Winter Car Seat Safety:
It’s cold outside and this is the time of year children wear puffy winter coats to stay warm. Puffy coats can be unsafe when worn by a child strapped into a car seat. Experts at the American Academy of Pediatrics and NHTSA recommend no bulky clothing should be worn in car seats. This is because bulky clothing prevents a snug fit of the car seat harness on the child. Parents can use hats, gloves or light coats in the car seat to keep the child warm. Blankets or coats can be put on top of the car seat straps for extra warmth.
Pictured are examples.
Original source can be found here.