Ask an Expert: SIDS

Q: What exactly is SIDS, and why does sleeping on the back prevent it?

Answer from Dr. John V. McDonald, director of Neonatal Services at Providence St. Vincent Medical Center:

We think that sudden infant death syndrome (SIDS) results from babies “re-breathing” the carbon dioxide in their own breath. When a baby’s face is close to the mattress, loose pillows, or stuffed animals, the baby can be forced to inhale the carbon dioxide that he or she has just breathed out. Ultimately, this suppresses the baby’s breathing system.

For some time now, a national “Back to Sleep” campaign has been urging parents to have their babies sleep on their backs. This is the most effective way to prevent the kind of re-breathing I described above.

It’s been difficult to convert some parents’ thinking; many have traditionally thought that the greatest threat to their babies while sleeping was choking on the liquid that they spit up, so sleeping on the back seemed risky. But evidence has shown that sleeping on the back does not increase the risk of choking. In fact, since the Back to Sleep campaign launched in the mid-1990’s, overall infant mortality rates from all causes have gone down.

The most current data show that just 27 babies died of SIDS in Oregon in 1999. That’s down from a rate of about 100 per year before the campaign started.

At Providence hospitals, we give out t-shirts for newborns that read “This Side Up” as a reminder that sleeping on the back is safest. We believe strongly that all babies should sleep on their backs, and that loose pillows or stuffed animals should be kept out of the crib.

Last updated: June 2003

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