Choosing a Mattress
There are a few things to keep in mind when selecting a crib mattress—the first thing is to check your store's return policy. While cribs and mattresses normally adhere to standard sizes, you can't be sure you have a perfect fit until you give it a try. According to the Juvenile Products Manufacturers Association (JPMA), "crib mattresses should fit snugly with no more than two fingers width between the edges of the mattress and the crib side."
Along with the finger check, test the mattress for firmness. You're not looking for the cushy feel you may prefer in your mattress; you want something that will holds its shape and stay flat. Push down on the center and sides of the mattress to test that the mattress holds its shape under weight. You can try this in the store, but plan on doing a more thorough test at home.
Don't hesitate to return a mattress if you don't think it fits correctly in your crib, or if it's not firm enough. Some 150 coil-counts are firmer than others, while some high-density foam mattresses might appear a better fit for your particular crib. Try before you buy! Several reliable brands offer models that adhere to both federally mandated and stricter voluntary standards. Look for the JPMA seal on the package.