Frances Biagioli, MD
Selecting a child safety seat for your child is important because the correct seat can protect your child if you are in a crash. There are several types of seats available, and knowing which type your child needs at what age, and when to move to the next type, is important.
Types of Child Safety Seats
Infant Seats
Infant seats are designed for use in the first few months to year of a child's life. They face the rear of the car.
Convertible Seats
These seats convert from rear-facing to forward-facing. The rear-facing position is used when the child is younger, and forward when the child is older.
Forward-Facing Seats
These seats face the front of the car and are for older children who still need a harness (the seatbelt webbing that attaches a child to a child safety seat) but are too small for an adult safety belt.
Booster Seats
These seats are used for children who are too big for a forward-facing or convertible seat, but not yet big enough to fit in the adult safety belt. Booster seats help "boost" a child in his seat so that the safety belt fits correctly. Booster seats can only be used when there is both a shoulder and lap safety belt (they can't be used where there is only a lap-belt). Low-back boosters should only be used if there is a head rest in the auto, high-back boosters can be used if there is no head rest.
Height and Weight Limits
By law, all child safety seats must be labeled with the height and weight limits of the seat. These limits are usually printed on a sticker on the side of the seat. It is not safe to have your child use a seat if s/he is too big or too small for it. When your child is getting close to the height or weight limit of her/his seat you should start looking for a new seat with a higher weight or height limit.
But Which Type of Child Safety Seat Should My Child Use?
There are three phrases that will help you decide which type of child safety seat to use for your child:
• Backwards is best
• 20-40-80
• Boost them until they are big enough
Backwards is Best
You should keep your child in a seat that faces the back of the car as long as possible.
An infant's head is proportionally bigger than an adult's head and an infant's neck muscles are not very strong. When the infant faces the rear of the car, the back of the child safety seat cradles the head and neck during a crash. If the infant is facing the front of the car during a crash, there is nothing supporting his head and neck and the force of a crash can severely injure the infant's head and neck. For these reasons, a child should use a child safety seat that faces the rear of the car (an infant seat or a rear-facing convertible seat) as long as possible and for a minimum of one year AND 20 pounds. For example: if a nine-month-old is 22 pounds, he should face the rear of the car, and if a 15-month-old is only 18 pounds, he should face the rear of the car. One year and 20 pounds are the minimums to turn a child facing forward; it is safest to keep your baby facing the rear of the car up to the weight and height limits of your rear-facing seat.
20-40-80
Before your child is 20 pounds, 40 pounds, or 80 pounds, you should check your child safety seat for its height and weight limits.
As mentioned above, all child safety seats have both height and weight limits. You should read the sticker on the side of the seat, and change your child's seat if he is getting close to the height or weight limit of the seat. There are three weights that may need a bigger seat: 20 pounds, 40 pounds, and 80 pounds.
20 Pounds
Most infant seats will have a weight limit of about 20 pounds (the range is 20 to 22 pounds) and a height limit of 26 to 29 inches. Another way to tell if your child is outgrowing the seat is if his head is within one inch of the top of the seat then he is too tall for it.
40 Pounds
Most convertible seats will fit children up to a weight of 40 pounds and 40 inches. Some seat limits go higher, but the harness straps (the seatbelt webbing that is in the child seat) often have to be removed at weights greater than 40 pounds. So if your child is almost 40 pounds, check your seat's labels and instructions and see if you will need to alter the seat (remove the webbing) or get a new seat.
80 Pounds
Most adult safety belt systems in a car do not fit a child until he is at least 80 pounds and 4 feet 9 inches tall. If your child does not fit into a convertible seat any longer and he does not fit into a car's safety belt, he should use a booster seat.
Height limits are as important as weight limits when thinking if your child needs a new seat. For example, if your child is tall and thin then he may exceed the height limit before the weight limit. So the "20-40-80" memory key only is meant as a guide to remind you to look at your child seat's weight and height limits.
Boost Them Until They are Big Enough
Your child should use a booster seat until he is big enough for the adult safety belt.
When your child outgrows his child safety seat with a harness, he will not be big enough to fit into an adult safety belt for some time. Your child should use a booster seat until the safety belt fits correctly.
The correct fit of a safety belt is when all three of the following are present:
1) The lap belt part of the safety belt is low and tight across the hips or upper thighs (the lap belt should not be on the belly).
2) The shoulder part crosses the middle chest and the middle shoulder bone (the belt should not be on the neck or face).
3) Your child can sit back against the seat back and his legs bend over the front of the seat (his legs need to be long enough).
In a crash, if your child is using a safety belt when he is too small, the safety belt may hurt him or the belt could fail to keep him in the car. Booster seats raise your child up in the seat just enough so that the adult safety belt fits safely and correctly.
Choosing the Right Seat is Only the Start
Once your child has the correct child safety seat, it still needs to be put into the car securely and correctly. Each seat and automobile may have different instructions on how best to get the child safety seat securely attached to the car. If the child safety seat is too loose it may not protect your child in a crash. Always read the instructions for the child safety seat and for your car to make sure you are putting the child safety seat in correctly. If you need help, you may be able to get it checked at a child safety seat inspection station by a certified child passenger safety technician. Stations and technicians can be located through the National Highway Traffic Safety Administration (NHTSA) online at http://www.nhtsa.dot.gov/ or by calling 888-DASH-2-DOT; or through SeatCheck online at www.seatcheck.org or by calling 866-SEAT-CHECK.
Resources
There are many resources to help you select a child safety seat and to install it correctly. The following are a list of some of your options.
National Highway Transportation Safety Administration Auto Safety Hotline
1-888-DASH-2-DOT (1-888-327-4236)
www.nhtsa.dot.gov/portal/site/nhtsa/menuitem.9f8c7d6359e0e9bbbf30811060008a0c/
American Academy of Pediatrics
www.aap.org/healthtopics/carseatsafety.cfm
Click on "Car Safety Seats: A Guide for Families 2006
SafetyBeltSafe U.S.A.
800-745-SAFE (800-745-7233), (in Spanish: 800-747-SANO [800-747-7266]); www.carseat.org
Child Safety Seat Manufacturers
All child safety seats are labeled or embossed with the 1-800 number for the company who made it. You can call this number for seat-specific questions. It is useful to have the model number and date of manufacture when you call - this information is also located on the child safety seat on a sticker.
(All pictures taken from National Highway Transportation web site www.nhtsa.dot.gov)
Fran Biagioli, M.D. is board certified Familiy Medicine doctor. She sees patients and teaches students in Portland Oregon. Her intrest in automotive safety started prior to medical school when she worked as an engineer in a crash testing lab.
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