According to the Centers for Disease Control and Prevention (CDC), sudden infant death syndrome (SIDS) claims the lives of approximately 4,000 infants each year in the United States. When evaluating which infants could be most at risk, no single risk factor is likely to be sufficient to cause a SIDS death; rather, several risk factors combined may contribute to cause an at-risk infant to die of the condition. A new study has found that infants residing at high altitudes have a significantly higher risk of the syndrome. The findings were published on May 25 in the journal Pediatrics by researchers at the University of Colorado School of Medicine (Aurora, Colorado) and Emory University School of Medicine (Atlanta Georgia).
The study authors note that numerous theories regarding SIDS suggest hypoxia (decreased oxygen level) is a common factor. Infants living at altitude experience a degree of hypoxia; however, a link between SIDS incidence and infant residential altitude has not been fully explored. Therefore, they conducted a retrospective (backward looking) study by reviewing data from the Colorado birth and death registries from 2007 through 2012. A statistical analysis was conducted to determine the association between residential altitude and SIDS.
The researchers also evaluated the impact of the American Academy of Pediatrics’ Back to Sleep campaign across various altitudes from 1990 to 2012 to evaluate the interaction between sleep position and altitude. The campaign provided education and outreach to childcare providers regarding safe sleep recommendations. Its objectives were to: promote the Back to Sleep message in child care programs; raise awareness and change practices in child care settings; disseminate information on national child care recommendations/standards related to SIDS risk reduction, and support states to enhance existing and establish new child care regulations.
The study group comprised 393,216 infants born between 2007 and 2012 (51.4% boys; average birth weight 3194 grams [7 pounds]). Overall, 79.6% of the subjects resided at an altitude of less than 6,000 feet, 18.5% resided at 6,000 to 8,000 feet, and 1.9% resided at altitudes higher than 8,000 feet. No significant differences were found among the mothers of all the infants. Compared to residence less than 6,000 feet, residence at high altitude (more than 8,000 feet), was associated with a 2.3-fold increased risk of SIDS.01–5.24). Before the Back to Sleep campaign, the incidence of SIDS in Colorado was 1.99/1,000 live births and decreased to 0.57/1000 live births after its implementation. The Back to Sleep campaign was found to have a similar effect for all the altitude groups.
The authors concluded that residence at high altitude was significantly associated with an increased risk for SIDS. In addition, the Back to Sleep campaign decreased the risk of SIDS among infants living at the various altitudes.
Most deaths due to SIDS occur between 2 and 4 months of age, and incidence increases during cold weather. African-American infants are twice as likely and Native American infants are about three times more likely to die of SIDS than Caucasian infants. More boys than girls are SIDS victims. Other potential risk factors include:
- Smoking, drinking, or drug use during pregnancy
- Poor prenatal care
- Prematurity or low birth weight
- Mothers younger than 20
- Tobacco smoke exposure following birth
- Overheating from excessive sleepwear and bedding
- Stomach sleeping