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. SIDS is sometimes called crib death. This is because the death may happen when the baby is sleeping in a crib. SIDS is one of the leading causes of death in babies from ages 1 month to 1 year. It happens most often between 2 and 4 months old. SIDS and other types of sleep-related infant deaths have similar risk factors.

What causes SIDS?

Researchers don't know the exact cause of SIDS. Studies have shown that some babies who die from SIDS have the following:

  • Problems with brain functioning. Some babies have problems with the part of the brain that helps control breathing and waking during sleep. Babies born with problems in other parts of the brain or body may also be more likely to die from SIDS.

  • Differences in genes. Some genes and the environment may work together to increase the risk for SIDS.

  • Problems with heart functioning. Some studies found a link between heart function and SIDS.

  • Infection. Some babies who die from SIDS have respiratory infections before death. SIDS happens more often during the colder months, when respiratory illnesses are more common.

Who is at risk for SIDS?

Most babies who die from SIDS and other sleep-related deaths have one or more risk factors. Some risk factors can be prevented. There are many risk factors for SIDS. They may include the following:

Risk factors for the mother

  • Being a young mother

  • Smoking during pregnancy

  • Late or no prenatal care

  • Not breastfeeding

  • Using alcohol or illegal drugs

Risk factors for the baby and the environment

  • Preterm birth

  • Low birth weight

  • Sleeping on the belly

  • Not breastfeeding

  • Not getting routine childhood shots (immunizations)

  • Being around cigarette smoke

  • Sleeping on a soft surface

  • Sleeping with loose blankets, pillows, or other objects

  • Sharing a bed with parents or siblings, especially in places where there is alcohol or drug use

  • Being too warm or overbundled

What are the symptoms of SIDS?

There are no symptoms or warning signs of SIDS that can be used to prevent it.

How is SIDS diagnosed?

The diagnosis of SIDS is made when the cause of death is unexplained after a full investigation. An investigation includes:

  • Examining the body after death

  • Examining where the death took place

  • Reviewing the baby’s symptoms or illnesses before death

  • Any other related health history

How is SIDS treated?

There is no specific treatment for SIDS.

Can SIDS be prevented?

There is no way to tell which babies will die from SIDS. But known risk factors for SIDS and other sleep-related deaths can be controlled by:

  • Getting prenatal care. Early and regular prenatal care can help reduce the risk for SIDS. You should also follow a healthy diet and not smoke or use drugs or alcohol while you are pregnant. These things may reduce the chance of having a premature or low-birth-weight baby. Premature or low-birth-weight babies are at higher risk for SIDS.

  • Putting babies on their back for sleep and naps.  Babies should be placed on their back for all sleeping until they are 1 year old. Don't lay your baby down on their side or belly for sleep or naps.

  • Not using sitting devices for routine sleep. Infant seats, car seats, strollers, infant carriers, and infant swings are not advised for routine sleep. These may lead to blockage of a baby's airway or suffocation. If your baby is in a sitting device, remove them from the device and put them in the crib or other appropriate flat surface as soon as is safe and practical.

  • Putting babies in other positions while they are awake.  Putting your baby in other positions helps your baby grow stronger. It also helps prevent your baby from having a misshaped head. When your baby is awake, hold your baby. Give your baby time on their tummy while awake and supervised for short periods of time beginning soon after coming home from the hospital. Slowly increase tummy time to at least 15 to 30 minutes each day by 7 weeks old. Try not to let your baby sit in a seat or swing for long periods of time.

  • Using correct bedding. Your baby should sleep on a firm, flat mattress or firm surface with no slant. Cover the mattress with a fitted sheet. Don’t use fluffy blankets or comforters. Don’t let your baby sleep on a waterbed, air mattress, sofa, sheepskin, pillow, or other soft material. Don’t put soft toys, pillows, or bumper pads in the crib.

  • Not overheating. Keep your baby warm but not too warm. The temperature in your baby’s room should feel comfortable to you. Don't overbundle, overdress, or cover a baby's face or head. Don't put a hat on your baby when indoors.

  • Sharing a room. The American Academy of Pediatrics advises that babies sleep close to the parent's bed, but in a separate crib or bassinet for babies. This is advised ideally for the baby's first year. But you should do this at least for the first 6 months.

  • Not sharing a bed. Don't put your baby to sleep in a bed with other children. Don’t put your baby to sleep on a sofa, either alone or with another person. Don't share your bed with your baby, especially if you are using alcohol or other drugs. You can bring your baby to your bed for feedings and comforting. But return your baby to the crib for sleep. Bed sharing is also not advised for twins or other multiples.

  • Not allowing smoking around your baby. The risk of SIDS is higher for babies whose mothers smoked during pregnancy. Don’t smoke when you are pregnant and don’t let anyone smoke around your baby. Babies and young children exposed to smoke have more colds and other diseases. They also have a higher risk for SIDS.

  • Taking your baby for checkups and vaccines.  If your baby seems sick, call your baby’s healthcare provider. Take your baby in for regular well-baby checkups and routine shots. Some studies show that fully vaccinating your child lowers the risk for SIDS. 

  • Breastfeeding your baby. Give your baby only human milk for at least 6 months, unless your healthcare provider tells you otherwise. This means no water, sugar water, juice, or formula, unless your baby’s healthcare provider tells you to do so. Experts advise continuing to use human milk for feed for 1 year or longer. This depends on if both you and your baby want to do this. Using human milk for a year or longer reduces the risk for SIDS and many other health problems.

  • Thinking aboutgiving your baby a pacifier during sleep time. You may give your baby a pacifier during routine sleep and nap time once breastfeeding is well-established. This is often after the first few weeks. But don’t hang pacifiers around your baby's neck. Don’t attach pacifiers to your baby’s clothing, stuffed toys, or other objects.

  • Not using positioning devices and home cardiorespiratory monitors. Don't use wedges, positioners, or special mattresses to help decrease the risk for SIDS and sleep-related infant death. These devices have not been shown to prevent SIDS. In rare cases, they have resulted in infant death. Cardiorespiratory monitors sold for home use are also not helpful in preventing SIDS.

  • Always placing cribs, bassinets, and play yards in hazard-free areas. Be sure there are no hanging cords, wires, or window curtains nearby. This reduces the risk for strangulation.

When should I call my child’s healthcare provider?

If you or someone else in your home smokes, talk with your healthcare provider about quitting. If you have any questions or concerns about SIDS risk factors, talk with your baby’s healthcare provider.

Key points about SIDS

  • Sudden infant death syndrome (SIDS) is the sudden and unexplained death of a baby younger than age 1. It is most common between 2 and 4 months old.

  • Researchers don't know the exact causes of SIDS.

  • There is no way to tell which babies will die from SIDS.

  • Most babies who die of SIDS have 1 or more risk factors.

  • There are many possible risk factors for the baby. These include being around cigarette smoke, sleeping on a soft surface, or co-sleeping with parents or siblings.

Next steps

  • To lower the risk for SIDS, get regular prenatal care and breastfeed your baby. Don't smoke during pregnancy.

  • To lower the risk for SIDS and other sleep-related deaths, your baby should sleep and take naps on his or her back. 

  • Your baby should sleep in the same room with you for at least the first 6 months. Ideally, it should be for the first year. Place the baby close to your bed, but in a separate bed or crib for infants.

Online Medical Reviewer: Donna Freeborn PhD CNM FNP
Online Medical Reviewer: Kimberly Lee MD
Online Medical Reviewer: Stacey Wojcik MBA BSN RN
Date Last Reviewed: 8/1/2022
© 2000-2024 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.