Cookies on the Bupa website

We use cookies to help us understand ease of use and relevance of content. This ensures that we can give you the best experience on our website. If you continue, we'll assume that you are happy to receive cookies for this purpose. Find out more about cookies



Cot death and sudden infant death syndrome (SIDS)

Cot death is when a baby under a year old dies suddenly and unexpectedly. If after a detailed investigation the death remains unexplained, the medical term is sudden infant death syndrome (SIDS). It's also known as sudden unexplained death in infancy (SUDI).

More than 200 babies die suddenly and unexpectedly in the UK every year. Cot death can happen to any baby, but it's more common in babies between two to four months, premature babies, and babies with a low birth weight. It's also more common in baby boys than girls.

Most cot deaths happen when a baby is asleep in their cot at night.

Read more Close


  • Causes Causes of cot death

    Identified causes

    Less than half of all cot deaths have a specific cause. Possible causes include a serious infection, an accident or a previously unknown problem that your baby was born with (a congenital condition). This may include a heart or lung problem. However, there are a large number of potential causes, which is the reason why the investigation has to be so thorough.


    If no specific cause is found to explain the death of your baby, it's defined as SIDS or SUDI. Research suggests that a number of different factors may be linked to SIDS. These factors aren't thought to actually cause SIDS, but may make your baby more at risk. These factors can be divided into two groups – those that you can modify and those you can’t.

    Factors you don't have any control over and can’t modify include:

    • the age of your child, as SIDS is more common in babies who are two to four months old
    • if your baby was born prematurely, particularly if you share a bed with your baby
    • having a family history of SIDS
    • the sex of your baby, as around seven out of 10 babies who die from SIDS are boys
    • your baby having a previous life-threatening event, such as if they stopped breathing

    Risk factors you do have control over and can change or modify include:

    • your baby's exposure to cigarette smoke – both while you're pregnant and after your baby is born
    • placing your baby on their chest or side to sleep
    • using soft bedding, such as quilts, mattresses, pillows and duvets
    • using a second-hand mattress
    • sharing a bed with your baby or sleeping with your baby on the sofa
    • overheating – either from a high room temperature or from too much bedding

    Private GP Service

    Got a health worry? Discuss it with a Bupa GP. Wherever possible we aim to get you an appointment the next day.

  • What happens after a cot death? What happens after a cot death?

    If your baby was one of twins, triplets or more, you may need to take your other baby (or babies) into hospital for observation. This is important, as some rarer causes of sudden death in infancy run in families.

    A thorough investigation will be done to try to find out why your 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 your baby's death.

    The people who will be involved in the investigation can vary depending on where you live. They may include a coroner (an official who enquires into sudden, unexpected deaths), a paediatrician (a doctor who specialises in children's health), a pathologist (a doctor who performs the autopsy), social workers, police officers, health visitors and midwives.

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

    You 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 you.

    If a specific cause of death is found, this will be registered on the death certificate. If your baby’s death remains unexplained after the investigation, the death is usually registered as SIDS or SUDI.

  • Reducing the risk of cot death Reducing the risk of cot death

    Although it’s impossible to prevent SIDS, there are a number of things you can do to reduce the chances of it happening.


    • If your baby is unwell, see your doctor promptly.
    • If your baby has a high temperature, try to keep him or her cool.


    Exposure to cigarette smoke (during pregnancy or after birth) is known to increase the risk of cot death. One in five deaths from SIDS are thought to be linked to passive smoking.

    • 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 or Moses basket in your bedroom.

    • Always lie your baby on his or her back to sleep.
    • Place your baby with their feet at the foot of the cot to prevent them wriggling down under the covers.
    • Don't fall asleep with your baby while you’re 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 with bedding.

    Don't share a bed with your baby if you or your partner:

    • have been drinking alcohol
    • have taken medication that makes you drowsy
    • are very tired
    • smoke


    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 is needed to understand why this is before official recommendations can be made regarding the risks and benefits of using dummies.

    If you're breastfeeding, don't introduce a dummy until around a month (wait until your baby is breastfeeding well). Also, reduce the use of a dummy gradually when your baby is around six to 12 months to prevent dental problems.


    Babies who are breastfed 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).
    • Keep your baby's head uncovered.
    • Feel your baby's chest to check if 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 dress your baby in suitable clothing for the conditions – don’t add more than one layer of clothing than an adult would wear comfortably in the same environment.
    • 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.
    • 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 to ensure that your baby doesn't overheat.

