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.
  • 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.
The sudden unexpected death of a baby, when there is no apparent cause of death, is now called sudden unexpected death in infancy (SUDI), which 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 by providing a safe sleeping environment (safe cot, safe mattress, safe bedding). Put your baby to sleep on their back, with their head uncovered. Do not expose your baby to tobacco smoke (before birth and after). These steps can greatly reduce your baby’s risk of dying suddenly and unexpectedly, although they can’t provide a complete guarantee.

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. SUDI occurs in both bottle-fed and breastfed babies. Of those who die, around 60 per cent are boys.

Causes of SUDI

People once suspected such things as choking, parental neglect or accidental smothering, but the real cause of SUDI remains unknown. There are no consistent warning signs to alert us to the risk of SUDI. Sometimes, the baby wasn’t feeding well on the day they died or may have had a slight cold or tummy upset.

Minor infections are often found in SUDI babies, but these infections are mild and not enough to have caused death. In some cases, the baby has bloodied froth or vomit around their mouth, but this occurs naturally soon after death and doesn’t cause the 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 84 per cent since 1990.

The incidence of SUDI in Australia generally 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 back in 1990.

Lowering your baby’s risk of SUDI

Several simple childcare practices can greatly lower the risk of SUDI.

Sleeping arrangements and SUDI

The risk of SUDI is increased if your baby sleeps on their stomach. It is important to put your baby to sleep on their back. Over time, this may slightly flatten the back of your baby’s skull, but any ‘positional moulding’ 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 in New Zealand and the UK has shown that sleeping a baby in the same room, but not in the same bed, with the parents in the first six to twelve months of life is protective. This is thought to be because parents 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:
  • Don’t put your baby on a water bed or bean bag.
  • Don’t use soft bedding like quilts, doonas, duvets or pillows.
  • Use a firm, well-fitting mattress.
  • Don’t use cot bumpers.
  • Keep soft toys out of the cot.
  • Position your 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).

Tobacco smoke and SUDI

If either parent smokes during the pregnancy, the baby has 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 the 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. A good rule of thumb is to 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.
  • Bed-sharing – there is an increased risk of SUDI if an adult who is a smoker shares their bed with a baby. Even if you don’t smoke, bed-sharing can still be unsafe if your baby is less than four months old, slips under the bedding or into pillows, is trapped between the bed and the parent or the wall, falls out of bed, overheats or is rolled on. Don’t share a bed with your baby if you have been drinking alcohol or are affected by other drugs. There is a very high risk of infant death and sleeping accidents when a baby shares a sofa or couch with an adult during sleep.

Factors that do not increase the risk of SUDI

Factors that don’t affect the risk of SUDI include:
  • Immunisations – the highest incidence of SUDI happens between the ages of two months and four months, which 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
  • Specific baby-care products – there is no convincing scientific research 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.

Education and SUDI

In 2010, a scientific consensus forum reviewed the evidence from the Australian SIDS and Kids Safe Sleeping Health Promotion Program and recommended that future ‘Reducing the Risk’ campaign messages should continue to focus on educating the public about the SUDI risk factors. However, SUDI can still occur, even when all the known risk factors have been ruled out.

Feelings of guilt and blame after SUDI

There is a common belief that marital break-up often follows the death of a baby, but this hasn’t been supported by experience or research. 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: August 2014

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