Children are least likely to be injured in a car crash when they are properly restrained and riding in the back seat, according to a study published Monday.

Researchers say the findings support new laws requiring that children who have outgrown child safety seats must ride in belt-positioning booster seats. “However,” they report in the March issue of the journal Pediatrics, “it is important to note that considerable added benefit would be realized with requirements for rear seating.”

Based on four years’ worth of crash data collected from 15 U.S. states, the study authors estimate that more than 1,000 serious injuries could have been avoided had all children in the study been properly restrained in the back seat.

The study defined proper restraint as car seats or booster seats for children younger than 9, and seatbelts with lap and shoulder straps for older children.

The U.S. National Highway Traffic Safety Administration recommends that children between the ages of 4 and 8 ride in belt-positioning booster seats, which allow a car’s shoulder and lap belts to fit across their bodies properly. Children can graduate from the seats once they are 4 feet 9 inches tall, according to the agency.

In recent years, many U.S. states have been upgrading their seatbelt laws to fall in line with these recommendations.

The new findings “support the current focus on age-appropriate restraint” in state laws, according to the study authors, led by Dr. Dennis R. Durbin of Children’s Hospital of Philadelphia.

But, they add, the study also points to the importance of having all children younger than 13 ride in the rear seat of a vehicle. [

For the study, the researchers collected data on nearly 18,000 children younger than 16 who were involved in car accidents between 1998 and 2002. Parents gave information on where their children were sitting and what type of restraints they were using at the time of the accident.

Overall, Durbin’s team found, children who were inappropriately restrained were twice as likely as those who were properly strapped in to suffer serious injuries, such as broken bones, concussion or trauma to the internal organs. Those who were riding with no restraints - just 3 percent of the study population - had a three-fold greater risk of injury.

A child’s position in the car also showed its own effect on the risk of serious injury; children sitting in the front passenger seat were 40 percent more likely to be injured compared with those riding in the rear seat.

Children who were riding in the back seat with proper restraints had the lowest rate of serious injury - just 1.1 percent, versus 2.1 percent of children who were properly restrained in the front seat and 8.7 percent of those who were riding unrestrained in the front passenger seat.

“On the basis of these findings,” the authors conclude, “educational campaigns, anticipatory guidance, and legislative interventions should continue to emphasize age-appropriate restraint but should add an additional focus on the promotion of rear row seating, with appropriate restraint, for all children (younger than) 13 years of age.”

SOURCE: Pediatrics, March 2005.