Decide whether to buy an innerspring or foam mattress. Innerspring mattresses are made of steel coils, while their foam counterparts are comprised of polyurethane. Foam mattresses tend to be less expensive, as they are made of less material than innerspring mattresses. Innerspring mattresses are more expensive because of the steel content in the coils.
Examine the quality of the mattress. A quality foam mattress will be firm. A soft foam mattress indicates poor, thin polyurethane foam. A quality innerspring mattress should contain 150 coils and an edge rod. If you choose one with more, the coils are thinner, leading to the possibility of future breakage.
Opt for a mattress cover made of made of multiple layers, with one of the layers being nylon. Baby mattresses are covered in vinyl to help protect against fluid damage, but the vinyl does not protect the mattress from bodily force and tears. Plus, a mattress cover with nylon can help protect the mattress from dust mites.
Ensure that the mattress fits the crib properly. Most cribs and mattresses are a standard size, but if your crib is older, there may be a difference. To test the fit, try sticking your fingers between the mattress and the crib. You should not be able to stick two fingers in between the mattress and crib. Opt for the recommended mattress for your particular crib, or try placing a mattress on the display before purchasing.