SIDS prevention: Hypotheses about reducing risk

© 2009 – 2013 Gwen Dewar, Ph.D., all rights reserved

Guidelines for “SIDS prevention” are like guidelines about cancer prevention. Researchers don’t claim they know how to prevent SIDS in any given individual. But they’ve identified a number of practices that appear to increase the risk of sudden infant death syndrome.

Practices to AVOID include:

  • Prone sleeping (i.e., sleeping on the stomach)
  • Sleeping on a soft surface (including a soft mattress, pillow, or duvet)
  • Use of pillows or other soft objects that could cover the face
  • Maternal smoking and smoking by other household members
  • Maternal alcohol consumption during pregnancy
  • Overheating the baby (by overdressing or turning up the thermostat)

Why are these practices risky?

In some cases, it’s because they create an asphyxiation hazard. In other cases, it’s because they may interfere with the baby’s ability to arouse from sleep.

That’s important, because many researchers believe that SIDS caused by a failure to arouse during a potentially life-threatening event, like a severe episode of sleep apnea. (For more information, see this evidence-based article on the causes of SIDS.)

Is there anything else we can do?

Here are some other practices that might contribute to risk of SIDS.


Analyses of SIDS cases suggest that breastfeeding has a protective effect against SIDS. Compared to controls, breastfed babies were less likely to die of SIDS, even after controlling for maternal socioeconomic status, baby’s sleeping position, smoking, and bed sharing (Hauck et al 2011).

Why? It’s possible that safety-conscious moms are more likely to breastfeed, in which case breastfeeding isn’t the cause of lower SIDS rates, but merely a marker of a lifestyle associated with SIDS prevention practices.

But there are reasons to suspect that much more is going on. Experiments show that breastfeeding babies are more easily aroused from sleep (Horne 2006; Horne et al 2004; Franco et al 2000). And breastfeeding benefits a baby’s immune system. As a result, babies may be less likely to succumb to infections that could trigger a SIDS event (Vennemen 2009).

Sleeping in the same room with your baby

Experiments show that babies who share their mothers’ beds experience more arousals from sleep, which could conceivably reduce an infant’s risk of SIDS (Mosko et al 1997; Mao et al 2004). In fact, some researchers have speculated that the low rate of SIDS reported in Japan is attributable, in part, to traditional Japanese practice of mother-infant co-sleeping.

But studies of Western populations have failed to show any such protective effect. On the contrary, a recent case study of SIDS rates in Europe found that bed-sharing increased the risk of SIDS for infants under 20 weeks of age (Carpenter et al 2013). As Edwin Mitchell and Peter Blair (2012) have argued, some deaths would be prevented if parents were better informed about this risk.

What’s the going on? That’s not entirely clear, but it seems likely that bed-sharing, as it is typically practiced in Western countries, exposes babies to a number of hazards.

You can read about these hazards — and the general question of bed-sharing safety — here.

But bed-sharing isn’t the only way to co-sleep, and one thing seems to be uncontroversial:

Sleeping near parents, but on a separate, infant-appropriate surface, is an excellent way to minimize risk.

In a large study of European SIDS cases, researchers found that SIDS rates were lowest for babies who slept in the same room as their parents did, but in a separate crib or cot (Carpenter et al 2004).

Use of a fan

Both overheating and high CO2 levels put babies at greater risk. Does this mean that we can lower the SIDS risk if we improve the ventilation of the bedroom? The jury is still out, but it seems possible. A study of SIDS cases in California found that a baby was less likely to die of SIDS in a warm room if there was a fan in use (Coleman-Phox et al 2009).


Many people don’t like pacifiers. That’s because prolonged pacifier use can interfere with the normal growth of a baby’s palate. In addition, surveys suggest that pacifier use may reduce the duration of breastfeeding, and a recent questionnaire uncovered a link between pacifier and acute otitis media (Mitchell et al 2006; Rovers et al 2008).

