Can SIDS be prevented?

While there is no way to prevent SIDS completely, safe sleep practices can greatly reduce the risk.

Research has found 6 risk factors that are associated with SIDS. By addressing these risk factors, you can reduce the risk of SIDS:

• Put your baby to sleep your baby on their back (‘back to sleep’).
• Keep your baby’s head and face uncovered.
• Keep your baby’s environment smoke-free, before and after birth.
• Make sure they have a safe sleeping environment, night and day.
• Put your baby to sleep your baby in a cot in your room for at least the first 6 months after birth.
• Breastfeed your baby, if you can.

‘Back to sleep’

Place your baby on their back to sleep. Do this from the very beginning of their life, for both day and night sleeps. This will lower the risk of SIDS.

Babies sleeping on their backs are less likely to suffocate, overheat or vomit.

Once your baby can roll in both directions by themselves — rolling onto their side and front, and then back onto their back — then you can put your baby to sleep on their back and let them find their own natural sleeping position. You don't have to wake them during the night to turn your baby over to the back position.

If your baby can only roll one direction on their own, gently roll them on to their back whenever you see they have rolled onto their front or side.

Your baby might develop a flat spot on their head (also known as plagiocephaly, brachycephaly or misshapen head), if they lie in one position for long periods of time.

There are a few things you can do to reduce the chance of a flat spot:

• Change your baby’s head position (left or right) when you put them in their cot.
• Don’t leave your baby seated for long periods.
• Offer increasing amounts of tummy time when your baby is awake.

To encourage your baby to change their head position, you can:

• Place your baby at different ends of their cot.
• Change the position of their cot in the room.
• Put toys or mobiles in different places to attract their attention.

Keep your baby’s head and face uncovered

Ensure that your baby’s face and head is not covered when they are sleeping.

You may use a baby sleeping bag with fitted neck and arm holes rather than a blanket.

If you use blankets, they should be tucked in tightly. They should also be no higher than your baby’s shoulders. Put your baby’s feet at the bottom of the cot so they can’t slip down under the bedding.

Keep your baby’s head uncovered when indoors or in a car. That includes no head coverings like hats or hoods.

Keep your baby smoke-free before and after birth

Exposure to cigarette smoke can significantly increase your baby’s risk of sudden and unexpected death (SUDI). This applies to smoking both during pregnancy and after they are born.

The risk of SIDS is also higher if your baby sleeps with a parent who is a smoker.

Your doctor can support you to quit smoking, or you can call the Quitline on 13 QUIT (13 7848).

Don’t let anyone smoke in the same room as your baby. Anyone who wants to smoke should smoke outside, and should change their clothes before holding your baby. Don’t take your baby into smoky places.

Provide a safe sleep environment for your baby

Make sure the cot, mattress and bedding are safe and meet Australian standards.

The mattress should be firm, flat and clean. Make sure your baby can’t get wedged between their mattress and the cot sides.

Avoid putting these items in your baby’s cot:

• pillows
• fluffy toys
• quilts or doonas
• bumpers

Put your baby to sleep your baby in a cot in your room

The safest place for your baby to sleep is in a cot in a room with you, for at least the first 6 months of life.

It’s thought that increased supervision and observation of your baby is protective against SIDS.

Being in the same room during your baby’s daytime sleeps is also protective. A bassinette or portable cot can be used for daytime sleeps.

You may choose to share a sleep surface with your baby due to parenting preferences, cultural beliefs or living circumstances.

Sharing a sleep surface with your baby can increase the risk of SIDS. The risk is greater if you:

• have used alcohol
• have used drugs
• are very tired

Never put your baby to sleep on a sofa, bean bag, waterbed or pillow. There is a high risk of SIDS when a baby shares a sofa or couch with an adult during sleep.

The risk of SIDS isn’t increased if you feed, cuddle or play with your baby in your bed, but put your baby back in their cot before going to sleep.

Breastfeed your baby

There is very good evidence that breastfeeding your baby can help protect them against SIDS.

The protective effect of breastfeeding is stronger the longer you exclusively breastfeed.

If you can’t breastfeed, you can reduce the risk of SIDS using the other 5 safe sleep strategies.

SIDS in Aboriginal and/or Torres Strait Islander infants

There is a large gap in infant and child mortality between Aboriginal and Torres Strait Islander people and non-Indigenous Australians.

SIDS has been reported as a leading cause of Aboriginal and Torres Strait Islander infant death.

The key risk factors associated with SIDS in Aboriginal and Torres Strait Islander infants are:

• low birthweight
• premature birth
• maternal nutrition during pregnancy
• maternal smoking
• maternal alcohol use
• lack of regular antenatal care

Resources and support

You can read more about safe sleep for your baby.

To find out more about SIDS and safe sleeping, please visit Red Nose.

Make sure that your friends and family members know how to put your baby to sleep safely and learn about setting up a safe nursery. Video provided by Red Nose Australia.

Red Nose also offers support to anyone affected by SIDS. For more information call the Red Nose Grief and Loss Support Line on 1300 308 307.

Product Safety Australia has information and a video called Sleep Bub Safe.

Other languages

HealthTranslations Victoria has resources on reducing SUDI and SIDS in pictures and in a variety of community languages.

Aboriginal and/or Torres Strait Islander peoples

Keeping Bub Safe is a booklet produced by Red Nose to reduce the risk of SIDS and sleep accidents in Aboriginal Communities.