Kids should sit in rear-facing car seats until they are 2 years old instead of 1, says new advice from a group of American pediatricians and U.S. traffic safety officials.

Older kids too should ride in booster seats longer too, up to the age of 12, depending on their height, the new recommendations advise.

Parents have long been told to follow the weight and body length limits listed on their car seat. But many have used the general guideline of one year of age or 20 to 22 pounds (9.0 to 9.9 kg) as a guideline for when to move them into a front-facing car seat or when to turn their baby's convertible car seat around.

The American Academy of Pediatrics is worried that some parents have been turning their babies around too early, putting the children at risk of serious injury or death in the event of a crash.

So after carefully reviewing the latest data that shows that children in rear-facing car seats are more likely to surivive a crash, the AAP has issued a new policy statement. The statement says toddlers should sit in rear-facing car seats until age two, or for as long as they are within the weight and height limits listed by the car seat's manufacturer.

If a child under the age of two outgrows the weight limits for their infant car seat, they should be moved to a rear-facing convertible car seat and kept in that position until age two, the AAP now says. Only after the age of two should the car seat be turned forward-facing.

The U.S. National Highway Traffic Safety Administration issued separate but similar recommendations, stressing that there is no need to hurry to transition a child to the next restraint type.

"The best possible thing you can do is keep your child rear-facing as long as possible," the AAP's Dr. Benjamin Hoffman, who helped write the new policy, told Reuters. "We hope we will be able to convince parents to keep their children rear-facing longer."

Dr. Claude Cyr, a member of the Canadian Paediatric Society's Injury Prevention Committee, says the U.S. and Canadian recommendations are similar. But he tells CTV News that the re-wording of the AAP guidelines could compel a review of the Canadian guidelines to see if they could be made clearer.

The CPS guidelines state that only when a car seat's weight or height limits have been exceeded, should parents move their children into the next phase of car seat.

"Parents should be encouraged to continue to use a rear-facing seat as long as the height and weight limitations allow," the CPS guidelines read.

After kids have been moved into a front-facing car seat with five-point harnesses, they should stay in that seat until they reach the top height or weight limit allowed by the car seat's manufacturer. The AAP says the lowest maximum weight limit for forward-facing car seats is 40 lb (18 kg), while some models of can accommodate children up to 65 lb (30 kg).

Kids who exceed those weight limits should then move to a booster seat used with the car's seatbelt, until they are tall enough to fit correctly with just the seat belt. That's usually when kids are between eight and 12 years old, or when they've reached 4 feet 9 inches (145 centimetres).

For a seat belt to fit properly, the lap belt must lie snugly across the upper thighs or lap, not the stomach. The shoulder belt should lie snug across the shoulder and chest and not cross the neck. A poorly fitting seat belt can cause abdominal and spinal injuries in a crash.

And no child younger than 13 should ride in the front seat, both groups remind.

According to the new AAP statement, published in the journal Pediatrics, 1,500 kids under 16 die every year in car crashes in the U.S.

Child safety seats have been shown to cut the risk of death by 28 per cent compared with seatbelts; they also reduce non-fatal injuries.

Car seats with five-point harnesses are able to distribute the energy of a crash over a bigger area of the body, instead of concentrating it on the points where a seatbelt touches the body: the shoulders, belly and hips.

Booster seats too have also been found to reduce the risk of non-fatal injury among 4- to 8-year-olds by 45 per cent compared with seat belts alone, the AAP says.