They look cozy, comfy, and colorful but quilts, blankets, pillows, and plush toys in cribs can be deadly for young babies. Infants don't have the muscle strength or coordination to prevent their noses and mouths from being blocked by soft bedclothes and toys. This leaves them at high risk for suffocation, smothering, and sudden infant death syndrome.

The risk bedding in the crib poses for young babies has been known for a while, but it appears parents and care providers haven't gotten the message. Or maybe those beautiful blankets and quilts are hard to resist.

A recent study found that between 2000 and 2010, deaths from unintentional sleep-related suffocation had doubled, even though the rates of sudden infant death syndrome (SIDS) had decreased from 66.3 to 52.7 per 100,000 live births in the U.S.

Images in the media also tend to portray infants sleeping with blankets and pillows, which may give mothers the idea that this is an appropriate practice. It is not.

The researchers found that covering babies with thick blankets had declined by roughly 50 percent, but they did not see significant declines in bedding materials placed under infants.

“This finding raises a concern that parents may incorrectly perceive the recommendations as only pertaining to items covering or around the infant, and not include items under the infant,” the study authors wrote.

In 1996, the American Academy of Pediatrics recommended that infants should be put to sleep on firm mattresses free of soft surfaces and potential gas trapping objects.

A 1999 safety alert by the Consumer Product Safety Commission, the National Institute of Child Health and Human Development, and the AAP task force additionally advised that infants be put to sleep on their backs, on a firm, tight-fitting mattresses, in a crib that met safety standards, with no pillows, quilts, comforters, sheepskins or other pillow-like soft products in the crib.

The researchers, from the Centers for Disease Control, Yale School of Medicine, the Boston University School of Public Health and the Boston University School of Medicine, used phone interview data from 1993-2010 to get a picture of how bedding was used with almost 19,000 infants who were 8 months or younger. They questioned care providers about their use of all manner of blankets, pillows, sheepskins, pillows and other bedding both on and underneath the sleeping infants.

While the overall use of infant bedding declined during the study period from 85.9% to 54.7%, the study showed that over half the infants were still being put to bed in unsafe environments.

Unsafe bedding was most commonly used when infants shared adult beds, were routinely placed to sleep on their sides, or shared a sleep surface with other siblings. Mothers who were under 20 years of age and had less than a high school education were also more likely to use unsafe bedding in their infants' cribs, so were black and Hispanic mothers.

Mothers believed that infants were more comfortable in some types of bedding, and that they could keep the bedding away from the infants' faces and heads or protect them from suffocation by using crocheted products with large holes, the researchers found. Mothers also reported using pillows as barricades to prevent infants from rolling off the sleeping surface.

Images in the media also tend to portray infants sleeping with blankets and pillows, which may give mothers the idea that this is an appropriate practice. It is not.

The investigators conclude that the danger from unsafe sleep practices is still widespread and more attention is needed to educate new parents on safe sleep practices. Sleep sacks that zip around the baby or footed pajamas are the best way to keep infants warm and avoid the risk of suffocation.

The study is published online in Pediatrics.