Introduction 

Sudden infant death syndrome (SIDS) – also known as cot death – is the sudden, unexpected and unexplained death of an apparently well baby.

In the UK, at least 300 babies die suddenly and unexpectedly every year. This statistic may sound alarming, but SIDS is rare and the risk of your baby dying from it is low.

Most deaths happen during the first six months of a baby’s life. Infants born prematurely or with a low birthweight are at greater risk, and SIDS is also more common in baby boys.

SIDS usuallys occur when a baby is asleep, but it can occasionally happen while they are awake.

Parents can reduce the risk of SIDS by not smoking while pregnant or after the baby is born, and always placing the baby on their back when they sleep (see below).

What causes SIDS?

No-one knows exactly what causes SIDS, but it is thought to be the result of a combination of factors.

Experts believe SIDS occurs at a particular stage in a baby’s development, and that it affects babies who are vulnerable to certain environmental stresses.

This vulnerability may be due to being born prematurely or to low birthweight, or other reasons not yet identified. 

Environmental stresses could include tobacco smoke, getting tangled in bedding, a minor illness or having a breathing obstruction.

Babies who die of SIDS are thought to have problems in the way they respond to these stresses and how they regulate their heart rate, breathing and temperature.

Although the cause of SIDS is not fully understood, there are things you can do to reduce the risk (see below).

What can I do to help prevent SIDS?

Follow the advice below to help prevent SIDS:

  • Place your baby on their back to sleep, in a cot in the room with you.
  • Don't smoke during pregnancy or let anyone smoke in the same room as your baby.
  • Don't share a bed with your baby if you or your partner smoke or take drugs, or if you have been drinking alcohol.
  • Never sleep with your baby on a sofa or armchair.
  • Don't let your baby get too hot or too cold.
  • Keep your baby’s head uncovered. Their blanket should be tucked in no higher than their shoulders.
  • Place your baby in the "feet to foot" position (with their feet touching the end of the cot or pram).
  • If possible, breastfeed your baby. See Why breastfeed? for more information.

Read more about reducing the risk of SIDS.

Seeking medical advice if your baby is unwell

Babies often have minor illnesses, which you don't need to worry about. Give your baby plenty of fluids to drink and don't let them get too hot.

If you are worried about your baby at any point, see your GP or call NHS 111 for advice.

Dial 999 for an ambulance if your baby:

  • stops breathing or turns blue
  • is struggling for breath 
  • is unconscious or seems unaware of what's going on
  • won’t wake up
  • has a fit for the first time, even if they seem to recover

Read more about spotting signs of serious illness in children.

Support services

If a baby dies suddenly and unexpectedly, there will need to be an investigation into how and why your baby died. A post-mortem examination will usually be necessary. This can be very distressing for the family.

The police and healthcare professionals work closely to investigate unexpected infant deaths and ensure the family is supported. They should be able to put you in touch with local sources of help and support.

Many people find talking to others who have had similar experiences helps them cope with their bereavement.

The Lullaby Trust provides advice and support for bereaved families. Specially trained advisers are available on their helpline (0808 802 6868). You can also visit their website for further bereavement information and advice.

The Babyloss and Sands websites are also useful resources for those affected by the death of a baby during pregnancy, at birth or shortly afterwards.

Read more about bereavement.

Bereavement: coping with grief after a neonatal death

An expert discusses neonatal death, when a baby dies within 28 days of being born. David and Leigh's twins Kristina and Lucy were born prematurely at 25 weeks and died aged 17 and 21 days. They describe how they grieved and coped in their own way.

Media last reviewed: 23/04/2014

Next review due: 23/04/2016

Getting your baby to sleep

Tips to help your baby sleep, including where they should sleep, establishing a routine

Page last reviewed: 16/12/2013

Next review due: 16/12/2015