Especially for babies and children, it is of course particularly important that the children's mattress is absolutely free of harmful substances. Most children's mattresses are made of foam and do not have a so-called lying zone, as is usual with mattresses for adults. This is because children are much lighter than adults. In addition, the spine of the little ones does not have to be relieved as much.
Nevertheless, you must pay attention to the right firmness when buying. Ideally, the mattress should be neither too hard nor too soft. However, it must be robust. Especially for energetic toddlers, the mattresses have to withstand a lot.
Some children's mattresses have two different sides with different degrees of firmness. This has the advantage that you can simply turn the mattress over if necessary, as soon as the child has grown and thus become heavier.
The core of the mattresses should be breathable, because toddlers often sweat during sleep.