Child seats in the car

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Why do children need to be restrained in the car?

The greatest risk to a child after the age of one in the UK is an accident. Crashes on the road account for over half of these.

In the first 14 years of life one in every 50 children will have been killed or injured travelling as a passenger in a car. Children that are properly restrained in a car are:

  • 90 per cent less likely to be killed
  • 75 per cent less likely to be seriously injured
  • 67 per cent less likely to be slightly injured

Most crashes happen within a few miles of home, on everyday trips and at speed of less than 30mph.

It is on these short, local journeys where the risk is highest, that many children sometimes travel unrestrained often because the distance is short or parents are in a rush.

In a crash children are more vulnerable than adults because:

  • They are smaller and more likely to be thrown around or flung out of the car.
  • Their neck muscles and spine are weaker, ribs and pelvic bones are underdeveloped and some organs less well protected. This makes internal injury more likely.
  • A child’s head is bigger and heavier in relation to body size, which means they are more likely to be thrown head first and suffer head injuries.
  • A young child’s skull is not as protective as an adult’s so life threatening brain injuries are more likely.

Adult seat belts are designed for people over 1.5m (4ft 11ins), not children. The legal height when a child doesn’t need to use a booster cushion is 1.35m (4ft 5ins), but to keep your child safe and the adult seat belt fitted properly they are better using them until they are 5ft tall. This may not be popular but is certainly safer so don’t be in a hurry to stop using the booster cushion, particularly if the adult seat belt would go across your child’s neck or the lap belt above their hips.


Choosing a seat

All child restraints must have the United Nations “E” mark.

The latest version of the standard is R44.04. Older versions (for example R44.02) will not provide the level of protect given by the current standard.

Many seats are not fitted properly in the car and will not protect your child in a crash. Always make sure a seat fits properly in your car before you buy it. Many retailers have staff trained to fit car seats but check you are happy with it before you buy.

Be very careful of old or second-hand seats. They may be damaged (the damage may not be obvious) or worn out, may not come up to current standards and fitting instructions may be missing.

Many vehicles have ISOFix fittings. ISOFix seats are fitted directly onto the fittings located between the back and seat cushions of the car’s seats. They are quick and easy to fit and don’t have the problems often found when fitting a seat using the adult seat belt.



The I-size standard for child seat was introduced throughout the European Union in 2013. This will run alongside the R44.04 standard and eventually replace it. I-size is based around the ISOFix system and in the end will mean that every child seat will fit in any car. The standard should remove the fitting problems that affect many child seats – particularly those fitted with an adult seat belt.

I-size is based on a child’s height, rather than weight, which will make it easier to be sure you are using the correct seat. One of the benefits is that children will be in rear facing seats for longer – until they are at least 15 months old. This gives much better protection for your child’s head, neck and vital organs.


Do not:

  • put a child in the same belt as an adult. In a crash the adult would crush the child
  • put more than on child in a seat belt
  • carry a baby on an adult’s knee. Even at low speeds the forces involved in a crash are so huge would be impossible to hold on.

Pregnant women must wear seat belts as normal except the lap belt should be kept lower, under the bump and not across the unborn baby.

The first seat your baby will need is a group 0 or 0+ seat. They are all rear facing and are sometimes call infant carriers or baby seats.

They are designed for babies from birth up to around 10kgs (22lbs) for group 0 seats and from birth to 29lbs for 0+ seats.

These seats need to:

  • protect a baby’s head from direct impact
  • spread forces over a large area of the body to protect the rib cage
  • prevent force onto the abdomen

The Group 0 and 0+ seats are designed to give maximum protection. Babies are carried partially reclined, which spreads the force of a front impact over the whole of a baby’s back. The head and neck are supported and no pressure is put on their abdomen. The adjustable harness that holds the baby into the seat must always be fastened and tightened so that you can get no more than the flat of your fingers between baby and the straps.

The seat can be fitted using an adult seat belt, or attached to a base that is fitted using the adult seat belt or ISOFix attachment points if it is an ISOFix seat.

Don’t be tempted to move onto the next size seat too early, as your baby must be the minimum weight for the Group 1 seat and travelling backwards offers the best protection. Despite the age guidance on a seat you should go by your child’s weight and size, not their age. The top of your baby’s head should not come above the back of the seat.

Once your child has reach around 13kgs in weight and can sit unaided for a reasonable period of time, you will need to look at the next stage (Group 1) seat.

These seats will take your child from around 9kgs to 18kgs (20 to 40lbs). The age range given for group 1 seats is approximately nine months to four years, but it is more important to go by your baby’s weight than their age. Don’t be in a rush to move them onto this seat, as it is safer for them to be in a rear facing group 0 or 0+ seat until they have grown out of it.

Many children will not reach the minimum weight for this seat until they reach a year or more.

