Child safety advocates have renewed warnings about the risks of using second-hand child car restraints, as an inquest examined an eight-week-old baby's death in a car crash on Queensland's Sunshine Coast.

Kidsafe Queensland says faulty or incorrectly used child restraints are putting babies, toddlers and children in danger of serious injury or death.

Chief executive officer Susan Teerds says many parents do not understand the potential hazards.

"Second-hand restraints are a big problem because often the new parent doesn't know how to use them, the instruction booklet might be missing or other components might be missing," she said.

"The other thing is they don't know if it has been in a collision, where there has been structural damage to the car, it needs to be destroyed.

"Also if it's been sitting in a garage and the built-in harness straps have gotten very mouldy, which means deteriorating the straps, they won't hold in a collision."

Ms Teerds says improper use could have critical consequences.

"They may get thrown out of the car with their restraint or they might slip out of their restraint if it has not been used correctly," she said.

"There are just so many things that could happen - it is really critical to know how to use a restraint properly."

Fatal crash

The dangers were highlighted in a coronial inquest into the death of a baby and a couple in the Sunshine Coast hinterland.

Elizabeth Joan Cardwell, 19, her baby Isabella Rose Cardwell, and her partner Gregory Ryan Sanderson, 28, were killed when their car rolled and hit a tree at Winya, near Kilcoy on December 6, 2011.

The inquest found excessive speed was a major factor in the crash.

Mr Sanderson, who was driving the car, was travelling at up to 118 kilometres per hour, more than double the recommended 40 kilometres per hour speed.

When the crash happened, Isabella was thrown from the car and ended up two or three metres away.

Eight-week-old baby Isabella Rose Cardwell was killed with her mother in a car crash. ( Audience submitted: Natalie Cardwell )

The baby had been wrapped in a blanket before being strapped into a baby capsule in the back seat of the car.

It was a second-hand baby capsule, given to the mother by her stepsister.

But it was given to her without the instruction booklet, which warned never to wrap a baby in a blanket before placing it in a restraint.

This is because blankets substantially reduce friction.

New standards

Standards Australia is reviewing mandatory regulations for child car restraints.

In handing down his findings this week, Coroner John Lock recommended that Standards Australia considers making it mandatory for capsules to be made with instruction booklets and warnings permanently attached.

"It has become evident to me as a result of a number of deaths involving children and various second-hand products, that a common factor has been that instruction manuals are not handed down bringing with it risks of incorrect installation of use," he told the inquest.

He said the Queensland Government should also conduct public awareness campaigns on the safe use of child restraints.

Sorry, this video has expired Coroner makes baby capsule recommendations ( Maria Hatzakis )

Hopes for change

The crash victims' family hopes changes prevent others from experiencing the pain they have felt.

Natalie Cardwell lost her daughter and grandaughter in the accident.

She says the crash has taken a heavy toll on the family.

"It's very horrific to have a police man come to you front door, telling you that your daughter's been killed in a car crash," she said.

"It's something that you just can't explain and it's something that's with you forever.

"The baby being wrapped in the blanket and in the car seat under the straps is something that we never thought about.

"It's something that maybe might have saved her, if she was not in the blanket first, so I think that's something that other parents need to be aware of."

Advice for parents

Kidsafe says parents do not need to completely rule out using second-hand child restraints. ( ABC TV News - file image )

Despite the risks, Kidsafe Queensland says parents do not need to completely rule out using second-hand child restraints, but they should just take precautions.

Ms Teerds says many parents cannot afford to buy new ones, they should just beware of the risks of using second-hand restraints.

She says parents need to know the history and age of the child restraint and make sure it has all the necessary pieces including an instruction booklet.

Ms Teerds says they should not use one that has been involved in a crash, is more than 10 years old, or shows any signs of wear and tear.