Sudden infant death syndrome (SIDS) is the unexpected, unexplained death of a seemingly healthy baby less than one year old. SIDS is sometimes known as crib death because the infants often die in their cribs.
SIDS is the leading cause of death in babies between 1 month and 1 year old. Most SIDS deaths occur when babies are between 1 month and 4 months old.
While the cause is unknown, studies have identified several factors that may increase a baby’s risk of SIDS. The single most significant risk factor is sleeping position. Babies who are placed to sleep on their stomachs are much more likely to die of SIDS compared to babies placed on their backs.
What is SIDS?
SIDS refers to the sudden and unexplained death of an infant younger than one year old that does not have a known cause even after a complete investigation. This includes a thorough autopsy, examination of the death scene, and a review of the clinical history.
Some key facts about SIDS:
– SIDS is the leading cause of death among infants 1 month to 1 year old.
– Most SIDS deaths occur when babies are between 1 and 4 months old.
– SIDS is rare after a baby reaches 6 months old.
– SIDS is more common in boys than girls.
– SIDS deaths occur quickly and silently, usually during sleep.
– SIDS is sometimes called crib death or cot death because many babies who die of SIDS are found in their cribs.
The cause of SIDS is unknown. Researchers believe SIDS may be associated with defects in the parts of an infant’s brain that control breathing and waking during sleep. But more research is needed.
What are the risk factors for SIDS?
While the cause is unknown, several factors have been identified that increase the risk of SIDS. The main risk factors include:
Sleeping position
The single most significant risk factor for SIDS is sleeping position. Babies who are placed to sleep on their stomachs are much more likely to die of SIDS compared to babies placed on their backs.
Specifically, stomach sleeping increases the risk of SIDS by 2 to 13 times compared to back sleeping. Side sleeping also doubles the risk compared to back sleeping.
The increased risk associated with stomach sleeping may be due to several factors:
– Stomach sleeping can increase the chance of rebreathing exhaled air, which builds up carbon dioxide around the baby.
– Stomach sleeping can increase the risk of overheating.
– Stomach sleeping makes it more difficult for a baby to lose heat through dissipation.
– Stomach sleeping may create more pressure on a baby’s jaw, which can cause airway obstruction.
For these reasons, experts universally recommend back sleeping as the safest sleep position to reduce the risk of SIDS.
Bed sharing
Babies who share a bed with parents, siblings or anyone else are at higher risk for SIDS. Bed sharing increases the risk of SIDS by up to 5 times, especially when the baby is younger than 4 months old.
The increased risk may occur because the baby can become overheated, get into a position that compromises breathing, or rebreathe exhaled air in the shared bedding. Parents might also accidentally roll onto or overlay the baby while sleeping.
For these reasons, the American Academy of Pediatrics recommends room sharing without bed sharing. Room sharing means the baby sleeps in the same room as the parents but has a separate approved sleep surface designed for infants, like a crib or bassinet.
Soft bedding
Using soft bedding in a baby’s sleep area is linked to an increased risk of SIDS. This includes items such as blankets, bumper pads, pillows, quilts, sheepskins and stuffed toys.
These soft surfaces can increase SIDS risk by causing overheating or covering the baby’s face. If items are placed near the baby’s face, the baby may rebreath exhaled carbon dioxide. Soft bedding may also cause accidental suffocation.
The safest sleep environment for a baby is a firm sleep surface without any loose bedding. A fitted sheet on a safety-approved crib mattress is recommended.
Maternal smoking
Babies born to mothers who smoked during or after pregnancy are at higher risk for SIDS.
Maternal smoking before and after birth is associated with a 2 to 5 fold increase in SIDS risk. The more a mother smokes, the higher the risk. The risk is significantly higher if the mother smoked during pregnancy.
Secondhand smoke exposure also increases SIDS risk. Infants who are around smokers have up to a 6 times higher risk of SIDS compared to babies not exposed to secondhand smoke.
Smoking may contribute to SIDS by impairing fetal development, especially the development of the brainstem which controls cardiorespiratory functions during sleep. Smoking also increases respiratory infections and may cause physical changes that make SIDS more likely.
