When purchasing a crib mattress for your infant, there are various factors to keep in mind when making the selection process. Size is certainly one of them, as are firmness, breathability and safety features.

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Baby mattresses are regulated for size and shape to reduce the risk of SIDS (Sudden Infant Death Syndrome), which can be caused by suffocation. But there can still be variance within these measurements.

Size

Your baby's crib mattress must fit securely inside their crib to prevent suffocation or sudden infant death syndrome (SIDS). Standard crib mattresses tend to measure 28 inches wide by 52 inches long; however, before making a purchase you should check its dimensions first.

The US Consumer Products Safety Commission regulates the interior dimensions of full-size crib mattresses to prevent head entrapment and suffocation. They must measure at least 27 1/4 inches wide by 51 3/4 inches long, and no more than 6 inches thick; this regulation helps safeguard against head entrapment and suffocation.

Many full-size cribs can convert to accommodate twin mattresses when the time comes, making the mattress choice for children's rooms easy. A twin mattress measures 38 inches wide by 75 inches long; it is the most commonly chosen mattress size in children's bedrooms as it also fits small bed frames, daybeds and bunk beds. Most single-sided twin mattresses may include both firm infant side as well as soft toddler side that can be switched when child grows older.

Firmness

Crib mattresses must be firm to ensure babies' safety, which prevents them from sinking in and increasing the risk of suffocation, while helping them stand easily when it's time to stand.

Firmness can also prevent hands, feet, and pacifiers from becoming trapped between the mattress and crib rails – preventing injury as well as potential suffocation from occurring.

To prevent this, ensure the gap between your crib mattress and its sides of no greater than two fingers. You can do this by placing it inside the crib and gently pressing on its corners with your fingertips.

Many modern cribs feature an attached mattress, designed to fit snugly within their frame. If yours doesn't, a mattress pad may help prevent gaps from forming in its framework. Also ensure no stuffed animals, blankets or pillows are in your baby's crib when sleeping as this could block airflow and increase risk for Sudden Infant Death Syndrome (SIDS).

Materials

Crib mattresses typically consist of materials like cotton, polyester and polyurethane foam. Foam mattresses tend to be lighter and less costly than innerspring ones and come with either insulation or waterproof covers to protect the mattress from liquid spillage, leakage and mildew growth.

Some crib mattresses are specifically formulated to be "breathable." These mattresses, typically constructed from materials like wool, cotton and organic textiles, claim to offer better sleep conditions, reduce risks such as suffocation and overheating and prevent rebreathing – an action linked to SIDS.

There are various nonstandard sizes of crib mattresses, including twin XL and full-size mattresses. According to Consumer Product Safety Commission regulations, nonstandard mattresses must fit snugly into a crib so as to leave no more than an inch between its edge and the side of the crib and its edge of mattress – and ensure your child does not roll off! A firm mattress will help to ensure your infant does not roll off accidentally during sleep time.

Safety

Selecting a crib mattress size that meets US Consumer Product Safety Commission regulations is of utmost importance when selecting one for your baby's safety. Regulations state that standard crib mattresses must measure 27 1/4 inches wide by 51 5/8 inches long with no greater gap of more than one inch inside their respective cribs, to reduce head entrapment and suffocation risks between mattress and crib sides and infants climbing out when older. In order to prevent accidental head entrapments between mattress and sides and infants climbing out when older, height limits must also ensure no child can climb out once inside. Furthermore, mattresses must snugly inside their respective cribs without creating gaps larger than 1 inch between it and its respective cribs when being stored within its respective cribs when not being used by its user(s).

Some crib mattresses are specially made to be more breathable, which reduces the risk of overheating and "rebreathing," or breathing in their own carbon dioxide, a practice thought to contribute to SIDS. Look out for such mattresses, usually identified by a green label.