Living at high altitude can increase risk of SIDS

As a new parent, there’s nothing scarier than the possibility of SIDS. In Canada, about 150 infants a year (1 in 2,000 live births) die from Sudden Infant Death Syndrome, which is the unexplained death, usually during sleep, of an otherwise healthy baby under age one. You’re taught to put your baby to sleep on their back, stop smoking, and remove blankets and bumpers from the crib, practices that reduce the risk of SIDS. Now, a new study has identified another risk factor for SIDS: living at a high altitude.

“We became interested in a potential link between altitude and SIDS based on other studies that focused on oxygen quality in infants who had died of SIDS,” explains Amber Khanna, the study’s senior author and an assistant professor of medicine and pediatrics at the University of Colorado Denver. “Anything that hampers the baby’s ability to breathe high-quality oxygen—whether it’s blankets in the crib, lying on their stomach or second-hand smoke—can increase the risk of SIDS. So that led us to think that maybe altitude, which is associated with a decreased amount of oxygen in the air, may be related to SIDS as well.”

The new study, “Sudden Infant Death Syndrome and Residential Altitude,” to appear in the June 2015 issue of Pediatrics, looks at birth and death registries in Colorado from 2007 to 2012, and compares the records with the altitudes of the infants’ homes. It reveals that infants who lived at an altitude higher than 2,438 metres had a 2.3 times greater incidence of SIDS compared with infants who lived below an elevation of 1,829 metres.

Previous studies have shown that babies are more likely to have hypoxia (a condition where the blood and tissues aren’t adequately oxygenated) when they’re sleeping at altitude. It’s thought that hypoxia somehow triggers SIDS, but more research is needed to determine the process behind it.

For the most part, Canadians needn’t worry about this finding—there aren’t any cities over 2,438 metres in Canada. (Lake Louise in Alberta is the country’s highest elevation town, at 1,661 metres.)

“The real implications are global,” says Khanna. Around the word, there are 63 million people living at altitudes above 2,438 metres.

But even for the Colorado families at high altitude, Khanna says the risk of SIDS, at 0.79 per 1,000 live births, is still too low for drastic action, like advising parents move to a lower elevation. She recommends, instead, that families living at altitude should be extra vigilant about all of the other SIDS risk factors they can control.

Tips for reducing the risk of SIDS

• Always put baby to sleep on his back. Since the Back to Sleep campaign launched in 1994 in the US, the rate of SIDS has dropped by more than 50 percent. Canada launched the campaign in 1999 and has seen similar results.
• Place baby on a firm mattress to sleep—never on a pillow, couch or other soft surface.
• Remove blankets and bumpers from the crib to reduce the risk of suffocation or “re-breathing” (breathing in his own exhaled air, which contains more carbon dioxide).
• Follow the recommended immunization schedule. Studies show that vaccinated babies have a 50 percent lower risk of SIDS.
• Keep baby’s room temperature comfortable but not hot—some researchers suggest a too-warm baby could go into a deeper sleep and be difficult to wake.
• Don’t smoke, drink or do drugs when pregnant, and don’t expose an infant to second-hand smoke. Babies of moms who smoked during pregnancy are three times more likely to die of SIDS than babies born to non-smoking moms, and exposure to secondhand smoke doubles an infant’s risk of SIDS.

Tips courtesy of Amber Khanna and the American Academy of Pediatrics.

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