Sudden unexpected death in infants (SUDI and SIDS)

What is SUDI?#

The sudden and unexpected death of a baby, when there is no obvious cause, is called sudden unexpected death in infancy (SUDI). It 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 following a few simple practices, the most important of which is always placing your baby on their back to sleep.

Lowering your baby’s risk#

Several simple practices can greatly lower your baby’s risk of SUDI:

• Provide a safe sleeping environment, day and night: a safe cot, a firm and flat mattress that is not tilted, and safe bedding.
• Put your baby to sleep on their back, with their face and head uncovered.
• Sleep your baby in their own safe cot in the parent or caregiver’s room for the first 6 to 12 months.
• Keep your baby smoke-free, before and after birth.
• Breastfeed your baby if you can.

A safe cot is one that meets the recognised safety standard for cots where you live. All new and second-hand cots should meet that standard and carry a label to say so. If you plan to use a second-hand cot, check that it meets the standard, is no more than 10 years old and is not broken.

If you have twins or other multiples, each baby needs their own safe sleep environment.

SUDI is most common in babies aged between 2 and 4 months, but it can also happen to younger and older babies. Babies who are born premature, are unwell or have a low birth weight are at greater risk. SUDI occurs in both bottle-fed and breastfed babies, and around 60 per cent of those who die are boys.

What causes SUDI?#

The cause of SUDI is not known. There are no consistent warning signs, but there are risk factors to consider. These include a baby’s underlying vulnerability, their age, and external factors such as overheating and unsafe sleeping practices. Minor infections are often found in babies who die of SUDI, but these are mild and not enough to have caused death. Research into the causes of SUDI continues.

The number of babies dying suddenly and unexpectedly has fallen dramatically since safe-sleep campaigns began, and the rate continues to decline in many countries. It is now around one in every 3,000 births.

Always sleep your baby on their back#

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

Healthy babies placed on their backs are less likely to choke on vomit than tummy-sleeping babies. Back-sleeping keeps the airways clear and allows the baby’s protective reflexes (gag, swallow and arousal) to work at their best.

Over time, back-sleeping may slightly flatten the back of your baby’s skull. This is called “positional plagiocephaly”. It usually corrects itself, without any medical treatment, before the child’s first birthday. You can help by giving your baby supervised tummy time while they are awake and are not tired or hungry.

Sleeping arrangements#

Your baby should sleep in their own safe sleeping environment in your room, next to your bed, for the first 6 to 12 months. Research shows that sleeping a baby in the same room — but not the same bed — as a parent or caregiver during this time can reduce the risk of SUDI by about half. This is thought to be because the adult can see the baby and easily check that they are safe. The protective effect does not work if the baby shares a room with other children, probably because children cannot tell whether the baby is safe.

In some cases, babies are found with bedding over their faces. To help prevent this:

• Place your baby on their back.
• Position your baby’s feet at the bottom of the cot.
• Draw the bedding no higher than the chest and tuck it in firmly on three sides.
• Use a safe sleeping bag that fits well across the neck and chest so the baby cannot slip inside, has sleeves or arm holes so the baby can move their arms freely, and has no hood or head covering.
• Use a firm, flat, well-fitting mattress that is not tilted.
• Remove soft bedding such as quilts, duvets and pillows.
• Never use cot bumpers.
• Keep soft toys out of the cot.

Tobacco smoke and SUDI#

Babies exposed to tobacco smoke, both during pregnancy and after birth, have a higher risk of SUDI. Stop smoking before you conceive, or as soon as you can during the pregnancy — the less you smoke, the lower your baby’s risk. If your partner smokes, encourage them to quit. Keep your home smoke-free at all times, and do not allow anyone to smoke around your baby or near where your baby sleeps.

Other factors#

A few other factors can affect the risk of SUDI.

Temperature. Overheating is a significant risk factor. Babies regulate their temperature mainly through the face and head, so hats and bonnets must be removed for sleep. 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, and seek medical advice as appropriate.

Baby-care products. There is no convincing scientific evidence that any specific product reduces the risk of SUDI. This includes positional aids such as anti-roll devices and items that fasten a baby in position. Adding extra items to the cot increases the risk of overheating and suffocation, so they are best avoided.

Babywearing. If you use a carrier or sling, choose one that is firm and keeps your baby upright so you can see their face, their back is straight, and their chin is off their chest.

Sharing a sleep surface. Falling asleep holding a baby on a couch, chair or bean bag is always unsafe. Move yourself and your 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 your baby, when:

• you are overly tired or unwell
• you or your partner have recently drunk alcohol
• you or your partner smoke, even if not in the bedroom
• you or your partner have taken anything that makes you feel sleepy or less aware
• your baby is very young (less than 4 months old), born premature or small for their gestational age

Immunization and SUDI#

SUDI happens most often between 2 and 4 months of age — around the same time that babies are often immunized. However, there is no link between the two. In fact, there is some evidence that immunized babies are at lower risk of SUDI than babies who are not immunized. Your baby should be immunized according to the standard schedule where you live.

After a SUDI#

Bereaved parents often feel guilt, anger, fear, blame and despair. Because the causes of SUDI are unknown, parents may come up with their own explanations and blame themselves. It can help grieving parents to talk with people outside the family — such as other bereaved parents, doctors, social workers or counsellors — although many find their most valuable support comes from their own family and friends.

Key points#

• These steps can greatly reduce your baby’s risk of dying suddenly and unexpectedly.
• SUDI is more common in babies aged between 2 and 4 months, but it can also happen to younger and older babies.
• Babies who are born premature, unwell or of low birth weight are at greater risk.
• The cause of SUDI is not known.
• There are no consistent warning signs that a SUDI might occur, but there are risk factors to consider.

Where to get help#