Sudden Infant Death Syndrome (SIDS)

Dr. Archana NirulaMBBS,PG Diploma

January 16, 2020

March 06, 2020

Sudden Infant Death Syndrome
Sudden Infant Death Syndrome

If welcoming a newborn into your family is joyful, then the baby’s sudden and unexplained passing can be traumatic. This is precisely the reason why awareness about Sudden Infant Death Syndrome or SIDS is very important, and taking precautions to prevent it even more so. 

SIDS, also known as cot or crib death, is not a new issue. The sudden death of an infant, especially during sleep, was mentioned by the Assyrians in the eighth/ninth centuries BCE and is also referred to in the Bible. But despite knowing about it for centuries, the precise causes of SIDS are not known yet. While its occurrence has dropped by 10% in the last two decades in developed countries, it is still a major cause of infant deaths in developing countries like India.

What is Sudden Infant Death Syndrome (SIDS)?

SIDS is defined as the sudden and unexplained death - usually during sleep - of an infant who is younger than a year. According to the SIDS International Global Strategy Task Force and the World Health Organization, infants between the ages of two and five months are more at risk of dying due to this syndrome. About 80% of the deaths occur in the age group of one month to six months, and 15% happen between 7-12 months. About 5% of deaths due to SIDS were reported to have happened after 12 months, so passing the one-year mark does not necessarily reduce the risk of SIDS.

Based on what is known, SIDS is not contagious, and there are no consistent symptoms or signs that can be taken as warnings before SIDS happens. SIDS occurs in both breastfed and bottle-fed infants, and can happen in any place where the baby sleeps - cribs, bassinets, rocking cots, prams and car seats.

While the occurrence of SIDS has been known for ages, it’s only following the publication of epidemiological studies in the late 1980s and 1990s that public healthcare providers - global, government and charitable - were able to devise a list of do’s and don’ts that could offer some guidance about SIDS to new parents and caregivers.

Symptoms and diagnosis of Sudden Infant Death Syndrome (SIDS)

SIDS can strike any infant under the age of one year without any symptoms showing up before death. This lack of symptoms is also directly related to the diagnosis of SIDS, which is based on exclusion - meaning that when all other causes of death, from infections to animal bites to organ failure or birth defects are excluded, doctors deduce that the infant died due to SIDS. This process of exclusion usually involves an investigation of the scene of death, a review of the baby’s clinical history and an autopsy.

Causes of Sudden Infant Death Syndrome (SIDS)

Despite extensive studies and research into SIDS, its exact causes are not yet known and the precise reasons for death might vary from baby to baby. There are, however, a few physical and sleep environmental stressors that can increase the chances of SIDS.

  1. Physical causes behind Sudden Infant Death Syndrome (SIDS)
  2. Sleep environmental causes behind Sudden Infant Death Syndrome (SIDS)

Physical causes behind Sudden Infant Death Syndrome (SIDS)

If your infant has any of the following physical factors, then it can cause SIDS.

  • Limited brain development: In some babies, the portion of the brain that regulates breathing and waking up during sleep are not fully matured yet. This brain function impairment makes them more susceptible to SIDS. Other cognitive function issues can cause SIDS too.
  • Low birth weight: Premature babies and multiple birth babies (twins, triplets or more) are usually born with a low birth weight, which also means that their brains are not fully developed at the time of birth and they will be unable to perform certain automatic actions. This can cause SIDS.
  • Respiratory infections: Many babies who died from SIDS were also suffering from minor respiratory infections. According to the SIDS International Global Strategy Task Force, however, autopsies performed on such babies revealed that these infections were mild and “insufficient to have caused death."

Sleep environmental causes behind Sudden Infant Death Syndrome (SIDS)

Since SIDS usually occurs while the baby is asleep, there are a few factors associated with the baby’s sleeping environment and patterns that can cause this syndrome. 

  • Sleeping on the stomach or side: If your baby is put to sleep on his or her stomach or side, it can cause difficulty in breathing and lead to death by suffocation.
  • Sleeping on a soft surface: If the baby is sleeping on a soft and loose comforter, mattress or on a waterbed then these can obstruct the baby’s airways.
  • Sharing a bed: Sharing a bed with parents can be fatal for infants because adults’ beds have many features (headboard gaps, large pillows, sheets, etc) that can obstruct the baby’s airways.
  • Overheating: Being too warm during sleep, either due to layers of clothing or stuffy climate in the bedroom, can also cause SIDS.

Risk factors of Sudden Infant Death Syndrome (SIDS)

Although SIDS can occur to any infant, a few risk factors increase the chances of this syndrome. These risk factors are associated with both the mother and the infant.

Infant risk factors:

  • According to the SIDS International Global Strategy Task Force, male infants are more affected by SIDS than female infants.
  • Infants between the ages of two to six months are more likely to be affected by SIDS.
  • Infants whose siblings or cousins have died due to SIDS are more at risk of dying of SIDS.
  • Infants who had a premature birth and had a lower birth weight are at a higher risk of SIDS.
  • Infants who haven’t received their immunization shots are more at risk of SIDS.

