A newborn spends a great deal of time sleeping, and children who are sleeping in normal beds will spend most of their growing years in the same bed and perhaps with the same mattress for most of these years. Therefore, it is good to research and select mattresses that provide the best sleeping conditions for the child with the acknowledgment that a child's growth is occurring while he is in his bed.
Based on federal regulations, a crib mattress should be 51 inches long and 27 inches wide. If two fingers fit side by side between the side of the baby crib and the mattress, then there is a safety risk. A child can sleep in a crib until she is about 3 1/2 feet tall.
A twin mattress is sized to be 39 inches wide by 75 inches long. This is the smallest of all the mattresses. This size mattress is meant for one person; generally, a person who is no more than 5 feet 7 inches. For taller sleepers, a Twin XL is more suited, as these mattresses add an additional 5 inches to the total length.
Crib mattresses generally come in two varieties, which are common to twin mattresses as well. Foam mattresses are one potential type. These mattresses are light and easily picked up to change the sheets. But, lighter is not necessarily better; having a higher density and thus increased firmness is most important.
Spring mattresses can be easily found for both types of bed, however, their density varies based on the types of springs that are used. Crib mattresses need at least 150 coils. Twin mattresses are more often found with foam toppers or pillow toppers, so the density the coils provide is less important. There are also air mattresses in a twin size, but these are not available for cribs.
Crib mattresses come with coverings, while twin mattresses do not. For a crib mattress, the covering may be made of either vinyl or nylon. Generally, nylon is more durable in terms of not tearing. However, the quality is determined by the thickness, the amount of reinforcement and the fillers. Store-bought covers for twin mattresses tend to have a fabric covering to them or a padding to make the bedding more comfortable.
All mattresses should have fire retarders that prevent them from burning easily. Still, checking to ensure that the mattress is fire retardant is a good idea. For a crib mattress, however, the most important concern is ventilation. A newborn should sleep on his back, but in the case that he rolls over, mattresses may have ventilation to prevent Sudden Infant Death Syndrome.