Dr. David Katz at the University of Colorado reviewed 393000 births between 2007-2012. Of these 80% live between 3000-6000 ft. Only 1.9% live over 8000 ft. Death rates from Sudden Infant Death Syndrome (SIDS) state-wide was 4.2 per 10,000 but over 8000 ft the rate was 7.9/10000.

Another study Bu Dr Richard Johnson et.al. was published in 2021 in the Science Reports.  This included all births as recorded in the CDC database between 2005 and 2010. Altitude was determined by county of birth. The analysis included many factors including race, ethnicity, marital status, parity, prenatal visits, sex, birthweight, gestation, maternal age, education and smoking status, paternal age and race, and live birth order. Of these over 25 million births, there were 23,673 SIDS deaths. For the 9,245 mothers giving birth at over 8000 feet there were 10 SIDS deaths in 6 years.

Although this is twice the rate o f SIDS at lower altitude, it is still a very small number.  It is possible that hypoxia is a contributing factor, since low oxygen can cause apnea, but there is no research on this. Meanwhile parents are urged to place their babies on their backs to sleep and remove all soft material from the sleep area.