Sudden Infant Death Syndrome

Right after a baby is born, parents hear from the nurse, “place your baby on her or his back to prevent SIDS”.

What is SIDS?

Sudden Infant Death Syndrome (SIDS) is the sudden and unexplained death of a baby younger than 1-year-old. Most cases occur when the infant is supposed to be sleeping, which is why the phrase “crib death” is also used.

SIDS is the leading cause of death among infants 1 month to 1 year of age. Most SIDS deaths occur between 1 and 4 months of age. According to the CDC, there are about 3,400 cases of SIDS per year in the United States. SIDS is diagnosed after all other possible causes are ruled out.

Sudden infant death syndrome (SIDS) is the leading cause of death in infants between 1 month and 1 year of age.

Decreasing the risk of SIDS

SIDS occurs more often in infants placed on their stomachs to sleep than in those placed on their backs. An infant should not be placed on their side to sleep because they can easily roll onto their stomach.

Researchers believe this position of sleeping on the stomach may increase “rebreathing”. As infants breathe in exhaled air, the level of oxygen decreases, and the level of carbon dioxide increases. Normally, if a baby is rebreathing exhaled air and not getting enough oxygen, the brain will signal them to wake up and cry to get more oxygen. Babies who die from SIDS may have a problem with this part of the brain that controls breathing and waking during sleep. Placing an infant to sleep on their back allows exhaled air to leave the area around the face so that fresh oxygen is available.

Anatomy of trachea and esophagus contrasted in baby sleeping back position and baby sleeping in stomach position

Image courtesy of the Safe to Sleep® campaign, for educational purposes only; Eunice Kennedy Shriver National Institute of Child Health and Human Development,; Safe to Sleep® is a registered trademark of the U.S. Department of Health and Human Services.

All healthy infants younger than 1-year-old should be placed on their backs to sleep. Older infants might move themselves and not stay on their back all night. Once an infant can consistently roll from back to front and front to back, it’s fine to let them sleep in any position they choose. Continue placing them on their back when you lay them down, but you do not need to reposition them if they move themselves.

Also, be sure they are not on a soft mattress and do not sleep with soft objects or loose blankets and pillows.

Safe sleep guidelines

Even though medical professionals don’t know the exact cause of SIDS, research shows there are effective ways you can reduce the risk, such as selecting a safe crib and creating a safe sleeping environment for your baby.

How to choose a safe crib

  • Bars should be spaced no more than 2 3/8 inches or less apart.
  • Do not use decorative cutouts for headboards and footboards. Corner posts that could cause injury or snag clothes need to be removed.
  • Do not use a crib with drop rails.
  • The top of the crib rail should be at least 26 inches from the top of the mattress. It’s important to remember to lower the mattress as your child gets taller. Once your child is almost 3 feet tall then it is time to change to a bed, or a mattress on the floor if you are worried your child will fall out of bed.
  • Make sure the mattress is very firm and fits snugly with no space between it and the rails/walls of the crib.
  • Place the crib away from windows and radiator/heat elements. Be sure the crib is not near strings from blinds or curtains.

What does a safe sleep environment look like?

Always place your baby on his or her back to sleep, for naps and at night. They should also sleep in the same room as you, but not in the same bed (room-sharing without bed sharing). Do not allow your baby to sleep in an adult or child bed, couch, or on a chair alone, with you or anyone else. Room-sharing is recommended until your baby is at least 6 months old, but ideally until they are 12 months old.

Example of a safe sleep environment with infant on back on firm, flat surface with no crib bumpers, blankets, pillows, or toys

Image courtesy of the Safe to Sleep® campaign, for educational purposes only; Eunice Kennedy Shriver National Institute of Child Health and Human Development,; Safe to Sleep® is a registered trademark of the U.S. Department of Health and Human Services.

  • Use a firm mattress with a safety-approved crib, covered by a fitted sheet.
  • Do not use blankets, pillows, sheepskin, or crib bumpers in the crib. Remove all soft objects, toys, and loose bedding from the crib.
  • Do not use mobiles as they may fall and become a potential cause of strangulation.
  • Do not allow your baby to get too hot; dress him or her in sleep clothing such as a one-piece sleeper or sleeper sack. Do not use a blanket. Keep the room temperature at a level that is comfortable for an adult.
  • Use all flame-retardant fabrics (sleepwear, sheets, and curtains) for the baby’s room.
  • Do not smoke or let anyone else smoke around your baby.

Further recommendations

  • Do not use home monitors or commercial devices marketed to reduce the risk of SIDS.
  • Supervised, awake tummy time is recommended daily to facilitate development and minimize the occurrence of positional plagiocephaly (flat head).
  • Infants should receive all recommended vaccinations.
Categories: Infants, Safety, Sleep
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