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INFORMATION & ADVICE - Cot death and sudden infant death syndrome (SIDS)

baby on back asleep on a cot mattress

This factsheet is for people who have experience of cot death or sudden infant death syndrome (SIDS), or who would like information about it.

Cot death, or 'sudden unexpected death of an infant' (SUDI), is the sudden and unexpected death of a baby under two. If no specific cause of death is found, the death is usually registered as being caused by SIDS.

About cot death

Around 300 babies die suddenly and unexpectedly in the UK every year. Cot death can happen to any baby, but babies between one and four months, premature babies, low birthweight babies and boys are more at risk.

Babies who die from cot death appear to die painlessly in their sleep. It usually happens when the baby is asleep in his or her cot at night (between midnight and 9am), but can also happen during any other period of sleep such as when in the pram or even in a carer's arms.

What happens after a cot death?

If the baby who has died was one of twins, triplets or more, the other baby (or babies) will be taken into hospital for observation.

When a baby dies, a thorough investigation is carried out to try to find out why the baby died and to gather information that may help to prevent cot deaths in the future. This investigation is standard procedure in all cot deaths and doesn't in any way imply suspicion or blame surrounding the baby's death.

Many different people are involved in the investigation, including a coroner (an official who enquires into sudden, unexpected deaths), GPs, paediatricians (doctors who specialise in children's health), social workers, police officers, health visitors and midwives.

When the full results from the investigation are available, a case discussion meeting, attended by all of the people involved in the investigation, will take place. This may be up to 12 weeks after the death.

The baby's parents will be kept informed of the investigation procedure and progress at all times. At the end of the investigation, a doctor will usually discuss the findings with them.

If a specific cause of death is found, this will be registered on the death certificate. If the cause of death remains unexplained after the investigation, the death is usually registered as SIDS. Sometimes the terms 'unascertained', 'cot death' or 'SUDI' will be used.

Causes of cot death

Identified causes

A specific cause is identified in around one in 10 cot deaths. Possible causes include serious infection, accident, or a previously unknown problem that the baby was born with (a 'congenital' condition) such as a heart defect or lung problem.


If no specific cause can be found to explain the death, it's defined as SIDS. Research has suggested that a number of different factors may be linked to SIDS. It's believed that these factors don't actually cause SIDS, but may make a baby more at risk. These factors include:

  • allergies
  • bacterial and viral infections
  • unknown genetic conditions
  • problems in the area of the brain that controls breathing
  • irregular heartbeat
  • accidental suffocation
  • overheating

Reducing the risk of cot death

A campaign to reduce the risk of cot death was launched in 1991 by the Foundation for the Study of Infant Deaths (FSID) and the Department of Health. The recommendations they made have helped to reduce the number of cot deaths reported every year in the UK by three-quarters.


  • If your baby is unwell, seek medical advice promptly.
  • If your baby has a high temperature (fever), try to keep him or her cool.


Exposure to cigarette smoke (during pregnancy or after the birth) is known to increase the risk of cot death.

  • Don't smoke during pregnancy - this applies to both mothers and fathers.
  • Don't let anyone smoke in the same room as your baby - ask them to smoke outside.
  • Don't share a bed with your baby if you or your partner smokes.


  • For the first six months, the safest place for your baby to sleep is in a cot in your bedroom.
  • Always lie your baby on his or her back to sleep.
  • Place your baby with his or her feet at the foot of the cot to prevent wriggling down under the covers.
  • Don't fall asleep with your baby while sitting or lying on a sofa or armchair.
  • Don't let your baby sleep with a pillow.
  • Use a firm mattress with a waterproof cover for your baby's cot.
  • Always make sure that bedding is tucked in securely.
  • Make sure your baby's head isn't covered.

Don't share a bed with your baby if:

  • he or she is under three months
  • he or she was premature or less than 2.5kg (5.5 pounds) at birth
  • you have been drinking alcohol
  • you have taken medication that makes you drowsy
  • you're very tired


There is some evidence to suggest that giving your baby a dummy when you settle him or her to sleep may help to reduce the risk of cot death. However, more research in this area is needed before official recommendations can be made regarding the risks and benefits of using dummies.

If you're breastfeeding, you shouldn't introduce a dummy until around one month. You should try to reduce the use of a dummy gradually when your baby is around 12 months to prevent dental problems.


