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First Years Aug 16, 2019
9 Minutes

SIDS: the risk factors and the positive ways you can reduce them

It’s probably fair to say that Sudden Infant Death Syndrome (SIDS or ‘Cot Death’) is one of the things that new parents fear the most. It is a major source of anxiety and the risk of it has been known to drive a parent mad and drive that urge to go in every five minutes to check the baby is still breathing (something familiar to most new parents….). This article looks at the science based risk factors but, as usual, most importantly what you can do as parents to reduce risks where you can. As usual there is no easy ‘fix’ or guarantee that this will stop the worst case (we wish) but doing positive things where you can related to factors where science suggests there is increased risk is never a bad thing! Once again, we hope that knowledge here is empowering and can help you feel just that little bit better that you are doing something positive:

We know that the riskiest time for a baby when it comes to SIDS is the first six months of life, with the peak being between 2 – 4 months and then the risk subsiding from six months and coming down significantly at a year old.

Here are some of the stats to know: 

50% of SIDS cases occur between 7.6-17.6 weeks old, after six months the number of cases falls to around 10% of total. So, this is the time for the greatest vigilance when it comes to your new baby. (1)

What causes it?

Despite millions of dollars spent on research over many decades the reality is we are yet to find a single proven cause which is not ideal. However, there are various arguments which centre around a combination of risk factors put together which essentially mount to ‘stress factors’ that overwhelm the body’s ability to cope and regulate itself.

We are going to take a look at them and most importantly what you can do to reduce your baby’s risk as a result:

Premature birth: we know that babies born prematurely are inherently more vulnerable. There are various factors behind why this may be: Some link it to a combination of systemic inflammation, susceptibility to infection, early life stressors, reduced neurodevelopment and low birth weight (2) amounting to a reduced ability to regulate stress response to external factors. Of course as a parent, there is not much you can do about your child being premature, however, the good news is there are things that science shows can be helpful to reducing risks associated with an increase in SIDS: 

Improving weight gain and reducing stress in a premature baby is good all around. Interestingly enough, some of the latest research has shown a significant benefit from parents interacting as much as possible in the earliest days and being incorporated into the daily care of the child within the NICU. Click here for much more. Secondly, there has been some significant findings around the role that music can play in the earliest days when it comes to stress relief and brain development both of which have links to SIDS (1) click here for much more and how as a parent you can take an active role reducing some of these risks.

Of course the main thing with a premature baby is vigilance and ensuring you reduce other risk factors that are within your control as much as possible (more on this below).

One additional factor we cannot change is the fact that statistically baby boys are more likely to have SIDS than female babies with a ratio of 60:40 (1). Once again, all you can do in this situation is to be vigilant and reduce the other risk factors (below) as much as you can:

So: having a boy or a premature baby is not so much in your control, however, here are some actors you can potentially control: 

Belly sleeping: so thankfully the awareness around this has grown substantially in recent years. We now know that lying ‘prone’ aka on the stomach more than triples the risk of SIDS (8). So always placing a baby to sleep on its back is a simple way to reduce risk.

But why does this make such a difference? There are a variety of explanations here, however, interestingly enough it has been linked back to our friend the gut or more specifically the gut microbiome and immunity: ‘early studies show differences between the gut microbiome of SIDS babies compared with healthy babies.’ (2)

Once again click here for much more on the importance of a healthy gut for both the mother during pregnancy and for a developing baby’s lifelong health. However, connected to this:

We also know that lying on the belly ‘enhances ingestion/inhalation of bacteria on the sleeping surface’ (2) which is another reason why you need to ensure that your baby sleeps on a new/clean mattress with sheets and bedding changed regularly. 

Unfortunately co-sleeping also increases the risks: Evidence shows that the longer a parent and an infant bed share, the higher the risk for sleep-related causes of infant death, such as suffocation. It is also linked to the mattress being contaminated. (15)

A review of 19 studies from the United Kingdom, Europe and Australasia with 1472 SIDS cases and 4679 controls showed that, even for low-risk infants, bed sharing was associated with a five-fold increased risk of SIDS in the first 3 months of life. (20) Similarly sofas are a risk with an American study reporting that 13% of infant sleep-related deaths were on sofas between 2004-2012.(19) – this is in part linked to it being a contaminated surface. (2)

The best bet is a Moses basket in the same room as you with a new waterproof mattress and simple organic cotton fitted sheet. 