    Baby breathing monitors

    There is no evidence that breathing or movement monitors help prevent cot death so only use one if your doctor advises you to.

  • Living with cot death Living with cot death

    Even after you take as many precautions as possible, babies can and do still die from cot death. You may have many different emotions and some parents have 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 if you have other children, they can look after them for you, prepare meals and do the shopping.

    Dedicated charities, support groups and associations offer 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 Having another child

    The decision to have another child after losing a baby to cot death isn't an easy one. You will know if and 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 your 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. They may be able to offer you additional support during your pregnancy and after the birth of your new child.

  • FAQs FAQs

    I have lost a child to cot death before and am now pregnant again. Is it likely I will lose another child to cot death?


    If your baby has died from SIDS, the paediatrician (a doctor who specialises in children's health) who is in charge of the investigation after your baby's death will meet with you to discuss the results. This will include going over any implications of the results for planning a future family. Occasionally an inherited disorder, such as a heart problem, may cause more than one baby to die unexpectedly.


    If a cause of death was established for your baby, talk to your doctor or midwife about any tests or precautions that may be appropriate during your pregnancy and after your new baby is born. Also ask your midwife about support services in your area, such as the care of the next infant (CONI) programme, which is a collaboration between The Lullaby Trust and local health services to support families who have been bereaved by cot death as they prepare for their next child.

    During your pregnancy and after the birth of your baby, the CONI programme can offer:

    • regular visits from a health visitor
    • a symptom diary so you can note down any concerns, which you can then discuss with your health visitor
    • weight charts to help you to keep track of your baby’s growth and development
    • a room thermometer to make sure that your baby’s room (and any other room in which your baby sleeps) is at the correct temperature (16 to 20°C)

    The Scottish Cot Death Trust provides services with healthcare professionals across Scotland.

    I have just lost my baby to cot death and have been told that a post-mortem examination must be done. Why? What might this involve?


    Losing a baby to cot death and being told that a post-mortem examination must be done can be very upsetting. However, it's important to remember that this is a standard procedure in this situation and it may help to find out why your baby died. This may help you in planning your future family.


    National guidelines make it a requirement for all health authorities to fully investigate cot death cases.

    After a cot death, a specially trained police officer and a paediatrician will usually visit you at home (if this is where your baby died). They will want to talk to you to about your baby’s medical history and that of your family, and the circumstances of your baby's death. This may include where your baby was and the time he or she died. . The police may also ask other people who have had contact with your baby for information, such as your midwife, health visitor and GP. A post-mortem examination will be ordered by the coroner and done by a specially-trained pathologist (a doctor who specialises in establishing causes of death). This will usually be within 48 hours of your baby's death.

    The main aim of a post-mortem is to establish if there is an identifiable cause of your baby's death, such as an infection or a problem with one of your baby's organs (for example, their heart, lungs or brain). A pathologist will carry out a detailed external and internal examination of your baby and look for any signs of disease. He or she will take samples of your baby's blood, urine and some small tissue samples. You may be asked permission for samples of brain tissue to be used for research into how to prevent other babies dying from SIDS. The results of the post-mortem may not be available for many weeks due to the time it takes to carry out all of the laboratory tests.

    It's important to remember that post-mortems are done in all cases of unexpected death and your baby will be treated with the utmost care, respect and dignity at all times. A post-mortem is the best chance to find out why your baby died. However, sometimes, despite a detailed post-mortem and investigation, the exact cause of death will remain unknown.

    Is it safe to use second-hand baby equipment, such as a mattress?


    Ideally, buy a new mattress for a new baby. It's been shown that there is a link between the use of second-hand mattresses and cot death.


    The link between second-hand mattresses and cot death is most apparent with mattresses that come from another household (for example, bought second-hand or given to you second-hand). However, there is still an increased risk of cot death if you re-use a mattress that was bought brand new for an older child in your own home.

    Research has investigated why second-hand mattresses may increase the risk of SIDS. For example, it has looked at if mattresses contaminated with bacteria or substances that cause allergies increases the risk, but there are no clear answers yet.

    Ideally, buy a new mattress for a new baby. However, if you need to re-use a mattress only do so if:

    • the mattress was made with a waterproof covering
    • the mattress cover is in good condition – no tears, splits or holes
    • the mattress is firm, doesn’t sag anywhere and fits the cot without any gaps
    • you clean and dry the mattress thoroughly before you use it

    If you have any questions about the best way for your baby to sleep, ask your health visitor.

