OTTAWA — Transport Canada is boosting the weight limit for children in car seats, so that heavier and older children will now be able to stay in full car seats longer.

Rising childhood obesity rates mean that many young children are packing on extra pounds. Under the current rules, children can remain in car seats up until a maximum of 48 lbs.

In newly-tested car seats with stronger structuring, the maximum weight limit would be 65 lbs. This brings Canadian regulations in line with changes made in the United States in 2003.

"Having this kind of a seat can keep them in a harness for longer and can be installed just with a lap-belt," Shawna DiFilippo of Safe Kids Canada told CTV News.

Under the old rules, kids at about age three and 45 lbs would have to switch to a booster seat, because the full front-facing car seat wasn't sturdy enough.

New rules, which took effect May 1, allow for the sale of full front facing car seats -- with 5 point harnesses -- for children up to 65 lbs.

The "age three" description has been removed from the rules, meaning children up to about age six should remain in these seats.

One mother wondered how her growing child would respond to using such a seat.

"I can't see my child wanting to get into something that looks like a baby should be in it," said Audra Yap.

But while some children are anxious to get out of car seats, crash tests have show that the full car seat provides the best safety in an automobile accident.

Transport Canada began studying the new rules not only because of rising childhood obesity rates (which have tripled in the past 20 years), but because of confusion parents were experiencing with the transition from infant, baby and booster seats.

Some children at the age of seven were being strapped in with seat belts, when their lower weight indicated that a child seat was still required.

The new heavy-duty car seats will be on the Canadian market by summer.

While some parents may have to purchase these newer, 65-lbs seats, it also means parents can stick with their main car seats for longer, rather than having to switch over to booster seats.

Meanwhile, south of the border, some states are seeking to change their laws to require children stay in restraints through the age of eight and 80 lbs.