New rule sets height guide for child seats

Height as well as weight must be taken into account in deciding what restraint is safest for a child, says a standards expert. Photo / Supplied

Parents unsure what car restraints will best safeguard their children should soon have a new category to choose from - based on the height rather than weight of youngsters.

It follows the introduction of a joint Australian and New Zealand standard aimed at protecting all children, from birth until the age of 10, from being propelled out of vehicles in road smashes or receiving internal injuries from being restrained incorrectly.

Instead of recommending weight ranges for each type of car restraint, the standard will require newly designed products to include clear marks to show minimum and maximum shoulder heights for their child occupants.

Australian researcher Associate Professor Lynne Bilston, a member of a transtasman committee which issued the standard in February, told a Plunket car-restraint conference in Auckland last week that a maximum weight of 26kg specified for existing booster seats was too low for many children unable to fit safely into adult seatbelts.

"With the increasing weight of our children, that means a lot of parents are transiting their children out of booster seats well before they get to fit into seatbelts."

She said 26kg was the weight of an average 8-year-old child who was well short of the ideal minimum height of 148cm recommended internationally for the safe use of adult belts without the assistance of booster seats.

That is the height of an average child aged 11.

Paediatricians say children's skeletal structures are too undeveloped to hold adult belts low enough in their laps, putting them in danger of serious abdominal injuries when the belts ride up over their stomachs in car crashes.

Last week's conference reviewed several serious crashes in Auckland last month involving unrestrained or incorrectly restrained youngsters, including two 4-year-old boys who died in separate smashes and a 6-year-old girl who has been left a paraplegic.

Dr Bilston said that although the new standard would not outlaw existing car restraints, some manufacturers intended to recertify their products to meet it by adding shoulder-height labels to them.

But she also expected some continuing confusion, especially as New Zealand parents would still be able to buy car restraints made according to European and United States standards, which retained weight ranges.

She said the Australian-New Zealand standard had been upgraded to take account of the fact that weight was not a key issue in restraining children in booster seats.

That was because all the force of a crash was exerted on the seatbelt anchoring the booster seat to the inside of a car, and the belt itself was designed to restrain an adult male.

Her personal view, which she said was not an official position of the standards committee, was that parents should keep children in existing booster seats even after they reach 26kg.

The new standard also stipulates minimum and maximum heights for front-facing restraints used by younger children, generally those under 4, who are secured by over-shoulder harnesses.

There is no minimum height for rear-facing baby restraints, although restraints able to be converted to face the front of vehicles will need a label prescribing the qualifying height for the changeover.

Dr Bilston said research showed many parents were very confused about when their children should move between car restraint categories, and introducing height labels should greatly assist them.

There was a 4kg overlap between the maximum prescribed 18kg for occupants of a front-facing restraint, and the minimum 14kg for a booster seat.

"That has the side effect of encouraging parents, as soon as children become 14kg, to put them in a booster seat, which is clearly not what we wanted."