    Can you die of SIDS later in life?


    SIDS describes sudden infant death syndrome – when a young infant (who is less than one) dies and there is no explanation why. Sudden death can also happen to children and adults but the terms used to describe this are different.


    SIDS is when a baby under a year old dies suddenly and unexpectedly and the death remains unexplained after a detailed investigation.

    There are a number of terms to describe sudden death in children and adults, including sudden unexplained death in childhood (SUDC) and sudden adult death syndrome (SADS). The term sudden death syndrome describes when either a child or adult has a sudden, unexpected death, which can happen when they are asleep, awake, or just after exercise.

    Most sudden deaths are due to a heart condition and are known as sudden arrhythmia death or sudden cardiac death syndrome. The majority of people this happens to have no warning signs or prior symptoms. Most of the time, this is due to inherited heart conditions, which include:

    • long QT syndrome (LQTS)
    • short QT syndrome (SQTS)
    • Brugada syndrome
    • catecholaminergic polymorphic ventricular tachycardia (CPVT)
    • progressive cardiac conduction defect (PCCD)
    • idiopathic ventricular fibrillation (IVF)
    • Wolff-Parkinson-White (WPW) syndrome

    Researchers think SIDS may be partly due to the same causes that are responsible for sudden death in children and adults.

    After a sudden death in a family (including SIDS), it’s sometimes possible for other members of the family to have tests to identify if a pre-existing condition may have caused the sudden death. If a problem is found, any affected family members may be able to have treatment to prevent or reduce the risk of sudden death.

    Sometimes doctors cannot find a cause for the sudden death. This may be because the person who died didn’t inherit a condition and he or she is the first member of the family to have a problem. There may have been another cause that the tests cannot find. It’s also possible that other members of the family are carriers and don’t have any symptoms of the condition (and therefore have a low risk of sudden death).

    If a member of your family has died suddenly and you are concerned about the risk of it happening to you or another member of your family, ask your GP for advice about screening tests.

  • Resources Resources

    Further information


    • Sudden infant death syndrome. eMedicine., published 27 February 2012
    • Sudden infant death syndrome in emergency medicine. eMedicine., published 9 March 2011
    • Cot death facts and figures. The Lullaby Trust., published August 2013
    • Are some babies and children at greater risk? Scottish Cot Death Trust., accessed 30 April 2013
    • Sudden infant death syndrome: a guide for professionals. The Lullaby Trust., published March 2013
    • If the child was a twin. Scottish Cot Death Trust., accessed 29 April 2013
    • Guidelines for the investigation of newborn infants who suffer a sudden and unexpected postnatal collapse in the first week of life. British Association of Perinatal Medicine., published March 2011
    • The child death review. The Lullaby Trust., published December 2011
    • Sudden unexpected death in infancy: a multi-agency protocol for care and investigation. The Royal College of Paediatrics and Child Health and the Royal College of Pathologists., published September 2004
    • What is sudden infant death? The Lullaby Trust., accessed 30 April 2013
    • Parliamentary briefing: passive smoking and children. Royal College of Physicians., published May 2012
    • American Academy of Pediatrics. SIDS and other sleep-related infant deaths: expansion of recommendations for a safe infant sleeping environment. Pediatrics 2011; 128(5):1030–40. doi:10.1542/peds.2011-2284.
    • Using a dummy. The Lullaby Trust., accessed 30 April 2013
    • Care of the next infant (CONI). The Lullaby Trust., accessed 30 April 2013
    • Sudden infant death syndrome in emergency medicine follow-up. eMedicine., published 9 March 2011
    • Next infant support programme. Scottish Cot Death Trust., accessed 1 May 2013
    • Frequently asked questions. Scottish Cot Death Trust., accessed 1 May 2013
    • The lullaby trust: Evidence base The Lullaby Trust., published September 2012
    • Inherited heart conditions: sudden arrhythmic death syndrome. British Heart Foundation., published 22 May 2009
    • Conditions home. Sudden Arrhythmic Death Syndrome - SADS UK., accessed 7 May 2013
  • Has our information helped you? Tell us what you think about this page

    We’d love to know what you think about what you’ve just been reading and looking at – we’ll use it to improve our information. If you’d like to give us some feedback, our short form below will take just a few minutes to complete. And if there's a question you want to ask that hasn't been answered here, please submit it to us. Although we can't respond to specific questions directly, we’ll aim to include the answer to it when we next review this topic.

