Quick Answer: Crib death, also called SIDS (Sudden Infant Death Syndrome), is the sudden, unexplained death of an otherwise healthy infant under 1 year old. The single most effective preventive measure is placing babies on their back to sleep on a firm, flat surface. SIDS risk is highest between 1 and 4 months. Always follow Canadian Paediatric Society safe sleep guidelines. If you have concerns, speak with your paediatrician.
In This Guide
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What Is Crib Death / SIDS?
Crib death is the common Canadian term for SIDS -- Sudden Infant Death Syndrome. It describes the sudden, unexpected death of an apparently healthy infant under one year of age, where no cause of death can be identified even after a thorough investigation that includes a full autopsy, a review of medical history, and an examination of the sleep environment.
SIDS is, by definition, a diagnosis of exclusion. If an explanation is found, the death is classified differently. SIDS is a devastating and disorienting loss for families precisely because of this absence of explanation. Parents who have done everything right can still experience it.
In Canada, SIDS accounts for roughly 100 to 150 infant deaths per year. The rate has fallen dramatically since the 1990s, when the "Back to Sleep" public health campaign began. In the three decades since that campaign, SIDS deaths in Canada and comparable countries dropped by more than 80%. This is one of the most successful public health outcomes in paediatrics, and it was achieved through a change in one behaviour: sleep position.
The Triple Risk Model
The leading scientific theory of SIDS is the "triple risk model," proposed by researchers Filiano and Kinney. It holds that SIDS occurs when three factors coincide: (1) an underlying vulnerability in the infant, often neurological, such as impaired brainstem arousal responses; (2) a critical developmental period, specifically the first 6 months; and (3) an external stressor or trigger, such as prone sleeping, soft bedding, or exposure to cigarette smoke. This model explains why SIDS is not entirely preventable (we cannot always know about the underlying vulnerability) but why eliminating environmental risk factors meaningfully reduces deaths.
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What Causes SIDS?
The precise cause of SIDS remains unknown, which is part of what makes it so difficult for families to process. Research has identified patterns and associations, but not a single, definitive mechanism.
The most consistently supported hypothesis involves abnormalities in the brainstem, specifically in the regions that control responses to low oxygen and rising carbon dioxide during sleep. In typical infants, a drop in oxygen triggers an arousal response: the baby rouses, moves, breathes more deeply. Researchers have found that some infants who die of SIDS have lower levels of serotonin and related receptors in the brainstem's arousal regions, potentially impairing this protective response.
This is not a defect that can be identified in advance with standard testing. It is why SIDS families often describe their baby as completely healthy, growing normally, with no warning signs.
Risk Factors
| Risk Factor | Effect on Risk | Modifiable? |
|---|---|---|
| Prone (stomach) sleeping | Major increase | Yes -- always place on back |
| Soft sleep surface | Major increase | Yes -- use firm flat mattress |
| Loose bedding, pillows, bumpers in crib | Significant increase | Yes -- remove all soft objects |
| Maternal smoking during pregnancy | 3 to 4x increased risk | Yes -- smoking cessation programs |
| Secondhand smoke exposure | Significant increase | Yes -- smoke-free home |
| Bed sharing (especially with smokers) | Significant increase | Yes -- room share, not bed share |
| Age 1 to 4 months | Highest risk window | No -- developmental |
| Premature birth / low birth weight | Increased risk | Partially -- prenatal care |
| Male sex | Slightly higher risk | No |
| Overheating | Moderate increase | Yes -- appropriate room temperature and clothing |
Canadian Safe Sleep Guidelines
The Canadian Paediatric Society (CPS) and Health Canada publish evidence-based safe sleep recommendations. These are the most important steps parents can take to reduce the risk of crib death.
Safe Sleep: The Core Rules from the Canadian Paediatric Society
- Always place baby on their back to sleep -- for every sleep, naps and nighttime, until age 1. Even if your baby can roll, start them on their back. This is the single most impactful action.
- Use a firm, flat sleep surface -- a Health Canada-approved crib, cradle, or bassinet with a tight-fitting firm mattress. Not a car seat, stroller, swing, couch, or adult bed.
- Room share, not bed share -- the CPS recommends sleeping in the same room as the infant for at least the first 6 months, on a separate surface. Room sharing reduces SIDS risk by up to 50%.
- Keep the sleep area clear -- no pillows, loose blankets, bumper pads, stuffed animals, positioners, or wedges in the sleep area.
- Smoke-free environment -- no smoking during pregnancy and no secondhand smoke in the home or car after birth. This is one of the highest-impact modifiable risk factors.
- Keep cool -- room temperature between 16 and 20 degrees Celsius. Dress baby in one layer more than you would wear comfortably. Watch for signs of overheating (sweating, flushed skin, rapid breathing).
- Offer a pacifier -- the CPS supports offering a pacifier at sleep onset after 1 month of age (or after breastfeeding is established). Research associates pacifier use with reduced SIDS risk.
- Breastfeed if possible -- breastfeeding, even partially, is associated with reduced SIDS risk.
- Immunize on schedule -- contrary to some concerns, research shows vaccines do not increase SIDS risk and may be protective.
The Crib Mattress and Safe Sleep
The requirement for a firm, flat crib mattress is not a preference. It is a specific safety standard. A soft surface can conform around an infant's face during sleep, reducing airflow and potentially trapping exhaled carbon dioxide. Even a brief period of elevated CO2 in a sleeping environment can be dangerous for infants with reduced arousal capacity.
