A new study has concluded that American children are increasingly too fat to safely fit into child safety seats. The use of child safety seats in cars is required by law, but the researchers writing in the April issue of Pediatrics say there are too few seats available to handle the girth of obese children.

According to study estimates, a total of 283,305 children one to six years of age in the United States would have a difficult, if not impossible, time fitting safely and appropriately into a child safety seat because of their age and weight. The vast majority of these children are three years of age and weigh more than 40 lb (182,661 children). For these children, there are currently only four child safety seat types available, each of which costs between $240 and $270.

"While we await reductions in the childhood obesity epidemic, it is essential to develop child safety seats that can protect children of all shapes and sizes," said Lara Trifiletti, the lead researcher for the study.

"Motor vehicle crashes pose the single greatest risk to children, accounting for 23% of injury deaths among infants and 30% among preschool-aged children. Options for maximizing the protection of obese children in automobiles must be identified," she said.

The types of appropriate child safety seats were assessed by using National Highway Traffic Safety Administration 2005 Child Safety Seat Ease of Use Ratings. Estimates of the numbers of children weighing above the maximal weight for those child safety seats were calculated by using the tabulations of growth curves based on National Health and Nutrition Examination Survey 1999 to 2000 data that were assembled by the National Center for Health Statistics and the US Census for the year 2000.

Obesity is generally considered a health problem with long-term consequences. However, there is an immediate need for child safety seats that have been designed, tested and approved for use at higher weights.

"Debate regarding what to do to reduce and to prevent childhood obesity is just beginning," Trifiletti said. "We do know, however, that childhood obesity is increasing, and we can expect even more children to face the prospect of limited child safety seats available to protect them."

The research was supported by the Johns Hopkins Bloomberg School of Public Healths Center for Injury Research and Policy in Baltimore and conducted in collaboration with its researchers.