Special thanks to my daughter – Jade Collins for doing all the research on current child car seat safety – parents are often confused with the law and requirements. Especially as things keep changing.

Car seat safety

Car seat safety can seem rather complex. It’s not something that seems to be taught in many parenting classes even though they teach us how to wind a baby, different techniques for breastfeeding, preparing bottles safely, how to bath a baby and how change their nappies. However using a car seat correctly could save your child’s life in an accident and it is a legal requirement. Once you’ve identified the right seat for your child and checked that it fits your car correctly it’s then very important to check you are using the seat correctly. We will run through the basic things to check and then go into more detail around the two laws that are currently running.
The basic things to check:
-Are you using the correct seat for your child?
There is more detailed information below, but check your child’s weight (for a seat conforming to ECE R44.04) or height (for a seat conforming to i-size) are within the range for the seat you are using. Ages associated with the seat are normally a guide (except for 15 months mandatory rear facing on i-size products) and it is either the weight of height (depending on the seat) that is really essential. The seat should have stickers on it telling you this information.
-Is the seat correctly adjusted for your child?
No bulky clothing, the harness of the child seat should be as close to the child’s skin as possible so that they are safely restrained and so that in an impact the child would remain secure. The harness should be flat against the child’s body. You should not be able to pinch any slack in the harness. You should just be able to squeeze one-two fingers between the child’s shoulder and the harness, anymore and it is too loose. Instead of bulky clothing you can buy special blankets and cosy toes with holes for the harness to keep your child warm so the harness remains tight.
Check the instructions for your seat but most seats recommend the harness is adjusted level to the child’s shoulders, or just below the shoulder for reward facing, or just above for forward facing. Any newborn or similar inserts may have weights or other guidelines printed on labels or manuals to tell you when they are safe to remove as your child grows.
-Does the seat fit your car?
With around of 70% of car seats being used incorrectly, it’s important that new parents understand the basics in car safety. There are currently two laws running and parents can currently pick between which law they choose to confirm to, by buying a seat that meets the standards of either ECE R44.04 or i-size.
If you buy a seat from an independent retailer, Halfords,
Mothercare or another retailer they should offer free fitting to ensure the seat you have chosen fits your car. If you already have a seat some retailers will offer to check it for you.
Why wouldn’t a seat fit a car? 
Buckle crunch – the webbing from the cars seat belt should hold the child seat in place, if the cars buckle is on or over the frame of the car seat this is buckle crunch. It it a problem as the seat belt will stretch whereas the buckle could shatter causing the seat to become free in an impact.
Forward set anchorage points – this is where the bolt securing the lap section of the cars seat belt is too far forward, meaning that the seat moves more than an inch from side to side or backwards and forwards.
Seat shape/ material – bucket seats, leather seats, seats with funny angles all mean that the surface of the child seat does not get enough contact or grip to fit securely, this can even be a factor when fitting isofix seats. Also the angle the child seat is fitted may be too upright, particularly for smaller babies.
Isofix – not all are compatible, some have support legs that cannot be used with most cars underfloor storage. Some need a third isofix point know as a top tether point (normally located in the boot of the car) in order to fit.
Types of car seats
IT IS RECOMMEND YOU KEEP YOU CHILD IN THE LOWEST GROUP POSSIBLE UNTIL THEY HAVE OUTGROWN THE SEAT – either in weight or the child’s head level or eye level (check your seats instructions) becoming level with the top of the seat. This will offer your child the most protection and give them longer to develop before graduating to the next group child seat.
0-10kg (22lb)
Rear facing
0-13kg (29lb)
Rear facing
Often designed to be used on pushchairs.
Often have a base to make transition from car to pushchair easier.
Start rear facing, many have to be turned forward facing at 10kg or 13kg. Check your seats instructions. Newer ones tend to allow rearward facing until the 18kg limit.
Group 0+1/2
Start rear facing, many have to be turned forward facing at 10kg or 13kg. Check your seats instructions. Newer ones tend to allow rearward facing until the 18kg limit. Depending on the seat from 15/18kg the harness is removed and used as a high backed booster seat.
Group 1
Normally forward facing but some reward facing seats available.
GROUP 1/2 
Typically rear facing until 25kg some of these allow forward facing from 9kg.
Group 1-2-3
Normally forward facing but some reward facing seats available. Depending on the seat, from 15-18kg the harness is removed and used as a high backed booster seat.
Group 2-3
High backed booster seats.
Group 3
22kg 125cm – 36kg
Booster cushion. We recommend using the above group 2-3 seat with the back on until it is outgrown in height or weight.
Birth-105cm (birth to APPROXIMATELY 4 YEARS)
67-105cm (APPROXIMATELY 6 months – 4 years)
The high backed booster phase is in progress but thought to be 100-150cm allowing the use of a seat for longer.
I-size seats are currently all isofix fitted, in the future there will also be belted options that conform to i-size. 
ECE R44.04
This is the oldest of the two laws. It ultimately states that once a child reaches 9kg (20lb) and can comfortably sit unaided, that you may turn your child into a group 1 forward facing seat. Group 1 seats cover 9-18kg which tends to be around 9 months – 4 years.
From 15kg-36kg (approx 4-12 years) a high backed booster seat can be used.
i-size R-129
i-size has been developed to improve upon car safety by making fitting of the seat to the car, finding an appropriate seat for your child’s size easier and also more stringent crash testing. Instead of weight, i-size seats focus on height measurements.
If you buy an i-size product you are agreeing to keep your child reward facing until at least 15 months old, but staying rear facing until 4 years of old is still the safest option. This is because Children are at a 500% greater risk of serious neck and spine injury when forward facing. The weight of a child’s head is 25% of their overall body weight, an adults is nearer 6%. This paired with their vertebrae not fusing until around the age of 4/5 years, means they are at a heightened risk of these serious injuries. Including internal decapitation, which is where the crash forces on a child’s neck severe the spinal cord which is often fatal, if not normally resulting in paralysis and other drastic life changing injuries.
i-size also offers greater crash testing. A new crash test dummy is used, called the Q dummy. This dummy is more similar to a child than the old P dummy and measure more points of force in crash tests. Side impact testing is not mandatory on the old regulation, i-size has made it mandatory for all seats classified as i-size.
Compatibility- originally isofix was brought out in order to eliminate problems that can occur from belted seats, like buckle crunch and forward set anchorage points. It was meant to make seats universal to all cars. Unfortunately some seats use support legs (which are not compatible with most cars underfloor storage) and some require top tether points (a third anchor normally found in the boot, on the back of the seats of the car and occasionally even in the roof, it is important to identify it is a top tether point and not a luggage hook by using the cars manual or looking for a top tether symbol), not all cars have top tether points and isofix unfortunately was not universal, as it had been intended to be. i-size will be if you buy a car that is i-size and an i-size seat the seat will fit into that car.
Footnote – it is also worth noting that a child’s length of time should be limited in a car seat. If you are going on a long journey you should stop  regularly. Oxygen saturation levels have been proven to dip when left in infant carriers for extended periods of time. It is recommended to remove babies from infant carriers to a lay flat pram or Moses basket if not in the car and also to plan journeys with extra stops when the baby needs to be in the seat.