I was told that head huggers and bunting bags are not safe to use with car seats. Why not?
Head huggers and bunting bags that are purchased separately from the car seat are not regulated, and do not have safety standards attached to them. The concern relates to the extra padding that they add behind the child which affects the tightness of the harness system. Excess padding will compress in a collision, loosening the harness straps. If the harness straps loosen too much, there is an increased risk of the child parachuting out of the car seat. Transport Canada has published a notice regarding after-market devices such as head huggers and bunting bags.