A safety agency in the United States has released a new study indicating nearly half of children who have died in playpens suffocated from soft bedding.

The U.S. Consumer Produce Safety Commission studied the reports of more than 200 babies who have died since 1988.

"This study shows, for the first time, that the same dangers exists when using pillows, quilts, and comforters in playpens," said Ann Brown, CPSC chair, in a statement.

Infants should be placed on flat, firm mattresses

Many parents use playpens as places for infants to sleep and play. The CPSC is urging parents to take extra precautions.

It's reminding caregivers to place infants on their backs on a firm, flat mattress and not to add any extra soft bedding such as pillows, quilts or comforters.

According to the CPSC, parents and caregivers should take these steps:

• Before using a playpen, make sure it has not been recalled. Call the manufacturer's hotline
• Resist buying second-hand infant furniture, unless you know it is a safe model to use
• Always put a baby down to sleep on his back in a playpen or crib with no soft bedding, such as quilts, comforters and pillows
• Use only the mattress provided by the manufacturer. Do not add additional mattresses in playpens
• Check that the playpen is in good shape. Using a modified or improperly repaired unit can create hazards
• Make sure the top rails of the units lock into place automatically. Many older playpens with top rails have had to be manually rotated into a locked position have been recalled
• Do not use playpens with catch points, such as protruding hardware. Millions of older units with protruding hardware have been recalled
• If using a mesh-sided playpen, make sure the mesh is less than 1/4 inch (approx. 6.5 mm) in size and that it is attached securely. This will help prevent strangulation