This type of seat can be fitted using an adult seat belt or with ISOFix attachments if it is an ISOFix seat. These seats fitted using the adult seat belt frequently don’t fit properly – they should be held in firmly with no sideways or forwards movement when you push and pull them.

Your child is held into the seat with a five-point harness, which includes a crotch strap to prevent them sliding out feet first. The harness straps should be kept tight so you can get no more than the flat of your fingers between your child and the straps.

Once you child has reached around 18kgs (40lbs) in weight you should start looking for the next stage, which is a booster seat.

Booster seats are for children in the weight range 15 to 25kgs (33 to 55lbs). Many children are ready to move into this seat when they are about four years old but it is important that you go by their weight and size rather than age.

The seat puts your child in the right position so the adult seat belt gives the best protection. Slots guide the adult seat belt around them so it runs over the right parts of the body – diagonal part of the belt across the shoulder, not across the neck and the lap belt across the hips not over the soft part of the abdomen.

Both the seat and your child are held in place by the adult seat belt.

Most booster seats are made for use with an adult lap and diagonal seat belt. However some are designed for use where only a lap belt is fitted.

Some booster seats can also be adapted for use as a booster cushion (Group 2 and Group 3).

Booster cushions are for children too big for a booster seat but too small to use an adult seat belt on its own. They are designed for children weighing 22 kg (48lbs) or more.

They raise a child so the adult seat belt fits and have a number of other safety features. Household cushions and other ways of raising your child will not be safe.

The adult seat belt should go across your child’s shoulder, not their neck. The lap belt should go across their hips, not the soft part of the abdomen.

The seat guide age range is six years and upwards but your child’s weight and height are more important than their age.

This seat should be used until they reach the minimum legal height to use an adult seat belt without a child restraint (1.35m or 4ft 5ins) or until they are 12 years old. However it is recommended that they continue to use the booster cushion until they are 5ft tall as it is unlikely the adult seat belt will fit correctly until they are around this height.

Fitting your child into the seat correctly is always important:

The harness on a baby seat or child seat should be tight. You should only be able to get the flat of your fingers between baby and belts. Don’t worry – they will be comfortable. Slack belts can lead to unnecessary bruising and injury in a crash.

Don’t cover the red release button with blankets or anything else. In an emergency, any delay in getting a child out of the car could be dangerous.

With a booster seat or booster cushion the adult seat belt should be adjusted so the belt goes across your child’s shoulder not on their neck. The lap belt should go across their hips, not the abdomen.

Never use a rear facing baby seat (Group 0 or 0+) in the front seat of a car if there is an active air bag. The back of the seat will be too close to the inflating air bag, which could cause serious or fatal injuries to your child.

Always fit seats following the manufacturers instructions. Fitting child seats can be a problem and many are not correctly fitted even by some retailers who are failing to give correct advice and support. For more information on fitting child seats go to the Good Egg Safety website.

Child seats (Group 1) should be fitted as tightly as possible, the seat pushed firmly into the upholstery and the adult seat belt webbing pulled as tightly as possible. You should not be able to move them side-to-side or forwards when pushed and pulled firmly.

ISOfix baby or child seats (Group 0+ and Group 1) are fitted directly onto ISOFix attachments between the back and seat cushions in your car. The adult seat belt is not used. They are quicker and easier to fit accurately and safely.

As most crashes are front or front/side impacts the safest place in the car is in the back seats. Generally, children and air bags don’t mix well because of the force with which the bags inflate. However, if you need to put your child in the front seat (in forward facing seats only) make sure the car seat is as far back as possible so any injury caused by an air bag inflating is reduced.

There is often confusion about what the law says about children using seat belts. The following information summarises the law and who is responsible.

Age of child Front seat Rear seat Who is responsible?
Child under three years old. Correct child restraint (seat) must be used. Correct child restraint (seat) must be used. If one is not available in a taxi, may travel unrestrained. Driver
Child from third birthday up to a height of 1.35m (approximately 4ft 5ins) tall or 12th birthday, whichever they reach first. Correct child restraint must be used. Correct child restraint must be used where seat belts are fitted. Must use an adult seat belt in rear seat if correct child restraint not available:

  • in a taxi
  • for a short distance in an unexpected necessity
  • if two occupied child restraints prevent fitting of a third.
Child aged 12 or 13 years or a younger child more than 1.35m (approx 4ft 5ins) tall. Adult seat belt must be worn if available. Adult seat belt must be worn if available. Driver
Child aged 14 years or more and adults. Seat belt must be worn if available. Seat belt must be worn if available. Passenger


Road Safety Team
Transport, Highways and Environment
8-9 Billet Lane
North Lincolnshire
DN15 9YH

Monday to Thursday: 8.15am to 4.45pm

Friday: 8.15am to 4pm