CHICAGO - Many young children are too heavy for standard car-safety seats, and manufacturers are starting to make heftier models to accommodate them, according to research on the obesity epidemic's widening impact.
More than a quarter of a million U.S. children ages 1 to 6 are heavier than the weight limits for standard car seats, and most are 3-year-olds who weigh more than 40 pounds, the study found.
Unless exceptionally tall, a 3-year-old weighing more than 40 pounds would generally be considered overweight.
Lead author Lara Trifiletti said researchers at a safety center at Johns Hopkins Hospital became interested in the topic because they saw children "who were very obese and our car-seat technicians were having a hard time finding car seats to fit them."
She did the research at Johns Hopkins but now works at Ohio State University's Children's Research Institute.
Using inadequate car seats for heavy children could put them at increased risk for injury in a car accident, the researchers said.
"We don't recommend that a parent use a restraint system for a child that has outgrown that system," said Eric Bolton, a spokesman for the National Highway Traffic Safety Administration.
Based on growth charts and the 2000 Census, at least 283,305 children ages 1 to 6 are too heavy for standard safety seats. That includes nearly 190,000, or almost 5 percent, of 3-year-olds, the researchers said.
Their study appears in the April edition of Pediatrics, being released today.
Trifiletti said the phenomenon mostly affects youngsters whose weight exceeds the limits of standard seats with built-in safety harnesses, which are designed for 1-to-3-year-olds weighing up to 40 pounds. These heavier young children are not mature enough or tall enough for "booster" safety seats, which are recommended for ages 4 and up and typically use the car's safety belts for restraints, she said.
More than 23 percent of U.S. children aged 2 to 5 were overweight and more than 10 percent were obese in 2001-02, government data show. New data out later this week are expected to show the upward trend has continued.
Britax introduced two harness seats with 65-pound weight limits last year.
Dorel Juvenile Group, maker of Cosco brand car-seats, also introduced a harness seat in 2005 for kids up to 65 pounds.
The NHTSA last year proposed new requirements for manufacturers that choose to make seats for older and/or heavier children. Those who do would be required to build seats to protect kids up to 10 years old and/or weighing up to 80 pounds in 30 mph crashes. The agency also would create an 80-pound crash-test dummy for testing child safety seats, 25 pounds heavier than the existing simulators, Bolton said.