Parents and caregivers who place car seats on beds, kitchen counters and other places outside the car injured 43,000 U.S. children over five years, researchers reported on Monday.

More than 3,400 of the children were injured badly enough to require hospitalization, the researchers told a meeting of the American Academy of Pediatrics.

"Many families learn the importance of strapping an infant car seat into a vehicle, but they do not learn about the dangers of using infant car seats as carriers or placing them on countertops or beds," Dr. Shital Parikh of Cincinnati Children's Hospital Medical Center told the meeting.

Most of the children were injured on the head, but they also broke leg and arm bones, he said.

"When parents or caregivers place the infant car seat on top of a table or elevated surface, the infant can wiggle and end up toppling off out of the seat onto the floor, which can lead to severe injuries," Parikh said in a statement.

"Another accident that can happen is the turning over of the car seat on to a soft surface, which can lead to suffocation."

Parikh used a Consumer Products Safety Commission database to make his calculations.