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Sudden Infant Death Syndrome (SIDS)

What Is SIDS?

Sudden infant death syndrome (SIDS) is the sudden and unexplained death of a baby younger than 1 year old. Most SIDS deaths are associated with sleep, which is why it's sometimes still called "crib death."

Can SIDS Be Prevented?

A lack of answers is part of what makes SIDS so frightening. SIDS is the leading cause of death among infants 1 month to 1 year old, and remains unpredictable despite years of research.

Even so, the risk of SIDS can be greatly reduced. Most important: Babies younger than 1 year old should be placed on their backs to sleep — never on their stomachs or on their sides. Sleeping on the stomach or side increases the risk for SIDS.

Who Is at Risk for SIDS?

Most SIDS deaths happen in babies between 1 and 4 months old, and cases rise during cold weather.

Babies might have a higher risk of SIDS if:

  • their mother smoked, drank, or used drugs during pregnancy and after birth
  • their mother had poor prenatal care
  • they were born prematurely or at a low birth weight
  • there's a family history of SIDS
  • their mothers were younger than 20 when they gave birth
  • they are around tobacco smoke after birth
  • they get overheated
  • they sleep on a soft surface
  • they sleep with soft objects or loose blankets and pillows
  • they sleep in a parent’s bed

Doctors diagnose most health problems based on the symptoms they cause. But SIDS is diagnosed after all other possible causes of death have been ruled out. This review helps tell true SIDS deaths from those due to accidents, abuse, and previously undiagnosed conditions, such as heart problems.

Why Is Stomach Sleeping Dangerous?

SIDS is more likely in babies placed on their stomachs to sleep than babies sleeping on their backs. Babies also should not be placed on their sides to sleep. A baby can easily roll from a side position onto the belly during sleep.

Some researchers believe that stomach sleeping may block the airway. Stomach sleeping can increase "rebreathing" — when babies breathe in their own exhaled air — particularly if the baby is sleeping on a soft mattress or with bedding, stuffed toys, or a pillow near their face. As the baby rebreathes exhaled air, the oxygen level in the body drops and the level of carbon dioxide rises.

Infants who die from SIDS may have a problem with the part of the brain that helps control breathing and waking during sleep. If a baby is breathing stale air and not getting enough oxygen, the brain usually triggers the baby to wake up and cry to get more oxygen. If the brain is not picking up this signal, oxygen levels will fall and carbon dioxide levels will rise.

In response, the AAP's (American Academy of Pediatrics) "Back to Sleep" campaign recommended that all healthy infants younger than 1 year old be placed on their backs to sleep.

Babies should be placed on their backs until 12 months of age. Older infants may not stay on their backs all night long, and that's OK. Once babies consistently roll over from front to back and back to front, it's fine for them to be in the sleep position they choose. Do not use positioners, wedges, and other devices that claim to reduce the risk of SIDS.

Common Concerns

Some parents might worry about "flat head syndrome" (positional plagiocephaly). This is when babies develop a flat spot on the back of their heads from spending too much time lying on their backs. Since the "Back to Sleep" campaign, this has become more common. But it's easily treatable by changing a baby's position in the crib and allowing for more supervised "tummy time" while babies are awake.

Some parents may worry that babies put to sleep on their backs could choke on spit-up or vomit. There's no increased risk of choking for healthy infants or most babies with gastroesophageal reflux (GER) who sleep on their backs. Doctors may recommend that babies with some types of rare airway problems sleep on their stomachs.

Parents should talk to their child's doctor if they have questions about the best sleeping position for their baby.

What Is "Safe to Sleep"?

Since the AAP's recommendation, the rate of SIDS has dropped greatly. Still, it is the leading cause of death in young infants. The Safe Sleep campaign reminds parents and caregivers to put infants to sleep on their backs and provide a safe sleep environment.

Here's how parents can help reduce the risk of SIDS and other sleep-related deaths:

  • Get early and regular prenatal care.
  • Place your baby on a firm, flat mattress to sleep, never on a pillow, waterbed, sheepskin, couch, chair, or other soft surface.
  • Cover the mattress with a fitted sheet and no other bedding. Keep soft objects and loose bedding out of the sleep area.
  • Do not use bumper pads in cribs. Bumper pads can be a suffocation or strangulation hazard.
  • Practice room-sharing without bed-sharing. Experts recommend that infants sleep in their parents' room — but on a separate surface, like a bassinet or crib next to the bed — until the child's first birthday, or for at least 6 months, when the risk of SIDS is highest.
  • Breastfeed, if possible. Exclusive breastfeeding or feeding with expressed milk is most protective, but any breastfeeding has been shown to reduce the risk of SIDS.
  • Offer a pacifier to your baby at sleep time, but don’t force it. If the pacifier falls out during sleep, you don’t have to replace it. If you're breastfeeding, wait until breastfeeding is firmly established.
  • To avoid overheating, dress your baby for the room temperature and don't overbundle. Don't cover your baby's head while they're sleeping. Watch for signs of overheating, such as sweating or feeling hot to the touch.
  • Don't smoke during pregnancy or after birth. Infants of moms who smoked during pregnancy are more at risk for SIDS than those whose mothers were smoke-free; exposure to secondhand smoke also raises a baby's risk, and that risk is very high if a parent who smokes shares the bed with a baby.
  • Do not use alcohol or drugs during pregnancy or after birth.
  • Don’t let your baby fall asleep on a product that isn’t specifically designed for sleeping babies, such as a sitting device (like a car seat), a feeding pillow (like the Boppy pillow), or an infant lounger (like the Dock-a-Tot, Podster, and Bummzie).
  • Don’t use products or devices that claim to lower the risk of SIDS, such as sleep positioners (like wedges or incliners) or monitors that can detect a baby’s heart rate and breathing pattern. No known products can actually do this.
  • Don’t use weighted blankets, sleepers, or swaddles on or around your baby.
  • Make sure that all sleep surfaces and products you use to help your baby sleep have been approved by the U.S. Consumer Product Safety Commission (CPSC) and meet federal safety standards.
  • Make sure your baby gets all recommended immunizations. Studies have shown that babies who receive their vaccines have a lower risk of SIDS.

For parents and families who have experienced a SIDS death, many groups, including First Candle, can provide grief counseling, support, and referrals.

Reviewed by: Elana Pearl Ben-Joseph, MD
Date Reviewed: Jul 1, 2022

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