    Let us know what you think using our short feedback form
    Ask us a question
  • Related information Related information

  • Author information Author information

    Reviewed by Rachael Mayfield-Blake, Bupa Heath Information Team, August 2013.

    Let us know what you think using our short feedback form
    Ask us a question

About our health information

At Bupa we produce a wealth of free health information for you and your family. We believe that trustworthy information is essential in helping you make better decisions about your health and care. Here are just a few of the ways in which our core editorial principles have been recognised.

  • Information Standard

    We are certified by the Information Standard. This quality mark identifies reliable, trustworthy producers and sources of health information.
    Information standard logo
  • HONcode

    This site complies with the HONcode standard for trustworthy health information: verify here.

    This website is certified by Health On the Net Foundation. Click to verify.

What our readers say about us

But don't just take our word for it; here's some feedback from our readers.

Simple and easy to use website - not alarming, just helpful.

It’s informative but not too detailed. I like that it’s factual and realistic about the conditions and the procedures involved. It’s also easy to navigate to areas that you specifically want without having to read all the information.

Good information, easy to find, trustworthy.

Meet the team

Image of Andrew Byron

Andrew Byron
Head of health content and clinical engagement

  • Dylan Merkett – Lead Editor – UK Customer
  • Nicholas Ridgman – Lead Editor – UK Health and Care Services
  • Natalie Heaton – Specialist Editor – User Experience
  • Pippa Coulter – Specialist Editor – Content Library
  • Alice Rossiter – Specialist Editor – Insights
  • Laura Blanks – Specialist Editor – Quality
  • Michelle Harrison – Editorial Assistant

Our core principles

All our health content is produced in line with our core editorial principles – readable, reliable, relevant – which are represented by our diagram.

An image showing or editorial principals

                  Click to open full-size image

The ‘3Rs’ encompass everything we believe good health information should be. From tweets to in-depth reports, videos to quizzes, every piece of content we produce has these as its foundation.


In a nutshell, our information is jargon-free, concise and accessible. We know our audience and we meet their health information needs, helping them to take the next step in their health and wellbeing journey.


We use the best quality and most up-to-date evidence to produce our information. Our process is transparent and validated by experts – both our users and medical specialists.


We know that our users want the right information at the right time, in the way that suits them. So we review our content at least every three years to keep it fresh. And we’re embracing new technology and social media so they can get it whenever and wherever they choose.

Our accreditation

Here are just a few of the ways in which the quality of our information has been recognised.

  • The Information Standard certification scheme

    You will see the Information Standard quality mark on our content. This is a certification programme, supported by NHS England, that was developed to ensure that public-facing health and care information is created to a set of best practice principles.

    It uses only recognised evidence sources and presents the information in a clear and balanced way. The Information Standard quality mark is a quick and easy way for you to identify reliable and trustworthy producers and sources of information.

    Certified by the Information Standard as a quality provider of health and social care information. Bupa shall hold responsibility for the accuracy of the information they publish and neither the Scheme Operator nor the Scheme Owner shall have any responsibility whatsoever for costs, losses or direct or indirect damages or costs arising from inaccuracy of information or omissions in information published on the website on behalf of Bupa.

  • British Medical Association (BMA) patient information awards

    We have received a number of BMA awards for different assets over the years. Most recently, in 2013, we received a 'commended' award for our online shared decision making hub.

Contact us

If you have any feedback on our health information, we would love to hear from you. Please contact us via email: Or you can write to us:

Health Content Team
Bupa House
15-19 Bloomsbury Way

Find out more Close

Legal disclaimer

This information was published by Bupa's Health Content Team and is based on reputable sources of medical evidence. It has been reviewed by appropriate medical or clinical professionals. Photos are only for illustrative purposes and do not reflect every presentation of a condition.

The information contained on this page and in any third party websites referred to on this page is not intended nor implied to be a substitute for professional medical advice nor is it intended to be for medical diagnosis or treatment. Third party websites are not owned or controlled by Bupa and any individual may be able to access and post messages on them. Bupa is not responsible for the content or availability of these third party websites. We do not accept advertising on this page.

For more details on how we produce our content and its sources, visit the 'About our health information' section.

ˆ We may record or monitor our calls.