Boosters, law change and myths.

November 1st, 2013 will see a law change that will require children aged 5-7yrs to ride in a booster seat (or child restraint with harness where they still fit correctly). Under current law children aged over 5 years old do not need a car seat or booster seat, only those aged 5-7 years “where a seat is available”, which will now extend to children until 8 years of age (NZTA, 2013).

Why the law change?
“Around five children are killed or injured every week on New Zealand’s roads and in the event of a crash, young school age passengers are at a higher risk if they are only restrained by an adult seat belt.” (ONE News, 2013) 

However the law change may be somewhat short-sighted in terms of the age/height/weight combination of things, as huge differences can be seen between two 7 year old children, one may stand at 130 cm tall, the other 115 cm tall, both of whom are too short to sit correctly in an adult seat belt, without a booster seat. A better move would be to see an age and height teamed up together, such as 10 years old or 140 cm tall. This would then see some children reaching the height requirement at 8.5 years old and others at 13 years old (obviously forfeiting the need at 10 years of age, unless the parents choose to continue past this time, which is perfectly safe where the child still fits within the requirements, height and weight, of the child restraint they’re using at the time).

Looking at the American Paediatrics (2013) growth charts (NZ Ministry of Health charts we found only went to 5 years of age), we plotted the age in which the average child would reach 148 cm, we found girls reached 148 cm around 11.5 years of age and boys closely behind at 11 years, 9 months. In contrast to this the lowest 5% of girls reached 148 cm at 13.5 years old and boys at nearly 14 years old. The tallest 5% of girls reached this height around 9 years, 9 months, and boys much the same.

The UK, in 2006, passed a law requiring children remain in booster seats until their 12th birthday, or 135 cm tall, whichever came first. While slightly lower than our intended goal of 148 cm tall but keeping the majority of children in boosters until they’re tall enough to pass the 5 Step Test to no longer require a booster seat.

According to Elizabeth Segedin of Starship Children’s’ Hospital in Auckland (NZCR, 2006), children required boosters until around 10-12 years of age, a few more years on top of the impending law change, and many more years on top of the current child restraint law.

Segedin found;

  • All 4 and 5 year olds required a car seat or booster seat
  • 90% of  6, 7, and 8 year olds required booster seats
  • 50% of  9 and 10 year olds
  • 10% of 11 and 12 year olds still required booster seats

In 2008 Sydney’s Child published the following statement;

“The rear seat of the average family car is too deep for almost half of adult women to sit upright and comfortably bend their knees over the edge of the seat, and the seat belt in the rear seat is unsafe for any person less than 145 cm tall. Children do not reach this height until around 11 years old, on average. There are two main concerns with being too small for an adult belt: the lap portion rides across the tummy, not the bony hips, causing abdominal injury in a crash, and the sash portion rides across the neck rather than the chest, causing injury to the neck and throat. Long seat cushions exacerbate these concerns by causing the child or small adult to slump so that their knees can bend at the edge of the seat, causing both parts of the seat belt to ‘ride up’.”

So while there are a few numbers being tossed about and wanted to be placed alongside the law change, from 135 – 148 cm, the latter being easiest to relate to everyday life, as it’s said to be the height of a New Zealand Police Highway patrol car. Although one issue some have addressed in regards to this figure (148 cm) is that people happen to know of adults who are around this height, so would they too need a booster seat? Well the answer to that is no, the reasons include, the law typically sees an age alongside the changes, and adults have been through puberty, which sees physical changes to their hips, pelvic region and upper chest, changes that allow the body to withstand greater forces in the unlikely event of a car crash than a child who has not yet been through puberty.

So what’s the purpose of a booster seat?
A booster seat is used primarily to assist with correctly placing an adult seat belt (full lap/sash seat belt) over a child’s body. The seat elevates them to sit high enough so the lap portion of the belt rests low down over their upper thigh, rather than over the lower abdomen. Thus then upper portion of the seat belt then sits away from the child’s neck, over their clavicle (collarbone). Some boosters come with a top tether to help secure the top portion of the seat, others do not require this, but each seat must be used correctly, this meaning that the seat belt passes though the shoulder belt guide, and then passing under the arm rests on each side where it’s then buckled into the car. The shoulder belt guide will be either under the head rest, to the side of the headrest or a small strap with a clip attached to the end, the clip sits on top of the child’s shoulder to help keep the seat belt as close to the shoulder as possible, without slipping off.

