Sudden unexpected death in infancy (SUDI), SIDS and fatal sleep accidents

About sudden unexpected death in infancy (SUDI)

When babies under one year die unexpectedly in their sleep, it’s often described as sudden unexpected death in infancy (SUDI).

When these deaths are investigated, they’re often found to be one of the following:

Fatal sleeping accidents: these deaths happen when babies suffocate or get trapped or strangled by things in their sleeping environments.
Sudden infant death syndrome, or SIDS: this is when investigations can’t find a cause of death.

Sometimes SUDI can be explained by a serious illness or a medical condition that the baby was born with.

SUDI is rare and accounts for around 3 deaths in every 10 000 births in Australia.

SUDI including SIDS and fatal sleeping accidents: the triple risk model

We don’t know exactly what causes sudden unexpected death in infancy (SUDI) including SIDS and fatal sleeping accidents.

We do know that all babies are at risk of SUDI including SIDS and fatal sleeping accidents. We also know that there are some factors that increase SUDI risk, particularly when three kinds of risk factors occur at once.

This is called the triple risk model.

The three risk factors in the triple risk model are vulnerability, age and environment. By themselves, each of these three types of risk might not cause an infant death. But in combination they increase the risk of SUDI including SIDS and fatal sleeping accidents.

Vulnerability
Some babies have an underlying risk of SUDI including SIDS and fatal sleeping accidents. This includes babies who were:

exposed to tobacco smoke or drugs before they were born
born prematurely or who were small when they were born.

Sometimes a baby’s vulnerability is unknown. It might be something to do with their heart or how easily they wake up.

Age
The risk of SUDI including SIDS and fatal sleeping accidents is greatest at 2-4 months, although the risk is there for the first 12 months.

Environment
Babies’ sleep environments can increase their risk of SUDI including SIDS and fatal sleeping accidents. The sleep environment includes how and where babies are put to sleep and other things happening around babies. These other things might include overheating and being exposed to tobacco smoke.

Babies who are already vulnerable and at a risky age are more likely to die of SUDI including SIDS and fatal sleeping accidents when they’re exposed to these risks.

You can’t usually control underlying vulnerabilities. And you can’t change your baby’s age, so you can’t control this type of risk. But you can reduce the overall risk of SUDI including SIDS and fatal sleeping accidents by following safe sleeping guidelines.

SUDI including SIDS and fatal sleeping accidents: risks you can avoid

Babies’ sleep environments include where and how babies sleep and what’s around babies when they sleep and at other times. Babies’ sleep environments have many risks for SUDI including SIDS and fatal sleeping accidents.

These are risks you can avoid.

Here are risks associated with how babies sleep. You should avoid:

sleeping babies on their tummies or sides
sleeping babies with faces or heads covered
letting babies get overheated – for example, by wearing too many clothes or hats or beanies to sleep.

Here are risks associated with where babies sleep. You should avoid:

sleeping babies on soft surfaces (like soft mattresses or waterbeds) or on sofas, with or without a parent
sleeping babies in cots that don’t meet Australian/NZ Standard AS/NZS 2172:2003
co-sleeping
sleeping babies where they could get trapped between mattress and cot, or between bed and wall.

Here are risks associated with what’s around babies. You should avoid:

exposing babies to tobacco smoke
sleeping babies with loose or fluffy bedding (like sheepskin or lamb’s wool), or with pillows, soft toys or cot bumpers
sleeping babies near things that could strangle them, like straps or cords from prams, car seats or blinds.

To learn how to avoid these risks, see our illustrated guide to reducing the risk of SUDI and SIDS. Choosing safe baby furniture, including cots, can help you avoid some of these risks too. And if you’re concerned about your baby’s health, see your child and family health nurse or GP.

Impact of SUDI including SIDS and fatal sleeping accidents

The sudden or unexpected death of a baby is one of the most difficult and devastating experiences that parents will ever face. They often feel anger, guilt, frustration and, above all, grief.

Parents often go over every moment in the last few hours or days of their child’s life, searching for clues. They might wonder whether their baby might still be alive if they’d done things a little differently. They might feel guilty they didn’t check on their baby one last time before going to sleep themselves, or that they didn’t wake their baby for a midnight feed.

When a child dies from SUDI including SIDS and fatal sleeping accidents, it can affect not only parents, but also brothers, sisters, grandparents, family members and friends.

There are support services available to parents and families at this difficult time.