Many child restraint systems (CRS) now offer the option of gradually adjusting the height of the headrest. This allows the seat to be used over a longer period of time as it does not become too small so quickly.
Nevertheless, a number of criteria should be taken into account when deciding on the correct height.
Child seats tend be a modeled on a smaller version of car seats. They do, of course, feature a series of characteristics and special requirements available in normal adult seats due to children being more fragile, the reason being that standard car seats are too big and the seat belt cannot operate effectively. The headrest is also en essential component for guaranteeing passenger safety which is why they are incorporated into child seats.
Not every CRS provides the opportunity of adjusting the height of the headrest. The ones that usually have this facility are child restraint systems from Groups I, II and III. Child seats for smaller children (Groups 0 and 0+) are usually based on just one complete piece.
To position the headrest at the correct height it is necessary to place the child in the child seat. This is the only way of being sure of what the ideal height is.
In this respect, it is recommendable for the child's temple to be at the narrowest area, meaning that the side flaps of the headrest should be level with the center of the child's head about 3 centimeters from the shoulder. At least half of the ear should be below the upper edge of the headrest. If the side flaps are positioned too high they will not offer protection from side-impact crashes.
We can also see if the child seat is the right one and therefore that the height is correct by observing the way in which the seat belt fastens (Groups II and III). The belt should cross the middle of the collar bone and not be too close to the neck.
In many cases leveling the height of the headrest also involves raising or lowering the height of the seat belt or the harness straps so that they adapt much better to the child's height.
Follow the manufacturer's instructions to adjust the headrest. There is usually a button or lever which, when activated, allows the headrest to be raised or lowered within limits. Once the correct height is established it is important to check that it has been correctly adjusted.
Adjustable headrests are found in child restraint systems that feature a backrest. In booster seats without backrests there is no alternative but to make use of the standard car headrests. The same criteria should be followed.
Remember that according to the latest regulation changes in respect of standardization, the only approved booster seats without backrests will be those standardized under ECE R44/04 as part of Group III (over 125 centimeters). All child seats standardized in line with ECE R129 are equipped with a backrest and consequently with a headrest. Of course, all this only affects manufacturers in respect of the choice of which seats they are able to sell. For the time being, users should not change their booster seats.
It will be clear that the height is no longer sufficient and that the time has come to change the seat when more than 1/3 of the head shows above the upper edge of the child seat i.e. above the ear. This means that the child is too tall to continue using the child seat and, therefore, that a more appropriate one is required.>
The effectiveness of headrests
The objective of headrests is to avoid neck and head injuries, especially the type known as whiplash, which usually occur in rear-end and head-on crashes.
The headrest also offers special protection in side-impact crashes in child seats equipped with side flaps.
An “adult” headrest should be about 4 centimeters from the head and also should have its height regulated in the same way as for children. It is advisable for the head's center of gravity (at eye level) to coincide with the most resistant part of the headrest. This should normally be at the same linear height, the highest part of the head should be level with the highest part of the headrest. It must not go beyond this point.
It is absolutely inadvisable to remove the headrest from the vehicle. This can only be done in specific cases such as, for example, to install a child seat correctly.
This video demonstrates the effectiveness of headrests: