Sudden infant death syndrome (SIDS) is the leading cause of death for babies between 1 month and 1 year old. SIDS isn’t any one illness or disease. Rather, it’s the diagnosis given when a child under a year old dies suddenly and an exact cause can’t be found after a death scene investigation, an autopsy, and a review of the child’s medical history. That it can happen without warning makes SIDS particularly devastating for families.


While SIDS can occur outside of cribs, it’s also known as crib death because it happens most often during sleep, usually between the hours of 10 at night and 10 in the morning.

What causes SIDS?

Most experts believe that SIDS occurs when a baby has an underlying vulnerability (such as immature or abnormal functioning of the heart, breathing, or arousal) and is exposed to certain stressors (such as sleeping tummy-down or on soft bedding) during a critical period of development.

The researchers found that infants who died from SIDS had lower than normal levels of serotonin in the brainstem. Serotonin helps regulate breathing, heart rate, and blood pressure during sleep.

There’s no guaranteed way to prevent SIDS, but you can greatly reduce the risk by following these recommendations for safe sleeping.

  • Put your baby to sleep on her back.
  • Make sure that every caregiver, including relatives and babysitters, knows to place your baby on her back to sleep during the first year of her life.
  • Of course, by the time your baby is 5 or 6 months old, she may be able toroll over onto her tummy by herself. By this age, her risk for SIDS has started to drop, though, so do your best to get her settled on her back and then don’t worry if she rolls over. Just make sure there’s nothing soft in her crib that she could get her face next to that would increase the risk of SIDS or suffocation.
  • One problem with putting your baby on her back so much is that she may develop a flat spot on the back or side of her head. This is calledpositional plagiocephaly. You can help prevent “flat head syndrome” by having your baby spend some supervised time on her tummy each day while she’s awake.
  • Choose bedding carefully.
  • Put your baby to sleep on a firm, flat mattress with no pillow or toys and nothing but a fitted sheet under him.
  • Don’t use products claiming to reduce the risk of SIDS, such as sleep positioners, wedges, or special mattresses. There’s no evidence that these work or that they’re even safe.
  • Finally, don’t let your baby sleep for extended periods in a car seat, stroller, swing, bouncy seat, infant carrier, or sling. This is particularly important for babies under 4 months because they can suffocate if their head rolls forward too much. If your baby falls asleep in one of these devices, transfer him to a crib or play yard as soon as is practical. When your baby is in an infant carrier or sling, make sure his nose and mouth are clear and not pressed against your body or the fabric.
  • Sleep in the same room as your baby.
  • Avoid overheating your baby.
  • Don’t cover your baby’s face or head with hats or hoods.
  • Get regular prenatal care.
  • Don’t smoke, drink alcohol, or use illegal drugs during pregnancy.
  • Keep your baby away from cigarette smoke.
  • Make sure your baby gets all his vaccinations.
  • Breastfeed if you can.
  • Offer your baby a pacifier when you put him down to sleep.

Some researchers suggest that swaddling – the practice of wrapping a baby securely in a blanket or cloth, may help prevent SIDS because it can help a baby sleep more soundly on his back. If your baby startles while he’s sleeping, his own body movements can wake him up. Swaddling can limit those movements and help a young baby feel more secure.

If you do swaddle your baby, use a thin blanket and make sure the room isn’t too warm. And, of course, never put your baby on his tummy when he’s swaddled.