In fact, they added, some parents make the switch to seat belts even before the child is ready for a booster seat.
"People understand the concept 'buckle up,' but 'buckle up' isn't enough," says Flaura Winston, who led the study. "We have to go further with reducing injuries. We have to get children into appropriate restraints."
Children's Hospital, along with the University of Pennsylvania, is involved in a research project with State Farm Insurance Cos. to look at how and why children are hurt or killed in motor vehicles. Car accidents are the leading cause of death and disability to children over the age of 1.
While the importance of using car seats and seat belts is now well-ingrained in the public consciousness, the project, now in its fourth year, has found that misuse of car seats and seat belts is common.
The project has found that 83 percent of children ages 4 to 8 are hooked in with seat belts. Because the belts are designed for a person who is at least about 4 feet, 9 inches tall and weighs at least 80 pounds, Winston said, the shoulder strap does not cross the chest at the proper place, allowing the upper body to be thrust forward, leading to head injury. Likewise, the lap belt can ride too high on the abdomen, putting children at risk for injury to the intestines, liver, spleen and spinal cord.
The use of a child booster seat, which is designed for children up to 60 to 80 pounds depending on the model, allows the belt to be positioned in the right place. Children should be kept in car seats until they are 40 pounds, usually around the age of 4.
Still, a seat belt is better than no restraint at all, said Winston, director of TraumaLink, a pediatric trauma research center at Children's.
In this new research, Winston's team looked at the cases of 2,077 children ages 2 to 5 who were in a crash between December 1998 and November 1999. The cases came from reports filed with State Farm in 15 states, including Pennsylvania and New Jersey, and the District of Columbia.
Of the 2,077 children in the study, 98 percent were restrained at the time of the crash, but nearly 40 percent of them were in seat belts. Belt use increased with age; 81 percent of the 5-year-olds were using them.
The researchers found that children in seat belts were 31/2 times more likely to suffer any type of significant injury and four times more likely to have a head injury compared with children in car seats or booster seats.
Winston's team has held focus groups to see why parents move their children too soon into seat belts. She said some parents operated on the belief that they were safe drivers and the chances of a crash were slim. Many are not aware of why small children need to be kept in a car seat or booster seat.
"They're hearing loud and clear, 'Buckle up,' and they're doing that," Winston said. "The next message is, 'Buckle up in a way that's appropriate for your child's height and weight,' and that's much more complex."
The message is starting to be heard. Ford Motor Co. announced in April that it would spend $15 million to distribute one million booster seats as part of a safety campaign.
Car Safety for Child Passengers
Car seats should always be placed in the back seat.
Infants, until at least 1 year old and at least 20 pounds, should ride facing the rear.
Children should be kept in car seats until they weigh 40 pounds, usually about age 4, and then should be switched to booster seats, which will allow seat belts to be properly positioned. Booster seats can be used until a child weighs 60 to 80 pounds, depending on the model of the seat.
Children younger than 12 should not ride in the front seat.
All passengers in seat belts should use the shoulder and lap belts.
SOURCES: Children's Hospital of Philadelphia and the Safe Kids Coalition of Southeastern Pennsylvania.
Susan FitzGerald's e-mail address is firstname.lastname@example.org