Maternal risk factors:

  • Being a young mother can increase the chances of preterm birth, and can in turn cause SIDS.
  • If the mother smokes before, during and after the pregnancy period, it can cause serious respiratory health issues for the baby, which in turn can lead to SIDS.
  • If the mother has used alcohol or illegal drugs during pregnancy then there are higher risks of her baby dying due to SIDS.
  • If the mother received late or no prenatal care - improper nutrition, vitamin and mineral supplements, rest, routine tests, screening and vaccinations, exercise - then her baby is at a higher risk of SIDS. 
  • If the mother is not breastfeeding due to any reason then her baby will be at a higher risk of SIDS.

How to prevent Sudden Infant Death Syndrome (SIDS)

Although there are no guaranteed ways of preventing SIDS from striking your newborn, there are a few measures you can take to reduce its risk.

  • Proper prenatal care: Taking good care of your health and diet during pregnancy can reduce the chances of premature labour and low birth weight of your babies. It’s important that you follow the recommended diet for pregnancy which includes all the necessary food groups, follow the routine pregnancy screening and vaccinations, and take vitamin and mineral supplements prescribed by your doctor. 
  • Cut off smoking, alcohol and illegal drugs: Smoking, drinking alcohol and drug abuse during pregnancy can affect the proper development of your baby, which in turn could lead to SIDS. Make sure you don’t do any of these things, and limit your caffeine intake during pregnancy too.
  • Always put the baby to sleep on the back: Since putting the baby to sleep on his or her stomach or sides can obstruct respiration, it’s best to always place him or her on his back during naps. Make sure this is followed by everybody who lays them down to sleep - spouses, relatives, nurses, etc. On the other hand, you can put the baby in other positions while he or she is awake.
  • Use safe bedding: It’s very important to ensure that the place where your baby sleeps is safe, so make sure there are no fluffy or loose comforters, pillows or toys around. Use a firm mattress and do not put your baby to sleep on a waterbed, sofa or other furniture.
  • Share a room, not a bed: The American Academy of Pediatrics recommends that infants should sleep in the same room as the parents, and this can also make the work of new mothers easier. However, it’s best not to share a bed with the baby, since your beds are more likely to have spaces where the baby can get stuck and suffocate, like the headboard gap, gaps between mattresses, bedsheets and blankets, pillows, etc. Maintain a safe sleeping area for your baby, and put them to sleep there even if you do let them play or feed in your bed.
  • Breastfeed your baby: For the first six months, make sure that you feed the baby only breastmilk unless otherwise recommended by the doctor. One of the benefits of breastfeeding is that it can reduce the risk of many health problems, improve your baby’s immunity, and may also reduce the risk of SIDS.
  • Take your baby for checkups and vaccinations: If your baby is healthy and is developing properly it can reduce the risk of SIDS immensely. It’s important to be in touch with your doctor, and take your baby for regular checkups. You must also ensure that your baby receives all the immunizations and vaccinations needed for his or her security and good health.
  • Don’t allow smoking around your baby: Infants who are exposed to smoking parents or guests are more likely to develop respiratory infections and other health issues. These can lead to SIDS, so make sure there is no smoke or air pollutant around your baby. This also applies for commercial incense sticks which are used for ritual purposes. 
  • Don’t overheat the sleeping area: While it’s important to keep your baby warm, it’s very important to not overheat the baby or his or her sleeping area. Don’t swaddle the baby too tightly, put on too many layers of clothing or cover the baby’s face or head. This can reduce the risk of SIDS.
  • Use pacifiers safely: You might want to give your baby pacifiers during regular sleep and nap times after a few weeks or months, but make sure you don’t hang or tie them around the baby’s neck or attach them to his or her clothing. Also make sure that the pacifiers aren’t large enough to obstruct normal breathing. 
  • Don’t use positioning devices: Avoid using positioning devices like side pillows to demarcate your baby’s sleeping area. These can cause SIDS and other sleep-related infant deaths.

Read more: How to swaddle a baby


  1. National Health Service [Internet]. UK; Sudden infant death syndrome (SIDS)
  2. World Health Organization [Internet]. WHO Regional Office for Europe Family and Reproductive Health Unit. Copenhagen. Denmark; Second Meeting of Focal Points on Reproductive Health/ Health of Women and Children in the European Region
  3. Stanford Children's Health: Lucile Packard Children's Hospital [Internet], Stanford. USA; Sudden infant death syndrome (SIDS)
  4. Boston Children’s Hospital [Internet]. Boston. Massachusetts. USA; Sudden Infant Death Syndrome (SIDS) Symptoms & Causes
  5. Duncan JR, Byard RW. Sudden Infant Death Syndrome: An Overview. In: Duncan JR, Byard RW, editors. SIDS Sudden Infant and Early Childhood Death: The Past, the Present and the Future. Adelaide (AU): University of Adelaide Press; 2018 May.
  6. Kinney, Hannah C. and Thach, Bradley T. The Sudden Infant Death Syndrome N Engl J Med. 2009 Aug 20; 361(8): 795–805. PMID: 19692691
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