Unsafe sleep environments
In addition to soft bedding, other sleep environment factors associated with increased SIDS risk include:
– Covering the baby’s head or face during sleep
– Letting the baby get too hot during sleep
– Having loose bedding, bumpers or other objects in the crib
– Sleeping on couches, armchairs or other soft surfaces
– Bed sharing with anyone who smokes, is impaired by drugs/alcohol, or is extremely tired
Creating a safe sleep environment by following guidelines can help reduce the risk of SIDS. Recommendations include placing the baby alone on his/her back in a crib without any loose bedding or other objects.
How common is SIDS?
SIDS is the leading cause of death among infants 1 month to 1 year old. In the United States, there are about 3,500 SIDS deaths each year. The SIDS rate has declined significantly over the past few decades:
| Time period | SIDS rate* |
|---|---|
| 1990-1994 | 1.2 per 1,000 live births |
| 1995-1998 | 0.8 per 1,000 live births |
| 1999-2001 | 0.6 per 1,000 live births |
| 2004-2006 | 0.5 per 1,000 live births |
*SIDS rate is measured by the number of SIDS deaths for every 1,000 live births
The decline in SIDS rates coincides with recommendations starting in 1994 to place babies on their backs for sleep. Before this change, most babies were placed to sleep on their stomachs.
However, SIDS rates have plateaued in recent years. And significant racial disparities persist, with SIDS rates remaining higher among some racial/ethnic groups including American Indians and Alaska Natives. This highlights the need for increased awareness around safe sleep practices.
Can SIDS be prevented?
There is no way to completely prevent SIDS because the exact causes are unknown. However, parents and caregivers can significantly reduce the risk of SIDS by creating a safe sleep environment and following recommended practices.
The American Academy of Pediatrics suggests the following guidelines to help prevent SIDS:
Always place baby on his/her back to sleep
The single most important way to reduce the risk of SIDS is to always place the baby on his or her back for naps and at nighttime. Stomach or side sleeping increases the risk.
Use a firm sleep surface
The baby should sleep on a firm, flat sleep surface covered by a fitted sheet. Do not use pillows, blankets, sheepskins or crib bumpers anywhere in the sleep area.
Room sharing is recommended
Share a room, but not the same sleeping surface. The baby should sleep in the parents’ room close to the parents’ bed in a separate approved sleep surface (crib, bassinet, etc.) for at least the first 6 months.
Keep soft objects away
Keep soft objects, toys and loose bedding out of the baby’s sleep area. Don’t use pillows, blankets, quilts, sheepskins and crib bumpers. Also avoid letting the baby’s head become covered by bedding.
Consider a pacifier at nap time and bedtime
Pacifiers may reduce the risk of SIDS, especially when used at nap time and bedtime. Don’t force the baby to take a pacifier though. If you’re breastfeeding, introduce pacifiers after 1 month old to ensure breastfeeding is well-established.
Avoid smoke exposure
Do not allow smoking around your baby. Don’t smoke during pregnancy or after birth. Eliminate secondhand smoke from caregivers, family and others around the infant.
Avoid letting baby overheat
Dress the baby in light sleep clothing and keep the room at a comfortable temperature. Use no more than 1 lightweight blanket.
Regular prenatal and well-baby care
Make sure the baby receives regular well-baby checkups and immunizations. Advice about reducing SIDS risk can be discussed at routine doctor visits.
Following these guidelines has been shown to significantly reduce the risk of SIDS. The most important way parents and caregivers can protect their baby is to always place them on their back to sleep – for naps and at nighttime.
Conclusion
SIDS is the unexpected, unexplained death of a seemingly healthy baby less than one year old. The exact cause is unknown, but research has identified several risk factors.
The single most significant risk factor for SIDS is stomach sleeping. Babies who are placed on their stomachs to sleep have a much higher risk of SIDS compared to babies placed on their backs. Back sleeping reduces the risk of SIDS by over 50%.
Other ways to lower the risk include avoiding bed sharing and soft bedding, preventing overheating, using a pacifier, avoiding smoke exposure and getting regular medical care. Following safe sleep guidelines can help prevent these tragic infant deaths. The most crucial step parents and caregivers can take is to always place babies on their backs to sleep.