Baby sleep sacks

A baby sleep sack, also known as an infant sleeping bag or wearable blanket, is a garment-like form of bedding that is worn by an infant during sleep instead of being placed loosely over the body.^[1] In infant safe-sleep guidance, wearable blankets are generally preferred to loose blankets because they provide thermal insulation while reducing the possibility of head covering, entrapment, and airway obstruction associated with movable bedding.^[2]

The use of a sleep sack does not replace other established safe-sleep measures, including placing the infant in the supine position on a firm, flat sleep surface and keeping pillows, quilts, soft objects, and loose bedding outside the sleep area.

A clinical review of infant sleeping bags concluded that the available case-control evidence indicated a level of safety comparable to, or potentially greater than, that of other forms of bedding when sudden infant death syndrome was used as the outcome.^[3] The same review emphasized that safe use depends on appropriate manufacturing, correct sizing, a suitable thermal overall grade, appropriate clothing underneath the garment, and adjustment for the temperature of the sleeping environment.^[4][5]

These thermal considerations are clinically relevant because excessive insulation and overheating have been independently associated with an increased risk of sudden infant death syndrome in case-control research.^[6][7]

A review of incidents reported to the United States Consumer Product Safety Commission identified five cases specifically involving wearable blankets, comprising one death, two injuries, and two incidents with the potential for injury.^[8][1]

Within the broader collection of incidents involving wearable blankets, swaddle wraps, and conventional swaddling, fatal outcomes were frequently associated with prone positioning and additional environmental hazards, particularly soft bedding.^[9][10]

Consequently, the safety of a sleep sack depends not only on the product category but also on correct fit, secure construction, appropriate closures, and use within an otherwise hazard-free sleep environment.^[11][4]

A conventional sleep sack should be distinguished from a swaddle wrap, which includes fabric panels or bands intended to restrain or closely wrap the infant’s torso and arms.^[12] Experimental and systematic-review evidence indicates that swaddling can increase sleep duration and reduce spontaneous arousals, but the combination of swaddling with prone or lateral sleep positioning is associated with an elevated risk of sudden infant death syndrome.^[13]

Swaddling that holds the hips and knees in extension and adduction has also beenassociated with developmental dysplasia of the hip, and infant sleep garments should therefore permit adequate flexion and movement of the lower limbs.^[12]

Weighted sleep sacks, weighted sleepers, weighted swaddles, and other weighted objects are not recommended for use on or near a sleeping infant.