May 25, 2015 2:04 PM EDT

A new study suggests babies that live at high altitudes may be at a greater risk for Sudden Infant Death Syndrome (SIDS) compared to infants living at lower altitudes.

Each year, around 3,500 infants under age one die unexpectedly in the United States. Still, public health experts remain uncertain for why SIDS occurs.

In a new study published Monday in the journal Pediatrics, researchers sought to determine whether altitude might play a role in SIDS risk. The researchers looked at residential altitude of over 393,000 Colorado infants, as well as their birth and death certificate data between 2007 and 2012.

After accouting for a variety of complicating factors, the researchers found that babies that lived above 8,000 feet had slightly over double the risk of experiencing SIDS compared to infants that lived under 6,000 feet.

The study did not determine why higher altitudes might increase the risk, but others have suggested that hypoxia, not having enough oxygen, may play a role in SIDS. Researchers suggest the findings should be kept in mind when coaching new parents.

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