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Child car seat safety

Why you need a baby or child car seat

By Alison Potter

Article 5 of 5

Child car seats are vitally important; they're specially designed to give babies and children the protection they need to help reduce the risk of serious injury.

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Children need their own specially designed child car seat to keep them safe in a crash because their bodies are not simply smaller versions of adult bodies. As babies' bodies are in the early stages of development, they need protection based on specific physical traits:

  • different proportions – babies have bigger heads and smaller limbs
  • babies' major organs are in different places
  • babies' bones and muscles are not fully formed
  • babies are more vulnerable to injury than adults.

Child car seats are designed to protect a child's most vulnerable areas at each stage of their development.

Find out which ones do the best job – see all our best child car seats.

And make sure you avoid those we've rated as Don't Buy child car seats

How long do you need to use a car seat for?

Children up to the age of 12 or up to 1.35 metres need to use a car seat. It is safest for a child to travel rearward facing for as long as possible, ideally up to the age of four.

What happens in a crash

There are three stages to every car crash:

Vehicle collision

When a car hits an external object it stops moving very abruptly, leading to rapid deceleration...

Human collision

...but the people inside the car carry on moving in the direction they were travelling in, until something stops them.

If unrestrained, they will crash into the fixtures inside the car such as the seats, dashboard or other passengers. They may also be ejected through the windows. This may result in serious injury or death.

Internal collision

Even if a person is restrained, their arms, legs, heads and internal organs will continue to move until they lose momentum.

Soft organs can all be damaged by hitting the bones that surround them at high speed – such as brain into skull, lungs into ribcage, liver and stomach into spine, and heart into sternum.

We crash-test baby and child car seats to find those that offer the best protection in a crash. 

Find the right car seat for your baby and child in our car seats reviews.

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How does a car seat and seat belt help?

Restraint systems – adult seat belts and child car seats – are designed to do three things:

  • keep people away from the vehicle structure during a crash
  • reduce their momentum in a controlled way
  • distribute the forces of a crash over the strongest parts of the body, with minimum damage to the soft tissues.

Why can’t children just use an adult seatbelt?

A three-point seat belt is designed to restrain an adult and prevent injuries by spreading the forces of a crash across their strong pelvic bones and ribcage.

Children are too small to position the adult belt over their shoulders and pelvis correctly, and their bones are not strong enough to absorb the energy of a crash without affecting their internal organs.

A proper child-restraint system provides the best protection for kids as they change and grow.

Can I use a carrycot instead of a child car seat?

Our experts agree that the safest way to transport babies is in a rearward-facing infant carrier. A good infant carrier will help protect your baby in both frontal and side impact crashes.

However, car seat carrycots can be a good solution for new-born babies, especially premature babies or those with medical conditions, that need to be transported lying flat.

In this instance we'd recommend a car seat carrycot with good crash test results.

However, there are some drawbacks with using this type of car seat you need to be aware of: 

  • A carrycot will take up a lot of space across the back seat, which may not be that practical if you have to transport multiple children. 
  • They can often be quite cumbersome to install.

Also, because they are suitable only for children up to 10kg, parents may change to a forward-facing seat (Group 1, from 9 to 18 kg) too early.

It's considered safest to keep your baby in the lowest group car seat until they reach the weight limit or outgrow it.

A pushchair carrycot should never be used in a car, unless it's approved for use as a child car seat.

We haven't found many carrycots and lie-flat child car seats that protect children adequately in our crash tests. For this reason, we don't generally recommend them.

If you already own one and it doesn't have good crash test results, we suggest you buy an alternative Group 0+ child safety seat for use in the car. 

The best car seats for babies - discover more top tips on using a carrycot car seat