Moving a child into an adult car seat too soon can increase the risk of a serious injury in a crash by 30 per cent, yet more than half of all parents are confused about when to do so.
An Australia-wide study found significant gaps in parents' knowledge about child restraints and booster seats that could be putting children's lives at risk.
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How to fit a car seat properly
Prof Lynne Bilston the Neuroscience Research Australia (NeuRA) demonstrates the best way to fit a child car seat.
More than half of respondents believed children could transition from a booster seat to an adult seat with sash seat belt by the age of seven, according to the study by the Monash University Accident Research Centre. It conducted an online survey of 380 parents who had 719 children under 16 years.
Lead researcher Suzanne Cross said most children would need to be older before they were safe in an adult seat because children's size and growth rates varied.
"An adult lap-sash seatbelt is designed for people with a minimum height of 145 centimetres. The average age of children reaching this height is between 10 and 12 years of age," Ms Cross said.
Children under 145 centimetres who use an adult seatbelt would likely have the belt positioned across their neck instead of mid-shoulder, or their stomach instead of their pelvic area, causing increased risk of serious injury in the event of a crash, she said.
Online forums reveal widespread confusion and even resistance by some parents to keeping children in booster seats, with one parent saying her child was embarrassed to be seen in a booster.
Vicki, who did not use her surname, is a parent who was involved in a serious crash that nearly killed her and her children. She warned against moving them too soon in a post on a leading pediatric hospital's forum. She said there was a need for more education about laws governing child restraints because there were far too many injuries.
![Confusion raises risk of injury: How to correctly fit a car seat.](http://web.archive.org./web/20171106084259im_/https://www.fairfaxstatic.com.au/content/dam/images/g/w/8/e/6/4/image.related.articleLeadwide.620x349.gzdihv.png/1509922234726.jpg)
"The height should be the law, not the age," she wrote. "I have seen many young children sit in the front seat and have an almost seven-year-old who is in no hurry to sit in the front seat after she saw the damage my airbags did to me. There should be more education around this issue as there are way too many injuries in children that are easily preventable if they are educated," she said.
In an exclusive investigation this year, The Sun-Herald revealed that a NSW study found half of all restraints had errors in how they were used. Some had up to seven errors each, ranging from failing to buckle the child in to slackness in the belts and sashes. Most often parents weren't aware they had made a mistake. Others were confused about what sort of restraint to use.
![The current laws on child car restraints. Source: NeuRA NSW](http://web.archive.org./web/20171106084259im_/https://www.fairfaxstatic.com.au/content/dam/images/g/z/e/2/r/q/image.related.articleLeadwide.620x349.gzdihv.png/1509922234726.jpg)
The new Monash study, published in the latest Journal of the Australian College of Road Safety, found parents of children under four years of age and women were better informed about child car seat safety than parents of older children and men, respectively.
While 64 per cent of parents felt their own driving abilities and safety choices influenced their child's safety, the study highlighted areas where some respondents lacked specific knowledge. Most parents want to do the right thing in keeping their children safe when travelling in a motor vehicle, and many recognised the need to check and adjust seatbelts and harnesses for each trip.
Ms Cross, a doctoral student, encouraged parents to use a booster seat that is suitable for their child up to the age of 10 years.