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Sudden Infant Death Syndrome (SIDS) Risk Factors

What Are 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 to their stomachs after being placed on their sides. One theory is that stomach sleeping increases the risk of the infant rebreathing his or her own exhaled air. A soft mattress, loose or plush bedding, a stuffed toy or a pillow can also lead to 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 found that maternal smoking during pregnancy increases the risk of SIDS up to five times. Also, secondhand smoke from a smoking father is also associated with an increased risk of SIDS.

Prematurity: Prematurity increases the risk of SIDS up to four times as compared with 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 dangerous for the infant.

Alcohol and illicit drugs: There is an increased risk of SIDS with prenatal and postnatal exposure to alcohol or drugs.

    This content was developed in partnership with the CHEST Foundation, the philanthropic arm of the American College of Chest Physicians.

    Page Last Updated: July 30, 2019

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