According to a study that looked at the hazards of children two years old and younger in "sitting and carrying devices," 48 percent of car seat deaths from 2004 to 2008 were from positional asphyxia. "The most important consideration for parents and caregivers is that the car seats are developed, designed, and tested for specific uses, with instructions and labels that define how to use them. Always remember children may not sleep or nap in car seats, baby swings, strollers, infant seats or bouncy seats. Should a child fall asleep in one of these devices, he or she must be moved to a crib/cot or other approved sleeping surface."