SIDS

Sudden infant death syndrome SIDS is an umbrella term for a child under 1 year of age inexplicably dying in their sleep. In a strict clinical sense what causes SIDS is unknown, but there are several known risk factors and ways to drastically reduce the chance of this happening. In 1994 the US National Institutes of Health launched the “Safe to sleep” public information campaign which encourages safe sleeping practices. This campaign resulted in a decline of more than 50% in SIDS cases in US. Most of the recommendations from health agencies world-wide are based on it.

How common is SIDS

To start with the conclusion: Sudden Infant Death Syndrome (SIDS) is uncommon, following safe sleep guidelines makes it even less common.

In 2022, the risk of being affected by SIDS in the US was 0.042% (42 cases per 100,000 live births).
In Europe the data from 2011 to 2018 shows a probability of 0.015% (0.15 cases per 1000 live births).

To be precise:
Any sudden unexpected infant death (SUID) can be attributed to either SIDS or to suffocation in bed. Since determining the exact cause of death is often impossible a significant proportion of sleep-related suffocation cases caused by unsafe sleep practices end up classified as SIDS. This explains how causes of SIDS are fundamentally unknown, yet the danger can still be heavily mitigated by adhering to safe sleep guidelines.
CDC SUID rates in US 1990-2024
CDC report SUID 2020-2024

To further highlight the importance of adhering to safe sleep guidelines:

Infants who were not placed to sleep supine [on their back] had nearly 2 times the odds of sleep-related suffocation … The use of soft bedding was associated with a 16-fold increase in odds of explained suffocation (aOR = 16.3, 95% CI: 5.0–53.3) and 5-fold increase in unexplained infant death, compared with no soft bedding use (aOR = 5.0, 95% CI: 3.2–8.0). Infants who were not placed to sleep in a crib, bassinet, or portable crib had 4 times the odds of explained suffocation death compared with infants who slept on an approved sleep surface. PMC9942004

SIDS risk by month

Babies between 0 and 4 months of age have the highest risk of SIDS/SUID. In US during 2011-2013 between 76% and 86% of SUID cases occurred from 0 to 4 months of age. 90% of all cases occurred before the 6-month, and becomes uncommon after 8 months.

With regard to SIDS specifically, 90% of cases occur before an infant reaches the age of 6 months. SIDS peaks between 1 and 4 months of age and is uncommon after 8 months of age Pediatrics (2022) 150; DOI 10.1542/peds.2022-057991

NOTE: The term “SIDS” applies only to infants younger than 1 year of age. As your child grows older they become more resilient to dangers like positional asphyxiation, but they still can get entrapped in the bedding structure or loose bedding. PMID: 10520608

Even after one year of age you should assess the risks whenever changing the sleeping arrangements.

How to prevent SIDS

The best way to reduce the risk of SIDS is creating a safe sleep environment for your baby. SUID/SIDS is rare, following safe sleep practices significantly lowers the risk even further by a large amount.

Below is a detailed overview of safe sleep practices, complete with supporting evidence and citations from various research papers. For a lengthier more technical review see: Updated 2022 Recommendations for Reducing Infant Deaths in the Sleep Environment published in Pediatrics (Vol. 150 e2022057990)

Place baby on their back for sleep

Young babies can not roll or reposition by themselves. Placing them on their back (supine position) ensures their airways are straight and the parent does not accidentally obstruct their breathing when putting them down. Additionally, the supine position minimises the risk of rebreathing previously exhaled air that is depleted of oxygen.

Once a baby gains the ability to roll on their front (3-6 months) they might choose to sleep on their front, you don’t need to re-set them to their backs. If the baby got into a position by themselves they should be able to move away from it if they need to as long as they are not swaddled.

• The above applies for all sleep times including naps.
• Insist that all caretakers put the baby to sleep in the supine position.
• A swaddled baby should never be put sleep on their front. See the chapter about common swaddling mistakes.

Use a firm flat mattress

When the mattress is to soft the baby’s face can sink into it and cause rebreathing of oxygen depleted air.

Fortunately the majority of developed countries heavily regulate baby sleeping surfaces. For example in the EU the EN 16890:2017+A1:2021 requirement for “Mattresses for cots and cribs” amongst other hazards, specifically tests the mattress hardness. It is illegal to sell baby sleep products on European markets without passing this certification.

• For cots or bassinets brought in developed countries, regulations exist that ensure the mattress is both firm and breathable enough to be safe.
• Avoid antique or DYI mattresses and baby sleeping surfaces. These did not pass any regulatory testing and also might use prohibited/dangerous materials like formaldehyde or led paint.
• In case you need to check if a mattress is firm enough for a baby the following testing methodology was published in the Australian and New Zealand Journal of Public Health.
• Infant car seats and similar baby containers are not designed for unsupervised sleep.

Do not bed share

There is no such thing as safe cosleeping.

54% of infants in the SUID Case Registry were surface sharing at the time of death. Findings from a meta-analysis showed surface sharing was associated with an almost threefold risk of SIDS. Surface sharing is associated with an increased odds for both sleep-related suffocation and unexplained infant death (adjusted odds ratios: 2.5 [95% confidence interval (CI) 1.1–6.0] and 2.1 [95% CI 1.4–3.2] respectively). Pediatrics (2024) 153 (3): e2023061984

Dangers of bed sharing include:

• A sleeping adult can accidentally roll over the baby suffocating them.
• The baby might get tangled on loose bedding, pillows or blankets.
• Risk of baby falling on the floor.
• Adult mattresses (even hard ones) are often too soft for a baby and pose suffocation hazards.

