Oftentimes a crib is handed down from mother to daughter/son when they are preparing to have their first child. These heirlooms have always been family favorites to pass down through the generations, especially cribs that are crafted from solid hardwood. While this is a lovely tradition, there is something that many new parents aren't aware of. If the crib is more than a couple generations old, it may not take a standard size crib mattress.
Today, the standard size crib mattress dimensions are 51 5/8" x 27 1/4" and they are generally at least 6" in depth. But understanding that, it is essential to look at the history of how this size came to be. Prior to 1974 there were no federal regulations that mandated size and materials that could be used in crib mattresses. Because the mattress needs to be snug to all sides between the frame and the mattress for the safety of the child, the government set up industry standards which must be adhered to.
Crib Mattress Dimensions
Getting back to heirloom cribs, it may not be possible to find a mattress that will fit the crib precisely, therefore, if the mattress will have more than 1/2" to 1" play on either side, do not use that crib, or keep the mattress that is in the crib and use non allergenic mattress covers and sheets. Mattress dimensions are extremely important for the sake of your baby, and those dimensions were specified with that in mind. When you shop for a mattress, keep in mind 52 x 27 x 6 or 7 and you will find a mattress that fits snugly into any crib manufactured after 1974.