Yes, but it’s very rare. This has happened in car seats when babies have been left in cars seats for many, many hours. It is most risky for newborns as their neck muscles do not allow them to move their heads. When left asleep in a car seat with their chin on the chest the trachea is restricted. This is called positional asphyxia and slowly reduces the oxygen levels in the blood. An example would be leaving a baby overnight to sleep in a car seat. The baby could eventually suffocate due to lack of oxygen.