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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 facedown on their stomachs or on their sides. Sleeping on the stomach or side increases the risk for SIDS.

Who Is at Risk for SIDS?

When considering which babies could be most at risk, no single thing is likely to cause a SIDS death. Rather, several risk factors might combine to cause an at-risk infant to die of SIDS.

Most SIDS deaths happen in babies 2 to 4 months old, and cases rise during cold weather. Black and Native American infants are more likely to die of SIDS than Caucasian infants. More boys than girls fall victim to SIDS.

Other possible risks include:

Doctors diagnose most health problems based on the symptoms they cause. But most SIDS diagnoses come only 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 cardiac or metabolic disorders.

Why Is Stomach Sleeping Dangerous?

SIDS is more likely among babies placed on their stomachs to sleep than among those 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 and hurt breathing. Stomach sleeping can increase "rebreathing" — when a baby breathes in his or her own exhaled air — particularly if the infant is sleeping on a soft mattress or with bedding, stuffed toys, or a pillow near the 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 continue to fall.

What Is "Back to Sleep"?

In response to evidence that stomach sleeping might contribute to SIDS, the American Academy of Pediatrics (AAP) created its "Back to Sleep" campaign, which recommended that all healthy infants younger than 1 year of age 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. There's no need to 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 is easily treatable by changing a baby's position in the crib and allowing for more supervised "tummy time" while he or she is awake.

Many parents fear that babies put to sleep on their backs could choke on spit-up or vomit. However, only babies with certain uncommon upper airway malformations may need to sleep on their stomachs. There's no increased risk of choking for healthy infants and most infants with gastroesophageal reflux (GER) who sleep on their backs.

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, SIDS remains the leading cause of death in young infants. The "Safe to Sleep" campaign builds on "Back to Sleep," reminding 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 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.
  • Put your baby to sleep with a pacifier during the first year of life. If your baby rejects the pacifier, 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.
  • Make sure your baby does not get too warm while sleeping. Dress your infant for the room temperature, and don't overbundle. 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. Parents who drink or use drugs should not share a bed with their infant.
  • Make sure your baby gets all recommended immunizations. Studies have shown that babies who receive their vaccines have a 50% 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.

Date reviewed: February 2017

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Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor.

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