Smoking: we know a smoking mother or smoke near a new baby can significantly increase the risk of SIDS and once again it is being linked in part to these all important microbes established within a mother: ‘smoking mothers increase the risk of bacterial and/or viral colonisation in their infants’ (2) and it is of course a similar picture to drugs/alcohol. Ensure that people who consume alcohol/smoke/take drugs do so well away from your baby at all times – it is really important. (19)

Breastfeeding: once again we know that breast milk has a number of very significant long term benefits for a baby’s brain development, for its immunity once again all linked to the development of a healthy gut microbiome. Click here for much more. Statisticsally babies who breastfeed, or are fed breastmilk, are at lower risk for SIDS than are babies who were never fed breastmilk. (14) and the research also suggests that the longer you can do it the lower the risks when it comes to SIDS.

Interestingly: sleeping with a pacifier/dummy has been shown to reduce risks. However, a couple of important points related to it:

  • Avoid using it until breastfeeding is well established (around 3-4 weeks)

  • Do not attach it to string, clothing, a stuffed toy or blanket as that carries a risk for suffocation, choking, or strangulation.

  • Don’t force your baby to use it. If the dummy falls out of your baby’s mouth during sleep, there is no need to put it back in. (18)

Circumcision: whilst the jury is still out as to the exact mechanism behind why this appears statistically to be linked to increased SIDS risk, so if you make the decision to circumcise your son then extra vigilance is warranted. (1, 6, 7)

What to do when your baby is in bed: 

  • Place your baby in the “feet to foot” position. This means their feet touching the end of the cot, Moses basket, or pram (they should not sleep for long periods in a car seat or pram – a Moses basket is best for longer naps).

  • Keep your baby’s head uncovered and their blanket should be tucked in no higher than their shoulders as this can cause the risk of SIDS to increase by five-fold. (13)

  • Use a mattress that is firm, flat, waterproof and new covered by a fitted sheet with no other bedding or soft items in the sleep area. Evidence does not support using cot bumpers to prevent injury and in fact they are linked to serious injuries and deaths from suffocation, entrapment, and strangulation.

  • Avoid products that go against safe sleep recommendations and any that claim they can reduce the risk of SIDS. There is currently no known way to prevent SIDS. Evidence does not support the safety or effectiveness of wedges or other items that claim to keep infants in a specific position or to reduce the risk of SIDS. If you are offered a product that promises to prevent it then be very wary.

Temperature is of course another factor:

Do not let your baby get too hot or too cold – a room temperature of 16 – 20oC, with light bedding, a swaddle or a lightweight baby sleeping bag, will provide a comfortable sleeping environment for your baby. (10)  Of course illness and a temperature in particular is the time to be extra vigilant and if in doubt you should always contact your healthcare provider as unfortunately SIDS risk is linked to illness in babies (2).

What tools can be helpful?

The really crucial point to note is that no product out there can fully protect or prevent SIDS from occurring as much as we may wish there was one. The best bet is to do whatever we can in order to reduce risks and increase our vigilance. There are some tools to help us do this, however we should always be aware that these are not enough on their own and should not be completely relied on in isolation.

Temperature Monitors: a basic thing you can do is to monitor the temperature in your baby’s bedroom. This can be a stand alone monitor or often comes in part with a camera to monitor your baby. Once again, ensuring the room isnt too hot or cold is an easy way to reduce risk.

Owlett sock: ‘smart tech’ is of course an increasing part of our lives and we now have ‘smart socks’ which can monitor various things for your baby and may be worth considering. The Owlett wireless monitor tracks the baby’s heart rate, oxygen level and sleep and this data can be streamed live to parents via an app. The theory is that it can then alert them if these readings become abnormal, prompting them to check on their child. Some people are concerned that it can caused extra anxiety and others feel more reassured it is there. Seems like personal preference!

Movement monitor: this is where a pad is placed under the mattress directly underneath where your baby sleeps. The idea is that if your baby stops breathing an alarm will go off. Our favourite is this one: but once again as a reminder this should not be the only think you rely on as these machines are not perfect.

Ultimately: there is (as of yet) no single known reason why SIDS occurs so all we have is the ‘risk’ factors that have been associated with it as above. Being aware and vigilant where you can is of course the best bet as sadly these things do happen. The good news is that overall the rates have been coming down since the 80s so lets hope that trend sticks!


  1. Elhaik, E: Neonatal Circumcision and Prematurity are associated with sudden infant death syndrome (SIDS): Journal of Clinical and Translational Research: 2019 Jan 10; 4(2): 136–151.

