Foam beds are popular choices for toddlers because they are lightweight and usually economical. Medium- to high-density polyfoam is commonly used since it is the most supportive. Memory foam is rare in a toddler mattress since its close cradling poses a safety risk. All-foam mattresses are usually very quiet since they absorb motion well. Foam off-gasses more than other materials, so new mattresses tend to have a chemical-like smell. Shoppers can look for manufacturers that off-gas in advance, which reduces odors by the time the mattress reaches your home.