Without a booster a child is at risk of an ill-fitting seat belt. Children become uncomfortable or tired and are more likely to slip the sash portion of the seat belt behind their back, under their arms or some even resort to placing it around their knees, thus then the issue of the lap belt where children slouch to bend their knees over the edge of the vehicle seat, draw their knees up to their chest to rest their feet on the seat edge, such actions could then see the child sliding out from under the lap part of the seat belt (submarining), causing injury to their lower organs. Where the seat belt is behind their back the belt becomes a lap only belt and internal decapitation likely. Where the seat belt is placed under their arm the belt can cause severe injuries to the ribs and lower internal organs. There have even been cases where children who have got bored in the car have placed the seat belt sash around their neck, add that to a sudden stop or accident and your child may not fare well at all.

Age, height or weight?
Ideally, your child should remain in their car seat until they reach the upper height and/or weight limit for that seat, the same goes for booster seats. There are seats on the market that will restrain in a harness up to 36 kg and boosters that will restrain your child to 54 kg. There is no magic age, height or weight where your child needs to come out of their seat. If you check the manual, or stickers on the side of your child’s seat you will find reference to the maximum height and weight, as long as your child does not exceed these and their eyes/ears do not pass the top sides of the seat shell, they can remain in their seat.

5 Step Test
For seat belt use without a booster seat there is a quick reference tool that you can use, this is called the “5 Step Test”, with these 5 steps you can see if your child is able to ride without a booster seat.

You must be able to answer “yes” to all of the 5 following questions:

1. Does the child sit all the way back against the auto seat?
2. Do the child’s knees bend comfortably at the edge of the auto seat?
3. Does the belt cross the shoulder between the neck and arm?
4. Is the lap belt as low as possible, touching the thighs?
5. Can the child stay seated like this for the whole trip?

Answered “no” to any of the 5 questions above? Then your child needs a booster seat to make both the shoulder belt and the lap belt fit right for the best crash protection. Your child will be more comfortable, too! Click here for printable copy (PDF)

Types of booster seats
There’s many different types of booster seats on the market, the primary purpose of these are to correctly place the seat belt over the child’s body to promote the correct fit over a smaller body.

Combined booster seat - A car seat with 5 point safety harness that later on becomes a booster seat, the harness is removed or stowed away under the cover, a shoulder belt guide located on the side of the seat, under the headrest or as an attachment to the back of the car seat. Armrests present a place for the lap portion of the seat belt to pass under (both sides).

Full back booster seat - A seat shell without a harness, may have an adjustable head rest, or be of fixed height. The seat will have armrests for the lap portion of the seat belt, and a guide for the shoulder portion of the seat belt. The seat may later on detach into two pieces allowing you to use the lower half as a half booster (see below).

Half booster seat - A half booster is the bottom portion of a booster seat, it has no back to rest against the vehicle seat. The child sits on top of the booster, the belt then passes under the arm rests, with the shoulder portion sitting against the child’s upper body, there may or may not be a shoulder belt guide attached to a webbing strap. If there is the strap hook must sit above the child’s shoulder. If there is no shoulder strap, and the belt cuts across the child’s neck, consider swapping to using a full back booster (as above) later returning to the half booster if required.

Generally these types of booster seats all have “belt guides” for the lap portion of the seat belt and the shoulder portion of the seat belt. The belt must always be correctly placed through these paths and your child sits correctly within the seat belt and car seat/booster shell. Where your child does not sit correctly in the shell, pulling seat belt, undoing the seat buckle etc., it’s worth considering your child’s mental maturity and placing them back into a harnessed car seat until they’re ready to use the booster seat responsibly.

Concerns raised by parents over the law change

Premature graduation

Premature graduation from boosters on the child’s 7th birthday, the issue here is that some parents will allow their children to go without a booster seat simply because they’ve just turned 7 years old. The truth is that many of these children will still benefit greatly from remaining in their booster seat for all car rides for some time yet. There is nothing magical about the number 7. If your child does not pass the 5 Step Test outlined above, keep them in their booster seat. Be in no hurry to graduate to a seat belt, as in this case the graduation is actually a step back in their safety.