Recent research has shown that babies who are breastfed (either exclusively, or in combination with formula milk) are less likely to die from cot death than babies who have only ever received formula milk.


Keep your baby at the right temperature.

  • The ideal room temperature for your baby is 18°C (a range of 16 to 20°C is acceptable).
  • Feel your baby's abdomen (tummy) to check he or she is the right temperature. If it's hot or your baby is sweating, take off some bedding or clothing. It's normal for babies to have cool hands and feet.
  • Always take off your baby's outdoor clothes when you come inside, even if this means waking him or her up to do so.
  • Don't let your baby sleep with a hot water bottle or electric blanket, next to a radiator, heater or fire, or in direct sunshine.
  • Don't use duvets or quilts if your baby is under 12 months.
  • Baby sleeping bags are an alternative to blankets and sheets. Make sure you get the right size and thickness and know what clothes your baby should wear underneath - always check the manufacturer's recommendations.

Baby breathing monitors

There is no evidence that breathing or movement monitors help prevent cot death and they should only be used on the guidance of a doctor. Many doctors believe they can provide a false sense of security.

Coping with cot death

Even after taking as many precautions as possible, babies can and do still die from cot death. When a baby dies, parents often have many different emotions, including overwhelming feelings of guilt and anger. Family and friends can be a valuable source of help and comfort at this difficult time. They can also help in practical ways, for example with looking after other children, preparing meals and doing shopping.

Dedicated charities, support groups and associations can provide advice and help to families affected by cot death. It may also help to talk to a counsellor who specialises in helping people cope with grief.

Your GP or health visitor can help you find a suitable counsellor or support group in your area.

Having another child

The decision to have another baby after losing a baby to cot death isn't an easy one. You will know when you're ready and when it's the right time for you.

Care of the next infant (CONI) schemes are available in many areas. They offer advice, support, increased monitoring for the new baby and frequent check-up visits. Ask your GP or midwife if there is a CONI scheme in your area. If there isn't, your local health authority may run its own equivalent scheme and will be able to offer you additional support during your pregnancy and after the birth of your new child.

Related topics

Further information

  • Foundation for the Study of Infant Deaths (FSID)
    020 7233 2090


  • Simon C, Everitt H, Kendrick T. Oxford Handbook of General Practice. 2nd ed. Oxford: Oxford University Press, 2007:906
  • Sudden unexpected death in infancy: a multi-agency protocol for care and investigation. Royal College of Pathologists and Royal College of Paediatrics and Child Health. 2004.
  • Cot death facts & figures. Foundation for the Study of Infant Deaths. 2006.
  • What is cot death? Foundation for the Study of Infant Deaths., accessed 9 July 2008
  • FAQ - current topics. Foundation for the Study of Infant Deaths., accessed 9 July 2008
  • Thach B. Tragic and sudden death: potential and proven mechanisms causing sudden infant death syndrome. EMBO J 2008; 9:114-118.
  • Reduce the risk of cot death - an easy guide. Department of Health, 2007.
  • Department of Health. The Pregnancy Book. 2007:119-127., accessed 2 January 2009
  • Anderson ME, Johnson DC, Batal HA. Sudden infant death syndrome and prenatal maternal smoking: rising attributed risk in the Back to Sleep era. BMC Med 2005; 3:4.
  • Looking after your baby. Foundation for the Study of Infant Deaths., accessed 11 July 2008
  • New dummy advice for parents. Foundation for the Study of Infant Deaths., accessed 11 July 2008
  • Breastfeeding reduces the risk of cot death. Foundation for the Study of Infant Deaths., accessed 11 July 2008
  • Keep an eye on your baby's room temperature. Foundation for the Study of Infant Deaths., accessed 11 July 2008
  • If you are bereaved. Foundation for the Study of Infant Deaths., accessed 11 July 2008
  • Care of the next infant (CONI). Foundation for the Study of Infant Deaths., accessed 11 July 2008
  • UNICEF UK statement on dummy use, sudden infant death syndrome and breastfeeding. UNICEF., accessed 8 December 2008

This information was published by Bupa's health information team and is based on reputable sources of medical evidence. It has been peer reviewed by Bupa doctors. The content is intended for general information only and does not replace the need for personal advice from a qualified health professional.

Publication date: May 2009

11th February 2010, 22:41
Page updated 5th Oct 2015, 13:25
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