While the majority of parents report using booster seats for their 4- to 8-year-old children, booster seat use among children who carpool is inconsistent, a new study suggests.

In a national survey, University of Michigan researchers asked 681 parents about their use of booster seats. Of those, 64 percent reported carpooling with children.

Of the carpooling parents, “we found that they were using booster seats less often for their own children, and they were also less likely to ask another parent to use a booster seat for their child,” said study co-author Dr. Michelle Macy, a lecturer in the Department of Emergency Medicine and Pediatrics at the University of Michigan.

Parents said they used a booster seat 76 percent of the time when driving their own children in the family car. But of these, only half said their child always uses a booster seat when riding with friends who do not use booster seats.

Further, one in five parents doesn't always ask other parents to use a booster seat for their child, the study showed.

The study is published online today (Jan. 30) in the journal Pediatrics.

States without booster seat laws

Most states have laws requiring booster seats for children, but in the three states without those laws — Arizona, Florida and South Dakota — reported use of booster seats was lower, especially as children got older, the researchers found. While 79 percent of parents reported using booster seats for 7- to 8-year olds in states with applicable laws, only 37 percent in states without corresponding laws reported doing so.

For carpooling parents, more than 90 percent reported using booster seats in states with child-restraint laws, while fewer than 50 percent reported using the seats in states without the laws.

National guidelines suggest using booster seats for children under 4 feet 9 inches tall, the height of an average 11-year-old, Macy said. No states specify height as the basis of their laws, she said.

One of the best ways to reduce injuries to children involved in traffic accidents is to make state laws consistent with these national height guidelines, Macy said. “Most of the state laws are set [so parents] use a booster seat until the child is eight,” she said.

The researchers gathered their data from 12 questions about booster-seat use and carpooling inserted into the C.S. Mott Children's Hospital National Poll on Children's Health, an ongoing study at the University of Michigan.

Booster seat hassle

For car poolers, one problem is the hassle involved with moving a booster seat from one car to another. Researchers could work with safety-seat or automobile manufacturers “to see if they can come up with some options that would be more portable for families,” Macy said.

The study does a good job investigating an important issue, said Dr. Mark Zonfrillo, leader of Child Passenger Safety Research at the Children's Hospital of Philadelphia.

“It was interesting to see that, although overall use in the family car was high, the rates for car pooling were lower,” Zonfrillosaid.

Both Zonfrillo and Macy said a strength of the study was its national sample of parents, but that self-reporting on surveys can sometimes be inaccurate. “We have no real way to verify if the parents do what they say they're doing,” Macy said. “They might report … more safety-seat use than they actually do.”

Healthcare workers need to help parents recognize the importance of booster seats for their children's safety, Macy said.

“We've come a long way, and the injuries and deaths have really gone down,” Macy said. “[Parents] should really consider the importance of being consistent with the way they're approaching safety with their kids, and not let [booster seats] become a point of conversation or compromise.”

Pass it on: While many parents are using booster seats for their 4- to 8-year olds, fewer parents use the seats in carpooling situations. Parents should insist that children use the seats in the family car and in other people's vehicles.

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