Health officials first warned parents not to use the devices in 2010 and cracked down on manufacturers who claimed they could prevent Sudden Infant Death Syndrome, which claims more than 2 000 infants a year in the United States.

But the 'sleep positioners' -- which typically feature bolsters attached to each side of a thin mat and sometimes a wedge to elevate the baby's head -- remain on the market.

Most of the babies, all four months of age or younger -- suffocated after rolling from their side to their stomach. Some were found trapped between the bolster and the side of the crib.

In addition to the 13 reported deaths since 1997, the Consumer Product Safety Commission has received dozens of reports of babies found in "hazardous positions within or next to the product" after they were placed on their back or side in the positioners.

"We urge parents and caregivers to take our warning seriously and stop using these sleep positioners so children can be assured of a safe sleep," Inez Tenenbaum, chairman of the Consumer Product Safety Commission, said in a statement.

Parents should also keep the crib free of pillows, comforters, quilts and toys, said Susan Cummins, a pediatric expert at the Food and Drug Administration.

"The safest crib is a bare crib," she said. "Always put your baby on his or her back to sleep. An easy way to remember this is to follow the ABC's of safe sleep -- Alone on the Back in a bare Crib."