Experts at children's charity The Lullaby Trust advise that the best cot mattress is firm, flat, and fits snugly in the cot with no gaps around the edges.
Some cots and cot beds come with their own mattress while others require one to be bought separately. For safety, you need the correct fit. They generally come in two standard sizes: 120cm x 60cm for a traditional cot, and 140cm x 70cm for a cot bed.
