Cot Death

Also known as: Sudden infant death syndrome (SIDS)


Cot death is the sudden and unexpected death of a baby for no obvious reason. The post-mortem examination may explain some of the deaths. Those that remain unexplained after post-mortem examination may be registered as sudden infant death syndrome (SIDS), sudden infant death, sudden unexpected death in infancy or cot death.


Medical text written April 2000 by Dr Sarah Levine, Medical Adviser to the Foundation for the Study of Infant Death, London, UK. Last updated July 2012 by Professor Peter Fleming, Professor of Infant Health and Developmental Physiology, Institute of Child Health, Bristol, UK and the Foundation for the Study of Infant Death, London, UK.

What are the causes?

No one knows yet why these babies die. Researchers think there are likely to be a number of different causes, or that a combination of factors affect a baby at a vulnerable stage of development. For example exposure to maternal smoking before birth may affect the development of important parts of the brainstem, making the baby more vulnerable.

Research has shown that certain babies are more at risk, namely boys, premature and low birth-weight babies. The vast majority of cot deaths happen to babies aged under six months and there is a peak occurrence at two to three months. Cot death can happen to any family, but it is more likely to happen in families living in difficult circumstances.

Since the introduction of the “Back to Sleep” campaign in 1991 the number of babies dying has fallen by around 80 per cent. However, cot death still claims the lives of 5 babies every week in the UK.

How can it be prevented?

To reduce the risk of cot death:

  • place your baby on the back to sleep
  • cut smoking during pregnancy – in both mothers and fathers
  • do not let anyone smoke in the same room as your baby
  • keep your baby’s head uncovered -­ place your baby with feet to the foot of the cot to prevent wriggling down under the covers
  • use of a baby sleeping bag avoids the possibility of head covering
  • if your baby is unwell seek medical advice promptly
  • never sleep with your baby on a sofa or armchair
  • breastfeed your baby for at least the first few weeks – the longer the better
  • parents should not sleep with their baby in their bed if either partner: is a smoker, even if they never smoked in bed or in their home; has been drinking alcohol; takes medication or drugs that make them drowsy; feels very tired. Bed sharing should be avoided if a baby was born prematurely, with a low birth weight or has a high temperature.
  • Ensure your baby receives all scheduled immunisations – immunisation may help reduce the risk of cot death

The safest place for a baby to sleep is in a cot in the parents’ bedroom for the first six months.

Inheritance patterns and prenatal diagnosis

Inheritance patterns
None. The risk of cot death is slightly increased in subsequent infants in families in which an infant has died, but there is no clear pattern of inheritance for most families

Prenatal diagnosis

Is there support?

Lullaby Trust

Helpline: 0808 802 6869
Office: 020 7802 3200

The Foundation is a Registered Charity in England and Wales No. 262191, established in 1971. It is the UK’s leading baby charity working to prevent sudden infant deaths and promote baby health. The Foundation achieves its aims through funding research, supporting families, promoting safe infant care advice to parents and professionals and working with professionals to improve investigations when a baby dies. In particular, it runs CONI (Care Of the Next Infant) with the NHS, to support bereaved families when they have subsequent babies. The Foundation has a network of trained befrienders and produces a range of publications including the leaflet ‘When a baby dies suddenly and unexpectedly’.

Group details last confirmed September 2015.

Scottish Cot Death Trust

Tel: 0141 357 3946

The Trust is a Registered Charity in Scotland No. SC003458. It provides support for families affected by the loss of a baby to cot death. The Trust raises funds for research, and educates the public and health care professionals about cot death and ways of reducing the risks.

Group details last updated March 2016.

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