What is SIDS?

This content was created by the National Sleep Foundation

You’ve probably heard of SIDS, but you may not know exactly what it stands for: Sudden Infant Death Syndrome. It’s actually a subset of something called SUID, which is short for Sudden Unexpected Infant Death. Every year in the United States, around 3,500 infants die from SUID, and 1,500 of those deaths are caused by SIDS.

SIDS happens when an infant (a baby who is younger than one year old) dies while asleep and a thorough investigation can’t determine the cause. Often it’s believed that suffocation is the cause, but autopsy tests can’t say with certainty whether or not that’s true. Instead, investigators look for signs that could cause suffocation, like soft bedding or the fact that the infant was sleeping with someone else in the bed (a practice that's often called co-sleeping).

To decrease your infant’s risk of dying from SIDS, there are some simple steps that you can take. First, place babies on their backs whenever they are put down to sleep. (When they are face down, they are more likely to accidentally suffocate.) Then look at the baby's sleeping environment. Use a firm mattress that's built for infants, put only one tight, fitted sheet on it, and remove pillows, bumpers, stuffed animals, and any other soft objects from the crib.

A sleep sack is also a good idea because it fits snugly on the infant (loose pajamas on infants can be a hazard). It also keeps the baby warm, so you don't need to add a blanket to the crib, which is considered dangerous. There’s also something that pregnant women and new mothers can do to reduce their baby’s risk of SIDS: Don’t smoke. When infants are exposed to smoke (both in utero and after birth), they are at a higher risk of SIDS.

SIDS isn’t caused by only external factors. Some babies have abnormalities in certain parts of their brains that have to do with controlling breathing and arousal from sleep. If those abnormalities exist, they have a higher risk of SIDS. Their risk also increases if they are born with a low birth weight or have had a recent respiratory infection, like a cold, which can cause breathing issues.