I get asked every week about crib bumper safety.  Here is what I have found based on the best information available at the time of posting:

SAFE KIDS USA POSITION STATEMENT

CRIB BUMPERS
Crib bumpers or bumper pads are a product parents commonly think increases the safety of their child’s crib. However, it is rare for contact between a baby and the sides of the crib to cause long-term injury, and soft products and bedding in the sleep environment are a risk for both SIDS and suffocation.
Infants have been known to suffocate from wedging the face against a crib bumper, from becoming wedged between the bumper and another object, and from the bumper tie wrapping around an infant’s neck. Crib bumpers also reduce the flow of fresh air around a baby during sleep. This may be a contributing factor to SIDS, as some babies may be unable to wake themselves enough to prevent hypoxia if they overheat or lack sufficient oxygen during sleep.
It is important to distinguish between SIDS and suffocation. Sudden Infant Death Syndrome (SIDS) is the sudden death of an apparently healthy infant under one year of age that remains unexplained after an autopsy, examination of the death scene and review of the baby’s health history. There is no known way to prevent all cases of SIDS, but one of the steps parents and caregivers can take to reduce risk is removing soft bedding from a baby’s crib.
It is only through a comprehensive death scene investigation that unintentional suffocation can be distinguished from SIDS or intentional suffocation (homicides). Even with a complete investigation, it is still difficult or impossible to determine the manner of many suffocation deaths. However, the majority of unintentional suffocations among infants happen while they are in unsafe sleeping environments.
A study in the September 2007 issue of The Journal of Pediatrics concludes that the risk of death or injury from crib bumpers outweighs their benefits.
Safe Kids USA’s policy is that parents and caregivers should not use any type of crib bumpers. Similarly, they should remove pillows, loose sheets, blankets, stuffed toys, sleep positioners and all other soft products from the crib before putting a baby to sleep.
Among the concurring organizations are:
American Academy of Pediatrics
American SIDS Institute