Many people chose cosleeping for the practical advantages it offers, but the research is clear: the safest place for a baby to sleep is in their own bassinet in the same room as you.

I highly recommend buying a “sidecar bassinet” which features a removable side-railing. Installing you next to your bed provides easy access to the baby, delivering the convenience of co-sleeping without any of the risk. Because a bassinet is designed specifically for newborn sleep it provides a firm sleeping surface, removes any risk for entrapment and provides a physical barrier preventing adults from accidentally rolling onto the child.

Sharing the room is recommended, it is both convenient and allow you to check on your baby during the night.

Avoid crib clutter

Keep all soft or loose items out of your baby’s crib. Loose blankets, pillows or plush toys pose a suffocation risk.

Are crib bumpers safe?
Crib bumpers pose the same risks as items mentioned above and their sale became prohibited in the US since 2022.

Simply use a fitted sheet over the mattress and swaddle your newborn in a weather appropriate blanket, that’s it. If you don’t want to swaddle a sleeping bag can be used.

Avoid secondhand smoking

CDC classifies second hand smoking as one of the primary causes of SIDS.

Canada’s health department estimates that 14-16% if all SIDS related deaths could be prevented by eliminating second-hand smoke exposure. Source: Canada’s health department on tobacco and SIDS

Prevent overheating

Young babies have poor temperature regulation, they loose heat quickly but also overheat easily.

You can tell if baby is overheating if they have sweaty back of their neck and their cheeks flush red. In more severe cases their breathing will become more rapid and laboured. Research shows that babies are safer being slightly cooler than being too hot. A baby that is too cold will wake up and their cheeks and chest will be cold to the touch. Do not rely on your baby’s hands or feet to tell if they are too hot or cold. Their developing circulatory system means their extremities will usually feel much cooler than the rest of their body

The ideal temperature range for sleep as per NHS safe sleep guidelines is between 16 and 20 degrees Celsius.

Babies should never sleep in next to a radiator, in direct sunlight or any other direct heat source. Hats or head covers should not be used during sleep.

Pacifier use is encouraged

While the exact mechanisms are not yet clear, several meta-studies from 1993 onwards show between 30% and 50% SIDS risk reduction attributed to pacifier use at the onset of sleep. Source: Investigation-of-sudden-infant-death-syndrome The American Academy of Pediatrics safe sleep guidelines advise using a pacifier at the start of sleep; You do not need to reinsert the pacifier if it drops out after your baby falls asleep.

Note that an early introduction of a pacifier can have negative effects on breastfeeding. See the chapter about how pacifiers can influence breastfeeding

Breastfeeding

Human milk has a protective effect against SIDS.

A meta-analysis conducted by Hauck et al. (published in Pediatrics) shows that babies who are breastfed for any amount or duration have a reduced risk of SIDS by roughly 50%. The protective effects increase for exclusively breastfed infants who have up to a 73% reduction in risk.

Breastfeeding is protective against SIDS, and this effect is stronger when breastfeeding is exclusive. The recommendation to breastfeed infants should be included with other SIDS risk-reduction messages to both reduce the risk of SIDS and promote breastfeeding for its many other infant and maternal health benefits. Pediatrics 2011 Jul; DOI: 10.1542/peds.2010-3000

Do not use baby containers for sleep.

A baby container is any piece of baby equipment that holds an infant in a fixed position or at an angle. Typical example are infant loungers, baby nests, pods etc. Several products in this category will feature in their marketing material a sleeping baby or advertise themselves as a sleeping device. Some of them even go as far as to claim they reduce the risk of SIDS when in fact it is the opposite.

Highlighting this point, Health Canada issued an urgent recall for several baby nest products in this category specifically because they pose a severe entrapment hazard risk of entrapment. A crib, cradle, or bassinet are the only safe environments for an infant’s unsupervised sleep as they feature a firm flat sleeping surface and stiff upright sides.

Infant car seats also fall into the category of baby containers, see our chapter dedicated to car seat sleep safety.

Annex: SIDS and predatory advertising:

SIDS is very scary (I am reliving the stress even when writing about it) and there are actors trying to capitalize on your fears.

I remember receiving many ads for gadgets that claim to prevent it: oxygen monitors, inclined sleepers, smart baby monitors with breathe rate detection and all other kinds of similar snake oil. These will be advertised as “the definitive preventative measure”, but when inspecting the fine-print you are guaranteed to see keywords like “for comfort” or “fitness tracker” or “not a medical device”.

None of these passed any sort of certification. The ads can claim anything but if something is legally classified as and “infant lounger” (as is the case for the baby nests) it can skip all the testing that is legally required for baby sleep products.

At best, they do nothing, at worst they are actually putting your newborn in danger. For example did you know that oximeters can cause skin burn if not used correctly?

There are currently no commercially available products that can prevent SIDS.

There are of course medical cases where special monitoring products are needed, but in this situation an actual medical professional will tell you exactly what to use, where to rent it and how to use it correctly.