Swaddling infants, especially when they are sleeping in a prone position or on their side, may increase the risk for sudden infant death syndrome (SIDS), according to a study published in Pediatrics.

The overall, age-adjusted odds ratio (OR) for swaddling was 1.58, though the risk varied by position placed for sleep. The risk of SIDS associated with swaddling seemed to increase in older infants.

The meta-analysis included 4 observational, case-control studies that used SIDS as an outcome and also included data on swaddling for the last or reference sleep. The studies span 2 decades and 3 geographic regions: parts of England, Tasmania in Australia, and Chicago in the United States.

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From all 4 studies, there were 760 SIDS cases compared with 1,759 control participants. The risk of SIDS with swaddling increased with age, with infants aged 6 months and older having the greatest risk (OR, 2.53).

For infants placed in the prone and side positions to sleep, swaddling doubled the risk for SIDS (OR, 12.99 for prone infants; OR, 3.16 for infants on their side) compared with non-swaddled infants. There was a small but significant risk of SIDS for swaddled infants placed on their back to sleep (OR, 1.93) compared with non-swaddled infants. Although being swaddled and then found sleeping prone was a rare occurrence (<1% among control subjects and 8% among infants with SIDS), it increased the risk of SIDS 19-fold.

Two studies included data on both the sleeping position the infants were placed in and the position they were found in. Of the 124 control infants who were swaddled, none was placed prone, 49 were placed on their side (24 remained on their side; 25 rolled onto their back) and 1 was placed supine (and was found prone). Of the 16 swaddled infants with SIDS who were found prone, 3 were placed and found prone, 8 were placed on their side and found prone, and 5 were placed supine and found prone.

“Current advice to avoid front or side positions for sleep especially applies to infants who are swaddled,” the researchers wrote.

The researchers noted that the 4 studies that were analyzed did not include precise definitions of swaddling; future studies of SIDS risk could create swaddling classifications by using photographic measures of how a swaddled infant was placed for sleep and how they were then found.


  1. Pease AS, Fleming PJ, Hauck FR, et al. Swaddling and the risk of sudden infant death syndrome: a meta-analysis. Pediatrics. 2016; doi:10.1542/peds.2015.3275.