The Risk of Side Sleeping

Until very recently, all of the "Back to Sleep" campaigns have stressed the importance of prone sleeping as a risk factor for SIDS and have considered side sleeping to be part of the solution rather than part of the risk. I would like to briefly review the relevant background information and to explain the newest recommendations.

International studies from the early 1990's reported a relative risk for SIDS that was 4-7 times greater for infants sleeping prone (on stomach) compared to infants sleeping on the side or supine (on back). In the initial "Back to Sleep" campaigns in other countries, much of the reduced incidence of SIDS associated with reduced incidence of prone sleeping was actually achieved with the side rather than supine position. For this reason, the "Back to Sleep" campaign started in the U.S. in June 1994 recommended the side or supine position as safe alternatives to prone sleeping.

The most recent data from England indicate that fewer than 5% of infants now sleep prone. Since most infants are sleeping side or supine, it is now possible to compare the relative risk of side compared to supine sleeping. Results reported at the International SIDS meeting in June in Washington, D.C. indicate that infants sleeping on the side are twice as likely to die of SIDS than infants sleeping supine. The reasons are not clear, but relative instability of the side position may be an important consideration; some infants placed on the side are found sleeping prone.

In summary, the available data lead to the clear conclusion that supine should be the only recommended sleep position for infants. Side sleeping is safer than prone sleeping, but the lowest risk is associated with supine sleeping. Remember, however, that supine sleeping is only "associated" with the lowest SIDS risk; it is not accurate to say that side or prone sleeping "causes" SIDS. Although the association is very real, much remains to be learned regarding what other factors associated with sleep position may be as important or even more important in determining the actual risk for SIDS in any individual.

Hope this is helpful.

Carl E. Hunt, M.D.
Toledo/Washington D.C.

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