Booster seat laws vary from state to state

Recent changes to booster-seat laws in Kentucky, Massachusetts and Michigan expose the hodgepodge of state rules that govern the use of safety seats by children older than four. The states are uniform in their requirement that children use a car seat until they outgrow front-facing child restraints, usually around the age of four and 40 pounds. But at that age and size kids are still too small to ride safely using only the vehicle's seats belts, which are constructed to fit adults. Booster seats elevate children to a height where they can wear the car's belts correctly.

As many as one half of children ages 4 to 7 are not properly protected when riding in a car, according to a study conducted by the National Highway Traffic Safety Administration.  In the study, 35 percent of children were prematurely using the car's seat belts without a booster and 15 percent were unrestrained— meaning not wearing a seat belt at all.

Not every state has a booster seat law. And even states that have passed laws fail to agree on what age, size or weight a child should be to graduate from a child restraint to car seat belts. New laws in Massachusetts and Michigan, for example, require children younger than eight or smaller than 4-feet, 9-inches to use booster seats. Kentucky's new law, however, only requires kids younger than seven and shorter than 4-feet, 2-inches to be belted in a booster.

With such a variety of state laws, it's hard for a parent to know what to do.  Jennifer Stockburger, program manager for vehicle and child safety at Consumers Union, says it's good to acquaint yourself with the laws in your state and others if you are planning to travel.  At CU, publishers of Consumer Reports, we recommend that you follow these four rules for determining whether your child is ready for adult seat belts rather than following your state's law alone.

1. Make sure the shoulder belt lies across the chest and shoulder blades and away from the neck.
2. Position the lap belt across the hips and upper thighs and not across the abdomen.
3. Make sure the child's back is against the seat back and that his knees bend comfortably over the seat cushion without needing to slouch.
4. Your child should be able to sit in that position comfortably for the duration of the trip.

Stockburger notes that children who are moved to adult belts prematurely too often suffer neck and abdominal injuries in car accidents.

CU is not alone in advocating that children remain in booster seats until they're ready for adult belts. NHTSA  recommends that children stay in booster seats until they are at least eight years old and 4-feet, 9-inches. So does the American Academy of Pediatrics, which has a  guide to child restraints on its Web site. Consumer Reports' Babies & Kids blog has a helpful timeline that parents can follow for proper car seat use for growing children.