Move them from a booster seat only when:

  • They exceed the stated weight limit for that seat, Or
  • They exceed the height for that seat shell, eyes/ears level with the top of the seat shell
  • They pass the 5 Step Test, on all points listed.

The cost of a booster seat, the confusion of a booster seat

A booster seat comes in 3 different varieties as listed above.
You can use a combined booster with the internal harness for your child as long as they do not exceed the weight limit for the harness (range is from 18-36 kg depending on your seat), if they still fit, it’s just as safe to keep them in the seat. If not, you need to change the seat over for booster mode, this means removing or stowing the harness, and setting the headrest at the correct height for your child (if fitted).

A half booster can be picked up for as little as $29, a full backed booster for around $299 and a combined booster for up to $499.

Consider your child’s/future children’s needs when buying a seat, if your child is already 5 years old and you want no more, or they’re your last, a full backed booster will meet your needs, if you want to have more, or your child is only 4 months old you’re best investment would be a convertible car seat that also offers booster mode, then you only need to buy one seat for your child and they can use it all the way through until they no longer need a car seat/booster.

Half Boosters – No longer legal?

A half booster is acceptable, though best left for the older children once they have outgrown a full-backed booster seat.
There are some people saying that half boosters are no longer being made, or that they no longer meet standards. Let’s correct this statement, they are still legal and they are still being made. The change is that Australia no longer accepts them under the revised 2010 AS/NZS standard. If they are made prior to this time, around 2011 or prior they can still be used as per the manufacturers specifications (in this case 14-26 kg) until they reach 10 years old. As Australia only accept their own standard you won’t see them coming out under brands like Safe-n-Sound, or Infa anymore but you will still find them legally available here under UK standard, and NZ standard (not the combined Australian & New Zealand standard though).

Grace Period and older kids

Parents have asked how long they have to get a seat sorted for their older children, like any law change a grace period is often given; this is now, July through to November. Yes you may right now have a 6 year old not using a booster, but they do need to be in one come November if they’ve not yet had their 7th birthday. We expect the Police to be out checking around schools and educating parents on the requirement, they are within their legal rights to ticket a fine if your child is not restrained in an approved child restraint, though initially they’re likely to give a warning.

This change is not about inconveniencing parents and families by having you place your child back into a booster seat, it’s about protecting those 260 children from injury or death each year on our roads, and matter of factually the majority of accidents happen only a few short km’s from a person’s home. So popping out to school, the mall, the sports field is when these accidents are most often going to occur.

Boosters with height markers (Australian standard) may differ greatly between brands, take a tape measure along with you to get one with high makers, so your child can remain in it for as long as possible. Some combined models have very small gaps between markers, so again, check these, or get a standalone booster seat so your child has greater opportunity to use the seat long term.

Seat shell heights, weight limits, shoulder markers.

There’s no requirement for car seat shells to be made to a set height, or weight limit, so when buying a child restraint for your child it’s important to factor in the height of the seat shell, shoulder slots/shoulder markers and the weight limit applied to that seat. Often enough the cheaper (non-half boosters) are shorter and won’t last as long, which may mean you need to purchase another seat not long after you’ve last bought.

In contrast however, you also need to be sure that your child’s car seat/booster is not going to obscure your own vision when driving and some of the newer seats on the market are good at this.

Passenger Safety

If your car does not have isofix you will want to have the seat tethered to the car at all times so it does not become a projectile in an impact, or if your car seat/booster does not tether or attach with isofix you will want to buckle the seat when not in use.

Why not just have belt adjusters in the rear of the car?

While some parents think this would solve the issue, the reality is that it won’t. A seat belt adjuster will only see the height at lower so the shoulder portion sits lower, it won’t address the lap portion of the seat belt, nor will it shorten the leg area of your vehicle seat. Without which would see children slouching to fit the belt correctly, and the lap portion sitting incorrectly over their body.


NZ Transport Authority. 

American Paediatrics.

New Zealand Child Restraints.

ONE News.

UK Booster Law.

SafetyBeltSafe USA.

Sydney’s Child.