Car crashes are the leading cause of death in kids over age 3 in the U.S., and yet many parents still don't use car seats properly or don't know what the guidelines are for car safety restraints, according to study in the American Journal of Preventive Medicine.

In 2011, the American Academy of Pediatrics (AAP) updated its child passenger safety guidelines, which recommend:

  • Rear-facing car seats for kids until at least age 2, or when the child exceeds the maximum height and weight recommended by the car seat manufacturer
  • Forward-facing car seats with a five-point harness for kids over 2, until the child reaches the seat's maximum weight and height
  • Booster seats until an adult seat belt fits properly, typically when the child reaches 57 inches in height (4 ft., 9 in.), between 8 and 12 years of age
  • Back seat riding with seat belt until age 13

The new study reviewed three years of data of 21,500 kids from the National Highway Traffic Safety Administration's 2007-09 National Survey on the Use of Booster Seats. The study revealed that more than 1 in 3 kids aged 11 to 12 were riding in the front seat, 1 in 4 children aged 8 to 10 were front seat passengers, as were 1 in 7 of those aged 6 to 7.

Read more from Time.