However, there may be a bright side. Case studies of SIDS victims consistently reveal that babies who use pacifiers are less likely to die of SIDS (Hauck et al 2005; Moon et al 2012). Why? It’s unclear. The apparently protective effect has been linked with both breastfed and bottle fed babies. And, although one experimental study found that babies who frequently use pacifiers were aroused more easily (Franco et al 2000), another did not (Hanzer et al 2008).


Some people worry that immunizations cause SIDS. But the scientific evidence suggests otherwise. When researchers examined the period shortly after infants were vaccinated, they found no evidence of any increase in sudden infant death (Kunhert et al 2012). And in a meta-analysis of published SIDS studies, researchers found that SIDS rates were almost 50% lower among babies who’d been immunized (Vennemann et al 2007).

It makes sense that immunizations could reduce the risk of SIDS. Immunized babies are less likely to contract infections that might trigger a SIDS event. But, because physicians often delay immunizations when babies are ill, it’s also possible that the immunized babies were healthier to begin with. More research is needed to distinguish between these explanations.

What about swaddling?

Swaddled babies experience fewer startles while they sleep. In addition, they have fewer arousals during an infant sleep stage called “quiet sleep,” and arousals of shorter duration during a stage known as “active sleep”(Gerard et al 2002).

This indicates that swaddled infants sleep more deeply, which could put them at higher risk for SIDS. And epidemiological studies support the idea.

The babies at greatest risk are those who are swaddled and placed on their stomachs. In addition, older babies — who are capable of rolling over — are at heightened risk even when their caregivers lay them to bed on their backs.

While some case-control studies (Ponsonby et al 1993; Wilson et al 1994; Thach 2009) have reported that swaddling posed no increased risk to certain babies — infants who were placed to sleep on their backs, and who were too young to turn themselves over — a recent meta-analysis found that even these babies were at slightly higher risk (Pease et al 2016). 

For this reason, experts urge that caregivers who swaddle follow strict safety guidelines — placing swaddled babies on their backs, checking to make sure that babies don’t reposition themselves, and abandoning the practice of swaddling once babies are old enough to turn themselves over. In addition, it’s important to avoid swaddling too tightly. Babies should be able to move their hips and knees freely, and their chests shouldn’t be constricted. For more information, see the swaddling guidelines in this article.

The takeaway: Steps we can take to reduce the risk of SIDS

  • Put a baby on his or her back when it’s time to sleep
  • Make sure the baby’s sleep surface is firm
  • Keep the baby’s face and head uncovered
  • Avoid overheating the baby
  • Remove pillows, soft toys, and loose bedding from the baby’s sleep environment
  • Don’t swaddle babies who are old enough to turn themselves on their stomachs

In addition:

  • Pregnant women shouldn’t smoke and babies shouldn’t be exposed to second-hand smoke.
  • Breastfeeding may help babies arouse from sleep and avoid potentially dangerous infections.
  • Most researchers recommend that babies sleep in same room (in a crib or cot) where their parents sleep
  • Parents interested in bed-sharing should get informed about known hazards, and   review these safety guidelines for reducing risk.
  • On warm days, the use of a fan might help reduce the risk of SIDS.
  • Pacifier use, which is undesirable in some respects, might contribute to SIDS prevention. However, nobody knows why.
  • Although the causation is unclear, babies who are immunized are less likely to die of SIDS.

References: SIDS prevention practices

Carpenter RG, Irgens LM, Blair PS, England PD, Fleming P, Huber J, Jorch G, and Schreuder P. 2004. Sudden unexplained infant death in 20 regions in Europe: case control study. Lancet 363(9404): 185-191.

Coleman-Phox K, Odouli R, and Li DK. 2008. Use of a fan during sleep and the risk of sudden infant death syndrome. Arch Pediatr Adolesc Med. 162(10):963-8.

Franco P, Seret N, Van Hees JN, Scaillet S, Groswasser J, Kahn A. 2005. Influence of swaddling on sleep and arousal characteristics of healthy infants. Pediatrics. 115(5):1307-11.

Franco P, Scaillet S, Groswasser J, and Kahn A. 2001. Pacifiers during sleep and sudden infant death. Eur J Pediatr. 160(7):448.

