Sudden infant death syndrome (SIDS) is the sudden and unexplained death of a seemingly healthy baby under 1 year old. SIDS usually happens during sleep, and occurs without warning, making it particularly devastating. Though you can’t prevent SIDS, you can significantly reduce your baby’s risk by using safe sleep practices for babies. The first step is to always put your baby on their back to sleep in a safe crib, bassinet, or play yard with no loose bedding.

IN THIS ARTICLE

• What is Sudden Infant Death Syndrome (SIDS)? 
• What causes SIDS? 
• How can I reduce the risk of SIDS? 
• SIDS risk by age 

What is Sudden Infant Death Syndrome (SIDS)?

Sudden infant death syndrome (SIDS) is the diagnosis given when a baby under 1 year old dies suddenly and an exact cause can’t be found.

Babies between 2 and 4 months old are most at risk for SIDS, and 90 percent of cases occur in babies under 6 months old.

The number of infant deaths from SIDS has declined by more than half since 1992 – that’s when the Pediatrics recommended putting babies to sleep on their back – but SIDS is still the leading cause of death for babies under 1 year old.

SIDS falls under the broader category of sudden unexpected infant deaths (SUIDs), which typically occur during sleep or in a baby’s sleep area. SUIDs also include deaths from accidental suffocation or strangulation, and from unknown causes.

According to the Centers for Disease Control and Prevention (CDC), there are about 3,400 baby deaths every year from SUIDS. While that number is tragic – and can be terrifying for new parents – it’s important to remember that this is very unlikely to happen to your baby.

And, even though there’s no sure way to prevent SIDS, you can take important steps to reduce your baby’s risk.

What causes SIDS?

Researchers have learned a lot about SIDS, but they still have no definitive answer to what causes it.

Most experts believe that SIDS occurs when a baby has an underlying physical vulnerability (such as immature or abnormal functioning of the heart, breathing, or arousal) and is exposed to certain stressful factors (such as sleeping tummy-down or being dressed too warmly) during a critical period of development.

Recent research suggests that inadequate levels of the brain chemical serotonin may make an infant more vulnerable to SIDS. Experts found that up to 70 percent of babies who died from SIDS had lower than normal levels of serotonin in the brain stem. Serotonin helps regulate breathing, heart rate, and blood pressure during sleep.

Researchers have also identified common risk factors for SIDS, as well as ways to protect your baby.

SIDS risk factors

• Being premature: Babies born early and at a low birth weight are at higher risk.
• Age: Babies younger than 4 months old are at higher risk.
• Sex. Boys are at slightly higher risk than girls.
• Being a twin. Twins have twice the risk of SIDS, which is largely due to the overall lower birth weight of twins.
• Maternal factors: Babies of women who smoked or used drugs or alcohol during pregnancy, had inadequate prenatal care, or were younger than 20 when they gave birth are at higher risk.
• Family history: Babies with a sibling or cousin who died of SIDS are at higher risk.
• Race: The risk of SIDS is highest for infants who are Black, Native American, or Alaskan Native, followed by white. Asian/Pacific Islander and Hispanic infants are at lower risk.
• Secondhand smoke: Babies who live with smokers are at higher risk.

How can I reduce the risk of SIDS?

Follow safe sleep recommendations from the pedtrician to reduce your baby’s risk of SIDS and other types of sleep-related death. It’s also crucial that all of your baby’s caregivers follow these guidelines, including relatives, babysitters, and childcare providers like nannies and daycare staff.

About 15 to 20 percent of SIDS deaths happen in childcare settings. This is a surprisingly high number considering that babies spend less time sleeping at daycare than they do at home. This statistic shows how important it is to make sure that everyone who cares for your child follows safe sleep practices for babies.

To reduce the risk of SIDS:

• Put your baby to sleep on their back. This is one of the most important things you can do to help protect your baby. A baby’s risk of SIDS is two to 13 times higher if they sleep on their tummy instead of their back. When a baby sleeps tummy-down, they’re more likely to overheat, have pauses in breathing and fewer arousals, and rebreathe the air they’ve just exhaled, which contains less oxygen.
• Don’t share a bed with your baby. It’s associated with a higher risk of SIDS and accidental suffocation, strangulation, or entrapment. The pedtricians recommends that your baby sleep in your room, but not in your bed, at night for at least the first six months and ideally for the first year. Put your baby’s crib, bassinet, or play yard in your room, close to your bed. This arrangement may cut the risk of SIDS by as much as half.
• Use a firm, flat sleeping surface. Put your baby to sleep on a firm, flat mattress with only a fitted sheet under them. (It’s okay to put a thin, tight-fitting mattress pad under the sheet to protect against diaper leaks.) If your baby sleeps in a play yard or bassinet, use only the pad that comes with it – no extra cushions or padding. Don’t use crib bumpers or inclined sleepers – both are dangerous for babies and have been banned in the U.S.
• Keep your baby’s sleeping space empty. Don’t let your baby sleep with soft bedding, crib bumpers, loose blankets, stuffed animals, or pillows. They can lead to suffocation, strangulation, or entrapment. If your baby needs another layer for warmth, use a swaddle or sleep sack. Note: Do not use a weighted sleeper, swaddle, or sleep sack – the AAP says these products aren’t safe. And stop swaddling once your baby is close to rolling over, around 2 months old.
• Choose a safe crib, bassinet, or play yard. See our articles on the best bassinets, cribs, and play yards for tips on buying safe products. Also read our tips for childproofing your home to keep your baby’s sleeping environment free of hazards.
• Don’t fall asleep with your baby on a couch, glider, or armchair. These cushioned environments are dangerous for infants because of the increased risk of SIDS or suffocation. Don’t hold or feed your baby on a couch or comfy chair when you’re sleep deprived, because you could easily fall asleep. It’s safer to bring your baby into a bed that’s stripped of bedding, including blankets and pillows.
• Avoid overheating your baby. Dress your baby for sleep in no more than one layer more than an adult would wear to be comfortable in that environment. Watch for signs of overheating such as sweating, damp hair, or a chest that feels hot to the touch. Don’t put your baby to bed wearing an infant hat – this isn’t necessary and can cause overheating.
• Don’t let your baby sleep in a car seat, stroller, swing, or bouncer. This is particularly important for babies under 4 months. Infants can suffocate if they sleep in an inclined position. If your baby falls asleep in one of these products, transfer them to a crib, bassinet, or play yard as soon as possible.
• Keep your baby away from cigarettes and vaping. Studies show that a baby’s risk of SIDS rises with each additional smoker in the household, with the number of cigarettes smoked around them each day, and with the length of exposure to cigarette smoke. The AAP also recommends that anyone living with a baby avoid vaping (which can expose babies to nicotine) as well as marijuana, opioids, alcohol, and illicit drugs.
• Breastfeed if you can. The more and longer you breastfeed, the more protection your baby has against SIDS. A meta-analysis concluded that babies who were breastfed for at least two months cut their risk of SIDS in half, even if the babies weren’t exclusively breastfed. Breastfeeding for longer than two months provided increased protection.
• Make sure your baby gets vaccinated. Evidence suggests that getting all of your baby’s recommended vaccines on schedule may help protect against SIDS.
• Offer your baby a pacifier when it’s time to sleep. Studies show a lower incidence of SIDS among infants who use pacifiers, although experts don’t know whether there’s a direct cause and effect. Because of the correlation, the AAP suggests that you give your baby a pacifier when putting them down for naps and at bedtime for the first year of life – as long as your baby likes it and it’s a safe pacifier that isn’t attached to your baby’s clothing or a stuffed animal.
• Don’t use a home sleep monitor. Heart rate monitors, including wearable monitors, are widely sold – as are other monitors advertised as “safe sleep” products. Some are designed to detect a baby’s movement in the crib and alert you if it stops for a certain amount of time. But according to the paediatrician, there’s no evidence that these products reduce a baby’s risk of SIDS. Plus, they may give caregivers a false sense of security and make them less likely to follow safe sleep guidelines.

SIDS risk by age

After 6 months old, your baby’s risk of SIDS drops significantly. Researchers don’t know why the risk drops when it does, but a baby’s brain development and maturing physical ability probably play a role. During the first six months of life, a baby experiences rapid brain growth and developmental changes that affect sleep patterns, cardiorespiratory control, metabolism, and physical ability.

So when a more mature baby is placed in a sleep environment with pillows or loose bedding, for example, they may be able to lift their head, shift away, or roll over. An older baby can also overcome the risk by waking up and complaining more readily, or by better regulating their breathing.

But 10 percent of SIDS cases happen to babies over 6 months old, and older babies are still at risk for accidental suffocation or strangulation. That’s why experts recommend that you follow safe sleep recommendations until your baby’s first birthday – including placing your baby on their back when you put them down to sleep.

Once your baby is strong enough to roll over, don’t worry about them not staying on their back all night. If your baby rolls onto their side or stomach while sleeping, you don’t have to flip them onto their back. But it is important to stop swaddling once your baby starts trying to roll over or is able to get out of the swaddle. These scenarios can cause your baby to get unsafely bound up in the swaddle, have their face covered, or even suffocate in a face-down position.

Also, stop using a bassinet once your baby is pushing up onto their hands and knees. Once your baby reaches this milestone, they could fall out. Make sure to follow the manufacturer’s recommendation for your bassinet – because they aren’t as deep, heavy, and sturdy as cribs, bassinets are usually only safe to use until your baby is between 4 and 6 months old.

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