What you need to know about booster seats

Parents must put the ‘belts on bones’



Booster seats are the last hurrah of car seats.

Determining when your child should begin to use a booster seat should be based on bone development and maturity.

Many booster seat manufacturers say children should weigh 30 to 40 pounds to use them, but this does not take into account children who are both thin and tall — they may exceed the height allowance, but not the weight.

Early transitions to booster seats can result in ejection. There are tragic stories you can read through the Kyle David Miller Foundation regarding this issue.

The purpose of a booster seat is to position your child so the lap-shoulder safety belt in your car properly fits them. According to New Hampshire state law, when a child turns 7 they are no longer required to sit in a booster seat, but most children do not properly fit a seat belt until they are between the ages of 10 to12.

If a 7-year-old weighs 56 pounds, in a car crash at just 10 mph that’s 560 pounds of force that is put on a child’s organs and intestines.

That’s why we say “belts on bones”— bones are made to be strong and support force, to jump, and play, and fall and roll. If 560 pounds of force is placed on the soft tissues, organs are going to be compressed and the child will likely sustain internal injuries. If children are not in a booster seat, there is the potential for “submarining,” which is when a child is in a car crash and slips under the seat belt, incurring serious injuries, or death.

When can your child safely use a seat belt? The American Academy of Pediatrics recommends a minimum height of 4 feet, 9 inches tall and the ability to pass the five-step test below.

Simply stated, that’s when the seat belt fits them the same way it fits you. Your child also may have a different seat belt fit depending on make, model and vehicle type.

Step 1: Does the child sit all the way back against the auto seat?

Step 2: Do the child’s knees bend comfortably at the edge of the auto seat?

Step 3: Does the belt cross the shoulder between the neck and arm?

Step 4: Is the lap belt as low as possible, touching the thighs?

Step 5: Can the child stay seated like this for the whole trip?

If the answer is “no” to any of these questions, your child still needs to sit in a booster seat, ensuring both the shoulder belt and lap belt fit correctly for the best crash protection.

In addition, all children should ride in the back seat until they are at least 13 as it is twice as safe as the front seat, and their bodies are not yet ready to support the force of an airbag. Development of bone strength is based on puberty, not on how big or tall a child may be.    

Julie Dietrich, CPSTI, is the New Hampshire Child Passenger Safety Program Coordinator.

More health columns from Dartmouth Hitchcock

What you need to know about CO

How to prevent carbon monoxide poisoning

The rules of (crossing) the road

Talk through pedestrian and traffic safety with your kids

Look before you lock

Heatstroke is a real danger for children left in hot cars

How to prevent tick-borne illnesses

Covering up, using repellent and checking yourself for ticks is key
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