Gerard CM, Harris KA, and Bradley BT. 2002. Spontaneous arousals in supine infants while swaddled and unswaddled during rapid eye movement and quiet sleep. Pediatrics 110(6): e70-76.

Hanzer M, Zotter H, Sauseng W, Pfurtscheller K, Müller W, Kerbl R. 2008. Pacifier use does not alter the frequency or duration of spontaneous arousals in sleeping infants. Sleep Med. 2008 Aug 4. [Epub ahead of print]

Hauck FR, Omojokun OO, Siadaty MS. 2005. Do pacifiers reduce the risk of sudden infant death syndrome? A meta-analysis. Pediatrics. 116(5):e716-23.

Hauck FR, Thompson JM, Tanabe KO, Moon RY, and Vennemann MM. 2011. Breastfeeding and reduced risk of sudden infant death syndrome: a meta-analysis. Pediatrics. 128(1):103-10.

Horne RSC, Parslow PM, Ferens D, Watts AM, and Adamson TM. 2004. Comparison of evoked arousability in breast and formula fed infants. Arch Dis Child 89: 22-25.

Kuhnert R, Schlaud M, Poethko-Müller C, Vennemann M, Fleming P, Blair PS, Mitchell E, Thompson J, and Hecker H. 2012. Reanalyses of case-control studies examining the temporal association between sudden infant death syndrome and vaccination. Vaccine. 16;30(13):2349-56.

Mao A, Burnham MM, Goodlin-Jones BL, Gaylor EE, and Anders TF. 2004. A comparison of the sleep-wake patterns of co-sleeping and solitary infants. Child Psychiatry and Human Development 32(2): 95-105.

Moon RY, Tanabe KO, Yang DC, Young HA, Hauck FR. 2012. Pacifier use and SIDS: evidence for a consistently reduced risk. Matern Child Health J. 16(3):609-14.

Mosko S, Richard C, McKenna J. 1997. Infant arousals during mother-infant bed sharing: implications for infant sleep and sudden infant death syndrome research. Pediatrics. 100(5):841-9.

Mitchell EA and Blair PS. 2012. SIDS prevention: 3000 lives saved but we can do better. N Z Med J. 125(1359):50-7.

Mitchell EA, Blair PS, L’Hoir MP. 2006. Should pacifiers be recommended to prevent sudden infant death syndrome? Pediatrics. 117(5):1755-8.

Moon RY and Fu L. 2012. Sudden Infant Death Syndrome: An Update. Pediatrics in Review 33(7): 314 -320.

Pease AS, Fleming PJ, Hauck FR, Moon RY, Horne RSC, et al. 2016. Swaddling and the Risk of Sudden Infant Death Syndrome: A Meta-analysis. Pediatrics DOI: 10.1542/peds.2015-3275.

Ponsonby A, Dwyer T, Gibbons LE, Cochrane JA, and Wang Y. 1993. Factors potentiating the risk of sudden infant death syndrome associated with the prone position. New England Journal of Medicine 329: 377-382.

Poyak J. 2006. Effects of pacifiers on early oral development. Int J Orthod Milwaukee. 17(4):13-6

Rovers MM, Numans ME, Langenbach E, Grobbee DE, Verheij TJ, Schilder AG. 2008. Is pacifier use a risk factor for acute otitis media? A dynamic cohort study. Fam Pract. 25(4):233-6.

Thach BT. 2009. Does Swaddling Decrease or Increase the Risk for Sudden Infant Death Syndrome? J Pediatr. 155(4): 461–462.

Vennemann MM, Höffgen M, Bajanowski T, Hense HW, Mitchell EA. 2007. Do immunisations reduce the risk for SIDS? A meta-analysis. Vaccine. 21;25(26):4875-9.

Wilson CA, Taylor BJ, Laing RM, Williams SM and Mitchell EA. 1993. Clothing and bedding and its relevance to sudden infant death syndrome: Further results from the New Zealand cot death study. J Pediatric Child Health 30: 506-512.

Content of “The latest ideas about SIDS prevention” last modified 10/13