Sudden Infant Death Syndrome (SIDS)
Sudden infant death syndrome (SIDS) is the sudden and unexpected death of an infant less than 1 year of age from an unknown cause. SIDS remains unpredictable with an unknown cause despite years of research. Certain factors such as sleeping position and maternal smoking are associated with SIDS.
Learn About SIDS
Sudden Infant Death Syndrome (SIDS) is the sudden and unexpected death of an infant less than 1 year of age from an unknown cause. SIDS is unpredictable and affects seemingly healthy babies.
- SIDS is the leading cause of death between 1 month to 1 year of age
- It remains unpredictable with an unknown cause despite years of research
- The risk can be greatly reduced by avoiding key risk factors such as placing infants on their stomachs or sides for sleep and maternal smoking
How common is SIDS?
SIDS is the leading cause of unexpected deaths in infants in developed countries. In 2010, 2,671 infants in the United States died from SIDS. It is more common in boys than girls. African-American and Native American infants are about three times more likely to die from SIDS than Caucasian infants. It is also more common in premature infants.
When Does it Happen?
It usually occurs during sleep and is thus often referred to as “crib death.” Although SIDS may occur at any time during the first year of life, these events happen most often between 2 and 4 months of age when the infant’s sleep patterns are still developing. SIDS is also more common during the cold weather months. Ninety percent of these deaths occur in infants up to 6 months old.
Why Does SIDS Happen?
Although risk factors have been identified, the precise cause of SIDS is unknown. The risk is greatest when the following three factors are present:
- A vulnerable infant (ie, born premature or exposed to maternal smoking while in the womb).
- During a time of developmental instability such as when sleep patterns are maturing.
- Being placed on the stomach to go to sleep. These infants are thought to have immature breathing reflexes resulting in a failure to awaken from sleep resulting in death.
Usually, more than one of these factors contributes to SIDS.
SIDS Risk Factors
What Are the Risk Factors?
- Sleeping Position: Sleeping on the stomach is a major risk factor for SIDS. Side sleeping is also a risk factor because infants may turn on their stomachs after being placed on their sides. One theory is that stomach sleeping increases the risk of the infant re-breathing his or her own exhaled air. A soft mattress, loose or plush bedding, a stuffed toy, or a pillow can lead to a small pocket of air around the baby’s mouth which traps exhaled air, which is high in carbon dioxide. When the baby breathes the exhaled air back, the carbon dioxide in the blood rises and the oxygen levels fall, possibly contributing to SIDS. Normally, people with rising carbon dioxide and falling oxygen wake up, but infants with SIDS may have an abnormality in the part of the brain that should waken them. Another thought is that sleeping on the stomach puts pressure on the infant’s jaw resulting in narrowing of the airway.
- Smoking during and after pregnancy: Many studies have found that maternal smoking during pregnancy increases the risk of SIDS up to five times. Also paternal smoking and exposure to second hand smoke during infancy have been associated with an increased risk of SIDS as well.
- Prematurity: Prematurity increases the risk of SIDS up to four times as compared to infants born at full term.
- Head covering and bedding: Loose and/or soft bedding such as duvets, quilts, bumper pads, stuffed toys and pillows, should be avoided in infants because they may cover the head of the infant, increase the risk for rebreathing and lead to suffocation.
- Bed sharing: Bed sharing refers to a baby sharing the same sleeping surface as another person. Bed sharing with an adult who may not wake up normally because of extreme fatigue, drugs, or alcohol has been shown to be hazardous for the infant.
- Alcohol and illicit Drugs: There is an increased risk of SIDS with prenatal and postnatal exposure to alcohol or illicit drugs.
SIDS Protective Factors
What Protects Babies From SIDS?
- Back to Sleep: Putting babies to sleep on their backs (ie, supine position) dramatically reduces the likelihood of reduction in SIDS. This led to the American Academy of Pediatrics recommending this in its 1992 “Back to Sleep Campaign” for all healthy infants less than 1 year of age. Since this recommendation, SIDS rates have dropped by more than 50%. Some parents are worried that their baby will develop a flat spot on the back of their heads from lying on their back all the time. This condition is easily treatable by allowing for more “tummy time” while your baby is awake during the day. Many parents are worried that their baby will choke on a spit-up if they are sleeping on their backs, but there is no increased risk of choking for healthy infants who sleep on their backs.
- Breast feeding: Breastfeeding of any duration is associated with a decreased risk of SIDS. The protective effect is strongest with exclusive breast feeding.
- Room sharing: Sleeping in the parental bedroom reduces the risk of SIDS by 50%. It is thought that this is because infants that sleep in the parental bedroom are less likely to suffocate and this also allows the infant to be nearby for feeding, comforting and monitoring.
- Pacifiers: Pacifiers appear to protect the infant from SIDS. However, the introduction of the pacifier is best left until after breastfeeding has started.
- Prenatal Care: There is evidence from several research studies that there is a lower risk of SIDS for infants whose mothers received regular prenatal care.
- Routine Immunizations: There is recent evidence that suggests that immunizations may have a protective effect against SIDS.
Tips for Reducing the Risk of SIDS
The American Academy of Pediatrics recommends the following to reduce the risk of SIDS in infants
- Place your baby back to sleep for every sleep. Avoid sleeping on the stomach and sides.
- Use a firm sleep surface: A firm crib mattress covered by a fitted sheet is recommended.
- Room-sharing without bed sharing is recommended.
- Keep soft objects and loose bedding out of the crib to reduce the risk of SIDS, suffocation and strangulation.
- Pregnant women should receive regular prenatal care.
- Avoid smoke exposure during pregnancy and after birth. It is estimated that 1/3 of all SIDS deaths could be prevented if maternal smoking could be eliminated.
- Avoid alcohol and illicit drugs during pregnancy and after birth.
- Breastfeeding is recommended.
- Consider offering a pacifier at nap time and bedtime. Because of the risk of strangulation, do NOT hang the pacifier around the infant’s neck. There is no need to reinsert the pacifier during sleep if it is expelled from the mouth.
- Avoid overheating: infants should wear no more than one layer more than an adult would wear to be comfortable in that environment.
- Infants should be immunized in accordance with recommendations from the American Academy of Pediatrics.
- Avoid commercial devices marketed to reduce the risk of SIDS (eg wedges, positioners, special mattresses). There is no evidence that these reduce the risk of SIDS or that they are safe.
- Do not use home cardiorespiratory monitors as a strategy to reduce the risk of SIDS. There is no evidence that they are effective.
- Supervised awake tummy time is recommended. This will help to counteract any effects of regular back sleeping on muscle development or the chance of developing flattening of the head (aka positional plagiocephaly).
Reshma Amin, MD | Kim French, MSDA, CAPPM, FCCP | De De Gardner, MSHP, RRT, FCCP
Date Last Reviewed