The American Academy of Pediatrics says that infants should sleep on a firm sleep surface to reduce the risk of Sudden Infant Death Syndrome, or SIDS. A quality crib mattress is key to creating a safe but firm sleep space. The coil count of a mattress is one of the biggest factors that can influence its firmness. In addition to the number of coils, the gauge of the steel can also make an impact.
Number of Coils
The AAP does not recommend a specific coil count for crib mattresses. However, the more coils that a mattress has, the more firm it will be. Most mattresses have a coil count between 80 and 250. The number of coils is not the actual "coil count." The coil count is the number of coils that would be in a full-size mattress based on the same spacing. Generally, a mattress with at least 150 coils will be firm enough for your baby.
Benefits of Higher Coil Count
If a mattress feels good to you, chances are it is too soft for your baby. A higher coil count can create a firmer mattress that offers your baby more support for proper alignment of the spine and to reduce the risk of breathing issues from poor posture while sleeping. A higher coil count can also create a flatter surface and a more even distribution of weight. When a mattress is too soft, your baby can roll more easily and can become sunk down in the mattress, which can increase the risk of SIDS.
Other Factors Influencing Firmness
The thickness of the steel used on the coils can also impact the firmness of the mattress. If the mattress has a very high coil count but the springs are very thin, the mattress won't be as firm. The higher the number on the gauge of the steel, the weaker it is. In general, you should look for coils that have a gauge of 13.5 or lower for sturdy springs and a firmer mattress.
Comparison to Foam Mattresses
Not all mattresses have coils. Foam mattresses can also provide a firm surface for your baby's sleep. With a foam mattress, you should look for the density of the foam, rather than the number of coils, to determine firmness. Since no number is available to gauge the density, the only way to determine it is to take the mattress between your hands and squeeze. The harder the mattress is to squeeze, the firmer it is.