Health Canada standards require that a crib mattress:
- Be firm and flat, without contouring or inclines
- Not compress more than 2.5 cm under the weight of the infant
- Fit snugly in the crib with no gap larger than 3 cm at any edge
- Not be a memory foam, pillow-top, or soft foam construction
- Be covered with a tight-fitting sheet only -- no loose bedding
Standard Canadian crib mattress dimensions are approximately 27.5 inches by 51.75 inches (70 cm by 132 cm). See our guide to crib mattress dimensions for full sizing information including travel crib and mini crib measurements.
Talking About Safe Sleep in Brantford
We have sold mattresses in Brantford since 1997, and over those decades we have seen parents, grandparents, and caregivers come in asking about crib mattresses. Public health messaging about safe sleep has evolved considerably over that time. Some grandparents recall a time when stomach sleeping was recommended -- the opposite of current guidance. If there is any confusion in your family about safe sleep guidelines, the most current information comes from the Canadian Paediatric Society and your child's healthcare provider. We are glad to discuss crib mattress safety standards when you visit, but paediatric health decisions belong with your healthcare team.
What About Inclined Sleepers and Infant Products?
A number of infant sleep products marketed in Canada make claims about safety or comfort that are not supported by current evidence, and some have been associated with infant deaths. Health Canada has issued recalls and advisories on inclined infant sleepers, loungers, and infant recliners used as sleep surfaces. The guidance is clear: infants should sleep on a firm, flat surface, not an inclined one.
If you have a product you are uncertain about, check Health Canada's consumer product safety recall database or speak with your child's healthcare provider before using it as a sleep surface.
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Dorothy at Mattress Miracle: "We talk to new and expecting parents every week. The single most important thing we tell them is that the safest sleep environment for an infant is the simplest one: a firm, flat crib mattress with a fitted sheet, in a crib that meets Health Canada SOR/2016-152 standards. No bumpers, no toppers, no pillows, no stuffed animals. The fewer items in the crib, the lower the SIDS risk. The Canadian Paediatric Society and Public Health Agency of Canada are unambiguous on this point."
SIDS Prevention in Quebec
SIDS prevention guidance in Quebec follows the same Public Health Agency of Canada and Canadian Paediatric Society standards as the rest of Canada. The French term is "syndrome de mort subite du nourrisson (SMSN)". Direction de santé publique de Montréal and Quebec public health follow identical safe-sleep recommendations: firm flat surface, fitted sheet only, back sleeping, room sharing for the first six months.
Frequently Asked Questions
What is the difference between crib death and SIDS?
Crib death and SIDS are the same thing. "Crib death" is the common term used in North America, while "cot death" is used in the UK and Australia. SIDS is the clinical term for the sudden, unexplained death of an apparently healthy infant under one year of age, even after a thorough postmortem investigation.
What age is highest risk for SIDS?
SIDS risk peaks between 1 and 4 months of age. Approximately 90% of SIDS deaths occur before 6 months. After 6 months the risk declines significantly, and SIDS is rare after 12 months. This is why safe sleep practices are especially critical in the first 6 months.
Can you prevent SIDS completely?
SIDS cannot be completely prevented because the exact cause is still unknown. However, following safe sleep guidelines, particularly placing babies on their back on a firm, flat surface and eliminating soft bedding and smoking exposure, can reduce the risk significantly. SIDS rates in Canada have dropped by more than 80% since the "Back to Sleep" campaign launched in the 1990s.
Is a firm crib mattress really necessary?
Yes. A firm, flat crib mattress is a specific requirement in both Canadian Paediatric Society and Health Canada safe sleep guidelines. A soft surface can conform to a baby's face and obstruct breathing. The mattress should not compress more than 2.5 cm under the baby's weight and must fit snugly in the crib with no gaps at the edges.
Does a pacifier help prevent SIDS?
Research suggests yes. A meta-analysis published in Pediatrics found that pacifier use during sleep was associated with a significantly reduced risk of SIDS. The American Academy of Pediatrics recommends offering a pacifier at the onset of sleep. For breastfed babies, wait until breastfeeding is well established, typically around one month, before introducing a pacifier.
Sources
- Filiano, J.J., & Kinney, H.C. (1994). A perspective on neuropathologic findings in victims of the sudden infant death syndrome: The triple-risk model. Biology of the Neonate, 65(3-4), 194-197. doi.org/10.1159/000244052
- Kinney, H.C., & Thach, B.T. (2009). The sudden infant death syndrome. New England Journal of Medicine, 361(8), 795-805. doi.org/10.1056/NEJMra0803836
- Canadian Paediatric Society. (2021). Safe sleep for your baby. Paediatrics & Child Health, 26(1), 56-57. doi.org/10.1093/pch/pxaa146
- Vennemann, M.M., et al. (2012). Pacifier use and the risk of sudden infant death syndrome. Pediatrics, 129(4), e854-e863. doi.org/10.1542/peds.2011-1987
- Moon, R.Y., & Task Force on Sudden Infant Death Syndrome. (2016). SIDS and other sleep-related infant deaths: Updated 2016 recommendations for a safe infant sleeping environment. Pediatrics, 138(5), e20162938. doi.org/10.1542/peds.2016-2938
- Carpenter, R., et al. (2013). Bed sharing when parents do not smoke: Is there a risk of SIDS? BMJ Open, 3(5), e002299. doi.org/10.1136/bmjopen-2012-002299
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Related Reading
- Crib Mattress Size: Dimensions and What to Know
- Sleep Training Baby: Methods and When to Start
- Infant Pacifier: Benefits, Risks, and When to Stop
- When Do Infants Sleep Through the Night?
- Sleep Regression: What Parents Need to Know About Baby Sleep Setbacks
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