  2. Goldwater PN: Infection the neglected paradigm in SIDS research: Archives of disease in childhood: 2017 Aug; 102(8): 767–772.

  3. Shannon DC, Kelly DH. SIDS and near-SIDS (second of two parts). N Engl J Med. 1982;306:1022

  4. Hoyert DL. Mortality associated with birth defects: influence of successive disease classification revisions. Birth Defects Res A Clin Mol Teratol. 2003;67:651–5.


  6. Ostfeld BM, Esposito L, Perl H, Hegyi T. Concurrent Risks in Sudden Infant Death Syndrome. Paediatrics 2010; 125(3). Doi:10.1542/peds.2009-0038

  7. Eran Elhaik. Neonatal circumcision and prematurity are associated with sudden infant death syndrome (SIDS). J Clin Transl Res 2019; 4(2): 136–151.

  8. Willinger M, Hoffman HJ, Hartford RB. Infant sleep position and risk for sudden infant death syndrome: report of meeting held January 13 and 14, 1994, National Institutes of Health, Bethesda, MD. Pediatrics. 1994;93:814–9.

  9. Paludan-Müller C, Ghouse J, Vad OB, Herfelt CB, Lundegaard P. Ahlberg G, Schmitt N, Svendsen JH, Haunsø S, Bundgaard H, Hansen T, Kanters JK, Olesen MS. Reappraisal of variants previously linked with sudden infant death syndrome: results from three population-based cohorts. European Society of Human Genetics 2019.

  10. American Academy of Pediatrics. (2016, October). SIDS and other sleep-related infant deaths: Updated 2016 Recommendations for a Safe Infant Sleeping Environment. Pediatrics, Nov;138(5). pii: e20162938. Epub 2016 Oct 24.

  11. Jeffery HE, Megevand A, Page H. Why the prone position is a risk factor for sudden infant death syndrome. Pediatrics 1999; 104Pt 1: 263–9.

  12. Ostfeld BM, Schwartz-Soicher O, Reichman NE, Teitler JO, Hegyi T. Prematurity and sudden unexpected infant deaths in the United States. Pediatrics 2017; 140: e20163334.

  13. Hauck FR, Herman SM, Donovan M, Iyasu S, Merrick Moore C, Donoghue E et al. Sleep environment and the risk of sudden infant death syndrome in an urban population: the Chicago infant mortality study. Pediatrics 2003; 111: 1207–14.

  14. Thompson JMD, Tanabe K, Moon RY, Mitchell EA,McGarvey C, Tappin D et al. Duration of breastfeeding and risk of SIDS: an individual participant data metaanalysis. Pediatrics 2017; 140: e20171324.

  15. . ”

  16. Marinelli KA, Ball HL, McKenna JJ, Blair PS. An Integrated Analysis of Maternal-Infant Sleep, Breastfeeding, and Sudden Infant Death Syndrome Research Supporting a Balanced Discourse. J Hum Lact. 2019 Jun 11:890334419851797. doi: 10.1177/0890334419851797

  17. Vennemann MMT, Höffgen M, Bajanowski T, Hense H-W, Mitchell EA. Do immunisations reduce the risk for SIDS? A meta-analysis. Vaccine 2007; 25: 4875–9.

  18. Moon RY, Task Force on Sudden Infant Death Syndrome. SIDS and other sleeprelatedinfant deaths: evidence base for 2016 updated recommendations for a safe infant sleeping environment. Pediatrics 2016; 138: e20162940.

  19. Horne RSC. Sudden infant death syndrome: current perspectives. Internal Medicine Journal 49 (2019) 433–438

  20. Carpenter R, McGarvey C, Mitchell EA, Tappin DM, Vennemann MM, Smuk M et al. Bed sharing when parents do not smoke: is there a risk of SIDS? An individual level analysis of five major case-control studies. BMJ Open 2013; 3: e002299.

  21. Rechtman LR, Colvin JD, Blair PS, Moon RY. Sofas and infant mortality. Pediatrics 2014; 134: e1293–30


This article is for informational purposes only. This article is not, nor is it intended to be, a substitute for professional medical advice, diagnosis, or treatment and should never be relied upon for specific medical advice. The information on this website has been developed following years of personal research and from referenced and sourced medical research. Before making any changes we strongly recommend you consult a healthcare professional before you begin.

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