Also called

  • Sudden Unexpected Death in Infancy (SUDI)
  • Sudden Infant Death Syndrome (SIDS)


  • Sudden unexpected death in infancy (SUDI) is the name for the sudden and unexpected death of a baby when there is no apparent cause of death. 
  • To reduce your baby’s risk of SUDI, always put your baby to sleep on their back. 
  • Make sure your baby’s head remains uncovered during sleep. 
  • Do not expose your baby to tobacco smoke before or after birth. 
  • Give your baby their own safe sleeping environment (safe cot, safe mattress, safe bedding). For the first six to twelve months of life, this should be located next to your bed.
  • Breastfeed your baby, if you can. Breastfeeding reduces your baby’s risk of SUDI by more than half.

The sudden unexpected death of a baby, when there is no apparent cause of death, is now called sudden unexpected death in infancy (SUDI). This includes sudden infant death syndrome (SIDS) and fatal sleep accidents. A baby can die of SUDI at any time of the day or night, but most die quietly in their sleep. SIDS used to be called ‘cot death’.

You can help reduce your baby’s risk of SUDI by providing a safe sleeping environment (safe cot, safe mattress, safe bedding). A safe cot is one that meets the Australian Standard for cots. All new and second-hand cots sold in Australia must meet the current Australian and New Zealand Standard for Cots (AS/NZS 2172:2003), and will carry a label to say so. If you are planning to use a second-hand cot, check that it meets those standards.

Put your baby to sleep on their back, with their head uncovered. Do not expose your baby to tobacco smoke (before birth and after). Breastfeed your baby, if you can. These steps can greatly reduce your baby’s risk of dying suddenly and unexpectedly.

Young babies and sudden unexpected death in infants (SUDI)

SUDI is more common in babies aged between two and four months, but it can also happen to younger and older babies. Babies who are born premature, unwell or are of low birth weight are at greater risk. SUDI occurs in both bottle-fed and breastfed babies. Of those who die, around 60 per cent are boys.

What causes SUDI?

The cause of SUDI is not known. There are no consistent warning signs to alert us to the risk of SUDI. Minor infections are often found in SUDI babies, but these infections are mild and not enough to have caused death. Research into the causes of SUDI continues. 

Incidence of SUDI

The number of babies dying suddenly and unexpectedly has reduced dramatically in Victoria. The Australian Bureau of Statistics (ABS) compiles statistics on SIDS in Victoria. It has found that the incidence of SIDS has fallen by as much as 85 per cent since 1990.

The incidence of SUDI in Australia as a whole is also on the decline. Currently, it is about the same as in other Western countries – around one in every 3,000 births, or 130 babies each year. This compares to about 500 Australian babies lost to SIDS in 1990.

Lowering your baby’s risk of SUDI

Several simple childcare practices can greatly lower your baby’s risk of SUDI. Follow the Red Nose Australia safe sleeping recommendations:

  • Sleep baby on their back from birth.
  • Keep their face and head uncovered.
  • Keep baby smoke free before and after birth.
  • Use a safe sleeping environment night and day.
  • Sleep baby in a safe cot in their parents’ or carers’ room.
  • Breastfeed baby if you can.

Sleeping arrangements and SUDI

It is very important to put your baby to sleep on their back. Your baby’s risk of SUDI is increased if they sleep on their stomach. 

Healthy babies placed to sleep on their backs are less likely to choke on vomit than tummy-sleeping babies. Back-sleeping ensures that babies’ airways are kept clear and their protective mechanisms (gag, swallow and arousal) can work at their best. 

Over time, sleeping on their back may slightly flatten the back of your baby’s skull. This is called ‘positional moulding’. It usually improves by itself without any medical intervention before the child’s first birthday.

Your baby should sleep in their own safe sleeping environment next to your bed for the first six to twelve months of their life. Research has shown that sleeping a baby in the same room, but not in the same bed, with parents or carers in the first six to twelve months of life is protective. This is thought to be because the parents or carers can see the baby and easily check to see that the baby is safe. 

This protective effect does not work if the baby is in a room with other children, probably because the children do not know if the baby is safe or not.

In some SUDI cases, the babies are found with bedding over their faces. Some suggestions to prevent this include: 

  • Place baby on their back and position baby’s feet at the bottom of the cot.
  • Tuck in the bedclothes securely or use a safe baby sleeping bag (which has fitted neck and armholes and no hood).
  • Use a firm, well-fitting mattress.
  • Remove soft bedding like quilts, doonas, duvets or pillows.
  • Never use cot bumpers.
  • Keep soft toys out of the cot.

Tobacco smoke and SUDI

If a baby is exposed to tobacco smoke in utero (during the pregnancy), they have a higher risk of SUDI. Babies exposed to tobacco smoke after birth are also at increased risk of SUDI. 

Stop smoking before you conceive or as soon as you can into the pregnancy. The less you smoke, the lower your baby’s risk of SUDI. 

If your partner smokes, encourage them to quit. Make your house a smoke-free environment at all times and don’t allow anyone to smoke near your baby.

Other factors influencing SUDI

There are other factors that may have a bearing on the risk of SUDI. These factors include: 

  • temperature – make sure your baby doesn’t overheat or get too cold. Dress your baby as you would dress yourself, to be comfortably warm. If your baby has a fever, use fewer bed coverings or none at all
  • specific baby-care products – there is no convincing scientific evidence that any specific baby-care product reduces the risk of SUDI. This includes positional aids for babies such as anti-roll devices and items that fasten a baby in position. Introducing additional items into the cot increases the risk of baby overheating and suffocating. These are significant risks for SUDI
  • sharing a sleep surface – can increase the risk of SUDI. Falling asleep holding a baby on a couch or chair is always unsafe. Move yourself and baby to a safe sleep surface if you think you might fall asleep. It is especially important not to share a bed or lie down holding a baby when:
    • you are overly tired or unwell
    • you or your partner have recently drunk alcohol
    • your or your partner smoke, even if you don’t smoke in the bedroom
    • you or your partner have taken any drugs that make you feel sleepy or less aware
    • baby is very young (less than four months old), born premature or is small for their gestational age. 

Immunisation does not increase the risk of SUDI

SUDI happens most commonly between the ages of two months and four months. This is around the same age that babies are often immunised. However, there is no link. In fact, there is some evidence that immunised babies are actually at a lower risk of SUDI than non-immunised babies.

Feelings of guilt and blame after SUDI

Some of the usual emotions felt by bereaved parents include guilt, anger, fear, blame and despair. Because the causes of SUDI are unknown, parents will often come up with their own explanations for the tragedy and blame themselves.

It may be helpful for grieving parents to talk with people outside the family, such as other bereaved parents, doctors, social workers or counsellors. However, many people find their most valuable support comes from their own family and friends.

Where to get help


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This page has been produced in consultation with and approved by: Red Nose (formally Sids and kids)

Last updated: September 2019

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