Using sitting or carrying devices, such as car seats, swings, or bouncers for making your baby sleep could lead to potential injury or death, say researchers including an Indian-origin doctor.

"Many parents use sitting or carrying devices, not realising that there are hazards when they do this," said Erich Batra, Penn State Milton S. Hershey Medical Centre in the US.

The researchers reviewed deaths that were reported to the US Consumer Product Safety Commission, of children under two years of age that occurred in sitting and carrying devices between April 2004 and December 2008.

The researchers analysed records for 47 deaths associated with sitting and carrying devices; all but one were attributed to asphyxia (positional or strangulation).

Two-thirds of the cases involved car seats; strangulation from straps accounted for 52 percent of the car seat deaths.

The remainder of deaths occurred in slings, swings, bouncers and strollers.

The elapsed time from when the infants were last seen alive to when they were discovered ranged from as little as four minutes to up to 11 hours.

The study included newborns as well as toddlers.

Contrary to popular belief, the restraints and design of infant sitting or carrying devices are not intended for unsupervised sleeping, the study pointed out.

"Infants and young children should not be left unsupervised when using a sitting or carrying device due to the risk of suffocation and death," Batra said.

The study is forthcoming in The Journal of Pediatrics.