A child seat must sit flat and snugly against your car's rear seat base and back in order for it to work properly. Also, unless you are using ISOFIX, you may find that your car's seatbelt isn't long enough to fasten round the child seat.
Another issue for child seats using the car's seatbelt is a scenario known as 'buckle crunch'. This is when a long seatbelt anchor point places the seatbelt buckle on a bend in the belt's route through the child seat.
This puts pressure on the buckle and, in an accident, can cause it to open and liberate the car seat. Don't be tempted to put a twist in a seatbelt stalk to shorten it and avoid this problem, as this could also compromise the belt's effectiveness in an accident.
Finding the right seat for your car
The good news is that it's pretty easy to find a car seat that fits your car. The best method - whether you are fitting a new baby seat or a booster seat for a child - is to get guidance from specially trained staff at your retailer.
It's a good idea to phone in advance to make sure there is a member of staff available when you plan to visit.
Alternatively, the manufacturer of your car or child seat should be happy to advise you on compatibility. If you buy online or via mail order, check how long you have to return the seat and get a full refund if there's a problem with the fit (distance-selling consumer laws give you a minimum of seven days to do this).
Buying a second-hand car seat
It can be tempting to save money by buying or accepting a secondhand seat but make sure you don't skimp on safety.
The seat should be a model that is still in production, so you can be sure it meets the current safety standards, and it should have all the necessary fittings. Missing instructions can often be downloaded from manufacturer websites.
Check that any adjusters work properly, that there is no wear to the straps and that all the original padding, such as shoulder pads or inserts, is present and properly located.
The condition of a used seat is as important as fit. If it has been involved in an accident, however minor, or even just dropped, its effectiveness could have been compromised in ways you may not be able to see with the naked eye. Older plastics can degrade over time, also compromising the seat's strength.
Where to position your car seat
The safest place to position your car seat is on one of the car's rear seats, rather than in the front.
In the back, your child is much better protected from injuries caused by frontal impact, including objects coming through the windscreen or broken screen glass. If your car has a middle rear seat that's level and wide enough to take the child seat properly, and has a three-point seat belt or ISOFIX points to fit it with, this position is even safer because it puts your child as far away as possible from the effects of a side impact. However, this does mean that you'll need to get into the car yourself to put a very young child in his or her seat and fasten the harness.
If you need to use only one of the outside rear seats, choose the one that's most often nearest the pavement when you park to protect you and your child from passing vehicles when you are getting in the car. This is particularly important with baby seats that you carry outside the car, and which require you to open the door fully if you are securing them with the car's seatbelt.
Children up front
If you want to put a child in a rear-facing seat in the car's front passenger seat you must, by law, deactivate the front passenger airbag. Check your car's manual if you don't know how to do this. If this option isn't available, don't put your child there: the force of the airbag hitting the back of the child seat could cause brain injury.
If you must position a child in a forward-facing seat in the front passenger seat, make this position as safe as possible by deactivating the airbag and moving the passenger seat back as far as possible to create extra distance from the front of the car.
Remember to switch the airbag back on when an adult sits here, and back off again if you replace the child seat.
Fitting your car seat safely
Even if you get your retailer's trained staff to fit your car seat for you, you need to know how to fit it correctly yourself - the seat needs refitting from time to time, as day-to-day use can cause the fixture points to work slightly loose.
When fitting your car seat, follow the instructions to the letter. If they're not printed on the seat itself, keep a copy of them in your car in case you ever need to refer to them when you're away from home. If you find the instructions at all unclear, visit your retailer or call the manufacturer.
In particular, when fitting a forward-facing Group 1 or Group 0+-1 seat, get inside the car so you can use your knee to press the baby seat hard against the car seat as you tighten the seat belt, to remove any slack in it. When correctly fitted, there should be hardly any forward or sideways movement in the child seat.
It's a good idea to check your car seat before every journey, particularly if there's any chance that anyone other than you may have even unwittingly tampered with the fittings for example, if a centre rear passenger has accidentally released the buckle on your child seat instead of their own seatbelt.
Securing your child
Make sure you know how to fit your child's harness, and regularly check that the straps are in the correct position for your child's shoulders.
Once the harness straps are tightened, you should be able to fit only one or two fingers horizontally between your child's chest and the straps. You'll need to adjust the harness every time your child uses the seat because the amount of clothing they are wearing will affect the fit of the harness. Bear in mind that the closer the harness is to your child's actual body, the less their body will move in an impact, so it's a good idea to remove particularly thick clothing before they get in the seat.
When seating an infant in a Group 2-3 high-backed seat or booster cushion, position the lap belt across the top of the child's thighs or the bottom of the pelvis and never across their abdomen. Pull the seat belt as tight as possible (although it is not necessary to engage the seat belt's ratchet system).
When your child fights the car seat
It's not unusual for children to try to escape their child seat. Toddlers in Group 1 seats may try to remove their arms from the harness straps, so make sure the harness is tight enough to prevent them from doing this. They are less likely to actually release the harness clasp as the EC standard test requires the clasp to be undone with more force than a child can apply. Never try to adapt the harness in any way to stop your child from getting out of it, because this could prevent anyone else from quickly releasing your child in an accident.
Older children can pose more of a problem, particularly because they only have to release the car's seatbelt buckle to free themselves. There are a number of ways you can try to stop them doing this:
• explain to your child that the seatbelt is there to keep them safe and stop them from getting hurt in an accident
• show them that you wear a seatbelt, and they can be just like you
• make a game or song about doing up your seatbelt that they will want to join in
• keep them entertained and distracted in the car, so that they don't fiddle with their seat out of boredom but make sure you're not distracted too
• don't to set off until everyone has their seatbelt fastened
• use the same techniques you use for preventing other unwanted behaviour, but avoid bribery in a situation that involves your child's safety
If your child undoes his or her seatbelt or harness during a journey, pull over as soon as it's safe to do so and do it up before continuing on your way.